Alternative Splicing of TaGS3 Differentially Regulates Grain Weight and Size in Bread Wheat.

Xiaoli Ren,Xigang Liu,Aamana Batool,Liya Zhi,Lei Liu,Deyuan Meng,Wei Zhang,Liqiang Song,Na Zhang,Qiannan Su,Jun Ji,Lin Guo,Junming Li

doi:10.3390/ijms222111692

Abstract

The heterotrimeric G-protein mediates growth and development by perceiving and transmitting signals in multiple organisms. Alternative splicing (AS), a vital process for regulating gene expression at the post-transcriptional level, plays a significant role in plant adaptation and evolution. Here, we identified five splicing variants of Gγ subunit gene TaGS3 (TaGS3.1 to TaGS3.5), which showed expression divergence during wheat polyploidization, and differential function in grain weight and size determination. TaGS3.1 overexpression significantly reduced grain weight by 5.89% and grain length by 5.04%, while TaGS3.2–3.4 overexpression did not significantly alter grain size compared to wild type. Overexpressing TaGS3.5 significantly increased the grain weight by 5.70% and grain length by 4.30%. Biochemical assays revealed that TaGS3 isoforms (TaGS3.1–3.4) with an intact OSR domain interact with WGB1 to form active Gβγ heterodimers that further interact with WGA1 to form inactive Gαβγ heterotrimers. Truncated isoforms TaGS3.2–3.4 , which lack the C-terminal Cys-rich region but have enhanced binding affinity to WGB1, antagonistically compete with TaGS3.1 to bind WGB1, while TaGS3.5 with an incomplete OSR domain does not interact with WGB1. Taking these observations together, we proposed that TaGS3 differentially regulates grain size via AS, providing a strategy by which the grain size is fine-tuned and regulated at the post-transcriptional level.

Highlights

IntroductionBread wheat (Triticum aestivum L.) is a global staple crop
GS31–51 and GS367−170, on the other hand, did not interact with WGB1 (Figure 5B). These results suggest that GS3 interacts with WGB1 through the organ size regulation (OSR) domain rather than the C-terminal Cys-rich region, and the section of the 15 amino acid residues in the OSR domain is essential for the binding of GS3 to WGB1
TaGS3.1 overexpression significantly reduced grain weight and length, TaGS3.2–3.4 overexpression did not significantly alter grain weight and size compared to wild type, and TaGS3.5 overexpression significantly increased grain weight and grain length

Summary

Introduction

Bread wheat (Triticum aestivum L.) is a global staple crop. As the prime breeding target in cereals, is determined by the panicles per plant, grain number per spike, and grain weight. Grain weight is the major determinant of yield potential, and it is largely dependent on grain size. Grain size has long been the critical target of selection in wheat breeding [1]

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Discussion

Conclusion