外源碧护与磷酸二氢钾通过茉莉酸信号途径促进烤烟叶片衰老的机制OA

Field maturity is one of the key factors affecting the yield and quality of tobacco leaves,and the progression of leaf senescence directly influences the development of field maturity in flue-cured tobacco.To investigate the mechanism by which foliar application of exogenous Bihu and potassium dihydrogen phosphate promotes tobacco leaf senescence through hormone signaling pathways,the flue-cured tobacco cultivar'Yunyan 87'was used as the experimental material.A randomized block design was adopted,with water spraying as the control(CK),and two treatments were established:Bihu(T1)and potassium dihydrogen phosphate(T2).The effects of the treatments on leaf yellowing rate,chlorophyll and carotenoid contents,expression of senescence marker genes,antioxidant enzyme activities,malondialdehyde content,endogenous hormone levels,and the expression of key genes involved in hormone signaling pathways were evaluated.The results showed that,compared with CK,both T1 and T2 significantly increased the proportion of yellowing leaves,reduced chlorophyll content,increased carotenoid content,upregulated the expression of senescence-associated genes,inhibited antioxidant enzyme activities,promoted malondialdehyde accumulation,and enhanced jasmonic acid content together with the expression of key genes in its signaling pathway.T1 and T2 showed comparable effects in accelerating leaf senescence and reducing antioxidant enzyme activities.However,in terms of jasmonic acid content,T1 increased the levels by 26.76%,63.01%,and 118.22%relative to CK on days 4,6,and 14,respectively,whereas T2 increased them by 33.80%,55.49%,and 100.44%,respectively.Taken together,both T1 and T2 treatments promoted tobacco leaf senescence by modulating hormone signaling pathways,suggesting that the hormone signaling network may represent an important regulatory route through which exogenous substances modulate leaf senescence during tobacco maturation.