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Authors: Bo Wei and Yuling Jiao.
Seed Biology (2024)
Abstract: "Grain size is a major determinate of bread wheat (Triticum aestivum) yield, which has a broad impact on worldwide food security. Not surprisingly, grain size underwent extensive artificial selection during wheat domestication and breeding. Recent advances in wheat molecular genetics and genomics have facilitated the elucidation of the molecular basis underlying grain size. Grain size determination is the cumulative result of source strength, photoassimilate remobilization, and sink strength. Here, we systematically review the recent progress in the cloning and molecular mechanisms of genes that regulate grain size in wheat following the source to sink flow. In addition, we discuss possible strategies for overcoming the trade-off between grain size and grain number, as well as synergetic improvement of grain yield and grain quality."
Authors: Jian Che, Xu Li and Yidan Ouyang.
Plant Communications (2024)
Excerpts: "The use of strong heterosis from indica-japonica hybrid rice could greatly increase yield potential in the future. Nevertheless, due to their long-term adaptation to different environments, indica and japonica rice varieties have evolved distinct phenotypic variations from growth to flowering. This leads to the existence of multiple reproductive barriers between the two subspecies. Consequently, prezygotic reproductive isolation caused by differentiated DFOTs and postzygotic reproductive isolation, such as hybrid sterility, which occurs in intersubspecific crosses, hinder the exploitation of indica-japonica hybrid rice (Figure 1)."
"Another possible approach for optimizing non-overlapping DFOTs might be the spraying of exogenous plant hormones (Wang et al., 2023). For example, spraying methyl jasmonate (MeJA) shows extensive applicability in regulating DFOT. In fact, OsMYB8 can regulate floret opening by inducing the accumulation of endogenous JA-Ile in lodicules. Latest research also confirmed the significance of JA in floret opening process, as overexpressing the JA biosynthesis gene OsOPR7 and knocking out the JA inactivation gene OsHAN1 can effectively promote the DFOT of japonica rice (Wang et al., 2024). Advanced DFOT can also be achieved by knockout of the JA signal suppressor genes OsJAZ7 and OsJAZ9. Other hormones, such as auxins and gibberellins, may also be involved in DFOT regulation and have the potential to improve DFOT."
Authors: Tatsuki Akabane, Nobuhiro Suzuki, Kazuyoshi Ikeda, Tomoki Yonezawa, Satoru Nagatoishi, Hiroyoshi Matsumura, Takuya Yoshizawa, Wataru Tsuchiya, Satoshi Kamino, Kouhei Tsumoto, Ken Ishimaru, Etsuko Katoh and Naoki Hirotsu.
Scientific Reports (2024)
Abstract: "An indole-3-acetic acid (IAA)-glucose hydrolase, THOUSAND-GRAIN WEIGHT 6 (TGW6), negatively regulates the grain weight in rice. TGW6 has been used as a target for breeding increased rice yield. Moreover, the activity of TGW6 has been thought to involve auxin homeostasis, yet the details of this putative TGW6 activity remain unclear. Here, we show the three-dimensional structure and substrate preference of TGW6 using X-ray crystallography, thermal shift assays and fluorine nuclear magnetic resonance (19F NMR). The crystal structure of TGW6 was determined at 2.6 Å resolution and exhibited a six-bladed β-propeller structure. Thermal shift assays revealed that TGW6 preferably interacted with indole compounds among the tested substrates, enzyme products and their analogs. Further analysis using 19F NMR with 1,134 fluorinated fragments emphasized the importance of indole fragments in recognition by TGW6. Finally, docking simulation analyses of the substrate and related fragments in the presence of TGW6 supported the interaction specificity for indole compounds. Herein, we describe the structure and substrate preference of TGW6 for interacting with indole fragments during substrate recognition. Uncovering the molecular details of TGW6 activity will stimulate the use of this enzyme for increasing crop yields and contributes to functional studies of IAA glycoconjugate hydrolases in auxin homeostasis."
Authors: Vincent Vadez, Alexandre Grondin, Karine Chenu, Amelia Henry, Laurent Laplaze, Emilie J. Millet and Andrea Carminati
Nature Reviews Earth & Environment (2024)
Editor's view: Moderate drought occurs widely, impacting crop yield. This Review discusses crop traits that can confer drought tolerance, the role of the environment and management, and how crop models predict their potential impact on yield.
