Abstract Climate change has resulted in alterations in temperature, soil salinity and droughts in many parts of the world. Carica papaya is one of the most important tropical fruits worldwide, although it is considered as a tolerant crop, water deficit stress affects its production. The aim of the present work was first to identify genes of the SHINE clade of AP2/ERF domain in the genome of C. papaya also, to characterize and compare the physiological performance, the total content of waxes and the expression levels of genes involved in wax biosynthesis in two papaya genotypes of contrasting tolerance (Maradol and Yuc1), when exposed to water deficit stress. Two genes (CpSHN1 and CpSHN2) were identified in C. papaya. It was clear that under water deficit stress, Yuc1 (a wild genotype collected at its center of origin), accumulated more cuticular waxes and had higher expression of both CpSHN1 and CpSHN2 genes than Maradol. This increased wax content might partly contribute to the higher water-deficit stress tolerance observed in Yuc1. Our results suggest that in response to water-deficit stress, CpSHN genes are involved in wax biosynthesis in C. papaya, allowing the accumulation of waxes (particularly alkanes). Both genotypes, showed tolerance to water stress, however the ability of Yuc1 to upregulate stress tolerance related genes faster than Maradol, might have favored an increased amount of waxes in leaves, contributing partly to its greater water-deficit stress tolerance than its commercial counterpart Maradol. The expression levels of CpSHN1 increased 30-fold in Yuc1 in response to water deficits and this was correlated with its superior ability to accumulate waxes. Although more studies are needed to further evaluate the functionality of CpSHN in water-limiting environments, our results suggest that CpSHN1 might be a good candidate gene to increase the water-deficit stress tolerance of this important tropical species.

中文翻译：

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番木瓜AP2/ERF结构域转录因子基因SHINE进化枝的鉴定；它们的基因表达及其在野生和商业木瓜基因型中蜡积累和缺水胁迫耐受性中的可能作用

摘要 气候变化导致世界许多地区的温度、土壤盐分和干旱发生变化。Carica papaya 是世界上最重要的热带水果之一，虽然它被认为是一种耐受性作物，但缺水压力会影响其产量。本工作的目的是首先鉴定木瓜基因组中 AP2/ERF 结构域 SHINE 进化枝的基因，表征和比较木瓜的生理性能、蜡的总含量和参与基因的表达水平。当暴露于缺水压力时，两种具有对比耐受性的木瓜基因型（Maradol 和 Yuc1）中的蜡生物合成。在木瓜中鉴定了两个基因（CpSHN1 和 CpSHN2）。很明显，在缺水压力下，Yuc1（在其起源中心收集的野生基因型），积累了更多的角质层蜡质，并且 CpSHN1 和 CpSHN2 基因的表达都高于 Maradol。这种增加的蜡含量可能部分有助于在 Yuc1 中观察到的更高的缺水胁迫耐受性。我们的结果表明，为了应对缺水压力，CpSHN 基因参与了木瓜中的蜡生物合成，从而允许蜡（特别是烷烃）的积累。两种基因型都表现出对水分胁迫的耐受性，但是 Yuc1 比 Maradol 更快地上调胁迫耐受相关基因的能力可能有利于叶片中蜡量的增加，部分原因是其比商业对应物 Maradol 具有更强的缺水胁迫耐受性. 响应于缺水，CpSHN1 的表达水平在 Yuc1 中增加了 30 倍，这与其优越的积累蜡的能力相关。尽管需要更多的研究来进一步评估 CpSHN 在限水环境中的功能，但我们的研究结果表明，CpSHN1 可能是提高这一重要热带物种缺水胁迫耐受性的良好候选基因。