Bacillus subtilis and Bacillus amyloliquefaciens Mix Suppresses Rhizoctonia Disease and Improves Rhizosphere Microbiome, Growth and Yield of Potato (Solanum tuberosum L.)

Abstract

Black scurf and stem canker caused by Rhizoctonia solani is a significant disease problem of potatoes. Currently, chemical methods are the primary means of controlling this pathogen. This study sought to explore an alternative approach by harnessing the biocontrol potential of a bacterial mix of Bacillus subtilis and Bacillus amyloliquefaciens against black scurf, and to determine their effect on rhizosphere microorganisms of soil microbiota. This study showed that these bacteria demonstrate antagonistic activity against Rhizoctonia solani. Reduced damage to potato plants during the growing season in Siberia was observed. The index of disease development decreased from 40.9% to 12.0%. The treatment of tubers with this mix of bacteria also led to a change in the composition of the rhizosphere microbiota (according to CFU, 16S and ITS sequencing). This effect was accompanied by a positive change in plant physiological parameters (spectrophotometric analysis). The concentration of chlorophyll in potatoes with the bacterial mix treatment increased by 1.3 fold (p ≤ 0.001), and of carotenoids by 1.2 fold (p ≤ 0.01) compared with the control. After bacterial mix treatment, the length of the aerial parts of plants was 1.3 fold higher (p ≤ 0.001), and the number of stems 1.4 fold higher (p ≤ 0.05). The yield of potatoes was increased by 8.2 t/ha, while the large tuber fraction was increased by 16% (p ≤ 0.05). The bacteria mix of Bacillus subtilis and Bacillus amyloliquefaciens suppressed the plant pathogenic fungus Rhizoctonia solani, and simultaneously enhanced the physiological parameters of potato plants. This treatment can be used to enhance the yield/quality of potato tubers under field conditions.

Bacillus velezensis B63 and chitosan control root rot, improve growth and alter the rhizosphere microbiome of geranium

“…Similarly, Wang et al (2023) reported that B. velezensis B19 was highly antagonistic to Panax notoginseng (Sanqi) root rot. Maslennikova et al (2023) found that a mix of B. subtilis and B. amyloliquefaciens suppressed R. solani, and improved the physiology of potato plants. El Hadrami et al (2010) and Liu et al (2016) showed that chitosan played a major role in enhancing plant resistance to diseases.…”

“…Choosing the best microbial strain is critical, as it has direct impact on colonization density and effectiveness. Bacillus, a heterotrophic saprophyte, is common in soil and aquatic habitats, particularly in soils, where it exists as latent spores at temperatures near 0°C, allowing these bacteria to resist adverse environmental conditions (Maslennikova et al, 2023). Bacillus velezensis, particularly strains GB03, QST 713, FZB42, and D747, has commercial potential for disease biocontrol and host plant growth promotion (Vallejo, 2023).…”

The Effect of Bacillus velezensis LJ02 Compounded with Different Fungi on the Growth of Watermelon Seedlings and Microbial Community Structure

“…Preliminary research found that Bacillus velezensis LJ02 reduces the occurrence of powdery mildew [12]. Bacillus mixed or compound with other biocontrol bacteria has a better disease control effect than a single strain [40]. The combined application of microbial agents with different mechanisms of action, different growth conditions and different ecological adaptability has stronger defense, coordination inhibition, and improve the disease prevention and stability [41].…”