Kumar Pawan, Kaplan Yulia, Endelman Jeffrey B, Ginzberg Idit
Institute of Plant Sciences, Agricultural Research Organization, Volcani Institute, 68 HaMacabim Road, P.O. Box 15159, Rishon LeZion 7505101, Israel.
Department of Horticulture, University of Wisconsin-Madison, Madison, WI 53706, USA.
Plants (Basel). 2023 May 22;12(10):2057. doi: 10.3390/plants12102057.
Potato tuber skin is a protective corky tissue consisting of suberized phellem cells. Smooth-skinned varieties are characterized by a clean, shiny appearance compared to the darker hue of russeted potatoes. The rough skin of russeted cultivars is a desired, genetically inherited characteristic; however, unwanted russeting of smooth-skinned cultivars often occurs under suboptimal growth conditions. The involvement of epigenetic modifiers in regulating the smooth skin russeting disorder was tested. We used smooth-skin commercial cultivars with and without the russeting disorder and three lines from a breeding population segregating for russeting. Anatomically, the russet skin showed similar characteristics, whether the cause was environmentally triggered or genetically determined. The old outer layers of the corky phellem remain attached to the newly formed phellem layers instead of being sloughed off. Global DNA methylation analysis indicated a significant reduction in the percentage of 5-methylcytosine in mature vs. immature skin and russet vs. smooth skin. This was true for both the smooth-skin commercial cultivars and the russeted lines. The expression level of selected DNA methyltransferases was reduced in accordance. DNA demethylase expression did not change between the skin types and age. Hence, the reduced DNA methylation in mature and russet skin is more likely to be achieved through passive DNA demethylation and loss of methyltransferase activity.
马铃薯块茎表皮是一种由栓质化木栓细胞组成的保护性木栓组织。与表皮呈深色的糙皮马铃薯相比，表皮光滑的品种具有干净、有光泽的外观特点。糙皮品种的粗糙表皮是一种理想的、可遗传的特征；然而，表皮光滑的品种在生长条件欠佳时常常会出现不必要的糙皮现象。我们对表观遗传修饰因子在调控表皮光滑糙皮紊乱中的作用进行了测试。我们使用了有糙皮紊乱和无糙皮紊乱的表皮光滑商业品种，以及来自一个糙皮性状分离的育种群体的三个株系。从解剖学上看，无论糙皮是由环境触发还是由基因决定，其表皮都表现出相似的特征。木栓质化木栓的旧外层仍附着在新形成的木栓层上，而不是脱落。全基因组DNA甲基化分析表明，成熟表皮与未成熟表皮以及糙皮与光滑表皮相比，5-甲基胞嘧啶的百分比显著降低。这在表皮光滑的商业品种和糙皮株系中均如此。所选DNA甲基转移酶的表达水平相应降低。DNA去甲基化酶的表达在不同表皮类型和年龄之间没有变化。因此，成熟和糙皮表皮中DNA甲基化的降低更有可能是通过被动DNA去甲基化和甲基转移酶活性丧失实现的。