Abstract: "Drought limits crop productivity and threatens global food security, with moderate drought stress — when crops grow at a reduced rate — commonly experienced. Increasing plant tolerance to moderate drought is a key target for adaptation and management, but efforts to understand and increase drought tolerance often focus on more extreme drought that causes complete crop failure and only consider crop genetics. In this Review, we discuss the influence of moderate drought on crop productivity and the role of physiological traits in drought tolerance and adaptation. Traits related to crop water use, water capture, water availability, transpiration efficiency and phenology impact drought adaptation, but their overall effect varies situationally. For example, early restrictions in transpiration, higher transpiration efficiency or altered tillering increase water availability during grain filling and can double yield in some drought scenarios. However, these same traits under less severe drought scenarios can also lead to yield penalties. To assess when and under what conditions traits will be beneficial, crop models are used to integrate the effects of genetics, the environment and management, estimating the expected yield responses under these combinations of scenarios and traits. More robust characterization of moderate drought tolerance and better integration between plant genetic information and modelling will enable the local selection of crop varieties suited to the expected drought scenarios."
Authors: Xiu Fang, Hao Wu, Wanchang Huang, Zhongxian Ma, Yue Jia, Yongwei Min, Qing Ma and Ronghao Cai.
Plant Physiology and Biochemistry (2024)
Highlights: • Mutation of the ZmWRKY92 gene resulted in decreased plant height in maize. • ZmWRKY92 is a nuclear localized protein with transactivation activity in yeast. • ZmWRKY92 binds to the W-box element in the promoter of GA synthesis-related genes.
Abstract: "The plant height is a crucial agronomic trait in contemporary maize breeding. Appropriate plant height can improve crop lodging resistance, increase the planting density and harvest index of crops, and thus contribute to stable and increased yields. In this study, molecular characterization showed that ZmWRKY92 is a nuclear protein and has transcriptional activation in yeast. ZmWRKY92 can specifically bind to the W-box (TTGACC), which was confirmed by double LUC experiments and Yeast one-hybrid assays. Subsequently we screened wrky92 mutants from a library of ethyl methanesulfonate (EMS)-induced mutants. The mutation of a base in ZmWRKY92 leading to the formation of a truncated protein variant is responsible for the dwarfing phenotype of the mutant, which was further verified by allelic testing. Detailed phenotypic analysis revealed that wrky92 mutants have shorter internodes due to reduced internode cell size and lower levels of GA3 and IAA. Transcriptome analysis revealed that the ZmWRKY92 mutation caused significant changes in the expression of genes related to plant height in maize. Additionally, ZmWRKY92 was found to interact with the promoters of ZmGA20ox7 and ZmGID1L2, which are associated with GA synthesis. This study shows that ZmWRKY92 significantly affects the plants height in maize and is crucial in identifying new varieties suitable for growing in high-density conditions."
Authors: Marta Del Bianco, Jiří Friml, Lucia Strader and Stefan Kepinski.
Journal of Experimental Botany (2023)
Abstract: "Amid the delays due to the global pandemic, in early October 2022, the auxin community gathered in the idyllic peninsula of Cavtat, Croatia. More than 170 scientists from across the world converged to discuss the latest advancements in fundamental and applied research in the field. The topics, from signalling and transport to plant architecture and response to the environment, show how auxin research must bridge from the molecular realm to macroscopic developmental responses. This is mirrored in this collection of reviews, contributed by participants of the Auxin 2022 meeting."
Authors: Jing Zhang, Shulin Liu, Chu-Bin Liu, Min Zhang, Xue-Qin Fu, Ya-Ling Wang, Tao Song, Zhen-Fei Chao, Mei-Ling Han, Zhixi Tian and Dai-Yin Chao.
Current Biology (2023)
Editor's view: Zhang et al. uncover the genetic basis underlying natural variation in soybean Mo concentration, highlighting the roles of GmMOT1.1 and GmMOT1.2. These genes improve soybean yield by facilitating Mo-dependent auxin synthesis in the leaves and offer promising implications for soybean breeding, especially in low-pH soil areas.
