AUTHOR=Xiao Zhiliang , Han Fengqing , Hu Yang , Xue Yuqian , Fang Zhiyuan , Yang Limei , Zhang Yangyong , Liu Yumei , Li Zhansheng , Wang Yong , Zhuang Mu , Lv Honghao 

TITLE=Overcoming Cabbage Crossing Incompatibility by the Development and Application of Self-Compatibility-QTL- Specific Markers and Genome-Wide Background Analysis

JOURNAL=Frontiers in Plant Science

VOLUME=Volume 10 - 2019

YEAR=2019

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2019.00189

DOI=10.3389/fpls.2019.00189

ISSN=1664-462X

ABSTRACT=<p>Cabbage hybrids, which clearly present heterosis vigor, are widely used in agricultural production. We compared two <italic>S5</italic> haplotype (Class II) cabbage inbred-lines 87–534 and 94–182: the former is highly SC while the latter is highly SI; sequence analysis of SI-related genes including <italic>SCR</italic>, <italic>SRK</italic>, <italic>ARC1</italic>, <italic>THL1</italic>, and <italic>MLPK</italic> indicates the some SNPs in <italic>ARC1</italic> and <italic>SRK</italic> of 87–534; semi-quantitative analysis indicated that the SI-related genes were transcribed normally from DNA to mRNA. To unravel the genetic basis of SC, we performed whole-genome mapping of the quantitative trait loci (QTLs) governing self-compatibility using an F<sub>2</sub> population derived from 87–534 × 96–100. Eight QTLs were detected, and high contribution rates (CRs) were observed for three QTLs: <italic>qSC7.2</italic> (54.8%), <italic>qSC9.1</italic> (14.1%) and <italic>qSC5.1</italic> (11.2%). 06–88 (CB201 × 96–100) yielded an excellent hybrid. However, F<sub>1</sub> seeds cannot be produced at the anthesis stage because the parents share the same <italic>S-</italic>haplotype (<italic>S57</italic>, class I). To overcome crossing incompatibility, we performed rapid introgression of the self-compatibility trait from 87–534 to 96–100 using two self-compatibility-QTL-specific markers, BoID0709 and BoID0992, as well as 36 genome-wide markers that were evenly distributed along nine chromosomes for background analysis in recurrent back-crossing (BC). The transfer process showed that the proportion of recurrent parent genome (PRPG) in BC<sub>4</sub>F<sub>1</sub> was greater than 94%, and the ratio of individual SC plants in BC<sub>4</sub>F<sub>1</sub> reached 100%. The newly created line, which was designated SC96–100 and exhibited both agronomic traits that were similar to those of 96–100 and a compatibility index (CI) greater than 5.0, was successfully used in the production of the commercial hybrid 06–88. The study herein provides new insight into the genetic basis of self-compatibility in cabbage and facilitates cabbage breeding using SC lines in the male-sterile (MS) system.</p>