Isolation and evaluation of pomegranate (Punica granatum L.) endophytes against Ceratocystis fimbriata and Fusarium oxysporum, the causal agents of pomegranate wilt

Pomegranate wilt is a major disease that causes the complete death of the plant within a short period of time after its initial symptoms. In this study, a total of 69 fungal and 32 bacterial pomegranate endophytes were isolated and evaluated using the dual culture technique against wilt pathogens, viz., Ceratocystis fimbriata and Fusarium oxysporum. The leaf fungal endophyte LF30 was found effective against both pathogens, with 100 and 74.75% inhibition, respectively. Among shoot endophytes, the maximum inhibition was shown by isolate SF33 against C. fimbriata and SF21 against F. oxysporum. Among 18 leaf and 14 shoot bacterial endophytes, the shoot endophyte SB3 showed 84.28% and 61.96% inhibition against C. fimbriata and F. oxysporum, respectively. Based on molecular identification LF30 and SF33 was identified as Trichoderma harzianum and Trichoderma asperellum, respectively. The bacterial endophyte SB3 is identified as Bacillus vallismortis. Effective fungal endophytes were screened for the presence of endochitinase (ech42) and cellobiohydrolase (cbh1) genes through a PCR technique. The isolate T. asperellum was positive for both the cbh1 and ech42 genes, whereas T. harzianum was positive only for the cbh1 gene. To our knowledge, the use of endophytes to combat pomegranate wilt is the first study of its sort.