Paenibacillus polymyxa SQR-21 systemically affects root exudates of watermelon to decrease the conidial germination of Fusarium oxysporum f.sp. niveum

Abstract

Paenibacillus polymyxa SQR-21 has been identified as a potential agent for the biocontrol of Fusarium wilt in watermelon, which is caused by the pathogenic fungus Fusarium oxysporum f.sp. niveum (FON). In the present study, the effects of root exudates from watermelon plants inoculated or noninoculated with either SQR-21 or FON on conidial germination of FON were investigated. Compared to the control, conidial germination was decreased with root exudates from SQR-21-inoculated plants, but conidial germination was enhanced by root exudates from FON-inoculated plants. Maximal germination was found with root exudates from FON-inoculated plants after 30 d, which was 1.35 times more germination than the control. A split-root system was designed to verify that the alterations of the exudation pattern in SQR-21-inoculated or FONinoculated watermelon roots were not only local, but also systemic. Cinnamic acid was found in the watermelon root exudates. An assay to test the effects of cinnamic acid on conidial germination of FON revealed that the stimulation of conidial germination was observed from cinnamic acid concentrations ranging from 0 to 30 μg/ml. In conclusion, both of SQR-21 and FON systemically affects watermelon root exudates. These results will help to the better understanding of the plant-microbe communication and will guide to improve the biocontrol strategies against Fusarium wilt of watermelon plants.

PGPR’s mix treatment to Moringa improved plant growth and iron content in foliage as substantiated by biochemical and molecular methods

“…Organic acids such as oxalic acid, citric acid, ascorbic acid and malic acid are main components in root exudates (Ling et al 2011). Similarly, in the present study, oxalic acid and citric acid were detected in all the PGPR's treatments, including control plant root exudates.…”

The response of root-associated bacterial community to the grafting of watermelon

“…The rhizosphere of own-root watermelon also presented an over-representation of Bacilli (Fig. 4), which contained several well-known beneficial microbes, including Bacillus amyloliquefaciens (Xu et al 2013) and Paenibacillus polymyxa (Ling et al 2011). Further investigation also found some beneficial genera, such as Bacillus spp.…”

In vitro study of the growth, development and pathogenicity responses of Fusarium oxysporum to phthalic acid, an autotoxin from Lanzhou lily

“…This may be because the ecologically relevant concentrations of PA were relatively low and insufficient to cause such inhibition. Recent studies have shown that many plant species resist potential soil-borne pathogens by modifying the amounts and composition of organic acids in their root exudates (Hao et al 2010;Kamilova et al 2006;Li et al 2013;Ling et al 2011;Pan et al 2013). Consequently, we believe that decreasing the colony growth and biomass of F. oxysporum by PA would be one of the mechanisms by which lily plants resist this pathogen.…”