Plant Physiol:农科院曾大力和钱前研究组揭示水稻植株发育和叶片
2017年4月28日，国际植物学顶级期刊《Plant Physiology》杂志上在线发表了中国农业科学院水稻研究所种质创新课题组曾大力研究员和钱前研究员合作的题为“A rice PECTATE LYASE-LIKE GENE is required for plant growth and leaf senescence”的科研论文，论文揭示了水稻植株发育和叶片衰老新机制。冷语佳博士、杨窑龙博士和任德勇博士为共同第一作者，曾大力研究员和钱前研究员为共同通讯作者。
果胶裂解酶(PEL E.C.4.2.2.2)是众多果胶降解酶中的成员之一，其能够通过β-消除机制将去酯化的果胶降解成一个短链的果胶分子和一个4,5-不饱和寡聚半乳糖醛酸。果胶裂解酶的研究是在对植物病原菌Erwinia carotovora 和Bacillus polymyxa的研究中最先发现的，其在侵染过程中不仅使植物细胞壁降解，而且激活了植物的保卫系统。在植物中，果胶裂解酶的功能主要表现在花粉、花药和雌蕊发育、果实成熟、抗病和棉纤维的生长等方面。但其在水稻中还鲜有报道。
研究人员利用一个水稻矮杆、早衰突变体dwarf and early-senescence leaf 1(del1)，借助图位克隆手段分离了DEL1基因, 该基因编码一个果胶裂解酶前体(Pectate Lyase Precursor)。DEL1突变导致细胞壁组成成分及结构发生变化，同时引起同聚半乳糖醛酸(Homogalacturonan)甲酯化的升高。这些结果表明，果胶裂解酶介导的细胞壁变化可引起水稻植株发育和叶片衰老。
原文链接：
A rice PECTATE LYASE-LIKE gene is required for plant growth and leaf senescence
原文摘要：
To better understand the molecular mechanisms behind plant growth and leaf senescence in monocot plants, we identified a mutant exhibiting dwarfism and an early-senescence leaf phenotype, termed dwarf and early-senescence leaf (del1). Histological analysis showed that the abnormal growth was caused by a reduction in cell number. Further investigation revealed that the decline in cell number in del1 was affected by the cell cycle. Physiological analysis, transmission electron microscopy, and TUNEL assays showed that leaf senescence was triggered by the accumulation of reactive oxygen species. The DEL1 gene was cloned using a map-based approach. It was shown to encode a pectate lyase (PEL) precursor that contains a PelC domain. DEL1 contains all the conserved residues of PEL and has strong similarity with plant PelC. DEL1 is expressed in all tissues but predominantly in elongating tissues. Functional analysis revealed that mutation of DEL1 decreased the total PEL enzymatic activity, increased the degree of methylesterified homogalacturonan and altered the cell wall composition and structure. In addition, transcriptome assay revealed that a set of cell wall function and senescence related gene expression was altered in del1 plants. Our research indicates that DEL1 is involved in both the maintenance of normal cell division and the induction of leaf senescence. These findings reveal a new molecular mechanism for plant growth and leaf senescence mediated by PECTATE LYASE-LIKE (PLL) genes.
作者：曾大力和钱前
