The Bra1K array: an efficient and versatile 1K liquid-phase SNP chip for genetics and breeding in Chinese cabbage

Area of Science:

• Plant genetics and genomics
• Agricultural science
• Molecular breeding

Background:

• Advancing genetics and breeding in Chinese cabbage (Brassica rapa L. ssp. pekinensis) requires cost-effective and efficient genotyping platforms.
• The development of novel SNP chips is crucial for accelerating genetic research and crop improvement.

Purpose of the Study:

• To develop and validate the Bra1K array, a novel 1K liquid-phase SNP chip for Brassica rapa.
• To demonstrate the array's utility in phylogenetic analysis, genetic mapping, and marker-assisted breeding.

Main Methods:

• Genotyping by Target Sequencing (GBTS) was used to develop the Bra1K array with 1002 selected probes.
• The array incorporates markers for key agronomic traits, including disease resistance and flowering time.
• Phylogenetic analysis, high-density genetic map construction, and marker-assisted backcrossing were employed for validation.

Main Results:

• The Bra1K array facilitated phylogenetic analysis of 173 accessions, revealing population structure.
• Two high-density genetic maps were constructed, enabling the localization of genes for dark yellow petals (Br-drp1) and yellow leaves (BrYL1).
• Marker-assisted backcrossing rapidly introgressed the clubroot resistance gene Crr5 into an elite line with high recurrent parent genome recovery.

Conclusions:

• The Bra1K array is a versatile, efficient, and practical genotyping solution for Brassica rapa.
• It effectively integrates genetic exploration with molecular breeding applications.
• This platform accelerates the development of improved Brassica rapa varieties with desirable agronomic traits.