Straube Jannis, Chen Yun-Hao, Khanal Bishnu P, Shumbusho Alain, Zeisler-Diehl Viktoria, Suresh Kiran, Schreiber Lukas, Knoche Moritz, Debener Thomas
Institute of Plant Genetics, Molecular Plant Breeding Section, Leibniz University Hannover, Herrenhäuser Straße 2, 30419 Hannover, Germany.
Institute of Horticultural Production Systems, Fruit Science Section, Leibniz University Hannover, Herrenhäuser Straße 2, 30419 Hannover, Germany.
Plants (Basel). 2020 Dec 30;10(1):65. doi: 10.3390/plants10010065.
Exposure of the fruit surface to moisture during early development is causal in russeting of apple ( × Borkh.). Moisture exposure results in formation of microcracks and decreased cuticle thickness. Periderm differentiation begins in the hypodermis, but only after discontinuation of moisture exposure. Expressions of selected genes involved in cutin, wax and suberin synthesis were quantified, as were the wax, cutin and suberin compositions. Experiments were conducted in two phases. In Phase I (31 days after full bloom) the fruit surface was exposed to moisture for 6 or 12 d. Phase II was after moisture exposure had been discontinued. Unexposed areas on the same fruit served as unexposed controls. During Phase I, cutin and wax synthesis genes were down-regulated only in the moisture-exposed patches. During Phase II, suberin synthesis genes were up-regulated only in the moisture-exposed patches. The expressions of cutin and wax genes in the moisture-exposed patches increased slightly during Phase II, but the levels of expression were much lower than in the control patches. Amounts and compositions of cutin, wax and suberin were consistent with the gene expressions. Thus, moisture-induced russet is a two-step process: moisture exposure reduces cutin and wax synthesis, moisture removal triggers suberin synthesis.
苹果（×Borkh.）发育早期果实表面接触水分是导致果实产生锈斑的原因。接触水分会导致微裂纹形成和角质层厚度降低。周皮分化始于皮下组织，但仅在停止接触水分后才开始。对参与角质、蜡质和木栓质合成的选定基因的表达进行了定量分析，同时也分析了蜡质、角质和木栓质的成分。实验分两个阶段进行。在第一阶段（盛花后31天），果实表面接触水分6天或12天。第二阶段是在停止接触水分之后。同一果实上未接触水分的区域作为未接触水分的对照。在第一阶段，角质和蜡质合成基因仅在接触水分的区域下调。在第二阶段，木栓质合成基因仅在接触水分的区域上调。在第二阶段，接触水分区域的角质和蜡质基因表达略有增加，但表达水平远低于对照区域。角质、蜡质和木栓质的含量及成分与基因表达一致。因此，水分诱导的锈斑形成是一个两步过程：接触水分会减少角质和蜡质合成，去除水分会触发木栓质合成。
