Trichoderma harzianum promoting chrysanthemum cutting rooting and reshaping microbial communities in endophytic and rhizosphere environments

It is well known that Trichoderma harzianum promotes the growth and development of plants. This study aims to investigate the impact of T. harzianum on the cutting rooting and microbial communities in the endophytic and rhizosphere of chrysanthemum cuttings. The effects of T. harzianum on the rooting rate, root length, and root number of chrysanthemum cuttings were determined. Using Duncan's Multiple Range Test (DMRT), we investigated physiological indexes such as nutrients, hormones, and enzymatic activities to identify the key factors influencing the rooting of chrysanthemum cuttings. The endophytic and rhizosphere microbial communities were analyzed through high-throughput sequencing. Microorganism function was predicted using SPSS software, PICRUSt2, and the FUNGuild database. The results showed that T. harzianum greatly increased the chrysanthemum cuttings' rooting rate by 21.11 %. Furthermore, it caused the average root length to expand by 81.72 %, the total number of roots to increase by 72.23 %, and the dry weight of the roots to increase by 50 %. At the same time, T. harzianum markedly reduced the number of pathogenic microbes and greatly enhanced the abundance of beneficial microorganisms in the endophytic and rhizosphere. PICRUSt2 function prediction showed that the abundance of some enzymes involved in IAA, sugar, and starch synthesis from endophytic bacteria in chrysanthemum cuttings inoculated T. harzianum was significantly increased, and the primary nutrient type of the fungi was changed from pathotroph to saprotroph. Hence, we concluded that applying T. harzianum restored the endophytic and rhizosphere microorganisms, boosted nutrient and hormone levels, enhanced enzymatic activities, and enhanced cutting rooting. It also significantly reduced the number of pathogenic microorganisms in the plant and rhizosphere, potentially controlling the occurrence of phytopathogens. These results offer insightful information about the beneficial impacts of T. harzianum on the growth and development of plants.