Exocarp Properties and Transcriptomic Analysis of Cucumber (Cucumis sativus) Fruit Expressing Age-Related Resistance to Phytophthora capsici.
Exocarp Properties and Transcriptomic Analysis of Cucumber (Cucumis sativus) Fruit Expressing Age-Related Resistance to Phytophthora capsici.
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DOI：
10.1371/journal.pone.0142133
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Grumet R
中科院分区：
文献类型：
--
作者：
Ando K;Carr KM;Colle M;Mansfeld BN;Grumet R
非常年轻的黄瓜（Cucumis sativus）果实非常容易受到卵菌病原体辣椒疫霉（Phytophthora capsici）的感染。当果实完成指数生长时，在授粉后约10-12天（dpp），它们转变为抗性。年龄相关耐药性（ARR）的发展越来越被认为是对病原体的重要防御，然而，其潜在机制在很大程度上是未知的。在8 dpp（感病）和16 dpp（抗性）收获的黄瓜果实的果皮切片显示出与整个果实相同的接种反应，表明果实表面在防御辣椒疫霉中起重要作用。16号果实的外果皮角质层较厚，果皮组织的甲醇提取物在离体条件下对辣椒疫霉的生长有抑制作用，这可能是辣椒抗逆反应的物理或化学成分。果皮与果皮中特异表达的转录物显示出功能分化。主要在果皮中表达的转录本与果实表面相关功能一致，包括光合作用、角质层产生、对环境的响应和防御。果皮特异性转录物在16 dpp果实中相对于8 dpp果实表现出增加的表达，其高度富集（P<0.0001）以响应胁迫、信号转导以及细胞外和运输功能。特异性转录物包括与潜在的物理屏障相关的基因（即，角质层）、化学防御（类黄酮生物合成）、氧化应激、渗透防御和分子模式（MAMP）触发或效应物触发（R-基因介导）途径。从敏感和抗性年龄的水果果皮之间的基因表达的发育调节变化表明，随着器官达到完整的大小，增加防御程序。
Very young cucumber (Cucumis sativus) fruit are highly susceptible to infection by the oomycete pathogen, Phytophthora capsici. As the fruit complete exponential growth, at approximately 10–12 days post pollination (dpp), they transition to resistance. The development of age-related resistance (ARR) is increasingly recognized as an important defense against pathogens, however, underlying mechanisms are largely unknown. Peel sections from cucumber fruit harvested at 8 dpp (susceptible) and 16 dpp (resistant) showed equivalent responses to inoculation as did whole fruit, indicating that the fruit surface plays an important role in defense against P. capsici. Exocarp from 16 dpp fruit had thicker cuticles, and methanolic extracts of peel tissue inhibited growth of P. capsici in vitro, suggesting physical or chemical components to the ARR. Transcripts specifically expressed in the peel vs. pericarp showed functional differentiation. Transcripts predominantly expressed in the peel were consistent with fruit surface associated functions including photosynthesis, cuticle production, response to the environment, and defense. Peel-specific transcripts that exhibited increased expression in 16 dpp fruit relative to 8 dpp fruit, were highly enriched (P<0.0001) for response to stress, signal transduction, and extracellular and transport functions. Specific transcripts included genes associated with potential physical barriers (i.e., cuticle), chemical defenses (flavonoid biosynthesis), oxidative stress, penetration defense, and molecular pattern (MAMP)-triggered or effector-triggered (R-gene mediated) pathways. The developmentally regulated changes in gene expression between peels from susceptible- and resistant- age fruits suggest programming for increased defense as the organ reaches full size.