Clonostachys rosea Strain ST1140: An Endophytic Plant-Growth-Promoting Fungus, and Its Potential Use in Seedbeds with Wheat-Grain Substrate

Abstract

In this study, Clonostachys rosea strain ST1140, a naturally occurring endophyte in healthy roots of a pistachio tree, was identified morphologically and molecularly through DNA sequencing, and its endophytic ability and growth effect in/on three solanaceous plant species were tested. Three different organic substrates (bread wheat-grain, sawdust, and leonardite) were also investigated for their utility in cultivating and multiplying the strain. In-tray and pot experiments, the rates of seed germination and vegetative development of pepper, tomato, and eggplant inoculated with C. rosea at planting were compared to those of non-inoculated controls. In pot experiments, inoculating seedbeds with increasing doses of C. rosea strain ST1140 with wheat-grain substrate resulted in higher plant height values for all plant species, and the strain endophytically colonized the roots of all plant species. In-tray experiments revealed that ST1140 inoculation resulted in 2-4days earlier and 10% higher germination rates for all plant species, as well as more vigorous and accelerated seedling growth (10-13days earlier for seedlings at the 4-5 true leaf stage) on all inoculated plant species. Among three different organic substrates, wheat-grain was found to be the most effective for long-term cultivation and multiplication of the fungus, which could be of interest for its development as a commercial product. These results promised the strain ST1140's use as a biofertilizer in seedbeds with a wheat-grain substrate.