乙烯与赤霉素协同调控水稻胚芽鞘伸长生长OA

[Objective]Ethylene and gibberellin are key phytohormones regulating rice coleoptile elongation,however,the interaction of ethylene and gibberellin in coleoptile elongation remains unclear.This study aimed to investigate the molecular mechanism of ethylene and gibberellin in regulating coleoptile elongation.[Method]This study utilized transgenic rice lines of the core components of ethylene and gibberellin signaling pathways as experimental materials.The coleoptile lengths were examined with or without different phytohormone treatments.The expression levels of downstream genes of OsEIN2/OsEIL2 were detected by RT-qPCR.Yeast two-hybrid and pull-down assays were further employed to verify the interaction between OsSLR1 and OsEIL2.[Result]Exogenous phytohormones treatment revealed that both ethylene and gibberellin promoted coleoptile elongation,and they exhibited a synergistic effect.Paclobutrazol(PAC,a GA biosynthesis inhibitor)treatment or overexpression of the gibberellin inactivation gene OsGA2ox3 weakened the promoting effect of ethylene on coleoptile elongation,whereas exogenous application of gibberellin partially relieved the 1-MCP(1-Methylcyclopropene)inhibited coleoptile elongation,indicating that ethylene and gibberellin shared a common regulatory pathway in controlling coleoptile elongation.Further studies revealed that OsSLR1,a negative regulator of gibberellin signaling,interacted with OsEIL2.Moreover,OsEIN2/OsEIL2-regulated genes,such as OsERF63,OsERF73,OsHKT2;1 and OsGY1 were also regulated by OsSLR1.The OsSLR1 loss-of-function mutant slr1 exhibited a long coleoptile phenotype,and the promoting effect of ethylene on coleoptile elongation was further enhanced in slr1,suggesting that OsSLR1 was involved in ethylene-mediated coleoptile elongation and signal transduction.[Conclusion]In summary,this study revealed that OsSLR1 served as a crosstalk node for the synergistic regulation of coleoptile elongation by ethylene and gibberellin,and it interacted with OsEIL2 to co-regulate downstream signaling pathways and coleoptile elongation.This study not only enriched the understanding of the phytohormone interaction network in coleoptile growth,but also provided a theoretical basis and useful genes for the breeding of rice varieties suitable for direct seeding cultivation.