Characterization of Phytopathogenic Colletotrichum spp., an Etiology of the Fruit Rot of Pomegranate and its Management by Lactic Acid Bacteria.

The fungal phytopathogens belonging to the genus Colletotrichum were associated with pre-harvest fruit rot of pomegranates of Bhagwa and Ganesh varieties. The major morphological features of fungi were the presence of acervulus with conidia, setae and appressoria. Molecular identification was based on the sequencing of ITS1 and ITS2 region rDNA. The sequences were deposited in the NCBI GenBank database followed by phylogenetic analysis. The isolates were identified as C. gloeosporioides (Cg) and C. fragariae (Cf). The phytopathogens were pectinase, cellulase and xylanase producers. In artificially infected plant tissues, the levels of hydrolytic enzymes were elevated with an increasing disease rating scale that showed a perfect positive correlation (P < 0.05) between them. To manage this fungal fruit rot, two potent antifungal lactic acid bacteria (LAB), Lactococcus lactis subsp. cremoris PFL9 and Lactobacillus brevis PFR77, which inhibited the growth of Colletotrichum with an inhibition zone diameter of ≈ 30 mm were used as biocontrol agents. In the biocontrol experiment, the development of rot began on 4th day post-inoculation with Cf and all the wounds rotted in 10 days. In the case of PFL9 & PFR77, and Dithane-treated challenged fruits, the rotting commenced on 7th and 8th day, respectively. After 10 days post-inoculation, there was no significant difference between PFL9 and Dithane treatments (P > 0.05). Similar results were recorded in the case of Cg. Thus, the use of antifungal LAB delays rotting in wounds. This study represents the first report on applying LAB for controlling Colletotrichum-induced fruit rot in pomegranates.