【目的】分析玉米脱镁叶绿酸氧化酶基因ZmPAO序列多态性,并挖掘该基因与玉米成熟后期穗位叶叶绿素组分含量相关的功能位点,为基于ZmPAO开发功能标记提供结构信息,有助于对玉米成熟后期叶绿素代谢遗传机制的理解。【方法】以141份具有广...【目的】分析玉米脱镁叶绿酸氧化酶基因ZmPAO序列多态性,并挖掘该基因与玉米成熟后期穗位叶叶绿素组分含量相关的功能位点,为基于ZmPAO开发功能标记提供结构信息,有助于对玉米成熟后期叶绿素代谢遗传机制的理解。【方法】以141份具有广泛遗传变异的玉米自交系为试验材料组成关联群体,以2个环境7个时间点的叶绿素组分含量为表型数据,利用Tassel 5.0通过混合线性模型(MLM,mixed linear model)开展玉米脱镁叶绿酸氧化酶基因(ZmPAO)与成熟后不同时期叶绿素组分变化的相关变异位点的关联分析,并对性状的有效关联位点进行单倍型分析。【结果】在玉米生长后期大部分取样时间点的叶绿素组分含量变异较大,叶绿素a普遍低于叶绿素b的含量,最终总叶绿素(叶绿素a与叶绿素b的和)有下降趋势。结果共鉴定ZmPAO中19个有效功能位点,其中4个处于外显子区,1个位于UTR区域,其他均位于内含子区域;功能位点对叶绿素组分含量变异的表型解释率在3.89%~16.57%,总表型效应在5.24%~41.78%。来自第6个内含子的位点S3235对于Yang-chlb6有高达16.57%的表型解释率;第7外显子S3675分别解释了Yang-chla1和Yangchlb1表型变异的12.16%和14.14%。性状显著单倍型中有利位点和关联分析的变异位点偏好相似。【结论】有效功能位点挖掘和性状单倍型分析表明,ZmPAO外显子发生了2个氨基酸变异,均由疏水氨基酸转化为亲水氨基酸,说明该基因可能通过蛋白结构的变异进行调控,但较多关联位点处于非编码区,说明该基因也受转录水平的调控。转录水平受环境影响较大,故导致该基因出现不同地点因播期和生育期的不同找到的关联位点并不一致,但有效变异位点的存在具有普遍性。展开更多
该研究以黄瓜“津春2号”cDNA为模板,采用RT-PCR方法克隆得到黄瓜叶绿素降解关键酶(pheophorbide a oxygenase,PAO)基因(CsPAO),对其进行亚细胞定位观察,并采用实时荧光定量PCR技术和生物信息学技术,分析了CsPAO基因的表达模式及其编码...该研究以黄瓜“津春2号”cDNA为模板,采用RT-PCR方法克隆得到黄瓜叶绿素降解关键酶(pheophorbide a oxygenase,PAO)基因(CsPAO),对其进行亚细胞定位观察,并采用实时荧光定量PCR技术和生物信息学技术,分析了CsPAO基因的表达模式及其编码蛋白的特性。结果表明:(1)CsPAO编码545个氨基酸,理论等电点为6.09,蛋白相对分子质量为61.02 kD。蛋白预测发现,黄瓜CsPAO属于不稳定蛋白,具有2个蛋白结合位点,且存在跨膜现象。(2)荧光定量PCR结果表明,CsPAO基因表达响应水杨酸(SA)、茉莉酸(JA)和赤霉素(GA3)的调控,在高温(42℃)和低温(4℃)处理下CsPAO基因的表达量显著上升并达到最高,但黑暗处理对CsPAO基因表达没有影响;在黄瓜不同组织中花的表达显著高于根、茎、叶、萼、须、果。(3)亚细胞定位结果表明,CsPAO蛋白定位于叶绿体内。(4)系统进化树分析显示,黄瓜CsPAO与葫芦科植物苦瓜、西葫芦、南瓜、笋瓜等亲缘关系较近。本研究结果为进一步揭示黄瓜叶绿素降解的分子机制奠定了基础。展开更多
Leaf senescence is one of the major factors contributing to the productivity and the grain quality in crops. The regulatory mechanism of leaf senescence remains largely unknown. Here, we report the identification and ...Leaf senescence is one of the major factors contributing to the productivity and the grain quality in crops. The regulatory mechanism of leaf senescence remains largely unknown. Here, we report the identification and characterization of a rice e_aarly senescence 1 （easl） mutant, which displayed an early leaf senescence phenotype, accompanying by dwarfism and reduced tiller number, eventually leading to the reduction of grain yield. Map-based cloning revealed that the nuclear gene EAS1 encodes a pheophorbide a oxygenase （PaO）, a key enzyme for chlorophyll breakdown. A highly conserved Thr residue of PaO was mutated into Ile in the easl mutant. Phylogenetic analysis indicates that PaO is an evolutionarily conserved protein, and EAS1 is 68% identical to the Arabidopsis ACCERLERATED CELL DEATH （ACD1） protein. Unlike ACD1 that contains a single transit peptide, EAS1 contains two putative transit peptides at its N-ter- minus, which are essential for its functionality, suggesting that targeting of EAS1 to the chloroplast is likely mediated by a putative bipartite transit peptide. Consistently, only a short version of EAS1 lacking the first putative transit peptide, but not the full-length EAS1, was capable of rescuing the Arabidopsis acdl mutant phenotype. These results suggest that rice EASI represents a functional PaO, which is involved in chlorophyl/degradation and may utilize a unique mechanism for its import into the chloroplast.展开更多