Highlights: • Natural variation in soybean seed Mo concentration is driven by GmMOT1.1 and GmMOT1.2 • These two genes contribute to soybean yield by promoting Mo-dependent IAA synthesis • Five haplotypes of the two genes could be used as soybean breeding markers • Geographic distribution of the five haplotypes is related to soil pH
Abstract: "Soybean (Glycine max) is a crop with high demand for molybdenum (Mo) and typically requires Mo fertilization to achieve maximum yield potential. However, the genetic basis underlying the natural variation of Mo concentration in soybean and its impact on soybean agronomic performance is still poorly understood. Here, we performed a genome-wide association study (GWAS) to identify GmMOT1.1 and GmMOT1.2 that drive the natural variation of soybean Mo concentration and confer agronomic traits by affecting auxin synthesis. The soybean population exhibits five haplotypes of the two genes, with the haplotype 5 demonstrating the highest expression of GmMOT1.1 and GmMOT1.2, as well as the highest transport activities of their proteins. Further studies showed that GmMOT1.1 and GmMOT1.2 improve soybean yield, especially when cultivated in acidic or slightly acidic soil. Surprisingly, these two genes contribute to soybean growth by enhancing the activity of indole-3-acetaldehyde (IAAld) aldehyde oxidase (AO), leading to increased indole-3-acetic acid (IAA) synthesis, rather than being involved in symbiotic nitrogen fixation or nitrogen assimilation. Furthermore, the geographical distribution of five haplotypes in China and their correlation with soil pH suggest the potential significance of GmMOT1.1 and GmMOT1.2 in soybean breeding strategies."
Authors: Xi Chen, Chenchen Zhao, Ping Yun, Min Yu, Meixue Zhou, Zhong-Hua Chen and Sergey Shabala.
The Plant Journal (2024)
Abstract: "Developing climate-resilient crops is critical for future food security and sustainable agriculture under current climate scenarios. Of specific importance are drought and soil salinity. Tolerance traits to these stresses are highly complex, and the progress in improving crop tolerance is too slow to cope with the growing demand in food production unless a major paradigm shift in crop breeding occurs. In this work, we combined bioinformatics and physiological approaches to compare some of the key traits that may differentiate between xerophytes (naturally drought-tolerant plants) and mesophytes (to which the majority of the crops belong). We show that both xerophytes and salt-tolerant mesophytes have a much larger number of copies in key gene families conferring some of the key traits related to plant osmotic adjustment, abscisic acid (ABA) sensing and signalling, and stomata development. We show that drought and salt-tolerant species have (i) higher reliance on Na for osmotic adjustment via more diversified and efficient operation of Na+/H+ tonoplast exchangers (NHXs) and vacuolar H+- pyrophosphatase (VPPases); (ii) fewer and faster stomata; (iii) intrinsically lower ABA content; (iv) altered structure of pyrabactin resistance/pyrabactin resistance-like (PYR/PYL) ABA receptors; and (v) higher number of gene copies for protein phosphatase 2C (PP2C) and sucrose non-fermenting 1 (SNF1)-related protein kinase 2/open stomata 1 (SnRK2/OST1) ABA signalling components. We also show that the past trends in crop breeding for Na+ exclusion to improve salinity stress tolerance are counterproductive and compromise their drought tolerance. Incorporating these genetic insights into breeding practices could pave the way for more drought-tolerant and salt-resistant crops, securing agricultural yields in an era of climate unpredictability."
Authors: Alex Wakeman and Tom Bennett.
Journal of Experimental Botany (2023)
Abstract: "Cereals are a group of grasses cultivated by humans for their grain. It is from these cereal grains that the majority of all human calorie consumption is derived. The production of these grains is the result of the development of a series of hierarchical reproductive structures that form the distinct shoot architecture of the grasses. Being spatiotemporally complex, the coordination of grass shoot development is tightly controlled by a network of genes and signals, including the key phytohormone auxin. Hormonal manipulation has therefore been identified as a promising potential approach to increasing cereal crop yields and therefore ultimately global food security. Recent work translating the substantial body of auxin research from model plants into cereal crop species is revealing the contribution of auxin biosynthesis, transport and signalling to the development of grass shoot architecture. This review discusses this still-maturing knowledge base and examines the possibility that changes in auxin biology could have been a causative agent in the evolution of differences in shoot architecture between key grass species, or could underpin the future selective breeding of cereal crops."
Authors: Yakun Wang, Shengjia Tang, Naihui Guo, Ruihu An, Zongliang Ren, Shikai Hu, Xiangjin Wei, Guiai Jiao, Lihong Xie, Ling Wang,Ying Chen, Fengli Zhao, Peisong Hu, Zhonghua Sheng and Shaoqing Tang.
