Establishment and Application of a Multiplex PCR Assay for Detection of Sclerotium rolfsii, Lasiodiplodia theobromae, and Fusarium oxysporum in Peanut

PCR-based detection of Botryosphaeria canker pathogens in fig trees

Canker and dieback, caused by members of the Botryosphaeriaceae family, pose significant threats to plant productivity, food security, and natural ecosystems, particularly in economically important woody crops including fig trees. Detecting and identifying these pathogens is challenging due to their latent infections and the presence of multiple pathogens within the same host. In our study, we developed a PCR assay using three carefully selected primer pairs based on sequence differences in two protein-coding genes, β-tubulin and RNA polymerase II. The species-specific primers TUB-Bd1 (specific for Botryosphaeria dothidea), TUB-Np1 (specific for Neofusicoccum parvum), and RPB-Nd2 (specific for Neoscytalidium dimidiatum) effectively amplified target gene sequences in pure cultures and infected tissue samples using PCR and nested PCR conditions. The efficiency test results demonstrated that TUB-Bd1, TUB-Np1, and RPB-Nd2 primer pairs could detect specific DNA fragments at very low concentrations in nested PCR. Furthermore, we collected 180 symptomatic and asymptomatic fig samples from different regions of Fars Province, Iran. Applying the species-specific primer pair RPB-Nd2 in direct PCR led to the detection of N. dimidiatum in 25.5% of symptomatic woody samples and 13% of asymptomatic one-year-old branch samples of fig trees. This represents a significant improvement compared to the mere 6.67% detected using traditional culturing methods on PDA. Interestingly, neither B. dothidea nor N. parvum were detected in the 180 samples using nested PCR. Moreover, multiplex PCR enabled simultaneous DNA detection of the target Botryosphaeriaceae pathogens. Our findings emphasize the importance of molecular techniques for early detection of evident and latent infections caused by these three pathogens in fig trees.

Development and application of multiplex PCR for the rapid identification of four Fusarium spp. associated with Fusarium crown rot in wheat

Fusarium crown rot (FCR), caused by Fusarium spp., is a devastating disease in wheat growing areas. Previous studies have shown that FCR is caused by co-infection of F. graminearum, F. pseudograminearum, F. proliferatum and F. verticillioides in Hubei Province, China. In this study, a method was developed to simultaneously detected DNAs of F. graminearum, F. pseudograminearum, F. proliferatum and F. verticillioides that can efficiently differentiate them. Whole genome sequence comparison of these four Fusarium spp. was performed and a 20 bp sequence was designed as an universal upstream primer. Specific downstream primers of each pathogen was also designed, which resulted in a 206, 482, 680, and 963 bp amplicon for each pathogen, respectively. Multiplex PCR specifically identified F. graminearum, F. pseudograminearum, F. proliferatum and F. verticillioides but not from other 46 pathogens, and the detection limit of target pathogens is about 100 pg/μl. Moreover, we accurately determined the FCR pathogen species in wheat samples using the optimized multiplex PCR method. These results demonstrate that the multiplex PCR method established in this study can efficiently and rapidly identify F. graminearum, F. pseudograminearum, F. proliferatum, and F. verticillioides, which should provide technical support for timely and targeted prevention and control of FCR.

Transcriptomic-Proteomic Analysis Revealed the Regulatory Mechanism of Peanut in Response to Fusarium oxysporum

Peanut Fusarium rot, which is widely observed in the main peanut-producing areas in China, has become a significant factor that has limited the yield and quality in recent years. It is highly urgent and significant to clarify the regulatory mechanism of peanuts in response to Fusarium oxysporum. In this study, transcriptome and proteome profiling were combined to provide new insights into the molecular mechanisms of peanut stems after F. oxysporums infection. A total of 3746 differentially expressed genes (DEGs) and 305 differentially expressed proteins (DEPs) were screened. The upregulated DEGs and DEPs were primarily enriched in flavonoid biosynthesis, circadian rhythm-plant, and plant-pathogen interaction pathways. Then, qRT-PCR analysis revealed that the expression levels of phenylalanine ammonia-lyase (PAL), chalcone isomerase (CHI), and cinnamic acid-4-hydroxylase (C4H) genes increased after F. oxysporums infection. Moreover, the expressions of these genes varied in different peanut tissues. All the results revealed that many metabolic pathways in peanut were activated by improving key gene expressions and the contents of key enzymes, which play critical roles in preventing fungi infection. Importantly, this research provides the foundation of biological and chemical analysis for peanut disease resistance mechanisms.

Synthesis of Aminoalkyl Sclareolide Derivatives and Antifungal Activity Studies

Sclareolide was developed as an efficient C-nucleophilic reagent for an asymmetric Mannich addition reaction with a series of N-tert-butylsulfinyl aldimines. The Mannich reaction was carried out under mild conditions, affording the corresponding aminoalkyl sclareolide derivatives with up to 98% yield and 98:2:0:0 diastereoselectivity. Furthermore, the reaction could be performed on a gram scale without any reduction in yield and diastereoselectivity. Additionally, deprotection of the obtained Mannich addition products to give the target sclareolide derivatives bearing a free N-H group was demonstrated. In addition, target compounds 4-6 were subjected to an antifungal assay in vitro, which showed considerable antifungal activity against forest pathogenic fungi.