Genome-wide analysis of genetic variations between dominant and recessive NILs of glanded and glandless cottons

Cotton is an important economic crop in worldwide. It produces fiber for the textile industry and provides cottonseeds with high-quality protein and oil. However, the presence of gossypol limits the utilization of cottonseed. Two pairs of cotton near isogenic lines (NILs) with different pigment glands, i.e., Coker 312 vs Coker 312 W and CCRI12 vs CCRI12W, exhibit different gossypol contents. The glandless traits of Coker 312 W and CCRI12W are controlled by recessive and dominant genes, respectively. However, knowledge regarding the genomic variations in the NILs is limited. Therefore, the NILs genomes were resequenced and the sequencing depths were greater than 34×. Compared with the TM-1 genome, numerous SNPs, Indels, SVs, and CNVs were discovered. KEGG pathway analysis revealed that genes with SNPs and Indels from the recessive NILs and genes with Indels from the dominant NILs shared only one enriched pathway, i.e., the sesquiterpenoid and triterpenoid biosynthesis pathway, which is relevant to gossypol biosynthesis. Expression analysis revealed that key genes with variations that participate in the gossypol biosynthesis and pigment gland formation pathways had different expression patterns among the dominant, recessive glandless and glanded plants. The expression levels in the glanded organs were higher than those in their NILs. Altogether, our results provide deeper insight into cotton NILs with different pigment glands.