Agriculture (2023)
Abstract: "The use of male sterile lines (MSLs) of rice is essential for heterosis utilization. However, MSLs have a common defect in the elongation of the uppermost internode, eventually leading to incomplete panicle exsertion, blocking pollination, and reducing the hybrid rice seed yield. Previously, the elongated uppermost internode 1 (EUI1) was identified as an active gibberellin-deactivating enzyme that plays a key role in panicle exsertion from the flag leaf sheath in rice (Oryza sativa L.). We used an adenine base editor to edit EUI1 and obtained two types of homozygous transgenic plants (eui1-1 and eui1-2). The transcription and translation levels of EUI1 in the two mutants were significantly lower than in the wild type, as was the oxidation activity of EUI1 to active gibberellins (GAs), which also decreased. The contents of the plant hormones GA1, GA3, and GA4 in eui1-1 (1.64, 1.55, and 0.92 ng/g) and eui1-2 (0.85, 0.64, and 0.65 ng/g) panicles were significantly higher than the wild type (0.70, 0.57, and 0.42 ng/g). The uppermost internode lengths of the mutant were 26.5 and 23.6 cm, which were significantly longer than that of the wild type (18.0 cm), and the cell lengths of the mutant were 161.10 and 157.19 μm, which were longer than that of the wild type (89.28 μm). Our results indicate that the adenine base editing system could increase the content of endogenous bioactive GAs in young panicles by fine-tuning EUI1 activity, reduce the defect of panicle enclosure in MSLs and increase the yield of hybrid rice seed production."
Authors: Takashi Hirayama and Keiichi Mochida.
Plant and Cell Physiology (2022)
Abstract: "Agriculture is particularly vulnerable to climate change. To cope with the risks posed by climate-related stressors to agricultural production, global population growth, and changes in food preferences, it is imperative to develop new climate-smart crop varieties with increased yield and environmental resilience. Molecular genetics and genomic analyses have revealed that allelic variations in genes involved in phytohormone-mediated growth regulation have greatly improved productivity in major crops. Plant science has remarkably advanced our understanding of the molecular basis of various phytohormone-mediated events in plant life. These findings provide essential information for improving the productivity of crops growing in changing climates. In this review, we highlight the recent advances in plant hormonomics (multiple phytohormone profiling) and discuss their application to crop improvement. We present plant hormonomics as a key tool for deep physiological phenotyping, focusing on representative plant growth regulators associated with the improvement of crop productivity. Specifically, we review advanced methodologies in plant hormonomics, highlighting mass spectrometry- and nanosensor-based plant hormone profiling techniques. We also discuss the applications of plant hormonomics in crop improvement through breeding and agricultural management practices."
Authors: Jie Liu, Yingyin Yao, Mingming Xin, Huiru Peng, Zhongfu Ni and Qixin Sun.
Journal of Integrative Plant Biology (2022)
Abstract: "Bread wheat (Triticum aestivum L., AABBDD, 2n = 6x = 42), which accounts for most of the cultivated wheat crop worldwide, is a typical allohexaploid with a genome derived from three diploid wild ancestors. Bread wheat arose and evolved via two sequential allopolyploidization events and was further polished through multiple steps of domestication. Today cultivated allohexaploid bread wheat has numerous advantageous traits, including adaptive plasticity, favorable yield traits, and extended end-use quality, that have enabled its cultivation well beyond the ranges of its tetraploid and diploid progenitors to become a global staple food crop. In the past decade, rapid advances in wheat genomic research have considerably accelerated our understanding of the bases for the shaping of complex agronomic traits in this polyploid crop. Here, we summarize recent advances in characterizing major genetic factors underlying the origin, evolution, and improvement of polyploid wheats. We end with a brief discussion of the future prospects for the design of gene cloning strategies and modern wheat breeding."
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Authors: Yajun Gou, Yueqin Heng, Wenyan Ding, Canhong Xu, Qiushuang Tan, Yajing Li, Yudong Fang, Xiaoqing Li, Degui Zhou, Xinyu Zhu, Mingyue Zhang, Rongjian Ye, Haiyang Wang and Rongxin Shen.
Nature Communications (2024)
Editor's view: Florets of indica rice open earlier than japonica rice, hindering utilization of the cross subspecies heterosis. Here, the authors show that an OsMYB8-OsJAR1 module regulates diurnal floret opening time divergences between the two subspecies.
Abstract: "The inter-subspecific indica-japonica hybrid rice confer potential higher yield than the widely used indica-indica intra-subspecific hybrid rice. Nevertheless, the utilization of this strong heterosis is currently hindered by asynchronous diurnal floret opening time (DFOT) of indica and japonica parental lines. Here, we identify OsMYB8 as a key regulator of rice DFOT. OsMYB8 induces the transcription of JA-Ile synthetase OsJAR1, thereby regulating the expression of genes related to cell osmolality and cell wall remodeling in lodicules to promote floret opening. Natural variations of OsMYB8 promoter contribute to its differential expression, thus differential transcription of OsJAR1 and accumulation of JA-Ile in lodicules of indica and japonica subspecies. Furthermore, introgression of the indica haplotype of OsMYB8 into japonica effectively promotes DFOT in japonica. Our findings reveal an OsMYB8-OsJAR1 module that regulates differential DFOT in indica and japonica, and provide a strategy for breeding early DFOT japonica to facilitate breeding of indica-japonica hybrids."
