Pseudomonas aeruginosa SPT08, a tomato endophyte, improves plant growth and controls bacterial wilt in tomato

Endophytes are a class of non-pathogenic microorganisms that reside within a plant and contribute to their health. Here, we isolated several endophytes from cotyledon-stage tomato seedlings that inhibited the growth of Ralstonia pseudosolanacearum, the bacterial wilt pathogen of tomato. One such endophyte, Pseudomonas aeruginosa SPT08, protected tomato seedlings as well as grown-up plants from the wilt disease. SPT08 also improved the tomato plant height by 20% and root growth by 60% in weight. SPT08 colonization inside tomato seedlings as well as in grown-up plants was studied using green fluorescent protein to demonstrate its endophytic behavior. SPT08 exhibited twitching and swimming motility and produced extracellular enzymes such as pectinase, protease, and amylase. SPT08 tested positive for several plant growth-promoting features such as phosphate solubilization, production of siderophore, plant hormone auxin, hydrogen cyanide, and ammonia. These features were further corroborated with SPT08 whole genome sequence. SPT08 genome is 6265489 bp, with 66.59% G+C and 5786 coding genes, including type II, III, and VI protein secretion systems. The antiSMASH tool identified potential for several secondary metabolites, including antibiotics, in SPT08. This study underscores the utility of P. aeruginosa SPT08 bio-protection from bacterial wilt and growth promotion agent in tomato.