Enhanced Growth and Development of IAA-mutant dek18 Maize Variety and Alleviation of Abiotic Stresses Through the Synergistic effect of Penicillium roqueforti and Trichoderma reesei

To understand the regulatory role of auxin in endosperm development, defective kernel (dek18) indol-3 acetic acid (IAA) mutants of maize (Zea mays L.) were inoculated with endophytic fungal strains CGF-1 and CGF-II. The IAA mutant kernel (dek18) maize seeds have approximately 40% less dry matter in the endosperm, less auxin content and demonstrate low growth potential as compared to the wild-type. Here, the endophytic fungal strains CGF-1 and CGF-II with IAA potential were isolated from the roots of Solanum surattense Burm. f., and applied to assess the intrinsic response of IAA mutant dek18 maize seedlings development. Both fungal strains were identified based on colony morphology and 18S-rDNA gene sequencing as Penicillium roqueforti (CGF-1) and Trichoderma reesei (CGF-II). The isolated strains P. roqueforti and T. reesei that have phytohormones IAA, cytokinins, protein and enzyme potential were investigated for growth-promoting ability. After application of fungal strains, the development of radicle and plumule in the IAA mutant seedlings were enhanced as early as 7 days of germination. Moreover, inoculation of P. roqueforti and T. reesei significantly improved the growth parameters, like the length of roots and shoots, chlorophyll contents as well as roots and shoots fresh and dry weight after 30 days of germination. Further, active symbiotic association of P. roqueforti and T. reesei within the roots of IAA mutant maize seedlings was observed indicating that these endophytes may reduce the pressure on agricultural fields and could take us a step closer towards sustainable agriculture.