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Authors: Keisuke Okamoto, Taiki Inoue, Tsunesato Nagano, Sho Miyazaki, Ikuo Takahashi, Tadao Asami, Kazunori Okada, Kazuma Okada and Masatoshi Nakajima.
Bioscience, Biotechnology, and Biochemistry (2023)
Abstract: "MdDOX-Co, the ectopic expression of which is considered to cause the columnar tree shape, belongs to the 2-oxoglutarate-dependent dioxygenase (2ODD) family. It adds a hydroxyl group to position 12 of gibberellins. However, the 2ODD enzymes related to gibberellin biosynthesis and catabolism are phylogenetically distinct from MdDOX-Co. Thus, it is possible that substrates other than gibberellins exist in MdDOX-Co. To identify the previously unidentified substrate(s) of MdDOX-Co, we searched for MdDOX-Co-specific inhibitors. Chemical screening using GC-MS was performed to investigate the effects of 2,400 compounds that inhibited the catalytic reaction of MdDOX-Co, but not the catabolic reaction of GA 2-oxidase, an enzyme involved in gibberellin catabolism. By applying these two compounds in Arabidopsis, a chemical designated as TPDD that did not inhibit gibberellin biosynthesis was selected. The structure-activity relationships among the TPDD analogs were also obtained."
Authors: Dengan Xu, Yingjie Bian, Xumei Luo, Chenfei Jia, Qianlin Hao, Xiuling Tian, Qiang Cao, Wei Chen, Wujun Ma, Zhongfu Ni, Xiangdong Fu, Zhonghu He, Xianchun Xia and Shuanghe Cao.
Development (2023)
Summary: Transgenic, micromorphological, dynamic and multi-omic analyses in wheat reveal the underlying mechanism of the Green Revolution gene Rht-B1b in modulation of plant architecture and yield component traits.
Abstract: "The utilization of reduced plant height genes Rht-B1b and Rht-D1b, encoding homeologous DELLA proteins, led to the wheat Green Revolution (GR). However, the specific functions of GR genes in yield determination and the underlying regulatory mechanisms remained unknown. Here, we validated that Rht-B1b, as a representative of GR genes, affects plant architecture and yield component traits. Upregulation of Rht-B1b reduced plant height, leaf size and grain weight, but increased tiller number, tiller angle, spike number per unit area, and grain number per spike. Dynamic investigations showed that Rht-B1b increased spike number by improving tillering initiation rather than outgrowth, and enhanced grain number by promoting floret fertility. Rht-B1b reduced plant height by reducing cell size in the internodes, and reduced grain size or weight by decreasing cell number in the pericarp. Transcriptome analyses uncovered that Rht-B1b regulates many homologs of previously reported key genes for given traits and several putative integrators for different traits. These findings specify the pleiotropic functions of Rht-B1b in improving yield and provide new insights into the regulatory mechanisms underlying plant morphogenesis and yield formation."
Authors: Chunge Cui, Qiumei Lu, Zhangchen Zhao, Shan Lu, Shan Duan, Yang Yang, Yue Qiao, Liang Chen and Yin-Gang Hu.
Planta (2022)
Main conclusion Rht5 was narrowed to an approximately 1 Mb interval and had pleiotropic effects on plant height, spike length and grain size. TraesCS3B02G025600 was predicted as the possible candidate gene.
Abstract: "Plant height is an important component related to plant architecture, lodging resistance, and yield performance. The utilization of dwarf genes has made great contributions to wheat breeding and production. In this study, two F2 populations derived from the crosses of Jinmai47 and Ningchun45 with Marfed M were employed to identify the genetic region of reduced plant height 5 (Rht5), and their derived lines were used to evaluate its effects on plant height and main agronomic traits. Rht5 was fine-mapped between markers Kasp-25 and Kasp-23, in approximately 1 Mb region on chromosome 3BS, which harbored 17 high-confidence annotated genes based on the reference genome of Chinese Spring (IWGSC RefSeq v1.1). TraesCS3B02G025600 were predicted as the possible candidate gene based on its differential expression and sequence variation between dwarf and tall lines and parents. The results of phenotypic evaluation showed that Rht5 had pleiotropic effects on plant height, spike length, culm diameter, grain size and grain yield. The plant height of Rht5 dwarf lines was reduced by an average of 32.67% (32.53 cm) and 27.84% (33.62 cm) in the Jinmai47 and Ningchun45 population, respectively. While Rht5 showed significant and negative pleiotropic effects on culm diameter, aboveground biomass, grain yield, spike length, spikelet number, grain number per spike, grain size, grain weight and filling degree of basal second internode. The culm lodging resistance index (CLRI) of dwarf lines was significantly higher than that of tall lines in the two population. In conclusion, these results lay a foundation for understanding the dwarfing mechanism of Rht5."
