RESUMO
Sclerotinia sclerotiorum (Lib.) de Bary is the causative agent of stem white mold disease which severely reduces major crop productivity including soybean and rapeseed worldwide. The current study aimed to explore plant growth-promoting traits and biocontrol of new isolated Bacillus subtilis BS-2301 to suppress S. sclerotiorum through various mechanisms. The results indicated that the BS-2301 exhibited strong biocontrol potential against S. sclerotiorum up to 74% both in dual culture and partition plate experiments. The BS-2301 and its crude extract significantly suppressed S. sclerotiorum growth involving excessive reactive oxygen species (ROS) production in mycelia for rapid death. Furthermore, the treated hyphae produced low oxalic acid (OA), a crucial pathogenicity factor of S. sclerotiorum. The SEM and TEM microscopy of S. sclerotiorum showed severe damage in terms of cell wall, cell membrane breakage, cytoplasm displacement, and organelles disintegration compared to control. The pathogenicity of S. sclerotiorum exposed to BS-2301 had less disease progression potential on soybean leaves in the detached leaf assay experiment. Remarkably, the strain also demonstrated broad-range antagonistic activity with 70%, and 68% inhibition rates against Phytophthora sojae and Fusarium oxysporum, respectively. Furthermore, the strain exhibits multiple plant growth-promoting and disease-prevention traits, including the production of indole-3-acetic acid (IAA), siderophores, amylases, cellulases and proteases as well as harboring calcium phosphate decomposition activity. In comparison to the control, the BS-2301 also showed great potential for enhancing soybean seedlings growth for different parameters, including shoot length 31.23%, root length 29.87%, total fresh weight 33.45%, and total dry weight 27.56%. The antioxidant enzymes like CAT, POD, SOD and APX under BS-2301 treatment were up-regulated in S. sclerotiorum infected plants along with the positive regulation of defense-related genes (PR1-2, PR10, PAL1, AOS, CHS, and PDF1.2). These findings demonstrate that the BS-2301 strain possesses a notable broad-spectrum biocontrol potential against different phytopathogens and provides new insight in suppressing S. sclerotiorum through various mechanisms. Therefore, BS-2301 will be helpful in the development of biofertilizers for sustainable agricultural practices.
RESUMO
The yellow-spined bamboo locust (YSBL), Ceracris kiangsu Tsai, has historically had a significant impact on different bamboo varieties in East Asia and Southeast Asia. Since 2014, there have been many outbreaks of YSBL populations in Laos, and YSBLs subsequently invaded Southwest China in 2020 and 2023. However, there was limited information about the damage to staple crops. Life table parameters and fitness parameters were assessed using wheat, rice, waxy maize, and sweet maize under three different temperatures (25 °C, 30 °C, and 35 °C) in the laboratory. The results indicated that the YSBLs feeding on wheat seedlings displayed a significantly higher survival rate, a shorter developmental time, and a higher adult emergence rate compared to YSBLs feeding on the other host species at 30 °C. The developmental durations of 1st and 3rd instar YSBLs on wheat (1st: 8.21 ± 0.35 d; 3rd: 6.32 ± 0.34 d) and rice (1st: 7.19 ± 0.23 d; 3rd: 9.00 ± 0.66 d) were significantly shorter than those of 1st and 3rd instar YSBLs on waxy maize (1st: 13.62 ± 1.22 d; 3rd: 13.67 ± 6.33 d) and sweet maize (1st: 16.00 ± 1.79 d; 3rd: 18.00 ± 3.49 d) at 30 °C. The body lengths of male and female YSBLs on wheat (male: 29.52 ± 0.40 mm, female: 34.97 ± 0.45 mm) and rice (male: 28.85 ± 0.68 mm, female: 34.66 ± 0.35 mm) were significantly longer than those observed when they were fed on sweet maize (male: 25.64 ± 1.60 mm, female: 21.93 ± 6.89 mm). There were only male adults obtained on waxy maize. The phenotypic characteristics of the YSBLs feeding on rice seedlings were very close to those of the YSBLs feeding on wheat seedlings. A relatively slower decline was observed in the survival rates of YSBL nymphs on wheat and rice compared to those on waxy maize and sweet maize at 25 °C, 30 °C, and 35 °C. In short, this study implied that YSBLs prefer wheat and rice. This study is the first report of direct damage caused by the YSBL to wheat in the laboratory, and its results could be useful in improving our understanding of the host preference of the YSBL and providing strategies for the management of this pest in field crops.