Differential expression of pectate lyase during ethylene-induced postharvest softening of mango (Mangifera indica var. Dashehari)
Differential expression of pectate lyase during ethylene-induced postharvest softening of mango (Mangifera indica var. Dashehari)
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DOI：
10.1111/j.1399-3054.2006.00752.x
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发表时间：
2006-11-01
影响因子：
6.4
通讯作者：
Nath, Pravendra
中科院分区：
文献类型：
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作者：
Chourasia, Amita;Sane, Vidhu A.;Nath, Pravendra
果实成熟的特征是细胞壁的果胶和半纤维素多糖逐步解聚。几种细胞壁水解酶已被研究，它们在多种果实软化中的作用已被涉及。然而，关于果胶裂解酶（PL）的研究在果实组织中非常有限，果胶裂解酶通过糖苷键的β -消除作用降解果胶。我们从成熟的芒果（Mangifera indica var. Dashehari）中克隆了一个PL同源物MiPel1，它与高等植物PL基因具有序列相似性。MiPel1的1.7 - kb互补DNA（登录号AY987389）编码一个由437个氨基酸组成的假定蛋白质，它具有在其他PL中保守的所有基序和活性位点残基。在果实成熟过程中观察到转录本积累逐渐增加，但在1 - 甲基环丙烯处理的果实以及在无外源乙烯的空气中保存的对照果实中，表达显著延迟。该表达对果实具有特异性，且仅在成熟期间被触发。在叶片、茎和花等其他组织以及果实发育过程中未检测到转录本。成熟过程中MiPel1转录本积累的增加与Ca²⁺依赖的PL活性和果胶溶解的增加有关。据推测，PL的表达可能与成熟过程中的果胶降解密切相关，并在芒果软化中起重要作用。
Fruit ripening is characterized by progressive depolymerisation of pectic and hemicellulosic polysaccharides of the cell wall. Several cell-wall hydrolases have been studied and their role implicated in the softening of various fruits. However, studies related to pectate lyases (PL), which degrade pectins through beta-elimination of glycosidic linkages, have been very limited in fruit tissue. We have cloned a PL homologue, MiPel1 from ripening mango (Mangifera indica var. Dashehari), which shows sequence similarity to higher plant PL genes. The 1.7-kb complementary DNA of MiPel1 (accession number AY987389) encodes a putative protein of 437 amino acids, which possesses all the motifs and active site residues conserved in other PL. A progressive increase in transcript accumulation was observed during ripening but expression was delayed significantly in 1-methylcyclopropene-treated and control fruits kept in air without exogenous ethylene. The expression was specific to fruits and triggered only during ripening. No transcript was detected in other tissues such as leaf, stem and flower and during development of the fruit. The increase in transcript accumulation of MiPel1 during ripening was associated with an increase in the Ca+2-dependent PL activity and pectin solubilization. It is proposed that expression of PL may be closely associated with pectin degradation during ripening and play an important role in mango softening.