Enhanced growth of cabbage seedlings by a Paenibacillus isolate in the presence of Xanthomonas campestris pv. campestris

Abstract

Paenibacillus spp. Are rhizobacteria that can promote plant growth through a range of mechanisms. A New Zealand isolate of Paenibacillus, P16, has reduced the incidence of black rot, caused by Xanthamonas campestris pv. campestris (Xcc), in brassicas. To investigate if this response was provided through plant growth promotion, isolate P16 was co-applied with Xcc as a seed treatment. In the presence of Xcc, P16-treated seedlings had significantly greater root length, leaf area, and root and shoot dry weight compared to the positive control (Xcc alone). There were no significant differences in plant growth parameters between P16-treated seedlings in the absence of the pathogen and the negative control (seeds without Xcc or P16). Isolate P16 enabled plants to survive and grow normally by preventing disease development; the mechanism of disease suppression requires further investigation.