Comparative Proteomic Analysis of Different Isolates of Fusarium oxysporum f.sp. lycopersici to Exploit the Differentially Expressed Proteins Responsible for Virulence on Tomato Plants

The vascular wilt of tomato caused by Fusarium oxysporum f.sp. lycopersici is an important soil borne pathogen causes severe yield loss. The molecular characterization and their interaction with its host is necessary to develop a protection strategy. 20 isolates of F. oxysporum f.sp. lycopersici (FOL) were isolated from wilt infected tomato plants across Tamil Nadu. They were subjected to cultural, morphological, molecular and virulence studies. The results revealed that all the isolates produced both micro and macro conidia with different size, number of cells. The colors of the culture and growth pattern were also varied. In addition, chlamydospores were observed terminally and intercalary. The PCR analysis with F. oxysporum species-specific primer significantly amplified an amplicon of 600 bp fragment in all the isolates. Based on the above characters and pathogenicity, isolate FOL-8 was considered as virulent and FOL-20 was considered as least virulent. Proteomics strategy was adopted to determine the virulence factors between the isolates of FOL-8 and FOL-20. The 2D analyses have showed the differential expression of 17 different proteins. Among them, three proteins were down regulated and 14 proteins were significantly up regulated in FOL-8 than FOL-20 isolate. Among the 17 proteins, 10 distinct spots were analyzed by MALDI-TOF. The functions of the analyzed proteins, suggested that they were involved in pathogenicity, symptom expression and disease development, sporulation, growth, and higher penetration rate on tomato root tissue. Overall, these experiments proves the role of proteome in pathogenicity of F. oxysporum f.sp. lycopersici in tomato and unravels the mechanism behinds the virulence of the pathogen in causing wilt disease

Analysis of genetic diversity and population structure of Magnaporthe grisea, the causal agent of foxtail millet blast using microsatellites

Foxtail millet blast caused by Magnaporthe grisea is becoming a severe problem in foxtail millet growing regions of India. The genetic diversity and population structure of foxtail millet infecting M. grisea is crucial for developing effective management strategies, such as breeding blast-resistant cultivars. We analyzed thirty-two M. grisea isolates from ten foxtail millet-growing districts in Tamil Nadu, India for genetic diversity using twenty-nine microsatellite or simple sequence repeat (SSR) markers. A total of 103 alleles were identified with a mean of 3.55 alleles/locus. Gene diversity ranged from 0.170 to 0.717, while major allelic frequencies ranged from 0.344 to 0.906. The polymorphism information content (PIC) ranged from 0.155 to 0.680, with a mean value of 0.465. Population structure analysis of the genomic data sets revealed two major populations (SP1 and SP2) with different levels of ancestral admixture among the 32 blast isolates. Phylogenetic analysis classified the isolates into three major clusters. Analysis of molecular variance (AMOVA) showed high genetic variation among individuals and less among populations. Principal Coordinate Analysis (PCoA) revealed 27.16% genetic variation among populations. The present study provides the first report on the genetic diversity and population structure of the foxtail millet-infecting M. grisea population in Tamil Nadu, which could be useful for the development of blast-resistant foxtail millet cultivars

Complete Genome Sequence Analysis of <i>Bacillus subtilis</i> Bbv57, a Promising Biocontrol Agent against Phytopathogens

Plant growth-promoting rhizobacteria (PGPR) are a group of root-associated beneficial bacteria emerging as one of the powerful agents in sustainable plant disease management. Among the PGPR, Bacillus sp. has become a popular biocontrol agent for controlling pests and the diseases of several crops of agricultural and horticultural importance. Understanding the molecular basis of the plant growth-promoting and biocontrol abilities of Bacillus spp. will allow us to develop multifunctional microbial consortia for sustainable agriculture. In our study, we attempted to unravel the genome complexity of the potential biocontrol agent Bacillus subtilis Bbv57 (isolated from the betelvine’s rhizosphere), available at TNAU, Coimbatore. A WGS analysis generated 26 million reads, and a de novo assembly resulted in the generation of 4,302,465 bp genome of Bacillus subtilis Bbv57 containing 4363 coding sequences (CDS), of which 4281 were functionally annotated. An analysis of 16S rRNA revealed its 100% identity to Bacillus subtilis IAM 12118. A detailed data analysis identified the presence of >100 CAZymes and nine gene clusters involved in the production of secondary metabolites that exhibited antimicrobial properties. Further, Bbv57 was found to harbor 282 unique genes in comparison with 19 other Bacillus strains, requiring further exploration