Allium sativum and Allium cepa offer excellent potential for introgression and production of allicin and high total soluble solids into closely related wild Alliums

Abstract

High total soluble solids (HTSS) and high sulfur-containing compounds like allicin are highly demanded by industry due to their variety of pharmaceuticals, and ecologically friendly alternatives to synthetic preservation agents. Compared to wild Alliums, cultivated Alliums are a rich source of HTSS and allicin. For introgression of HTSS trait-related genes in wild Alliums and identification of HTSS containing Allium cepa genotypes, we mined 1178 AcSSR markers and evaluated 200 AcSSR in ten Alliums for polymorphism and cross-transferability. Out of 200 AcSSRs, 72 were polymorphic and cross-transferable in Alliums. Moreover, 96 Allium cepa has been used to identify HTSS-containing genotypes and validate the aforementioned 10 AcSSR markers. Using DNA genotyping based Jaccard dissimilarity-based NJ tree, these 96 Allium cepa were grouped into high total soluble solids (HTSS) and low total soluble solids (LTSS) groups. In addition, 96 Allium cepa populations have been divided into six (K = 6) and three (K = 3) groups based on a Bayesian model. From 96 Allium cepa populations, we identified diverse 9 subsamples of Alliums cepa, by application of the bioinformatics tool “power core”. Surprisingly, out of 9 Alliums cepa subsamples, 6 genotypes have LTSS, and 3 genotypes have HTSS traits. Since we were particularly interested in identifying genes coding for sulphur metabolism also, so we selected 50 differentially expressed genes based on their high expression in Allium sativum compared to Allium cepa. Of the 50 selected genes, 27 were found to be allinase and cystine metabolism genes, 15 were related to glutathione metabolis and 8 were involved in sulphur metabolism. Among 27 genes associated with allinase and cystine metabolism, 25, 18, and 24, as well as genes related to sulphur metabolism, 8, 7, and 8, and glutathione metabolism, 15, 11, and 10 transcripts of Allium sativum showed upregulation in relation to Allium cepa, Allium fragrance, and Allium fistulosum respectively. Real-time PCR expression profiling with a selected 10 sulfur metabolism-related coding genes confirms the authenticity of the RNA-Seq results. Therefore, Allium cepa genotypes which have HTSS, and Allium sativum which has high sulphur-containing compound-like allicin traits might be introduced into wild Allium using these AcSSR markers and genetic engineering approach.