Authors: Mumei Wang, Xiaopei Zhu, Zhen Huang, Minghao Chen, Peng Xu, Shitang Liao, Yongzhen Zhao, Yannan Gao, Jiahui He, Yutong Luo, Huixuan Chen, Xiaoying Wei, Shuai Nie, Jingfang Dong, Liya Zhu, Chuxiong Zhuang, Junliang Zhao, Zhenlan Liu and Hai Zhou.
Plant Biotechnology Journal (2024)
Abstract: "Inter-subspecific indica–japonica hybrid rice (Oryza sativa) has the potential for increased yields over traditional indica intra-subspecies hybrid rice, but limited yield of F1 hybrid seed production (FHSP) hinders the development of indica–japonica hybrid rice breeding. Diurnal flower-opening time (DFOT) divergence between indica and japonica rice has been a major contributing factor to this issue, but few DFOT genes have been cloned. Here, we found that manipulating the expression of jasmonate (JA) pathway genes can effectively modulate DFOT to improve the yield of FHSP in rice. Treating japonica cultivar Zhonghua 11 (ZH11) with methyl jasmonate (MeJA) substantially advanced DFOT. Furthermore, overexpressing the JA biosynthesis gene OPDA REDUCTASE 7 (OsOPR7) and knocking out the JA inactivation gene CHILLING TOLERANCE 1 (OsHAN1) in ZH11 advanced DFOT by 1- and 2-h respectively; and knockout of the JA signal suppressor genes JASMONATE ZIM-DOMAIN PROTEIN 7 (OsJAZ7) and OsJAZ9 resulted in 50-min and 1.5-h earlier DFOT respectively. The yields of FHSP using japonica male-sterile lines GAZS with manipulated JA pathway genes were significantly higher than that of GAZS wildtype. Transcriptome analysis, cytological observations, measurements of elastic modulus and determination of cell wall components indicated that the JA pathway could affect the loosening of the lodicule cell walls by regulating their composition through controlling sugar metabolism, which in turn influences DFOT. This research has vital implications for breeding japonica rice cultivars with early DFOT to facilitate indica–japonica hybrid rice breeding."
Authors: Mingzhi Xu, Zhenpeng Xu, Yanrong Liu, Yaling Liu, Jinghui Liu, and Wanjun Zhang.
Agronomy (2024)
Abstract: "Drought stress severely affects alfalfa (Medicago sativa L.) growth and production. It is particularly important to analyze the key networks of drought in alfalfa through physiological and molecular levels. However, how to quickly screen drought-tolerant alfalfa germplasm and how to elucidate the molecular pathways of alfalfa responding to drought are less studied. In this study, based on our previous research, we further verified the association between the heritability of ABA sensitivity during seed germination and drought tolerance of plants and identified the key pathways of drought tolerance differences between ABA-sensitivity (S1-0) and -insensitivity (S1-50) plants via RNA-seq and analysis. The results showed that the sensitivity to ABA in alfalfa seeds can be inherited and that plants that are insensitive to ABA during germination show stronger drought tolerance. An analysis of the differentially expressed genes (DEGs) revealed that ABA biosynthesis and signaling, amino acid metabolism, LEA, and wax synthesis-related pathways may be the key pathways that can be used for drought tolerance improvement in alfalfa. DEGs such as NCED, PYR/PYL, and PP2C may contribute to drought tolerance in the S1-50 plant. The study further confirms that screening with ABA at the seed germination stage can select alfalfa lines with good drought tolerance, which provides a new theoretical basis for alfalfa drought tolerance breeding. The expression of the key genes of alfalfa in response to drought stress was also tested."
Authors: HuiFang Xu and Xu Chen.
Scientia Sinica Vitae (2024)
Abstract: "Auxin is widely involved in plant growth and development and its adaptation to the environment, and is the most important hormone in plants. In the past two decades, studies based on the model plant Arabidopsis thaliana have confirmed that establishment of auxin gradient through biosynthesis, metabolism, polar transport and signaling pathways determines organogenesis and polarity of plant organs. With the development of gene editing and molecular breeding research, how to apply the theoretical results related to auxin pathway in crop improvement, and coordinate the ideal plant/root type of crops through the selection and combination of dominant genes is a key issue in this field. In this review, we summarize the latest research progress in auxin field in the past five years, refer to the contribution of auxin to the improvement of rice agronomic traits, and discuss and look forward to the possibility of auxin application on soybean breeding."
