叶绿素降解与作物产量密切相关,叶绿素降解延迟,能延长作物后期的光合能力,并提高作物产量。近年随着结构生物学、基因组测序和生物信息学的发展,人们已经在植物叶绿素降解机制的研究上取得了一系列进展,特别是对叶绿素降解的主要生化...叶绿素降解与作物产量密切相关,叶绿素降解延迟,能延长作物后期的光合能力,并提高作物产量。近年随着结构生物学、基因组测序和生物信息学的发展,人们已经在植物叶绿素降解机制的研究上取得了一系列进展,特别是对叶绿素降解的主要生化途径——脱镁叶绿酸氧化酶(pheide a oxygenase,Pa O)途径已有深入的了解。主要对近年来叶绿素降解代谢、调控机理、滞绿突变体等三方面的研究进展进行综述,并对未来研究方向进行了展望,旨为作物育种和光高效利用提供理论依据。展开更多
Chlorophyll （Chl） degradation causes leaf yellowing during senescence or under stress conditions. For Chl breakdown, STAY-GREEN1 （SGR1） interacts with Chl catabolic enzymes （CCEs） and light-harvesting complex II...Chlorophyll （Chl） degradation causes leaf yellowing during senescence or under stress conditions. For Chl breakdown, STAY-GREEN1 （SGR1） interacts with Chl catabolic enzymes （CCEs） and light-harvesting complex II （LHCII） at the thylakoid membrane, possibly to allow metabolic channeling of potentially phototoxic Chl breakdown intermediates. Among these Chl catabolic components, SGR1 acts as a key regulator of leaf yellowing. In addition to SGR1 （At4g22920）, the Arabidopsis thaliana genome contains an additional homolog, SGR2 （At4g11910）, whose biological function remains elusive. Under senescence-inducing conditions, SGR2 expression is highly up-regulated, similarly to SGR1 expression. Here we show that SGR2 function counteracts SGR1 activity in leaf Chl degradation; SGR2-overexpressing plants stayed green and the sgr2-1 knockout mutant exhibited early leaf yellowing under age-, dark-, and stress-induced senescence conditions. Like SGR1, SGR2 interacted with LHCII but, in contrast to SGR1, SGR2 interactions with CCEs were very limited. Furthermore, SGR1 and SGR2 formed homo- or heterodimers, strongly suggesting a role for SGR2 in negatively regulat- ing Chl degradation by possibly interfering with the proposed CCE-recruiting function of SGR1. Our data indicate an antagonistic evolution of the functions of SGR1 and SGR2 in Arabidopsis to balance Chl catabolism in chloroplasts with the dismantling and remobilizing of other cellular components in senescing leaf cells.展开更多
Jasmonic acid （JA） functions in plant development, including senescence and immunity. Arabidopsis thaliana CORONATINE INSENSITIVE 1 encodes a JA receptor and functions in the JA‐responsive signaling pathway. The Ar...Jasmonic acid （JA） functions in plant development, including senescence and immunity. Arabidopsis thaliana CORONATINE INSENSITIVE 1 encodes a JA receptor and functions in the JA‐responsive signaling pathway. The Arabidopsis genome harbors a single COI gene, but the rice （Oryza sativa） genome harbors three COI homologs, OsCOI1a, OsCOI1b, and OsCOI2. Thus, it remains unclear whether each OsCOI has distinct, additive, synergistic, or redundant func-tions in development. Here, we use the oscoi1b‐1 knockout mutants to show that OsCOI1b mainly affects leaf senescence under senescence‐promoting conditions. oscoi1b‐1 mutants stayed green during dark‐induced and natural senescence, with substantial retention of chlorophylls and photosyn-thetic capacity. Furthermore, several senescence‐associated genes were downregulated in oscoi1b‐1 mutants, including homologs of Arabidopsis thaliana ETHYLENE INSENSITIVE 3 and ORESARA 1, important regulators of leaf senescence. These results suggest that crosstalk between JA signaling and ethylene signaling affects leaf senescence. The Arabidopsis coi1‐1 plants containing 35S：OsCOI1a or 35S：OsCOI1b rescued the delayed leaf senescence during dark incubation, sug-gesting that both OsCOI1a and OsCOI1b are required for promoting leaf senescence in rice. oscoi1b‐1 mutants showed significant decreases in spikelet fertility and grain weight, leading to severe reduction of grain yield, indicating that OsCOI1‐mediated JA signaling affects spikelet fertility and grain filling.展开更多
Increasing photosynthetic capacity by extending canopy longevity during grain filling using slow senescing stay-green genotypes is a possible means to improve yield in wheat. Ethyl methanesulfonate （EMS） mutated whe...Increasing photosynthetic capacity by extending canopy longevity during grain filling using slow senescing stay-green genotypes is a possible means to improve yield in wheat. Ethyl methanesulfonate （EMS） mutated wheat lines （Triticum aestivum L. cv. Paragon） were screened for fast and slow canopy senescence to investigate the impact on yield and nitrogen partitioning. Stay-green and fast-senescing lines with similar anthesis dates were characterised in detail. Delayed senescence was only apparent at higher nitrogen supply with low nitrogen supply enhancing the rate of senescence in all lines. In the stay-green line 3 （SG3）, on a whole plant basis, tiller and seed number increased whilst thousand grain weight （TGW） decreased; although a greater N uptake was observed in the main tiller, yield was not affected. In fast-senescing line 2 （FS2）, yield decreased, principally as a result of decreased TGW. Analysis of N-partitioning in the main stem indicated that although the slow-senescing line had lower biomass and consequently less nitrogen in all plant parts, the proportion of biomass and nitrogen in the flag leaf was greater at anthesis compared to the other lines; this contributed to the grain N and yield of the slow-senescing line at maturity in both the main tiller and in the whole plant. A field trial confirmed senescence patterns of the two lines, and the negative impact on yield for FS2 and a positive impact for SG3 at low N only. The lack of increased yield in the slow-senescing line was likely due to decreased biomass and additionally a possible sink limitation.展开更多