Authors: Xuemei Si, Wanxin Wang, Ke Wang, Yunchuan Liu, Jiangping Bai, Yaxiong Meng, Xueyong Zhang and Hongxia Liu.
International Journal of Molecular Sciences (2021)
Abstract: "The elongation and development of wheat (Triticum aestivum L.) stem play an important role in plant architecture. The shortened stem would result in a sheathed spike and a low yield in crops. Unraveling the molecular mechanisms underlying a sheathed spike would be beneficial for plant architecture and yield improvement. We identified a novel gene, TaWUS-like (WUSCHEL-related homeobox-like), which regulated sheathed spike and plant architecture in wheat. The plant height of overexpression transgenic lines was significantly decreased and the spike was not completely elongated and enclosed in flag leaf sheaths. Moreover, the increase in tiller angle resulted in loose plant architecture and lower yield. The statistical and cytological analysis demonstrated that the length of the uppermost and secondary internode was significantly shortened, especially the uppermost internode which was only half the length of the wild-type. The size of parenchyma cells was obviously reduced and cell length on the longitudinal section was elongated insufficiently compared with wild-type. The analysis of hormone content showed that there was a lack of gibberellin A 3 (GA3) in internodes but a higher brassinosteroid (BR) content. TaWUS-like may inhibit the synthesis of GA3 and/or BR, thus affecting the function of signal transduction of these hormones, which further caused stem shortening and plant dwarfing in wheat."
Authors: Udita Basu and Swarup K. Parida.
Plant Biotechnology Journal (2021)
Abstract: "Plants have adapted to different environmental niches by fine-tuning the developmental factors working together to regulate traits. Variations in the developmental factors result in a wide range of quantitative variations in these traits that helped plants survive better. The major developmental pathways affecting plant architecture are also under the control of such pathways. Most notable are the CLAVATA-WUSCHEL pathway regulating shoot apical meristem fate, GID1-DELLA module influencing plant height and tillering, LAZY1-TAC1 module controlling branch/tiller angle, and the TFL1-FT determining the floral fate in plants. Allelic variants of these key regulators selected during domestication shaped the crops the way we know them today. There is immense yield potential in the “ideal plant architecture” of a crop. With the available genome editing techniques, possibilities are not restricted to naturally occurring variations. Using a transient reprogramming system, one can screen the effect of several developmental gene expressions in novel ecosystems to identify the best targets. We can use the plant's fine-tuning mechanism for customizing crops to specific environments. The process of crop domestication can be accelerated with a proper understanding of these developmental pathways. It is time to step forward towards the next-generation molecular breeding for restructuring plant types in crops ensuring yield stability."
Authors: Shiqing Dong, Xianxin Dong, Xiaokang Han, Fan Zhang, Yu Zhu, Xiaoyun Xin, Ying Wang, Yuanyi Hu, Dingyang Yuan, Jianping Wang, Zhou Huang, Fuan Niu, Zejun Hu, Peiwen Yan, Liming Cao, Haohua He, Junru Fu, Yeyun Xin, Yanning Tan, Bigang Mao, Bingran Zhao, Jinshui Yang, Longping Yuan and Xiaojin Luo.
PNAS (2021)
Significance: Rice breeding programs aim to develop cultivars with improved traits, including high grain yield and superior quality. In rice, OsPDCD5 encodes a programmed cell death 5 protein. Targeted mutagenesis of OsPDCD5 enhanced grain yield and plant architecture. Statistical analysis indicated that plot grain yield of OsPDCD5 knockout lines was enhanced by 6.25 to 20.13% in 11 popular or newly bred rice cultivars compared with the corresponding wild types. The OsPDCD5 knockout lines showed increases in milled rice percentage and gel consistency, and a decrease in amylose content. Our results provide insight into the molecular mechanism by which OsPDCD5 influences grain yield and plant architecture, and highlight a promising candidate gene for use in breeding programs designed to develop super rice cultivars.