Authors: Yilong Yao, Denghao Xiang, Nai Wu, Yao Wang, Yu Chen, Yang Yuan, Ying Ye, Dan Hu, Chang Zheng, Yu Yan, Qingya Lv, Xiaokai Li, Guoxing Chen, Honghong Hu, Haiyan Xiong, Shaobing Peng and Lizhong Xiong.
Molecular Plant (2023)
Abstract: "Rice ratooning, the fast outgrowth of dormant buds on stubble, is an important cropping practice in rice production. However, the low ratooning ability (RA) of most rice varieties restricts the application of this cost-efficient system, and the genetic basis of RA remains unknown. In this study, we dissected the genetic architecture of RA by a genome-wide association study in a natural rice population. Rice ratooning ability 3 (RRA3), encoding a hitherto not characterized nucleoredoxin involved in reduction of disulfide bonds, was identified as the causal gene of a major locus controlling RA. Overexpression of RRA3 in rice significantly accelerated leaf senescence and reduced RA, whereas knockout of RRA3 significantly delayed leaf senescence and increased RA and ratoon yield. We demonstrated that RRA3 interacts with Oryza sativa histidine kinase 4 (OHK4), a cytokinin receptor, and inhibits the dimerization of OHK4 through disulfide bond reduction. This inhibition ultimately led to decreased cytokinin signaling and reduced RA. In addition, variations in the RRA3 promoter were identified to be associated with RA. Introgression of a superior haplotype with weak expression of RRA3 into the elite rice variety Guichao 2 significantly increased RA and ratoon yield by 23.8%. Collectively, this study not only uncovers an undocumented regulatory mechanism of cytokinin signaling through de-dimerization of a histidine kinase receptor—but also provides an eximious gene with promising value for ratoon rice breeding."
Authors: Haiyan Zhao, Shuyuan Wan, Yanni Huang, Xiaoqiang Li, Tiantian Jiao, Zhijun Zhang, Baiquan Ma, Lingcheng Zhu, Fengwang Ma and Mingjun Li.
The Plant Cell (2024)
Abstract: "Auxin plays important roles throughout plant growth and development. However, the mechanisms of auxin regulation of plant structure are poorly understood. In this study, we identified a transcription factor of the BARLEY B RECOMBINANT/BASIC PENTACYSTEINE (BBR/BPC) family in apple (Malus × domestica), MdBPC2. It was highly expressed in dwarf rootstocks and it negatively regulated auxin biosynthesis. Overexpression of MdBPC2 in apple decreased plant height, altered leaf morphology, and inhibited root system development. These phenotypes were due to reduced auxin levels and were restored reversed after exogenous IAA treatment. Silencing of MdBPC2 alone had no obvious phenotypic effect, while silencing both class I and class II BPCs in apple significantly increased auxin content in plants. Biochemical analysis demonstrated that MdBPC2 directly bound to the GAGA-rich element in the promoters of the auxin synthesis genes MdYUC2a and MdYUC6b, inhibiting their transcription and reducing auxin accumulation in MdBPC2 overexpression lines. Further studies established that MdBPC2 interacted with the polycomb group (PcG) protein LIKE HETEROCHROMATIN PROTEIN 1 (LHP1) to inhibit MdYUC2a and MdYUC6b expression via methylation of histone 3 lysine 27 (H3K27me3). Silencing MdLHP1 reversed the negative effect of MdBPC2 on auxin accumulation. Our results reveal a dwarfing mechanism in perennial woody plants involving control of auxin biosynthesis by a BPC transcription factor, suggesting its use for genetic improvement of apple rootstock."
Author: Amy Lanctot.
Plant Physiology (2024)
Excerpts: "In this issue of Plant Physiology, Yang et al. use quantitative trail loci (QTL) and genome-wide association study (GWAS) mapping approaches to identify variation in a gene locus that affects soybean accessions’ ability to tolerate low phosphorus conditions.......By finding overlap in their results from these two approaches, they found single nucleotide polymorphisms (SNPs) identified in the GWAS that lay in one of their QTLs. This locus encoded a gene homologous to ARABIDOPSIS RESPONSE REGULATOR 1 (ARR1), a cytokinin response transcription factor, which they called GmRR1. Characterizing GmRR1 tissue-specific expression by qPCR, they found that GmRR1 is expressed most highly in the root and its expression changes in response to low phosphorus conditions, initially increasing and then decreasing"
"These quantitative traits increased more substantially under low phosphorus conditions, suggesting these mutants can better tolerate low phosphorus soil. Conversely, overexpression lines showed reduced root systems (Figure 1A), resulting in less biomass in both aerial and root tissue and affecting seed yield negatively as well (Figure 1B)....This suggests that inhibition of cytokinin signaling in these mutants occurs at the level of perception, which may cause feedback regulation that promotes cytokinin synthesis or transport (Figure 1C)."
