Plant growth-promoting characteristics of root fungal endophytes isolated from a traditional Cordillera rice landrace

Abstract: This study was conducted to isolate and characterize the plant growth-promoting potential of fungal endophytes from the roots of Diket red, a traditional rice plant from the Cordillera, Northern Luzon. Eighteen morphospecies of filamentous endophytes were isolated of which twelve isolates were successfully identified to the species level. These isolates were identified as Aspergillus versicolor, Aspergillus sp., Chaetosphaeria sp., Cladosporium cladosporioides, Hypocrea lixii, Microascus murinus, and Trichoderma harzianum. The identified twelve isolates were selected to screen in vitro for their plant growth-promoting characteristics, and evaluated in vivo for their beneficial effects on seedling vigor and early seedling growth. Isolate PPL14 produced the highest IAA at 55.5 μg ml^-1 and M. murinus PPL10 produced the highest amount of IAA at 3.73 μg IAA mg^-1 dry mycelia wt. The seedling vigor assay and in vivo plant growth promotion bioassay indicated overall positive effects of culture filtrate (CF) application of the endophyte isolates. Rice seeds and seedlings grown in aseptic condition and treated with endophyte CFs displayed significantly enhanced levels of germination, seedling vigor, shoot, root, and total plant growth, and biomass compared to non-treated control. Other plant growth-promoting characteristics were also studied including phosphate solubilization, siderophore production, ammonia production, and catalase activity. This study supports the potential use of fungal endophytes as bio-inoculants for plant growth promotion and enhancement of nutrient assimilation of agriculturally important crops.

Key words: 
• 18S rDNA /
• Endophytic fungi /
• Plant growth promotion /
• Rice landrace /
• Seedling vigor