Department of Horticulture, Sunchon National University, Suncheon, 57922, South Korea.
Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, 34141, South Korea.
Appl Biochem Biotechnol. 2018 Apr;184(4):1120-1141. doi: 10.1007/s12010-017-2613-2. Epub 2017 Sep 30.
Kohlrabi (Brassica oleracea var. gongylodes L.) is an important vegetable of the Brassicaceae family. The main edible part of kohlrabi is the swollen stem. The purple cultivars make anthocyanin mainly in the peel of the swollen stem, while in the leaf, it is limited to the midrib, but green cultivars do not. Anthocyanins are advantageous for both plants as well as humans. Two anthocyanin compounds were detected by high pressure liquid chromatography (HPLC) only in the peel of the purple kohlrabi cultivar. Three MYBs, three bHLHs, and one WD40 TF were identified as the candidate regulatory genes in kohlrabi. There was an abundance of transcript levels for the late biosynthetic genes more specifically for BoF3'H, BoDFR, BoLDOX, and BoGST in the purple peel while scarcely detectable in other tissues for both cultivars. The expression of BoPAP2 and BoTT8 was higher in the peel of the purple cultivar than the green cultivar. The expression of BoMYBL2.2 orthologue of Arabidopsis MYBL2, a negative regulator of anthocyanins, was dramatically decreased in the purple peel. The expression of BoACO1, a key gene for ethylene biosynthesis, and BoNCED3, an important gene of the ABA pathway, was down- and upregulated, respectively, in the peel of purple kohlrabi.
大头菜（芸薹属甘蓝变种根菾菜）是十字花科的一种重要蔬菜。大头菜的主要可食用部分是膨大块茎。紫色品种主要在膨大块茎的表皮中产生花青苷，而在叶片中则仅限于中脉，但绿色品种则没有。花青苷对植物和人类都有好处。通过高压液相色谱（HPLC）仅在紫色大头菜品种的表皮中检测到两种花青素化合物。鉴定出三个 MYB、三个 bHLH 和一个 WD40 TF 作为大头菜的候选调节基因。紫色表皮中晚期生物合成基因（特别是 BoF3'H、BoDFR、BoLDOX 和 BoGST）的转录水平丰富，而在两个品种的其他组织中几乎检测不到。紫色品种的 BoPAP2 和 BoTT8 的表达高于绿色品种。拟南芥 MYBL2 的同源物 BoMYBL2.2，花青素的负调控因子，在紫色表皮中的表达显著降低。乙烯生物合成的关键基因 BoACO1 和 ABA 途径的重要基因 BoNCED3 在紫色大头菜的表皮中分别下调和上调。