文摘叶绿素降解与作物产量密切相关,叶绿素降解延迟,能延长作物后期的光合能力,并提高作物产量。近年随着结构生物学、基因组测序和生物信息学的发展,人们已经在植物叶绿素降解机制的研究上取得了一系列进展,特别是对叶绿素降解的主要生化途径——脱镁叶绿酸氧化酶(pheide a oxygenase,Pa O)途径已有深入的了解。主要对近年来叶绿素降解代谢、调控机理、滞绿突变体等三方面的研究进展进行综述,并对未来研究方向进行了展望,旨为作物育种和光高效利用提供理论依据。
文摘Chlorophyll （Chl） degradation causes leaf yellowing during senescence or under stress conditions. For Chl breakdown, STAY-GREEN1 （SGR1） interacts with Chl catabolic enzymes （CCEs） and light-harvesting complex II （LHCII） at the thylakoid membrane, possibly to allow metabolic channeling of potentially phototoxic Chl breakdown intermediates. Among these Chl catabolic components, SGR1 acts as a key regulator of leaf yellowing. In addition to SGR1 （At4g22920）, the Arabidopsis thaliana genome contains an additional homolog, SGR2 （At4g11910）, whose biological function remains elusive. Under senescence-inducing conditions, SGR2 expression is highly up-regulated, similarly to SGR1 expression. Here we show that SGR2 function counteracts SGR1 activity in leaf Chl degradation; SGR2-overexpressing plants stayed green and the sgr2-1 knockout mutant exhibited early leaf yellowing under age-, dark-, and stress-induced senescence conditions. Like SGR1, SGR2 interacted with LHCII but, in contrast to SGR1, SGR2 interactions with CCEs were very limited. Furthermore, SGR1 and SGR2 formed homo- or heterodimers, strongly suggesting a role for SGR2 in negatively regulat- ing Chl degradation by possibly interfering with the proposed CCE-recruiting function of SGR1. Our data indicate an antagonistic evolution of the functions of SGR1 and SGR2 in Arabidopsis to balance Chl catabolism in chloroplasts with the dismantling and remobilizing of other cellular components in senescing leaf cells.
基金the support of ‘Cooperative Research Program for Agriculture Science & Technology Development (PJ00812802)’, Rural Development Administration, Republic of Korea
文摘Jasmonic acid （JA） functions in plant development, including senescence and immunity. Arabidopsis thaliana CORONATINE INSENSITIVE 1 encodes a JA receptor and functions in the JA‐responsive signaling pathway. The Arabidopsis genome harbors a single COI gene, but the rice （Oryza sativa） genome harbors three COI homologs, OsCOI1a, OsCOI1b, and OsCOI2. Thus, it remains unclear whether each OsCOI has distinct, additive, synergistic, or redundant func-tions in development. Here, we use the oscoi1b‐1 knockout mutants to show that OsCOI1b mainly affects leaf senescence under senescence‐promoting conditions. oscoi1b‐1 mutants stayed green during dark‐induced and natural senescence, with substantial retention of chlorophylls and photosyn-thetic capacity. Furthermore, several senescence‐associated genes were downregulated in oscoi1b‐1 mutants, including homologs of Arabidopsis thaliana ETHYLENE INSENSITIVE 3 and ORESARA 1, important regulators of leaf senescence. These results suggest that crosstalk between JA signaling and ethylene signaling affects leaf senescence. The Arabidopsis coi1‐1 plants containing 35S：OsCOI1a or 35S：OsCOI1b rescued the delayed leaf senescence during dark incubation, sug-gesting that both OsCOI1a and OsCOI1b are required for promoting leaf senescence in rice. oscoi1b‐1 mutants showed significant decreases in spikelet fertility and grain weight, leading to severe reduction of grain yield, indicating that OsCOI1‐mediated JA signaling affects spikelet fertility and grain filling.
基金Derkx AP received support from the Lawes Agricultural TrustRothamsted Research and the John Innes Centre receive funding from the Biotechnology and Biological Research Council of the United Kingdom
文摘Increasing photosynthetic capacity by extending canopy longevity during grain filling using slow senescing stay-green genotypes is a possible means to improve yield in wheat. Ethyl methanesulfonate （EMS） mutated wheat lines （Triticum aestivum L. cv. Paragon） were screened for fast and slow canopy senescence to investigate the impact on yield and nitrogen partitioning. Stay-green and fast-senescing lines with similar anthesis dates were characterised in detail. Delayed senescence was only apparent at higher nitrogen supply with low nitrogen supply enhancing the rate of senescence in all lines. In the stay-green line 3 （SG3）, on a whole plant basis, tiller and seed number increased whilst thousand grain weight （TGW） decreased; although a greater N uptake was observed in the main tiller, yield was not affected. In fast-senescing line 2 （FS2）, yield decreased, principally as a result of decreased TGW. Analysis of N-partitioning in the main stem indicated that although the slow-senescing line had lower biomass and consequently less nitrogen in all plant parts, the proportion of biomass and nitrogen in the flag leaf was greater at anthesis compared to the other lines; this contributed to the grain N and yield of the slow-senescing line at maturity in both the main tiller and in the whole plant. A field trial confirmed senescence patterns of the two lines, and the negative impact on yield for FS2 and a positive impact for SG3 at low N only. The lack of increased yield in the slow-senescing line was likely due to decreased biomass and additionally a possible sink limitation.
