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Abstract：
\'Akituki\' (Pyrus pyrifolia Nakai.) is a very popular and profitable pear cultivar in China. However, its high susceptibility to cork spot disorder has limited its expansion of cultivated area. The mechanisms of cork spot disorder have been discussed extensively, focusing on Ca2+ deficiency, yet no consensus has been made. In this study, we applied nitrendipine (NI) as a Ca2+ uptake inhibitor to explore the role of calcium in cork spot disorder occurrence. Results showed that NI treatment on the fruit remarkably increased the incidence of cork spot disorder; alteration of mineral contents happened at the early developmental stage of the fruit, especially on the outer flesh and the peel of the fruit; and this gap was filled gradually along with the expansion of the fruit. Significant differences in the expression levels of Ca2+ transport-related genes were found in the inner flesh, outer flesh and peel during the fruit growth period. The observation of free Ca2+ localization indicated the intracellular imbalance of Ca2+ in the NI-treated fruit. In conclusion, NI treatment reduced the calcium content in the fruit at an early developmental stage, altered the related expression of genes and influenced the cellular Ca2+ balance in the fruit, which prompted the occurrence of cork spot disorder. Measures for the prevention and control of cork spot disorder should be taken at the early stage of the fruit development in the field.
摘要：
\'Akituki\'（PyruspyrifoliaNakai。）是中国非常受欢迎且有利可图的梨品种。然而,其对软木塞斑病的高度易感性限制了其耕地面积的扩大。对软木斑紊乱的机制进行了广泛的讨论,关注Ca2+缺乏，然而，尚未达成共识。在这项研究中,我们应用尼群地平（NI）作为Ca2摄取抑制剂，以探讨钙在软木斑点疾病发生中的作用。结果表明，NI处理显著增加了果实软木斑病的发生率；矿物质含量的变化发生在果实的早期发育阶段，特别是在水果的外皮和果皮上；随着水果的扩大，这种差距逐渐被填补。内肉中Ca2+转运相关基因的表达水平存在显著差异,在果实生长期外皮和果皮。对游离Ca2+定位的观察表明在NI处理的果实中Ca2+的胞内失衡。总之,NI处理在早期发育阶段降低了果实中的钙含量，改变了相关基因的表达，影响了果实中细胞的Ca2+平衡，这促使了软木塞斑病的发生。在田间果实发育的早期，应采取防治软木斑病的措施。
