Pang Wenxing, Kim Yoon-Young, Li Xiaonan, Choi Su Ryun, Wang Yunbo, Sung Chang-Keun, Im Subin, Ramchiary Nirala, Zhou Guangsheng, Lim Yong Pyo
Molecular Genetics and Genomics Lab, Department of Horticulture, Chungnam National University, Daejeon, Republic of Korea.
College of Horticulture, Shenyang Agricultural University, Shenyang, China P.R.
PLoS One. 2015 Nov 4;10(11):e0142202. doi: 10.1371/journal.pone.0142202. eCollection 2015.
Cabbage belonging to Brassicaceae family is one of the most important vegetables cultivated worldwide. The economically important part of cabbage crop is head, formed by leaves which may be of splitting and non-splitting types. Cabbage varieties showing head splitting causes huge loss to the farmers and therefore finding the molecular and structural basis of splitting types would be helpful to breeders. To determine which anatomical characteristics were related to head-splitting in cabbage, we analyzed two contrasting cabbage lines and their offspring using a field emission scanning electron microscope. The inbred line "747" is an early head-splitting type, while the inbred line "748" is a head-splitting-resistant type. The petiole cells of "747" seems to be larger than those of "748" at maturity; however, there was no significant difference in petiole cell size at both pre-heading and maturity stages. The lower epidermis cells of "747" were larger than those of "748" at the pre-heading and maturity stages. "747" had thinner epidermis cell wall than "748" at maturity stage, however, there was no difference of the epidermis cell wall thickness in the two lines at the pre-heading stage. The head-splitting plants in the F1 and F2 population inherited the larger cell size and thinner cell walls of epidermis cells in the petiole. In the petiole cell walls of "747" and the F1 and F2 plants that formed splitting heads, the cellulose microfibrils were loose and had separated from each other. These findings verified that anomalous cellulose microfibrils, larger cell size and thinner-walled epidermis cells are important genetic factors that make cabbage heads prone to splitting.
十字花科的甘蓝是全球种植的最重要蔬菜之一。甘蓝作物中具有经济重要性的部分是叶球，它由叶片形成，叶片可能有易裂和不易裂两种类型。表现出叶球开裂的甘蓝品种会给农民造成巨大损失，因此，找出开裂类型的分子和结构基础将对育种者有所帮助。为了确定哪些解剖学特征与甘蓝叶球开裂有关，我们使用场发射扫描电子显微镜分析了两个对比的甘蓝品系及其后代。自交系“747”是早期叶球易裂类型，而自交系“748”是抗叶球开裂类型。成熟时，“747”的叶柄细胞似乎比“748”的大；然而，在结球前期和成熟阶段，叶柄细胞大小没有显著差异。在结球前期和成熟阶段，“747”的下表皮细胞比“748”的大。成熟阶段，“747”的表皮细胞壁比“748”的薄，然而，在结球前期，两个品系的表皮细胞壁厚度没有差异。F1和F2群体中的叶球开裂植株继承了叶柄中表皮细胞较大的细胞大小和较薄的细胞壁。在“747”以及形成开裂叶球的F1和F2植株的叶柄细胞壁中，纤维素微纤丝松散且相互分离。这些发现证实，异常的纤维素微纤丝、较大的细胞大小和薄壁表皮细胞是导致甘蓝叶球易裂的重要遗传因素。
