The cuticle is composed of cutin and cuticular waxes, and it is the first protective barrier to abiotic and biotic stresses in fruit. In this study, we analysed the composition of and changes in cuticular waxes during fruit development in nectarine (Prunus persica L. Batsch) cultivars, in parallel with their conductance and their susceptibility to Monilinia laxa. The nectarine waxes were composed of triterpenoids, mostly ursolic and oleanolic acids, phytosterols, and very-long-chain aliphatics. In addition, we detected phenolic compounds that were esterified with sugars or with triterpenoids, which are newly described in cuticular waxes. We quantified 42 compounds and found that they changed markedly during fruit development, with an intense accumulation of triterpenoids during initial fruit growth followed by their decrease at the end of endocarp lignification and a final increase in very-long-chain alkanes and hydroxylated triterpenoids until maturity. The surface conductance and susceptibility to Monilinia decreased sharply at the beginning of endocarp lignification, suggesting that triterpenoid deposition could play a major role in regulating fruit permeability and susceptibility to brown rot. Our results provide new insights into the composition of cuticular waxes of nectarines and their changes during fruit development, opening new avenues of research to explore brown rot resistance factors in stone fruit.

中文翻译：

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果实发育过程中油桃的表皮蜡质与表面电导率和对念珠菌的敏感性有关。

角质层由角质层和角质层蜡组成，并且是水果中非生物和生物胁迫的第一个保护性屏障。在这项研究中，我们分析了组成和油桃（果实发育期间改变表皮的蜡桃L. Batsch）品种，与他们的电导和他们的易感性并行褐疏花。油桃蜡由三萜类化合物组成，主要是熊果酸和齐墩果酸，植物甾醇和超长链脂肪族化合物。此外，我们检测到被糖或三萜类化合物酯化的酚类化合物，这些化合物在表皮蜡中有新描述。我们对42种化合物进行了定量分析，发现它们在果实发育过程中发生了显着变化，在最初的果实生长过程中三萜类化合物大量积累，随后在果皮木质素化结束时它们减少，最后长链烷烃和羟基化三萜类化合物最终增加直至成熟。表面电导率和对念珠菌的敏感性内果皮木质化开始时急剧下降，表明三萜类沉积物可能在调节果实的通透性和对褐腐病的敏感性中起主要作用。我们的结果为油桃表皮蜡的组成及其在果实发育过程中的变化提供了新见解，为研究核果中的褐腐抗性因子开辟了新的研究途径。