GW5 acts in the brassinosteroid signalling pathway to regulate grain width and weight in rice

Abstract

Grain size is a major determinant of grain yield in cereal crops. qSW5/GW5, which exerts the greatest effect on rice grain width and weight, was fine-mapped to a 2,263-bp/21-kb genomic region containing a 1,212-bp deletion, respectively. Here, we show that a gene encoding a calmodulin binding protein, located ∼5 kb downstream of the 1,212-bp deletion, corresponds to qSW5/GW5. GW5 is expressed in various rice organs, with highest expression level detected in young panicles. We provide evidence that the 1,212-bp deletion affects grain width most likely through influencing the expression levels of GW5. GW5 protein is localized to the plasma membrane and can physically interact with and repress the kinase activity of rice GSK2 (glycogen synthase kinase 2), a homologue of Arabidopsis BIN2 (BRASSINOSTEROID INSENSITIVE2) kinase, resulting in accumulation of unphosphorylated OsBZR1 (Oryza sativa BRASSINAZOLE RESISTANT1) and DLT (DWARF AND LOW-TILLERING) proteins in the nucleus to mediate brassinosteroid (BR)-responsive gene expression and growth responses (including grain width and weight). Our results suggest that GW5 is a novel positive regulator of BR signalling and a viable target for genetic manipulation to improve grain yield in rice and perhaps in other cereal crops as well.

GW5‐Like, a homolog of GW5, negatively regulates grain width, weight and salt resistance in rice

“…GW5L was co‐expressed with the plasma membrane‐targeted marker, OsSCAMP‐mCherry (Lam et al ) (Figure C). These assays indicated that GW5L was also localized at the plasma membrane, like GW5 (Liu et al ).…”

Whole-Genome Analysis of Candidate genes Associated with Seed Size and Weight in Sorghum bicolor Reveals Signatures of Artificial Selection and Insights into Parallel Domestication in Cereal Crops

“…In Arabidopsis , a kinase cascade consisting of HAIKU1, HAIKU2 , and MINISEED3 promotes seed development zygotically (Luo et al, 2005; Wang et al, 2010), while TTG2 (Garcia et al, 2005), AP2 (Ohto et al, 2009), and ARF2 (Okushima et al, 2005) are engaged in the maternal control of seed size. In rice, QTLs including GS3 (Mao et al, 2010), GS5 (Li et al, 2011), GW2 (Song et al, 2007), GW5 (Liu et al, 2017), GW8 (Wang S. et al, 2012), and GL7 (Wang Y. et al, 2015) were reported to regulate seed size by controlling cell division, while the influence of SRS3 (Kitagawa et al, 2010), D61 (Morinaka et al, 2006), and SRS5 (Segami et al, 2012) on seed size is related to the regulation of cell size. Additionally, the role of GIF1 in carbon partitioning during early seed-filling, which can impact seed weight, has been identified using functional analysis in rice (Wang et al, 2008).…”

OsmiR396d Affects Gibberellin and Brassinosteroid Signaling to Regulate Plant Architecture in Rice

“…In rice, the dephosphorylation of GSK3/SHAGGY-like Kinase (OsGSK2, a rice homolog of Arabidopsis BIN2) releases its suppression on BRASSINAZOLE-RESISTANT1 (OsBZR1), LEAF AND TILLER ANGLE INCREASED CONTROLLER (OsLIC), DWARF AND LOW-TILLERING (OsDLT), OVATE Family Protein 8, and REDUCED LEAF ANGLE1 to activate BR response and increase leaf angle (Bai et al, 2007;Wang, L et al, 2008;Tong et al, , 2012Zhang et al, 2012;Yang et al, 2016, Qiao et al, 2017. The kinase activity of OsGSK2 can also be directly inhibited by membrane protein GW5 (quantitative trait locus for grain width and weight on chromosome 5), which is a calmodulin-binding protein (Liu et al, 2017).…”