Comparative analysis of epiphytic and endophytic fungal communities in traditional rice seeds

Seed-associated fungal communities play a crucial role in plant health, stress tolerance, and crop productivity, particularly in traditional rice varieties cultivated under low-input systems. This study comparatively analysed the diversity and distribution of epiphytic and endophytic fungi associated with seeds of three traditional rice (Oryza sativa L.) varieties, Mapillai Samba, Karuppu Kavuni, and Karung Kuruvai, using serial dilution and culture-based isolation on Potato Dextrose Agar and Rose Bengal Agar. A total of 101 fungal isolates were recovered, comprising 34 epiphytic and 67 endophytic fungi, indicating a predominance of endophytic associations across all varieties. Karung Kuruvai harboured the highest fungal diversity, followed by Mapillai Samba and Karuppu Kavuni. Morphological and microscopic characterisation revealed diverse fungal genera, including Fusarium, Penicillium, Aspergillus, Alternaria, Trichoderma, Diaporthe, and Bipolaris, with Fusarium being the most dominant. The observed diversity highlights the ecological significance of seed-associated fungi and their potential role in enhancing seed health, stress resilience, and sustainable rice production. However, the study faced challenges such as limitations in culture-dependent methods, which may have underestimated the presence of non-culturable or slow-growing taxa. Additionally, distinguishing morphologically similar species posed difficulties, highlighting the need for molecular tools for more precise identification in future research.