Abstract: "Plant architecture is an important agronomic trait that affects crop yield. Here, we report that a gene involved in programmed cell death, OsPDCD5, negatively regulates plant architecture and grain yield in rice. We used the CRISPR/Cas9 system to introduce loss-of-function mutations into OsPDCD5 in 11 rice cultivars. Targeted mutagenesis of OsPDCD5 enhanced grain yield and improved plant architecture by increasing plant height and optimizing panicle type and grain shape. Transcriptome analysis showed that OsPDCD5 knockout affected auxin biosynthesis, as well as the gibberellin and cytokinin biosynthesis and signaling pathways. OsPDCD5 interacted directly with OsAGAP, and OsAGAP positively regulated plant architecture and grain yield in rice. Collectively, these findings demonstrate that OsPDCD5 is a promising candidate gene for breeding super rice cultivars with increased yield potential and superior quality."
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Authors: Xing Liu, Daniel P. Wickland, Zhicong Lin, Quilin Liu, Lucas Borges Dos Santos, Karen A. Hudson and Matthew E. Hudson.
Journal of Experimental Botany (2023)
Abstract: "Height is a critical component of plant architecture, significantly affecting crop yield. The genetic basis of this trait in soybean remains unclear. In this study, we report the characterization of the Compact mutant of soybean, which has short internodes. The candidate gene was mapped to chromosome 17, and the interval containing the causative mutation was further delineated using biparental mapping. Whole-genome sequencing of the mutant revealed an 8.7 kb deletion in the promoter of the Glyma.17g145200 gene, which encodes a member of the class III gibberellin (GA) 2-oxidases. The mutation has a dominant effect, likely via increased expression of the GA 2-oxidase transcript observed in green tissue, as a result of the deletion in the promoter of Glyma.17g145200. We further demonstrate that levels of GA precursors are altered in the Compact mutant, supporting a role in GA metabolism, and that the mutant phenotype can be rescued with exogenous GA3. We also determined that overexpression of Glyma.17g145200 in Arabidopsis results in dwarfed plants. Thus, gain of promoter activity in the Compact mutant leads to a short internode phenotype in soybean through altered metabolism of gibberellin precursors. These results provide an example of how structural variation can control an important crop trait and a role for Glyma.17g145200 in soybean architecture, with potential implications for increasing crop yield."
Authors: Zuliang Li, Baozhu Li, Junli Zhang, Hongliang Wang, Mao Wang, Siyi Guo, Pengtao Wang, Zhi Li, David W. Galbraith, Dandan Li and Chun-Peng Song.
The Crop Journal (2023)
Abstract: "Gibberellin (GA) functions in plant growth and development. However, genes involved in the biosynthesis and regulation of GA in crop plants are poorly understood. We isolated the mutant gad5-1 (GA-Associated Dwarf 5), characterized by dwarfing, short internodes, and dark green and short leaves. Map-based gene cloning and allelic verification confirmed that ZmGAD5 encodes ent-kaurenoic acid oxidase (KAO), which catalyzes KA (ent-kaurenoic acid) to GA12 conversion during GA biosynthesis in maize. ZmGAD5 is localized to the endoplasmic reticulum and is present in multiple maize organs. In gad5-1, the expression of ZmGAD5 is severely reduced, and the levels of the direct substrate of KAO, KA, is increased, leading to a reduction in GA content. The abnormal phenotype of gad5-1 was restored by exogenous application of GA3. The biomass, plant height, and levels of GA12 and GA3 in transgenic Arabidopsis overexpressing ZmGAD5 were increased in comparison with the corresponding controls Col-0. These findings deepen our understanding of genes involved in GA biosynthesis, and could lead to the development of maize lines with improved architecture and higher planting-density tolerance."
Authors: Lihua Zheng, Jiangqi Wen, Jinling Liu, Xiangzhao Meng, Peng Liu, Na Cao, Jiangli Dong and Tao Wan.
