Simultaneous transgenic suppression of LePG and LeExp1 influences fruit texture and juice viscosity in a fresh market tomato variety
Simultaneous transgenic suppression of LePG and LeExp1 influences fruit texture and juice viscosity in a fresh market tomato variety
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DOI：
10.1021/jf034165d
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发表时间：
2003-12-03
影响因子：
6.1
通讯作者：
Bennett, AB
中科院分区：
文献类型：
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作者：
Powell, ALT;Kalamaki, MS;Bennett, AB
西红柿是为新鲜食用或加工水果而种植的。水果的一些成熟相关过程可以促进或降低与新鲜和加工质量相关的属性。例如，细胞壁解体与新鲜水果硬度的损失以及加工番茄产品粘度的损失有关。几种酶有助于细胞壁多糖的分解。多聚半乳糖醛酸酶（PG，聚[ 1，4-α-D-半乳糖醛酸苷]葡聚糖水解酶，EC 3.2.1.15）是成熟番茄果实中最丰富的多糖水解酶之一，并且是果胶解聚的主要贡献者。扩展蛋白（LeExp 1）也丰富的成熟水果，并提出有助于细胞壁解体的非水解活性，可能是通过增加其他酶的底物可及性。单独抑制LePG或LeExp 1表达会导致软化和/或保质期特性改变。为了测试同时抑制LePG和LeExp 1表达是否会以相加或协同的方式影响果实质地，转基因番茄（Lycopersicon esculentum var.将LePG或LeExp 1表达降低的Ailsa克雷格系杂交。分析来自第三代后代的果实（对于两种转基因构建体均为纯合的）在葡萄藤上或离开葡萄藤成熟期间的硬度和其它质量性状。在田间生长的转基因番茄果实中，单独抑制LeExp 1或LePG并不能显著增加果实硬度。然而，抑制LePG和LeExp 1表达的果实在整个成熟过程中显着更坚固，并且在长期储存期间不易变质。从LePG和LeExp 1表达减少的转基因番茄果实制备的果汁比从对照果实制备的果汁更粘稠。
Tomatoes are grown for fresh consumption or for processing of the fruit. Some ripening-associated processes of the fruit can either contribute to or degrade attributes associated with both fresh and processing quality. For example, cell wall disassembly is associated with loss of fresh fruit firmness as well as with loss of processed tomato product viscosity. Several enzymes contribute to cell wall polysaccharide disassembly. Polygalacturonase (PG, poly[ 1, 4-alpha-D-galactouronide] glucanohydrolase, EC 3.2.1.15) is among the most abundant polysaccharide hydrolases in ripening tomato fruit and is the major contributor to pectin depolymerization. Expansin (LeExp1) is also abundant in ripening fruit and is proposed to contribute to cell wall disassembly by nonhydrolytic activity, possibly by increasing substrate accessibility to other enzymes. Suppression of either LePG or LeExp1 expression alone results in altered softening and/or shelf life characteristics. To test whether simultaneous suppression of both LePG and LeExp1 expression influences fruit texture in additive or synergistic ways, transgenic Lycopersicon esculentum var. Ailsa Craig lines with reduced expression of either LePG or LeExp1 were crossed. Fruits from the third generation of progeny, homozygous for both transgenic constructs, were analyzed for firmness and other quality traits during ripening on or off the vine. In field-grown transgenic tomato fruit, suppression of LeExp1 or LePG alone did not significantly increase fruit firmness. However, fruits suppressed for both LePG and LeExp1 expression were significantly firmer throughout ripening and were less susceptible to deterioration during long-term storage. Juice prepared from the transgenic tomato fruit with reduced LePG and LeExp1 expression was more viscous than juice prepared from control fruit.