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Exophiala sp. LHL08 reprograms Cucumis sativus to higher growth under abiotic stresses
Author(s) -
Khan Abdul L.,
Hamayun Muhammad,
Ahmad Nadeem,
Waqas Muhammad,
Kang SangMo,
Kim YoonHa,
Lee InJung
Publication year - 2011
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.2011.01508.x
Subject(s) - cucumis , biology , endophyte , abiotic stress , abiotic component , salicylic acid , botany , gibberellin , abscisic acid , horticulture , biochemistry , gene , paleontology
Endophytic fungi are potential sources of secondary metabolites; however, they are little known for phytohormones secretion and amelioration of plant growth under abiotic stresses. We isolated a novel endophyte from the roots of Cucumis sativus and identified it as a strain of Exophiala sp. by sequencing internal transcribed spacer/large subunit rDNA and phylogenetic analysis. Prior to identification, culture filtrate (CF) of Exophiala sp. has shown significant growth promotion of Waito‐C [a gibberellins (GAs)‐deficient mutant cultivar] and Dongjin‐byeo (normal GAs biosynthesis cultivar) rice seedlings. CF analysis of Exophiala sp. showed the presence of physiologically active GAs (GA 1 , GA 3 , GA 4 and GA 7 ) and inactive GAs (GA 5 , GA 8 , GA 9 , GA 12 and GA 20 ). Exophiala sp. had higher GAs in its CF than wild‐type strain of Gibberella fujikuroi except GA 3 . Influence of Exophiala sp. was assessed on cucumber plant's growth and endogenous abscisic acid (ABA), salicylic acid (SA) and bioactive GAs under salinity and drought stresses. Exophiala sp.‐treated plants have shown significantly higher growth and rescued the host plants from stress promulgated water deficit, osmotic and cellular damage. The altered levels of stress‐responsive ABA showed low level of stress confined to endophyte‐applied plants than control. Elevated levels of SA and bioactive GAs (GA 3 and GA 4 ) in endophyte‐associated plants suggest stress‐modulating response toward salinity and drought. In conclusion, symbiotic relations between Exophiala and cucumber have reprogrammed the host plant growth under abiotic stresses, thus indicating a possible threshold role of endophytic fungi in stress alleviation. This study could be extended for improving agricultural productivity under extreme environmental conditions.