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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: 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: 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: 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."
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.
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