Leaf senescence can impact crop production by either changing photosynthesis duration, or by modifying the nutrient remobiliza- tion efficiency and harvest index. The doubling of the grain yield in major cereals in th...Leaf senescence can impact crop production by either changing photosynthesis duration, or by modifying the nutrient remobiliza- tion efficiency and harvest index. The doubling of the grain yield in major cereals in the last 50 years was primarily achieved through the extension of photosynthesis duration and the increase in crop biomass partitioning, two things that are intrinsically coupled with leaf senescence. In this review, we consider the functionality of a leaf as a function of leaf age, and divide a leaf＇s life into three phases： the functionality increasing phase at the early growth stage, the full functionality phase, and the senescence and functionality decreasing phase. A genetic framework is proposed to describe gene actions at various checkpoints to regulate leaf development and senescence. Four categories of genes contribute to crop production： those which regulate （Ⅰ） the speed and transition of early leaf growth, （Ⅱ） photosynthesis rate, （Ⅲ） the onset and （Ⅳ） the progression of leaf senescence. Current advances in isolating and characterizing senescence regulatory genes are discussed in the leaf aging and crop production context. We argue that the breeding of crops with leaf senescence ideotypes should be an essential part of further crop genetic improvement.展开更多
Probenazole （3-allyloxy-l,2-benzisothiazole-1,1-dioxide, PBZ）, the active component of Oryzemate, could induce systemic acquired resistance （SAR） in plants through the induction of salicylic acid （SA） biosynthes...Probenazole （3-allyloxy-l,2-benzisothiazole-1,1-dioxide, PBZ）, the active component of Oryzemate, could induce systemic acquired resistance （SAR） in plants through the induction of salicylic acid （SA） biosynthesis. As a widely used chemical inducer, PBZ is a good prospect for establishing a new chemical-inducible system. We first designed artificially synthetic promoters with tandem copies of a single type of cis-element （SARE, JERE, GCC, GST1, HSRE, and W-box） that could mediate the expression of the tS-glucuronidase （GUS） reporter gene in plants upon PBZ treatment. Then we combined different types of elements in order to improve inducibility in the PBZ-inducible system. On the other hand, we were surprised to find that the cis-elements, which are responsive to jasmonic acid （JA） and ethylene, also responded to PBZ, implying that SA, JA, and ethylene pathways also would play important roles in PBZ＇s action. Further analysis demonstrated that PBZ also induced early events of innate immunity via a signaling pathway in which Ca2＋ influx and mitogen-activated protein kinase （MAPK） activity were involved. We constructed synthesized artificial promoters to establish a PBZ chemical-inducible system, and preliminarily explored SA, JA, ethylene, calcium, and MAPK signaling pathways via PBZ-inducible system, which could provide an insight for in-depth study.展开更多
基金supported in part by a grant to H.C.Jing from the National Natural Science Foundation of China(No.30970252)
文摘Leaf senescence can impact crop production by either changing photosynthesis duration, or by modifying the nutrient remobiliza- tion efficiency and harvest index. The doubling of the grain yield in major cereals in the last 50 years was primarily achieved through the extension of photosynthesis duration and the increase in crop biomass partitioning, two things that are intrinsically coupled with leaf senescence. In this review, we consider the functionality of a leaf as a function of leaf age, and divide a leaf＇s life into three phases： the functionality increasing phase at the early growth stage, the full functionality phase, and the senescence and functionality decreasing phase. A genetic framework is proposed to describe gene actions at various checkpoints to regulate leaf development and senescence. Four categories of genes contribute to crop production： those which regulate （Ⅰ） the speed and transition of early leaf growth, （Ⅱ） photosynthesis rate, （Ⅲ） the onset and （Ⅳ） the progression of leaf senescence. Current advances in isolating and characterizing senescence regulatory genes are discussed in the leaf aging and crop production context. We argue that the breeding of crops with leaf senescence ideotypes should be an essential part of further crop genetic improvement.
基金supported by the National Key Project of Transgenic Variety Development of China(Nos.2011ZX08009-004 and 2013ZX08009-004)Shanghai Key Laboratory of Bio-Energy Cropsthe Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),China
文摘Probenazole （3-allyloxy-l,2-benzisothiazole-1,1-dioxide, PBZ）, the active component of Oryzemate, could induce systemic acquired resistance （SAR） in plants through the induction of salicylic acid （SA） biosynthesis. As a widely used chemical inducer, PBZ is a good prospect for establishing a new chemical-inducible system. We first designed artificially synthetic promoters with tandem copies of a single type of cis-element （SARE, JERE, GCC, GST1, HSRE, and W-box） that could mediate the expression of the tS-glucuronidase （GUS） reporter gene in plants upon PBZ treatment. Then we combined different types of elements in order to improve inducibility in the PBZ-inducible system. On the other hand, we were surprised to find that the cis-elements, which are responsive to jasmonic acid （JA） and ethylene, also responded to PBZ, implying that SA, JA, and ethylene pathways also would play important roles in PBZ＇s action. Further analysis demonstrated that PBZ also induced early events of innate immunity via a signaling pathway in which Ca2＋ influx and mitogen-activated protein kinase （MAPK） activity were involved. We constructed synthesized artificial promoters to establish a PBZ chemical-inducible system, and preliminarily explored SA, JA, ethylene, calcium, and MAPK signaling pathways via PBZ-inducible system, which could provide an insight for in-depth study.
