Identification of pathogens for lily bulb rot and resistance evaluation of lily germplasm resources

【Objective】The study aimed to identify the pathogens for lily bulb rot in Honghe area of Yunnan and evaluate the resistance of lily germplasm resources，providing reference for high-quality lily production and the breeding of resistant varieties.【Method】Samples of lilies with bulb rot disease in Yunnan were collected. After isolating and culturing the pathogen，the spore morphology，as well as the morphology and size of sporulating cells，were observed under an optical microscope. A phylogenetic tree was constructed based on the similarity of ITS and TEF-1α sequences of the pathogens for lily bulb rot to identify the pathogen species causing bulb rot diseased cut lilies in Honghe area. Tibo lily bulbs and Chengying lily leaves were used as test materials to screen for the optimal inoculation method for lily bulb rot disease. The resistance of 156 lily germplasms to Fusarium proliferatum were evaluated，and the resistance grades were determined.【Result】In the samples of bulb rot diseased cut lilies in the Honghe area of Yunnan，15 strains of suspected pathogenic fungi with different morphologies were obtained through isolation and purification，among which strain No. 11 showed the highest virulence. Under the optical microscope，strain No.11 had a large number of microspores，with no sickle-shaped megaspore. The phylogenetic tree results showed that strain No.11 had more than 98% sequence similarity with F. proliferatum MW015680.1：2-519 strain LC13659，strain No. 11 was clustered with F. proliferatum strain MW016480.1：2-519 and F. proliferatum strain MK414217.1：20-677. Therefore，strain No. 11 was identified as F. proliferatum. The disease level was the highest when using lily scale injury inoculation. The results of resistance evaluation of 156 lily germplasms to F. proliferatum showed that，after scale inoculation，the cultivated variety Fredo had the lowest disease index（DI），which was 18.33%. The 69 lily resources，represented by Arbatax and Pretty Woman，exhibited moderate resistance（MR）. Among them，the germplasms with the highest DI were Wild Lily 1（Baoshan）and Yunnan Lily （Lijiang），reaching 96.67%.【Conclusion】The main pathogen causing lily bulb rot disease in Honghe area of Yunnan is F. proliferatum. Scale injury inoculation is a suitable method for resistance identification in lilies，and one lily germplasm highly resistant to F. proliferatum，Fredo，is selected.