Biological control of root rot fungus Macrophomina phaseolina and growth enhancement of Pinus roxburghii (Sarg.) by rhizosphere competent Bacillus subtilis BN1

Abstract

Bacterial isolates having antifungal and good plant growth-promoting attributes were isolated from chirpine (Pinus roxburghii) rhizosphere. An isolate, Bacillus subtilis BN1 exhibited strong antagonistic activity against Macrophomina phaseolina, and other phytopathogens including Fusarium oxysporum and Rhizoctonia solani. It was characterized and selected for the present studies. BN1 resulted in vacuolation, hyphal squeezing, swelling, abnormal branching and lysis of mycelia. The cell-free culture filtrate of BN1 inhibited the growth of M. phaseolina. Pot trial study resulted in statistically significant increase in seedling biomass besides reduction in root rot symptoms in chir-pine seedlings. BN1 treatment resulted in 43.6% and 93.54% increases in root and shoot dry weights respectively, as compared to control. Also, 80-85% seed viability was recorded in treatments receiving BN1 either alone or in the presence of M. phaseolina, compared to 54.5% with M. phaseolina. Bioinoculant formulation study suggested that maximum viability of bacteria was in a sawdust-based carrier. B. subtilis BN1 produced lytic enzymes, chitinase and b-1,3-glucanase, which are known to cause hyphal degradation and digestion of the cell wall component of M. phaseolina. In the presence of M. phaseolina, population of B1 was 1.5 9 10 4 c.f.u. g -1 root after one month, which increased to 4.5 9 10 4 c.f.u. g -1 root in three months. Positive root colonization capability of B. subtilis BN1 proved it as a potent biocontrol agent.

Pseudomonas aeruginosa KPSE 3 – An Endophytic PGPR for Bio Control of Potato Phytopathogens

“…So from antifungal activity results, the most promising culture KPSE3 was selected for bacterization in a replicated pot trial (Table 4). Similar type of results were recorded by Singh et al, 2008 they reported isolate B. subtilis BU 1 strongly inhibited growth of M. phaseolina with maximum inhibition of 74 % at 5 DAI. They also reported inhibition of F. oxysporum and Pythium sp.…”

Bio-suppression of Sclerotinia Stem Rot of Tomato and Biostimulation of Plant Growth Using Tomato-associated Rhizobacteria

“…In fact, IAA production by saprotrophs and endophytes has been reported to be involved in growth promotion in various plants and, thus, could be responsible, at least in part, for the presently observed plant growth promotion [62,63]. Similar combined effects are displayed by B. subtilis BN applied to chirpine seedlings where reduction in root rot symptoms caused by M. phaseolina in along with 43.6% and 93.45% increased root and shoot dry weight, respectively, are recorded as compared to the untreated control [64]. The use of bacteria as a soil treatment is more effective in suppressing disease than their use as a seed treatment [30].…”

Salinity-resistant plant growth promoting rhizobacteria ameliorates sodium chloride stress on tomato plants

“…A decrease in overall root and shoot weight has also been reported by Soussi et al (1998) in chickpea. This reduction in weight of plants under salt stress may be due to the inhibition or hydrolysis of reserved synthesizing food and its translocation to growing shoot parts (Singh et al 2008). Results show an increase in fresh weight and dry weight of plants grown in the presence of NaCl.…”