The Crop Journal (2022)
Abstract: "Alfalfa (Medicago sativa L.) is a nutritious forage crop with wide ecological adaptability. The molecular breeding of alfalfa is restricted by its heterozygous tetraploid genome and the difficult genetic manipulation process. Under time and resource constraints, we applied a more convenient approach. We investigated two MtGA3ox genes, MtGA3ox1 and MtGA3ox2, of Medicago truncatula, a diploid legume model species, finding that MtGA3ox1 plays a major role in GA-regulated plant architecture. Mutation of neither gene affected nitrogenase activity. These results suggest that MtGA3ox1 can be used in semidwarf and prostrate alfalfa breeding. Based on the M. truncatula MtGA3ox1 sequence, MsGA3ox1 was cloned from alfalfa, and two knockout targets were designed. An efficient CRISPR/Cas9-based genome editing protocol was used to generate msga3ox1 mutants in alfalfa. We obtained three lines that carried mutations in all four alleles in the T0 generation. Fifteen clonal plants were vegetatively propagated from each transgenic line using shoot cuttings. The plant height and internode length of msga3ox1 null mutants were significantly decreased. The number of total lateral branches, leaf/stem ratio and crude protein content of aerial plant parts of msga3ox1 mutants were significantly increased. Thus, we obtained semi-dwarf and prostrate alfalfa by gene editing."
Authors: Baiqiang Yan, Zongju Yang, Guanhua He, Yexing Jing, Huixue Dong, Lan Ju, Yunwei Zhang, Yingfang Zhu, Yun Zhou and Jiaqiang Sun.
Plant Communications (2021)
Abstract: "Improvement of plant architecture, such as reduced plant height under high-density planting, is of significance for agriculture production. Light and gibberellin (GA) are two essential external and internal cues affecting plant architecture. In this study, we characterize a direct interaction of distinct receptors linking light and GA signaling in Arabidopsis (Arabidopsis thaliana) and wheat (Triticum aestivum L.). We show that the light receptor CRY1 represses GA signaling through interaction with all five DELLA proteins and promoting RGA protein accumulation in Arabidopsis. Genetic analysis show that CRY1-mediated growth repression is achieved through the DELLA proteins. Interestingly, we find that CRY1 also directly interacts with the GA receptor GID1 to competitively inhibit the interaction of GID1-GAI. Further, we show that overexpression of TaCRY1a reduces plant height and coleoptile growth in wheat. Moreover, we demonstrate that TaCRY1a interacts with both TaGID1 and Rht1 to competitively attenuate the TaGID1-Rht1 interaction. Taken together, we propose that the photoreceptor CRY1 competitively inhibits the GID1-DELLA interaction, thereby stabilizing DELLA proteins and consequently enhancing DELLA-repressed plant growth."
Authors: Su Su, Jun Hong, Xiaofei Chen, Changquan Zhang, Mingjiao Chen, Zhijing Luo, Shuwei Chang, Shaoxing Bai, Wanqi Liang, Qiaoquan Liu and Dabing Zhang.
Plant Biotechnology Journal (2021)
Abstract: "Panicle architecture is a key determinant of grain yield in cereals, but the mechanisms governing panicle morphogenesis and organ development remain elusive. Here, we have identified a quantitative trait locus (qPA1) associated with panicle architecture using chromosome segment substitution lines from parents Nipponbare and 9311. The panicle length, branch number, and grain number of Nipponbare were significantly higher than CSSL-9. Through map-based cloning and complementation tests, we confirmed that qPA1 was identical to SD1 (Semi Dwarf1), which encodes a gibberellin 20 oxidase enzyme participating in gibberellic acid (GA) biosynthesis. Transcript analysis revealed that SD1 was widely expressed during early panicle development. Analysis of sd1/osga20ox2 and gnp1/ osga20ox1 single and double mutants revealed that the two paralogous enzymes have non-redundant functions during panicle development, likely due to differences in spatiotemporal expression; GNP1 expression under control of the SD1 promoter could rescue the sd1 phenotype. The DELLA protein SLR1, a component of the GA signalling pathway, accumulated more highly in sd1 plants. We have demonstrated that SLR1 physically interacts with the meristem identity class I KNOTTED1-LIKE HOMEOBOX (KNOX) protein OSH1 to repress OSH1-mediated activation of downstream genes related to panicle development, providing a mechanistic link between gibberellin and panicle architecture morphogenesis."
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