2025 Volume 42 Issue 3 Pages 317-326
The Lysinibacillus xylanilyticus strain GIC41 has been previously reported to promote spinach growth. This study evaluated GIC41’s potential as a biostimulant by assessing its ability to mitigate Pythium root rot and enhance plant growth across various cultivation systems. In a pot experiment, GIC41 application to potting soil reduced the disease severity index (DSI) by approximately 52% in spinach seedlings 15 days post-pathogen inoculation (dpi). Similarly, introducing GIC41 into hydroponic nutrient solutions decreased the DSI in tomato seedlings from 61% to 15% at 14 dpi. Reisolation experiments and quantitative real-time PCR analysis confirmed that GIC41 significantly suppressed root colonization by Pythium aphanidermatum in both spinach and tomato seedlings. Microscopic analysis showed that GIC41 treatment inhibited pathogen mycelial colonization and caused morphological abnormalities in about 93% of encysted zoospores on the tomato rhizoplane. Although GIC41 exhibited no direct anti-oomycete activity in dual culture, it produced protease. Notably, GIC41 treatment significantly improved plant growth, increasing tomato shoot dry weight and stem diameter by 47% and 43%, respectively. These findings suggest that GIC41 is a promising biostimulant, offering dual benefits of disease mitigation and growth promotion across different crops and cultivation systems.