"They found a strong selective signature on this locus, as the haplotype identified in their GWAS analysis as more prevalent in low-phosphorus tolerant accessions was much more frequently found in cultivated accessions compared to landraces (Figure 1D), and in particular was nearly universal in soybean varieties from Brazil, a large soybean producer. This analysis suggests that GmRR1 may have been a target during soybean domestication to promote soybean cultivation in phosphorus deficient soils."
Authors: Yanzhao Yang, Chengcai Chu, Qian Qian and Hongning Tong.
Trends in Plant Science (2024)
Highlights: Brassinosteroids (BR) signaling pathway is believed to be largely conserved among different species, although some components, steps, or events may differ between rice and Arabidopsis thaliana. BRs play essential roles in regulating both yield and stress-related traits, as well as in environmental adaptability, and thus hold promise for producing high-yielding and stable crops with less input. BR genes have been shown to be valuable for crop improvement employing various approaches. One prevalent method is to enhance the planting density of rice, maize, and wheat. Strategies such as exploring function-specific genes, identifying beneficial alleles, inducing favorable mutations, and optimizing the spatial hormone distribution can facilitate the utilization of BR genes towards the next Green Revolution.
Abstract: "The use of gibberellin-related dwarfing genes significantly increased grain yield during the Green Revolution. Brassinosteroids (BRs) play a vital role in regulating agronomic traits and stress resistance. The potential of BR-related genes in crop improvement has been well demonstrated, positioning BRs as crucial targets for the next agricultural biotechnological revolution. However, BRs exert pleiotropic effects on plants, and thus present both opportunities and challenges for their application. Recent research suggests promising strategies for leveraging BR regulatory molecules for crop improvement, such as exploring function-specific genes, identifying beneficial alleles, inducing favorable mutations, and optimizing spatial hormone distribution. Advancing our understanding of the roles of BRs in plants is imperative to implement these strategies effectively."
Authors: Ming-Yi Bai, Jinrong Peng, and Xiangdong Fu.
Chinese Bulletin of Botany (2023)
Abstract: Since the 1960s, the utilization of semi-dwarfing genes Rht-B1b and Rht-D1b has significantly improved the lodging resistance and harvest index of wheat (Triticum aestivum), leading to a doubling of global wheat production and triggering the “Green Revolution” in agriculture. Rht-B1b and Rht-D1b encode plant growth-inhibiting factors, DELLA proteins, which are negative regulatory factors in the gibberellin (GA) signaling pathway. Accumulation of DELLA proteins not only inhibits cell division and elongation, leading to a dwarf phenotype, but also suppresses photosynthesis and nitrogen use efficiency, resulting in semi-dwarf varieties requiring higher fertilizer inputs to achieve high yields. Addressing the challenge of “reducing fertilizer inputs while increasing efficiency” is a crucial issue for achieving green and low-carbon agriculture. Recently, Zhongfu Ni and his colleagues from China Agricultural University identified a novel “semi-dwarfing” regulatory module with potential breeding applications and demonstrated that reducing brassinosteroid (BR) signaling could enhance grain yield of wheat “Green Revolution” varieties (GRVs). They isolated and characterized a major QTL responsible for plant height and 1000-grain weight in wheat. Positional cloning and functional analysis revealed that this QTL was associated with a ~500 kb fragment deletion in the Heng597 genome, designated as r-e-z, which contains Rht-B1 and ZnF-B (encoding a RING E3 ligase). ZnF-B was found to positively regulate BR signaling by triggering the degradation of BR signaling repressor BRI1 Kinase Inhibitor (TaBKI1). Further experiments showed that deletion of ZnF-B not only caused the semi-dwarf phenotypes in the absence of Rht-B1b and Rht-D1b alleles, but also enhanced grain yield at low nitrogen fertilization levels. Thus, manipulation of GA and BR signaling provides a new breeding strategy to improve grain yield and nitrogen use efficiency of wheat GRVs without affecting beneficial semi-dwarfism, which will drive toward a new “Green Revolution” in wheat.
