Study On The Molecular Mechanism Of Photoreceptor TaCRY1 Regulating The Plant Height In Wheat

Plant height is not only a critical factor affecting plant architecture,but also an important agronomic trait affecting crop yield.The discovery of and sd1 in wheat and rice promoted the"green revolution" in the world,and the popularization of semi-dwarf wheat and rice varieties significantly promoted the improvement of grain yield worldwide.Light and gibberellin(GA)are two crucial cues affecting plant architecture,which regulate plant height mainly by affecting the stability of DELLA proteins.The proteins encoded by "green revolution gene" Rht-B1b and Rht-D1b are DELLA proteins,which are the main inhibitors of gibberellin(GA)signaling pathway,while the gene SD1 in rice encoded GA20ox,which is a GA synthetase.The regulation of Rht-1 and sd1 on plant height is mainly achieved by inhibiting GA signal transduction or GA biosynthesis,thus increasing the stability of DELLA protein and finally inhibiting plant growth.GA can induce the degradation of DELLA proteins to eliminate their inhibitory effect on plant growth,while light can promote the accumulation of DELLA proteins and inhibit plant growth by reducing GA levels.In this study,the physical and genetic interactions between GA receptor(gibberellin insensitive dwarf 1,GID1)or DELLA proteins with cryptochrome 1(CRY 1)was investigated respectively,and the effects of CRY1 on the physical interactions between GID1 and DELLA proteins was also examined.These results revealed the mechanism of blue light receptor and gibberellin receptor co-regulate plant height by regulating the stability of DELLA proteins.1.With the phylogenetic analysis of blue light receptors CRY1 and cryptochrome 2(CRY2)in wheat and Arabidopsis,the CRY1 homologous gene TaCRY1a-6A was cloned,and a set of pUbi:Flag-TaCRY1a transgenic lines with steady genetic characteristic were constructed.Phenotypic analysis showed that the plant height of the transgenic wheat lines was decreased about 10 cm than the wild-type ’Kenong 199’.This was consistent with the fact that CRY1 could inhibit the hypocotyl elongation under blue light in Arabidopsis.2.The sensitivity of CRY1 to GA3 and the genetic interaction between CRY1 and DELLA proteins were investigated with stable genetic transformation plants in Arabidopsis.We found that CRY1 negatively regulates GA response and promote the accumulation of DELLA proteins,and CRY1 regulated the hypocotyl elongation of Arabidopsis at least in part through the DELLA proteins.3.With the efficient Luciferase Complementation Imaging(LCI)assay,yeast two-hybrid system(Y2H)and co-immunoprecipitation(Co-IP),we proved for that CRY1 directly interacts with DELLA proteins and GID1 in a blue-light-dependent manner in wheat and Arabidopsis.4.LCI assay was performed to analyze the interaction regions between TaCRY1 and TaRht1 in wheat,and we found that the interaction between TaCRYla and TaRht-Bla was mainly mediated by the C-terminal domain of TaCRYla and the C-terminal domain of TaRht-B1a.Furthermore,LCI interference assay and confocal microscopy were conducted to observe the accumulation of RGA protein in Arabidopsis.We conclude that the blue light activated CRY1 competitively inhibited with the interaction between GID1 and DELLA proteins in wheat and Arabidopsis,which increasing the stability of DELLA proteins.Taken together,the photoreceptor CRY1 competitively inhibits GID1-DELLA interactions,thereby increasing the stability of DELLA proteins and promoting DELLA proteins to inhibit plant growth.The discovery of this mechanism will lay a solid theoretical foundation for further interpretation of the ideal plant type of crops.