Development of chloroplast derived SSR markers for genus Allium and their characterization in the allies for genetic improvement of Alliums

Abstract

Alliums are the most popular for their culinary usage and nutraceutical benefits. Their production is greatly affected by the multiple biotic and abiotic stresses. Poor characterizations of genetic resources are the major bottleneck in the genetic improvement of Alliums. Chloroplast-derived simple sequence repeat has recently gained much popularity due to their maternal inheritance and low recombination along with their hypervariable nature. In this study, 22 of the 28 chloroplast-derived markers from chloroplast genomes of A. cepa and A. sativum were reported as polymorphic and cross-transferable. Tetra nucleotide repeats were more prevalent (52 %) in these 22 cpSSR markers as compared to other repeat motifs. Further polymorphic information content of these 22cpSSR markers ranged from 0.007 to 0.427. Based on the genotyping of 22cpSSR markers, 25 Alliums were clustered into two groups (groups I, IIA, and IIB). This showed that cultivated Allium cepa and Allium sativum belong to group II rather than the majority of wild Alliums, which belong to group I. Hence This proved the widespread use of these AccpSSR and AscpSSR markers. Additionally, it was clear from 79 Alliums morphological and genotyping-based clustering that these 79 wild Alliums exhibit strong clustering consistency in genotyping and phenotyping-based dendrograms, hence confirming these cpSSR's discrimination potential. Allium tuberosum Rottler ex. Spreng is quite distinct from Allium fistulosum L, A. schoenoprasumas as well as Allium cepa var. aggregatum G.Don. Further Allium fistulosum L, A. schoenoprasum and Allium cepa var. aggregatum are closely related, according to genotyping-based dendrograms of 79 wild Alliums. Hence Allium fistulosum L, A. schoenoprasum, and Allium cepa provide a brilliant opportunity for introgression of the high total soluble content, high quercetin content, and allicin content of cultivated Allium into wild Allium as well as the biotic and abiotic stress tolerance of wild Alliums into cultivated Alliums. Subsequent clustering of 79 Alliums further allowed us to identify diverse Alliums for constructing a core collection. Hence present study will be useful for molecular breeding and genomic selection-based crop improvement.