Exploiting plant growth-promotingAmycolatopsissp. for bio-control of charcoal rot of sorghum (Sorghum bicolorL.) caused byMacrophomina phaseolina(Tassi) Goid

Abstract

One strain of Amycolatopsis sp. BCA-696, a rare genus of actinomycete, demonstrated previously for its plant growth-promotion traits in chickpea and sorghum, was tested for its antagonistic potential against Macrophomina phaseolina (the causal agent of charcoal rot disease of sorghum) by dual culture assay, metabolite production assay, and in greenhouse and field screens. In the dual culture and metabolite production assays, BCA-696 inhibited the growth of M. phaseolina. When BCA-696 was tested for its antagonistic activity under greenhouse and field conditions (two seasons) against charcoal rot of sorghum by tooth pick method of inoculation, it significantly reduced the disease. Scanning electron microscope analysis revealed that the xylem and phloem tissues of the BCA-696 treated stem samples were intact compared to that of disease control plants. This study indicates that the selected Amycolatopsis sp. BCA-696 has the potential to manage charcoal rot of sorghum.

Identification and Characterization of a Streptomyces albus Strain and Its Secondary Metabolite Organophosphate against Charcoal Rot of Sorghum

“…This implies that M. phaseolina was not able to colonize in the CAI-21-treated sorghum plants. Similar observations were noted with Streptomyces strains BCA-546 and CAI-8 [13] and Amycolatopsis [17]. These results support the hypothesis that the PGPR not only enhance the plant growth through root colonization but also exhibit indirect benefits such as disease suppression as reported in other studies [29][30][31].…”

“…Charcoal rot of sorghum has been reported to be managed under greenhouse conditions by Bacillus, Brevibacterium, Enterobacter, Acinetobacter, Pseudomonas, and Streptomyces [12,13,18]. However, under field conditions, there is only one report of managing the charcoal rot of sorghum using Amycolatopsis [17]. 21-treated plants when compared to the positive control.…”

“…Charcoal rot of sorghum has been reported to be managed under greenhouse conditions by Bacillus, Brevibacterium, Enterobacter, Acinetobacter, Pseudomonas, and Streptomyces [12,13,18]. However, under field conditions, there is only one report of managing the charcoal rot of sorghum using Amycolatopsis [17]. In the present investigation, when the S. albus CAI-21-and M. phaseolina-treated shoots were observed through the scanning electron microscope, the morphology and size of the phloem and xylem tissues were found to be normal and intact in the S. albus CAI-21-and M. phaseolina-treated stem samples when compared to positive control, where a major portion of the tissues (>90%) was In the present investigation, when the S. albus CAI-21-and M. phaseolina-treated shoots were observed through the scanning electron microscope, the morphology and size of the phloem and xylem tissues were found to be normal and intact in the S. albus CAI-21-and M. phaseolina-treated stem samples when compared to positive control, where a major portion of the tissues (>90%) was found to be damaged ( Figure 5).…”

“…CAI-21 was evaluated for its antifungal activity against M. phaseolina on two-week-old seedlings of susceptible sorghum line 296B using a blotter paper assay [17]. In brief, a total of 3 treatments (CAI-21 + M. phaseolina inoculation; positive control, only M. phaseolina inoculation; and negative control, only sterile water) were tested.…”

“…Advanced sowing date, use of pathogen-free (M. phaseolina-free) seed, solarization of soil, and treatment with thiram and carbendazim are some of the control measures usually employed to manage charcoal rot disease but with limited success [11,12]. Biocontrol of this soil and seed-borne pathogen has also been attempted with beneficial microorganisms such as Bacillus, Pseudomonas, Enterobacter, Trichoderma, Acinetobacter, Amycolatopsis, and Streptomyces [13][14][15][16][17]. This shows the importance of understanding the sorghum-M. phaseolina interactions and identifying more potent biocontrol strategies that could be combined with a moderate level of tolerance in the host to manage this disease.…”