外源磺肽素调控茭白分蘖的内源激素和转录组分析OA

INTRODUCTION:Zizania latifolia is the second largest aquatic vegetable(after lotus root)in China,with remarkable economic and nutritional value,but it is currently facing declining quality as well as production,and is in urgent need of breeding improvement.Phytosulfokine(PSK)is a recently discovered small peptide hormone for plant growth regulation with strong potential in agricultural applications.However,its molecular mechanisms in regulating tillering in Z.latifolia has not been investigated.In this study,we used PSK-treated Z.latifolia as the material,combined with transcriptome se-quencing(accession No.PRJNA1377146),fluorescence quantitative PCR validation and endogenous hormone determi-nation,to investigate the molecular and physiological mechanisms of PSK in regulating the tillering of Z.latifolia,and to provide a theoretical basis and technological support for the high-yield and high-quality cultivation of Z.latifolia. RATIONALE:PSK can regulate the physiological processes such as cell elongation and development of meristematic tissues,and can promote crop growth and delay senescence.To understand the molecular mechanisms of the PSK regulation,it is crucial to systematically analyze the changes in gene expression of Z.latifolia after PSK treatment,com-bined with the measurement of endogenous hormones and the tillering phenotypes,to uncover the key regulatory genes in the key metabolic pathways that control Z.latifolia tillering. RESULTS:PSK treatment significantly promoted tillering in Z.latifolia,with the number of tillers at 14 days of treatment being 122.22％higher than that of the control group.The optimal concentration of PSK treatment is 1 μmol·L-1,and the optimal application"window"is about 14 days after treatment.We identified a total of 806 differentially expressed genes(365 up-regulated and 441 down-regulated)after PSK treatment compared with the untreated tissues.GO enrichment analysis showed that the differentially expressed genes were mainly involved in biological processes such as response to water deficit,cell wall organization,and KEGG analysis showed that the differentially expressed genes were significantly enriched in the pathways of phenylpropane biosynthesis and tryptophan metabolism.Four differentially expressed genes were verified by fluorescence quantitative PCR.Furthermore,we measured the content of endogenous hormones,showing significantly increased content of growth hormone,gibberellin and jasmonic acid after PSK treatment(GA3 in-creased by 188.59％),and significantly decreased content of abscisic acid and cytokinin with significantly altered hormone ratios. CONCLUSION:We found that exogenous PSK regulates the tillering and growth of Z.latifolia through multiple pathways.It significantly alters the endogenous hormone levels,promotes the increase of growth-related hormones and inhibits the decrease of hormone-like hormones;it regulates the key metabolic pathways such as phenylpropane biosynthesis and fatty acid degradation,and influences the synthesis of the cell wall and energy metabolism;and it promotes the synthesis of indoleacetic acid through the expression of the key genes in the tryptophan metabolic pathway,which provides the material and signal basis for tillering.This study reveals the molecular mechanism of Z.latifolia tillering regulated by PSK,and provides theoretical support and potential technical solutions for improving the yield and quality of Z.latifolia.