Wheat is the most widely cultivated staple food crop globally, with over one-third of the world's population relying on wheat as their main food source. Morphological traits of leaves, spikes, and grains play crucial roles in determining crop growth, development, and yield. Therefore, studying the genes that control wheat plant architecture is essential for improving productivity and environmental adaptation. While several genes regulating plant architecture have been cloned and studied in plants such as Arabidopsis, rice, and maize, research on related genes in wheat has been relatively scarce due to the complexity of its genome.

 

Recently, the research team led by Professor Shisheng Chen from Peking University Institute of Advanced Agricultural Sciences (PKU-IAAS) published a paper titled "Mutations in wheat TaAPA2 gene result in pleiotropic effects on plant architecture" in the journal SCIENCE CHINA Life Sciences. The study reveals the dominant negative effects of mutations in the wheat TaAPA2 gene, encoding proteins with vWA and Vwaint domains, which may regulate wheat plant architecture through proton pumps (H+-ATPases).

 

 

In the preliminary stage, the team identified 18 independent wheat Ningchun 4 EMS mutagenesis families that exhibited various phenotypic changes in leaf and seed shape, reduced glume length, decreased leaf angle, and delayed flowering to different extents (Figure 1A). By fine mapping in two different mapping populations, the researchers identified the same candidate gene, TaAPA2 (Figure 1B). This gene encodes a unique protein with vWA and Vwaint domains, and point mutations in this gene lead to changes in multiple morphological traits in wheat. In addition to the 18 Ningchun 4 EMS mutants, the study also obtained EMS mutant lines in Zhoumai 36 and Cadenza, which have similar phenotypic changes caused by point mutations in the coding region of the TaAPA2 gene (Figure 1C). Further functional validation of TaAPA2 was carried out using CRISPR/Cas9 gene editing technology and transgenic experiments (Figure 1D). The study found that the mutant protein exhibits competitive interactions with the wild-type protein and exhibits a dosage effect (Figure 1E). These results suggest that the semi-dominant EMS mutants and gene editing mutations may act through dominant-negative effects.

 

In the collected materials of 128 common wheat and 158 spelt wheat samples, six haplotypes of the TaAPA2 protein were identified. Among them, haplotype H1 is dominant in common wheat varieties, while H2 is dominant in spelt wheat. TaAPA2 is predominantly expressed in spikes and the shoot apical meristem (SAM), and subcellular localization studies suggest its presence in the cytoplasm and cell membrane. Furthermore, the study found an interaction between TaAPA2 and TaCCDC115 (TraesCS2A02G364600) protein (Figure 1F), which is disrupted by the interaction protein TaVHA-c (TraesCS5D02G130000) from the V-ATPase complex, suggesting a potential regulatory mechanism among TaAPA2, TaCCDC115, and the V-ATPase complex. Overall, this study cloned the key gene TaAPA2, which regulates wheat plant architecture, laying the foundation for understanding the functional mechanism of proteins containing the vWA domain in regulating wheat plant morphology.

 

Dr. Shengsheng Bai and Dr. Guiping Wang from the PKU-IAAS are the co-first authors of this paper, while Professor Shisheng Chen and Associate Research Professor Zheng Wang from the same institution are the corresponding co-authors. Research Professors Yan Xue and Lihua Zhao the PKU-IAAS, as well as Dr. Chaozhong Zhang from the University of California, Davis, participated in this project. The research was supported by key projects in Shandong Province (ZR202211070163 and 2023LZGC022) and other funding sources.

 

Dr. Luxiang Liu's team from the Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, conducted research on this gene using other mutant backgrounds, and their paper was published simultaneously in SCIENCE CHINA Life Sciences in a "back to back" format. Concurrently, Professor Zhiyong Liu's team from the Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, also published their research on this gene in The Crop Journal. In addition, Professor Yiping Tong's team from the Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, is revising a research paper on this gene for publication in JIPB (Chang et al. 2024).

Figure The cloning, functional validation, and mechanistic analysis of the wheat TaAPA2 gene

 

Figure The phenotypes of mutant variants of the wheat TaAPA2 gene

 

Paper link:

https://doi.org/10.1007/s11427-024-2620-7