Authors: Jaclyn A. Adaskaveg and Barbara Blanco-Ulate.
Current Opinion in Biotechnology (2023)
Highlights • Fruit quality includes aspects of color, nutrition, flavor, texture, and shelf life. • Improving fruit quality can reduce food waste and increase nutritious food access. • Some consumer-based traits have declined with breeding longer shelf-life fruit. • Modulating ripening through breeding and biotechnology can improve fruit quality.
Abstract: "Fruit quality directly impacts fruit marketability and consumer acceptance. Breeders have focused on fruit quality traits to extend shelf life, primarily through fruit texture, but, in some cases, have neglected other qualities such as flavor and nutrition. In recent years, integrative biotechnology and consumer-minded approaches have surfaced, aiding in the development of flavorful, long-lasting fruit. Here, we discussed how specific transcription factors and hormones involved in fruit ripening can be targeted to generate high-quality fruit through traditional breeding and bioengineering. We highlight regulators that can be used to generate novel-colored fruit or biofortify fresh produce with health-promoting nutrients, such as vitamin C. Overall, we argue that addressing grower and industry needs must be balanced with consumer-based traits."
Authors: Aili Li, Chenyang Hao, Zhenyu Wang, Shuaifeng Geng, Meiling Jia, Fang Wang, Xiang Han, Xingchen Kong, Lingjie Yin, Shu Tao, Zhongyin Deng, Ruyi Liao, Guoliang Sun, Ke Wang, Xingguo Ye, Chengzhi Jiao, Hongfeng Lu, Yun Zhou, Dengcai Liu, Xiangdong Fu, Xueyong Zhang and Long Mao.
Molecular Plant (2022)
Editor's view: Exome sequencing of 287 wheat accessions representing a collection from the past 100 years in China and genome-wide association study identified epistatically interacting pleiotropic genomic loci for yield potential. Selection signatures identified suggest that the gibberellin pathway is fine-tuned in post-Green Revolution breeding efforts. This rich genomic diversity resource will be useful for the wheat research community.
Abstract: "Diversity surveys of crop germplasm are important for gaining insights into the genomic basis for plant architecture and grain yield improvement, which is still poorly understood in wheat. In this study, we exome sequenced 287 wheat accessions that were collected in the past 100 years. Population genetics analysis identified that 6.7% of the wheat genome falls within the selective sweeps between landraces and cultivars, which harbors the genes known for yield improvement. These regions were asymmetrically distributed on the A and B subgenomes with regulatory genes being favorably selected. Genome-wide association study (GWAS) identified genomic loci associated with traits for yield potential, and two underlying genes, TaARF12 encoding an auxin response factor and TaDEP1 encoding the G-protein γ-subunit, were located and characterized to pleiotropically regulate both plant height and grain weight. Elite single-nucleotide haplotypes with increased allele frequency in cultivars relative to the landraces were identified and found to have accumulated over the course of breeding. Interestingly, we found that TaARF12 and TaDEP1 function in epistasis with the classical plant height Rht-1 locus, leading to propose a “Green Revolution”-based working model for historical wheat breeding. Collectively, our study identifies selection signatures that fine-tune the gibberellin pathway during modern wheat breeding and provides a wealth of genomic diversity resources for the wheat research community."
Authors: Shakeel Ahmad, Liqun Tang, Rahil Shahzad, Amos Musyoki Mawia, Gundra Sivakrishna Rao, Shakra Jamil, Chen Wei, Zhonghua Sheng, Gaoneng Shao, Xiangjin Wei, Peisong Hu, Magdy M. Mahfouz, Shikai Hu, and Shaoqing Tang.
Journal of Agricultural and Food Chemistry (2021)
Abstract: "Zero hunger is one of the sustainable development goals set by the United Nations in 2015 to achieve global food security by 2030. The current harvest of crops is insufficient; feeding the world’s population and meeting the goal of zero hunger by 2030 will require larger and more consistent crop production. Clustered regularly interspaced short palindromic repeats-associated protein (CRISPR-Cas) technology is widely used for the plant genome editing. In this review, we consider this technology as a potential tool for achieving zero hunger. We provide a comprehensive overview of CRISPR-Cas technology and its most important applications for food crops’ improvement. We also conferred current and potential technological breakthroughs that will help in breeding future crops to end global hunger. The regulatory aspects of deploying this technology in commercial sectors, bioethics, and the production of transgene-free plants are also discussed. We hope that the CRISPR-Cas system will accelerate the breeding of improved crop cultivars compared with conventional breeding and pave the way toward the zero hunger goal."
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