文摘【目的】分析玉米脱镁叶绿酸氧化酶基因ZmPAO序列多态性,并挖掘该基因与玉米成熟后期穗位叶叶绿素组分含量相关的功能位点,为基于ZmPAO开发功能标记提供结构信息,有助于对玉米成熟后期叶绿素代谢遗传机制的理解。【方法】以141份具有广泛遗传变异的玉米自交系为试验材料组成关联群体,以2个环境7个时间点的叶绿素组分含量为表型数据,利用Tassel 5.0通过混合线性模型(MLM,mixed linear model)开展玉米脱镁叶绿酸氧化酶基因(ZmPAO)与成熟后不同时期叶绿素组分变化的相关变异位点的关联分析,并对性状的有效关联位点进行单倍型分析。【结果】在玉米生长后期大部分取样时间点的叶绿素组分含量变异较大,叶绿素a普遍低于叶绿素b的含量,最终总叶绿素(叶绿素a与叶绿素b的和)有下降趋势。结果共鉴定ZmPAO中19个有效功能位点,其中4个处于外显子区,1个位于UTR区域,其他均位于内含子区域;功能位点对叶绿素组分含量变异的表型解释率在3.89%~16.57%,总表型效应在5.24%~41.78%。来自第6个内含子的位点S3235对于Yang-chlb6有高达16.57%的表型解释率;第7外显子S3675分别解释了Yang-chla1和Yangchlb1表型变异的12.16%和14.14%。性状显著单倍型中有利位点和关联分析的变异位点偏好相似。【结论】有效功能位点挖掘和性状单倍型分析表明,ZmPAO外显子发生了2个氨基酸变异,均由疏水氨基酸转化为亲水氨基酸,说明该基因可能通过蛋白结构的变异进行调控,但较多关联位点处于非编码区,说明该基因也受转录水平的调控。转录水平受环境影响较大,故导致该基因出现不同地点因播期和生育期的不同找到的关联位点并不一致,但有效变异位点的存在具有普遍性。
文摘该研究以黄瓜“津春2号”cDNA为模板,采用RT-PCR方法克隆得到黄瓜叶绿素降解关键酶(pheophorbide a oxygenase,PAO)基因(CsPAO),对其进行亚细胞定位观察,并采用实时荧光定量PCR技术和生物信息学技术,分析了CsPAO基因的表达模式及其编码蛋白的特性。结果表明:(1)CsPAO编码545个氨基酸,理论等电点为6.09,蛋白相对分子质量为61.02 kD。蛋白预测发现,黄瓜CsPAO属于不稳定蛋白,具有2个蛋白结合位点,且存在跨膜现象。(2)荧光定量PCR结果表明,CsPAO基因表达响应水杨酸(SA)、茉莉酸(JA)和赤霉素(GA3)的调控,在高温(42℃)和低温(4℃)处理下CsPAO基因的表达量显著上升并达到最高,但黑暗处理对CsPAO基因表达没有影响;在黄瓜不同组织中花的表达显著高于根、茎、叶、萼、须、果。(3)亚细胞定位结果表明,CsPAO蛋白定位于叶绿体内。(4)系统进化树分析显示,黄瓜CsPAO与葫芦科植物苦瓜、西葫芦、南瓜、笋瓜等亲缘关系较近。本研究结果为进一步揭示黄瓜叶绿素降解的分子机制奠定了基础。
基金supported by grants from Chinese Academy of Sciences (No. XDA0801040102)National Natural Science Foundation of China (No. 30770209)State Key Laboratory of Plant Genomics (No. SKLPG2011A0210)
文摘Leaf senescence is one of the major factors contributing to the productivity and the grain quality in crops. The regulatory mechanism of leaf senescence remains largely unknown. Here, we report the identification and characterization of a rice e_aarly senescence 1 （easl） mutant, which displayed an early leaf senescence phenotype, accompanying by dwarfism and reduced tiller number, eventually leading to the reduction of grain yield. Map-based cloning revealed that the nuclear gene EAS1 encodes a pheophorbide a oxygenase （PaO）, a key enzyme for chlorophyll breakdown. A highly conserved Thr residue of PaO was mutated into Ile in the easl mutant. Phylogenetic analysis indicates that PaO is an evolutionarily conserved protein, and EAS1 is 68% identical to the Arabidopsis ACCERLERATED CELL DEATH （ACD1） protein. Unlike ACD1 that contains a single transit peptide, EAS1 contains two putative transit peptides at its N-ter- minus, which are essential for its functionality, suggesting that targeting of EAS1 to the chloroplast is likely mediated by a putative bipartite transit peptide. Consistently, only a short version of EAS1 lacking the first putative transit peptide, but not the full-length EAS1, was capable of rescuing the Arabidopsis acdl mutant phenotype. These results suggest that rice EASI represents a functional PaO, which is involved in chlorophyl/degradation and may utilize a unique mechanism for its import into the chloroplast.
