Plant growth-promoting endophytic microbiota from garlic bulbs

Garlic (Allium sativum L.) is a high-value horticultural crop whose bulbs provide a unique ecological niche for specialized endophytic microbiota. Despite their potential as microbial reservoirs for plant health and biocontrol, these endophytes remain poorly studied, particularly within clove meristems. This study investigated the cultivable endophytic communities from clove meristems of ten Mexican garlic varieties. A total of 119 bacterial isolates, belonging to 14 genera, and 38 fungal isolates, grouped into 2 genera, were obtained. The bacteria exhibited key functional traits, including nutrient solubilization, nitrogen fixation, and hydrolytic enzyme production, with most strains significantly promoting the growth of garlic explants. In contrast, the isolated fungi (Fusarium and Penicillium) proved pathogenic. In antagonism assays, Paenibacillus sp. MP10 and Rhodococcus sp. MP3 showed high inhibition (65.38-94.74%) against the tested fungal strains. In garlic germination assays, Pseudomonas sp. 1JPC and Enterobacter sp. 2AMTX, 2APTE, and 4AMTX increased root length 2-fourfold, root number 3-fourfold, and fresh weight approximately onefold. In maize bioassays, Phytobacter sp. 5AMCH94, Pseudomonas sp. 1APCY, and Paenibacillus sp. H1 enhanced seedling area by 20-60%, seedling length by 10-30%, root number by 30-140%, and dry weight by 40-50%. Furthermore, 16S rRNA sequencing revealed that inoculation with Paenibacillus sp. H1 increased endophytic bacterial diversity and the relative abundance of Comamonadaceae and Lactobacillaceae. These findings highlight the value of garlic meristems as reservoirs for microbial bioinoculant development and the recovery of conserved varieties.