Centre for Crop and Disease Management (CCDM), School of Molecular and Life Sciences, Curtin University, Perth, WA 6102, Australia.
School of Molecular and Life Sciences, Curtin University, Perth, WA 6102, Australia.
Plant Dis. 2024 Aug;108(8):2303-2308. doi: 10.1094/PDIS-11-23-2412-SC. Epub 2024 Jul 13.
(Lib.) de Bary, an economically devastating soilborne fungal pathogen known to cause disease across a wide range of plants, produces long-term inoculum called sclerotia that can germinate either carpogenically by ascospores infecting aboveground plant parts or myceliogenically to infect stem base and roots. Typically, for research purposes, diseases are initiated by direct contact methods, using mycelium agar plugs wrapped around the stem or sclerotia placed directly beneath root mass. However, reproducible noncontact methods leading to basal stem infection are not currently available. Therefore, the objective of this study was to develop effective noncontact protocols that consistently generate basal plant stem infection from in the soil. Using three host plant species (canola, lupin, and lettuce), we determined two methods that reliably produced basal stem infection. The first method, where mycelial agar plugs were positioned just below the soil surface at a distance of 5 mm from each seedling, led to 100% infection in all plants. The second method used pathogen-infested soil by mixing the soil with dry inoculum in the form of a powder prepared from mycelium-colonized organic substrates. Four substrates consistently produced 100% seedling infection at 4 days after inoculation (DAI): wheat bran, wheat grain, red rice, and hulled millet. In contrast, chia, canary, sesame, and ryegrass seed substrates resulted in less than 50% seedling infection at 10 DAI, and infection levels did not progress further. The two soil inoculation methods outlined in this study will enhance future research on the progression of . diseases, with the potential to screen disease-resistant host genotypes to basal . infection and, in particular, to test the effectiveness of soil applications of fungicides or biocontrol agents against . basal infection.
（Lib.）de Bary 是一种具有破坏性的土传真菌病原体，已知它可感染多种植物，会产生长期的菌核作为接种体，菌核可以通过子囊孢子感染地上植物部分进行产雌生殖，也可以通过菌丝体生殖感染茎基部和根部。通常，为了研究目的，通过直接接触方法启动疾病，使用包裹在茎上的菌丝琼脂塞或直接放在根团下的菌核。然而，目前还没有可重复的非接触方法导致基底茎感染。因此，本研究的目的是开发有效的非接触方案，从土壤中始终如一地产生对 的基底植物茎感染。使用三种宿主植物（油菜、羽扇豆和生菜），我们确定了两种可靠地产生基底茎感染的方法。第一种方法是将菌丝琼脂塞放置在距幼苗 5 毫米的土壤表面下方，导致所有植物的感染率达到 100%。第二种方法是使用受病原体污染的土壤，将土壤与以菌丝体定植的有机基质粉末形式的干燥接种体混合。四种基质在接种后 4 天（DAI）始终产生 100%的幼苗感染：麦麸、麦粒、红米和去壳小米。相比之下，奇亚籽、金雀花、芝麻和黑麦草种子基质导致幼苗感染率低于 50%，且感染程度没有进一步发展。本研究中概述的两种土壤接种方法将增强对 疾病进展的未来研究，有可能筛选对基底 感染具有抗性的宿主基因型，特别是测试杀菌剂或生物防治剂对土壤中 感染的有效性。
