Robert W. Holley Center for Agriculture and Health, USDA-ARS, Cornell University, Ithaca, NY, 14853, USA.
College of Horticulture, Sichuan Agricultural University, Wenjiang, 611130, Sichuan, China.
Theor Appl Genet. 2020 Jan;133(1):353-364. doi: 10.1007/s00122-019-03466-2. Epub 2019 Nov 1.
Gr5.1 is the major locus for cauliflower green curd color and mapped to an interval of 236 Kbp with four most likely candidate genes. Cauliflower with colored curd enhances not only the visual appeal but also the nutritional value of the crop. Green cauliflower results from ectopic development of chloroplasts in the normal white curd. However, the underlying genetic basis is unknown. In this study, we employed QTL-seq analysis to identify the loci that were associated with green curd phenotype in cauliflower. A F2 population was generated following a cross between a white curd (Stovepipe) and a green curd (ACX800) cauliflower plants. By whole-genome resequencing and SNP analysis of green and white F2 bulks, two QTLs were detected on chromosomes 5 (Gr5.1) and 7 (Gr7.1). Validation by traditional genetic mapping with CAPS markers suggested that Gr5.1 represented a major QTL, whereas Gr7.1 had a minor effect. Subsequent high-resolution mapping of Gr5.1 in the second large F2 population with additional CAPS markers narrowed down the target region to a genetic and physical distance of 0.3 cM and 236 Kbp, respectively. This region contained 35 genes with four of them representing the best candidates for the green curd phenotype in cauliflower. They are LOC106295953, LOC106343833, LOC106345143, and LOC106295954, which encode UMP kinase, DEAD-box RNA helicase 51-like, glutathione S-transferase T3-like, and protein MKS1, respectively. These findings lay a solid foundation for the isolation of the Gr gene and provide a potential for marker-assisted selection of the green curd trait in cauliflower breeding. The eventual isolation of Gr will also facilitate better understanding of chloroplast biogenesis and development in plants.
Gr5.1 是花椰菜绿花球颜色的主要位点，位于一个 236 Kbp 的区间内，包含四个最可能的候选基因。有色花椰菜不仅增强了作物的视觉吸引力，还提高了其营养价值。绿花椰菜是由于叶绿体在正常白花球中的异位发育而产生的。然而，其潜在的遗传基础尚不清楚。在这项研究中，我们采用 QTL-seq 分析鉴定了与花椰菜绿花球表型相关的位点。通过白花球（Stovepipe）和绿花球（ACX800）花椰菜植株的杂交产生了一个 F2 群体。通过对绿球和白球 F2 群体的全基因组重测序和 SNP 分析，在染色体 5（Gr5.1）和 7（Gr7.1）上检测到两个 QTL。通过 CAPS 标记的传统遗传作图验证表明，Gr5.1 代表一个主要 QTL，而 Gr7.1 则具有较小的效应。随后，在第二个包含更多 CAPS 标记的大型 F2 群体中对 Gr5.1 进行高分辨率作图，将目标区域缩小到遗传距离和物理距离分别为 0.3 cM 和 236 Kbp。该区域包含 35 个基因，其中 4 个基因代表花椰菜绿花球表型的最佳候选基因，它们是 LOC106295953、LOC106343833、LOC106345143 和 LOC106295954，分别编码 UMP 激酶、DEAD-box RNA 解旋酶 51 样蛋白、谷胱甘肽 S-转移酶 T3 样蛋白和蛋白 MKS1。这些发现为 Gr 基因的分离奠定了坚实的基础，并为花椰菜育种中绿花球性状的标记辅助选择提供了潜力。Gr 的最终分离也将有助于更好地理解植物中叶绿体的生物发生和发育。
