Putative Trichoderma harzianum mutant promotes cucumber growth by enhanced production of indole acetic acid and plant colonization

Aims Many Trichoderma species are well-known by their ability to promote plant growth and health. However, few studies have been conducted to improve their ability. Laboratory and greenhouse experiments compared the promotion of cucumber growth by the putative mutant Trichoderma harzianum T-E5 versus the wild-type SQR-T037 and bio-organic fertilizers fortified with them. Methods The putative mutant T-E5 was selected based on plant hormone production in liquid fermentation and then on the effects of T-E5 and SQR-T037 to promote plant growth and colonization of plant roots and rhizosphere soil of cucumber. Results High-performance liquid chromatography analysis showed that indole acetic acid (IAA) production by T-E5 was enhanced by 30.2 % as compared with SQR-T037. T-E5 treatment statistically increased cucumber plant biomass in soil and hydroponic experiments. Based on TaqMan reverse transcriptase-polymerase chain reaction, the population of T-E5 was almost ten times higher than SQR-T037 in the soil samples at 30 days. The endophytic colonization of roots and stems by the two strains had the same dynamic tendency, but T-E5 was much greater than SQR-T037 at any sampling time. Conclusions The putative mutant T-E5 enhanced the production of IAA and plant colonization ability, and this improvement had a great potential for further application of T-E5 in crop production.