High-density GBS-based genetic linkage map construction and QTL identification associated with leaf cuticular wax, adaxial stomatal density and leaf water retention capacity in banana

The drought tolerance quantitative trait locus (QTL) in Banana has not been studied to date. In this study, the susceptible parent Musa acuminata ssp. burmannicoides Colla -'Calcutta-4' and the resistant parent Musa balbisiana collection 'Bee hee kela' were crossed to produce an F1 mapping population of 96 individuals for the purpose of mapping drought tolerance traits in banana. Consequently, an entirely novel mapping population was developed using progenitor lines with distinct genomic compositions (A genome and B genome). We employed, the GBS (Genotype By Sequencing) technique to develop a genetic linkage map. The map contained a total of 1015 SNP markers, 11 linkage groups, and a total distance of 4828.88cM. The average distance between markers was 4.9cm. The two primary methods that a plant loses water are through stomata and cuticle transpiration, both of which is not beneficial for the plant. Thus, in the present investigation, the AB mapping population's adaxial stomatal count is measured using a microscopic technique, and leaf cuticular wax was estimated using a spectroscopic method. In addition, the leaf's water retention capacity was estimated. Genetic analysis showed that the drought tolerance traits exhibited moderate to moderately high PCV, GCV, and GAM values, as well as high heritability. Using the GBS-based genetic linkage map and phenotyping information, the QTL analysis identified five main QTLs for drought tolerance on chromosomes 2, 5, and 8. They were designated as wax13_1, wax15_1, wax15_2, lwrc_1, and asd_1. The PVE (per cent) of the identified QTLs varied between 15.9 and 19.8 percent. To our knowledge, this is the first report on the employing of SNP markers to identify QTLs associated with drought tolerance traits in banana. This study's findings will be helpful in fine-mapping and marker-assisted selection in banana for drought related traits.

Automated summary

In this study, a mapping population of 96 individuals was generated through crossbreeding of two banana parents. A genetic linkage map was constructed using GBS technique, which consisted of 1015 SNP markers. Five QTLs associated with drought tolerance traits were identified on chromosomes 2, 5, and 8. This is the first report of using SNP markers to study drought tolerance traits in banana, and the findings will contribute to fine mapping and marker-assisted selection for drought related traits.