Key Laboratory of Horticultural Plant Biology, Ministry of Education, Key Laboratory of Horticultural Crop Biology, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China.
Theor Appl Genet. 2022 Feb;135(2):473-483. doi: 10.1007/s00122-021-03977-x. Epub 2021 Oct 29.
We identified the loss of BoFLC gene as the cause of non-vernalization requirement in B. oleracea. Our developed codominant marker of BoFLC gene can be used for breeding program of B. oleracea crops. Many species of the Brassicaceae family, including some Brassica crops, require vernalization to avoid pre-winter flowering. Vernalization is an unfavorable trait for Chinese kale (Brassica oleracea var. chinensis Lei), a stem vegetable, and therefore it has been lost during its domestication/breeding process. To reveal the genetics of vernalization variation, we constructed an F population through crossing a Chinese kale (a non-vernalization crop) with a kale (a vernalization crop). Using bulked segregant analysis (BSA) and RNA-seq, we identified one major quantitative trait locus (QTL) controlling vernalization and fine-mapped it to a region spanning 80 kb. Synteny analysis and PCR-based sequencing results revealed that compared to that of the kale parent, the candidate region of the Chinese kale parent lost a 9,325-bp fragment containing FLC homolog (BoFLC). In addition to the BoFLC gene, there are four other FLC homologs in the genome of B. oleracea, including Bo3g005470, Bo3g024250, Bo9g173370, and Bo9g173400. The qPCR analysis showed that the BoFLC had the highest expression among the five members of the FLC family. Considering the low expression levels of the four paralogs of BoFLC, we speculate that its paralogs cannot compensate the function of the lost BoFLC, therefore the presence/absence (PA) polymorphism of BoFLC determines the vernalization variation. Based on the PA polymorphism of BoFLC, we designed a codominant marker for the vernalization trait, which can be used for breeding programs of B. oleracea crops.
我们发现 BoFLC 基因的缺失是甘蓝型油菜非春化需求的原因。我们开发的 BoFLC 基因共显性标记可用于甘蓝型油菜作物的育种计划。芸薹属的许多物种，包括一些芸薹属作物，需要春化作用来避免冬季前开花。春化作用是一种不利于中国白菜（芸薹属白菜变种。chinensis Lei）的不利性状，中国白菜是一种茎菜，因此在其驯化/育种过程中已经丢失。为了揭示春化变异的遗传学，我们通过杂交中国白菜（非春化作物）和羽衣甘蓝（春化作物）构建了一个 F 群体。利用混池分离分析（BSA）和 RNA-seq，我们鉴定出一个控制春化的主效数量性状位点（QTL），并将其精细定位到一个跨越 80kb 的区域。同线性分析和基于 PCR 的测序结果表明，与羽衣甘蓝亲本相比，中国白菜亲本的候选区域丢失了一个包含 FLC 同源物（BoFLC）的 9325bp 片段。除了 BoFLC 基因外，甘蓝型油菜基因组中还有其他四个 FLC 同源物，包括 Bo3g005470、Bo3g024250、Bo9g173370 和 Bo9g173400。qPCR 分析显示，在 FLC 家族的五个成员中，BoFLC 的表达量最高。考虑到 BoFLC 的四个旁系同源物的低表达水平，我们推测它们的旁系同源物不能补偿丢失的 BoFLC 的功能，因此 BoFLC 的存在/缺失（PA）多态性决定了春化变异。基于 BoFLC 的 PA 多态性，我们设计了一个春化性状的共显性标记，可以用于甘蓝型油菜作物的育种计划。
