Bacillus licheniformis PR2 Controls Fungal Diseases and Increases Production of Jujube Fruit under Field Conditions

Abstract

There is a growing interest in using biocontrol agents to control fungal diseases and increase the production of jujube fruit (Zizyphus jujua Miller var. inermis Rehder). The purpose of this study was to use Bacillus licheniformis PR2 to inhibit fungal diseases and promote fruit production in jujube orchards. B. licheniformis PR2 secreted 92.4 unit/mL of chitinase, which inhibited fungal phytopathogens through hyphal alterations with swelling and bulbous structures. B. licheniformis PR2 also inhibited mycelial growths of fruit fungal pathogens Botrytis cinerea, Colletotrichum gloeosporioides, and Phytophthora nicotianae by 81.3%, 60.1%, and 67.0%, respectively. B. licheniformis PR2 increased jujube fruit yield by 17.9 kg/tree by reducing rotting damage caused by fungal pathogens, with a yield 3.2 times higher than that achieved by the control without PR2 treatment. In addition, B. licheniformis PR2 produced auxin, which promoted cell division after flower fertilization, thus increasing fruit length and diameter by 1.2-fold compared to those of the control. These results confirmed that eco-friendly B. licheniformis PR2 could effectively control fungal diseases in jujube orchards and improve its fruit size and yield.

Antifungal Activity of Bacillus velezensis CE 100 against Anthracnose Disease (Colletotrichum gloeosporioides) and Growth Promotion of Walnut (Juglans regia L.) Trees

“…Therefore, there is a growing demand for crop production strategies that can reduce the use of agrochemicals, for instance, the use of microbial biocontrol agents as an alternative to fungicides. Environmentally friendly practices, such as biocontrol agents, are also important for promoting plant growth [ 21 , 22 , 23 ]. Thus, the role of active metabolites derived from plant growth-promoting bacteria (PGPB), such as the Bacillus species, as potential alternatives to chemical fungicides cannot be underestimated [ 24 , 25 ].…”

“…Biocontrol agents can colonize the plant rhizosphere, and secrete metabolites that control phytopathogens [ 25 ], and act as bio-fertilizers to enhance plant growth [ 26 ]. Bacillus spp., such as B. subtilis , B. licheniformis , B. amyloliquefaciens , and B. velezensis, are among the PGPB candidates that have been reported to have potential applications as biocontrol agents and plant growth-promoting bacteria because of their prominent traits [ 21 , 22 , 23 , 24 , 25 ]. PGPB have different biocontrol mechanisms against phytopathogenic fungi, including the production of secondary metabolites, such as antibiotics and lipopeptides [ 25 , 27 ].…”

Biological Control of Leaf Blight Disease Caused by Pestalotiopsis maculans and Growth Promotion of Quercus acutissima Carruth Container Seedlings Using Bacillus velezensis CE 100

“…canase, and protease, from various PGPBs that could potentially control plant fungal disease by antagonizing the growth and infection of phytopathogens [28][29][30][31][32]34]. These cell wall-degrading enzymes degrade the cell wall components of phytopathogens, which are mainly composed of chitin, glucan, and glycoprotein matrix [34][35][36].…”

“…These cell wall-degrading enzymes degrade the cell wall components of phytopathogens, which are mainly composed of chitin, glucan, and glycoprotein matrix [34][35][36]. Cell wall-degrading enzymes from PGPB have been reported to exhibit a wide range of antagonistic abilities against plant pathogens, such as Colletotrichum gloeosporioides, Fusarium oxysporum, Pestalotia diospyri, Botrytis cinerea, and Botryosphaeria dothidea [28][29][30][31][32]. Thus, it is vital to control Pestalotiopsis infections in forest seedlings, in order to produce high-quality seedlings for successful afforestation.…”

“…However, frequent application of chemical fungicides could potentially cause fungicide resistance [26], pollutes the environment, and negatively affects human health [27]. Recently, interest in the production of forest seedlings using eco-friendly technologies to replace the use of chemical products has increased and several studies have provided evidence about the control of plant disease using plant growth-promoting bacteria (PGPB) [28][29][30][31][32][33][34]. Specifically, Bacillus spp.…”