Dissecting the role of climacteric ethylene in kiwifruit (Actinidia chinensis) ripening using a 1-aminocyclopropane-1-carboxylic acid oxidase knockdown line
Dissecting the role of climacteric ethylene in kiwifruit (Actinidia chinensis) ripening using a 1-aminocyclopropane-1-carboxylic acid oxidase knockdown line
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DOI：
10.1093/jxb/err063
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发表时间：
2011-07-01
影响因子：
6.9
通讯作者：
Schaffer, Robert J.
中科院分区：
文献类型：
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作者：
Atkinson, Ross G.;Gunaseelan, Kularajathevan;Schaffer, Robert J.
在更年期果实成熟过程中，自催化（II型）乙烯产生启动了转录级联反应，控制了许多重要果实品质性状的产生，包括风味产生和软化。乙烯生物合成的最后一步是1-氨基环丙烷-1-羧酸（ACC）由ACC氧化酶（ACO）转化为乙烯。以抑制果实成熟相关的ACO基因为目标，培育了10个独立的猕猴桃品系，其中一个品系（TK2）的果实不产生可检测到的更年期乙烯。猕猴桃群体在收获时的成熟行为是不同步的，因此外源乙烯的短暂爆发使TK2和对照果实同步成熟。经过这样的处理，TK2和对照水果软化到“吃熟”的硬度。对照果实产生更年期乙烯，并在5 d后变软，而TK2果实在50 ~ 25 d内保持了食熟硬度，总挥发物产量显著降低。连续施用外源乙烯对成熟受阻的TK2果实进行了重新启动果实软化和典型成熟果实挥发物的检测。17500个基因芯片鉴定出401个在乙烯处理后发生变化的基因，包括参与细胞壁分解的聚半乳糖醛酸酶和果胶裂解酶，以及可能参与挥发性物质产生的醌氧化还原酶。许多基因变化与乙烯处理后观察到的软化和风味变化一致。然而，令人惊讶的是，大量功能未知的基因也被观察到，这可以解释成熟猕猴桃的独特风味和质地特性。
During climacteric fruit ripening, autocatalytic (Type II) ethylene production initiates a transcriptional cascade that controls the production of many important fruit quality traits including flavour production and softening. The last step in ethylene biosynthesis is the conversion of 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene by the enzyme ACC oxidase (ACO). Ten independent kiwifruit (Actinidia chinensis) lines were generated targeting suppression of fruit ripening-related ACO genes and the fruit from one of these lines (TK2) did not produce detectable levels of climacteric ethylene. Ripening behaviour in a population of kiwifruit at harvest is asynchronous, so a short burst of exogenous ethylene was used to synchronize ripening in TK2 and control fruit. Following such a treatment, TK2 and control fruit softened to an 'eating-ripe' firmness. Control fruit produced climacteric ethylene and softened beyond eating-ripe by 5 d. In contrast, TK2 fruit maintained an eating-ripe firmness for > 25 d and total volatile production was dramatically reduced. Application of continuous exogenous ethylene to the ripening-arrested TK2 fruit re-initiated fruit softening and typical ripe fruit volatiles were detected. A 17 500 gene microarray identified 401 genes that changed after ethylene treatment, including a polygalacturonase and a pectate lyase involved in cell wall breakdown, and a quinone oxidoreductase potentially involved in volatile production. Many of the gene changes were consistent with the softening and flavour changes observed after ethylene treatment. However, a surprisingly large number of genes of unknown function were also observed, which could account for the unique flavour and textural properties of ripe kiwifruit.