ECOFRIENDLY MANAGEMENT OF SHEATH ROT OF RICE CAUSED BY Sarocladium oryzae Sawada

Abstract

Rice plants showing the typical sheath rot disease symptoms were collected from the fifteen various rice growing areas of southern districts of Tamil Nadu. The various isolates of sheath rot pathogen showed their difference in their virulence, morphological, cultural and physiological characters. These isolates were subjected to characterization and the isolate SOMDU4 was identified as virulent. On the basis of nucleotide sequencing data the virulent isolate was identified as S. oryzae. To support the morphological identification of the several pathogenic isolates of Sarocladium, DNA were exposed to PCR amplification using universal primers of ITS1 and ITS4. The amplified genomic product was partially sequenced for the virulent isolate SOMDU4 and performed rDNA homology searches by using BLAST and NCBI (USA). The isolate SOMDU4 (MT111120.1) was 99 per cent homologus with the S. oryzae. newlineAmong the twenty isolates of Pseudomonas spp., PTN5 recorded the maximum (82.22 %) inhibition followed by PTN1 which recorded 77.78 per cent inhibition on the mycelial growth and among the twenty Bacillus spp., BTK1 isolate significantly recorded the highest (75.56) per cent reduction of mycelial growth of S. oryzae. newlineVariability among the fifteen isolates of S. oryzae and twenty isolates of Pseudomonas spp. and Bacillus spp. was analysed and confirmed by RAPD-PCR newlinetechnique. PCR was performed to identify the Pseudomonas spp. a fragment of approximately 1490 bp corresponding to the region of the 16S-23S rDNA. Partial sequencing of the effective isolates PTN1 and PTN5 were sequenced. Comparison of the nucleotide sequences with the database available in the NCBI Genbank disclosed that the isolates PTN1 and PTN5 were identified as Pseudomonas aeruginosa (MW404517.1) and Pseudomonas aeruginosa (MW404529.1) respectively. Genomic DNA of Bacillus spp. isolates was approximately amplified at 549 bp of 16S-23S rDNA. Partial sequencing of the effective isolate BTK1 was done and comparison of the nucleotide sequences with the database available