RESUMEN
The symbiotic interaction between leguminous and Bradyrhizobium sp. SUTN9-2 mainly relies on the nodulation process through Nod factors (NFs), while the type IV secretion system (T4SS) acts as an alternative pathway in this symbiosis. Two copies of T4SS (T4SS1 and T4SS2) are located on the chromosome of SUTN9-2. ΔT4SS1 reduces both nodule number and nitrogenase activity in all SUTN9-2 nodulating legumes. The functions of three selected genes (copG1, traG1, and virD21) within the region of T4SS1 were examined. We generated deleted mutants and tested them in Vigna radiata cv. SUT4. ΔtraG1 and ΔvirD21 exhibited lower invasion efficiency at the early stages of root infection but could be recently restored. In contrast, ΔcopG1 completely hindered nodule organogenesis and nitrogenase activity in all tested legumes. ΔcopG1 showed low expression of the nodulation gene and ttsI but exhibited high expression levels of the T4SS genes, traG1 and trbE1. The secreted proteins from ΔT4SS1 were down-regulated compared to the wild-type. Although ΔcopG1 secreted several proteins after flavonoid induction, T3SS (nopP and nopX) and the C4-dicarboxylate transporter (dct) were not detected. These results confirm the crucial role of the copG1 gene as a novel key regulator in the symbiotic relationship between SUTN9-2 and legumes.
RESUMEN
Mung bean (Vigna radiata L.), a vital legume in Asia with significant nutritional benefits, is highly susceptible to Cercospora leaf spot (CLS) caused by Cercospora canescens, leading to significant yield losses. As an alternative to chemical fungicides, bio-priming with rhizobacteria can enhance plant resistance. This study explores the potential of Bradyrhizobium sp. strain DOA9 to augment resistance in mung bean against CLS via root priming. The results reveal that short (3 days) and double (17 and 3 days) priming with DOA9 before fungal infection considerably reduces lesion size on infected leaves by activating defense-related genes, including Pti1, Pti6, EDS1, NDR1, PR-1, PR-2, Prx, and CHS, or by suppressing the inhibition of PR-5 and enhancing peroxidase (POD) activity in leaves. Interestingly, the Type 3 secretion system (T3SS) of DOA9 may play a role in establishing resistance in V. radiata CN72. These findings suggest that DOA9 primes V. radiata CN72's defense mechanisms, offering an effective bio-priming strategy to alleviate CLS. Hence, our insights propose the potential use of DOA9 as a bio-priming agent to manage CLS in V. radiata CN72, providing a sustainable alternative to chemical fungicide applications.
RESUMEN
BACKGROUND AND OBJECTIVE: Cellulase is an important enzyme that useful for agricultural residue hydrolysis such as plant stover, molasse, rice straw. Thermotolerant cellulases are required to apply in textile, food, detergent, biofuels and pharmaceutical applications. This research aimed to isolate the thermotolerant cellulase-producing bacteria from forest soil and to determine cellulase activity from isolated bacteria. MATERIALS AND METHODS: Soil samples were collected from the Roi Et Rajabhat University forest. One gram of soil sample was mixed with Luria-Bertani (LB) broth medium and incubated at 37°C with shaking at 150 rpm for 24 h. The cultured broth was streaked on LB agar plate and incubated at 37°C for 24 h. Cellulase-producing bacteria were isolated using Carboxymethylcellulose (CMC) agar plate. Four bacterial isolates which presented a clear zone on CMC agar plate after flooded with iodine solution, named CM1, CM2, CM3 and CM4. Cellulase activity of 4 isolated bacteria was determined against various pH (pH 4-8) and temperature (50-100°C). RESULTS: The results indicated that CM1 isolate showed the highest cellulase activity at 0.074 unit mL-1 at 80°C and pH5. All isolates were identified using 16S rRNA gene sequencing. The results indicated that CM1, CM3 and CM4 were identified as Pseudomonas stutzeri. while isolate CM2 was Bacillus subtilis. CONCLUSION: This is the first report presenting the thermotolerant cellulase produced by Pseudomonas stutzeri. The thermotolerant cellulase produced from Pseudomonas stutzeri in this study will be useful in many industrial processes using cellulase at high temperatures.