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

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.

Moderate Soil Drying-Induced Alternative Splicing Provides a Potential Novel Approach for the Regulation of Grain Filling in Rice Inferior Spikelets

“…AS is involved in most of the plant processes, including plant growth, development, and responses to external cues [ 47 ]. The function of AS on grain filling and yield has been a research hotspot for many years [ 26 , 27 , 48 , 49 , 50 , 51 , 52 ]. A single mutation at the 5′splice site of Waxy affects the alternative splicing of its pre-mRNA, resulting in the reduced levels of amylose [ 25 ].…”

“…Alternative splicing of OsLG3b has also been reported to control grain length and yield in rice [ 50 ]. When TaGS3 undergoes AS, it produces five splicing variants, resulting in opposite effects on grain weight and grain size [ 51 ]. Recently, a study also demonstrated that the AS of GS1;1 affects grain amylose content and sugar metabolism in rice [ 27 ].…”

Two alternative splicing variants of a wheat gene TaNAK1, TaNAK1.1 and TaNAK1.2, differentially regulate flowering time and plant architecture leading to differences in seed yield of transgenic Arabidopsis

“…AS can generate truncated proteins, disrupting main domains to form non-functional proteins ( Kalyna et al., 2012 ) or annulling interaction with other proteins and thereby impeding the formation of functional protein complexes ( Qin et al., 2017 ). Moreover, some splicing variants can antagonistically compete with other variant and interfere with its function in a negative manner ( Posé et al., 2013 ; Ren et al., 2021 ). Increasing evidences have demonstrated that AS participates in the regulation of plant growth and development.…”

“…The genome-wide AS profiling uncovered a very complex AS landscape in wheat, exhibiting that almost 22% of genes occur AS ( Yu et al., 2020 ). Increasing evidences have uncovered that AS events in wheat are enormously related to grain-related traits such as polyphenol oxidase activity ( Sun et al., 2010 ), starch synthase activity ( Zhou et al., 2018 ), and grain weight and size ( Ren et al., 2021 ). AS is also related to abiotic stresses tolerance ( Egawa et al., 2006 ; Liu et al., 2018 ) and disease resistance ( Wang et al., 2020 ; Sánchez-Martín et al., 2021 ).…”

Wheat Breeding through Genetic and Physical Mapping 2

“…On the same topic, Ren et al [6] studied a candidate gene for the yield component of grain weight and size in bread wheat. The authors identified five splicing variants of the Gγ subunit gene TaGS3 (TaGS3.1 to TaGS3.5), which showed expression divergence during wheat polyploidization and a differential function in grain weight and size determination.…”