Study Of Effect Of Blue Light On Gibberellin Signal Transduction During Photomorphogenesis In Arabidopsis Thaliana

Plant growth is affected by many environmental factors,such as temperature,humidity,light and so on.Light is not only a source of energy,but also a part of the environment that affects the growth and development of plants.Plants perceive light through light receptors,in which cryptochromes?CRYs?are the main light receptors in Arabidopsis thaliana,which participate in regulating the whole life cycle of plants.As for the endogenous factors affecting plant growth,hormone is an important factor in regulating plant growth and development.Gibberellin,as an important hormone,has been found and confirmed in the early stage,and plays an important role in the photomorphogenesis of plants.Our laboratory has demonstrated that blue light is involved in regulating the accumulation of active gibberellin?GA?in the photomorphogenesis in Arabidopsis thaliana.Whether blue light is involved in the regulation of GA signal transduction in light morphogenesis remains unclear.In this paper,we studied the effect of blue light on GA signal transduction during photomorphogenesis in Arabidopsis thaliana using blue light receptor mutants as materials,and obtained the following results:?1?Wild type Col-0 was seeded on 1/2MS medium containing GA₃ and PAC?Paclobutrazo?,and cultured under different blue light intensity.The longer the seedling hypocotyl was,the weaker the response of the seedling hypocotyl elongation to GA was.The response of cry1 mutant and CRY1-OX overexpression to GA under blue light was further detected.It was found that the response of cry1 mutant to GA was enhanced,while the response of CRY1-OX overexpression to GA was weakened.This indicated that CRY1mediated blue light inhibited the induction of GA to hypocotyl elongation.Further detection of the transcription level of gibberellin response related genes in cry1 mutant under blue light,PAC treatment or PAC and GA₃ treatment showed that the expression level of related genes in cry1 mutant was higher than that in wild type,which further indicated that blue light receptor CRY1 participated in the inhibition of gibberellin signal by blue light.?2?The protein level of GA signal inhibitor RGA in wild type Col-0 was detected after different concentrations of GA₃ were treated under blue light or dark.It was found that blue light inhibited the degradation of RGA induced by GA and improved the stability of RGA protein.This suggests that the inhibition of gibberellin signal by blue light may be achieved by stabilizing DELLA protein.?3?cry1rag-28 and cry1gai mutant plants were obtained by genetic hybridization.The hypocotyl length of cry1rag-28 double mutant was measured under blue light.It was found that cry1rag-28 double mutant had the same phenotype as cry1 single mutant,showing long hypocotyl.cry1gai double mutant showed intermediate phenotype,and its hypocotyl was shorter than cry1 single mutant and longer than gai single mutant,indicating that the introduced part of gai mutant restored cry1 phenotype.This suggests that DELLA is located downstream of CRY1 to regulate hypocotyl elongation in Arabidopsis under blue light.?4?Strong promoter plant vectors of GA receptors GID1a and GID1b were successfully constructed.The transgenic plants with high expression levels of 35S::GID1a and 35S::GID1b were obtained through selection of vectors,transformation of Arabidopsis thaliana and identification of Western blot,which laid a foundation for further study of the effect of blue light on GA signal transduction during photomorphogenesis in Arabidopsis.These results suggest that blue light receptor CRY1 mediates the signal transduction of gibberellin in blue light-inhibited photomorphogenesis and may be achieved by stabilizing DELLA protein.This provides clues for further study of the relationship between blue light and gibberellin signal transduction during photomorphogenesis in Arabidopsis thaliana.