United States Department of Agriculture, Agricultural Research Service, Sam Farr United States Crop Improvement and Protection Research Center, Salinas, CA, 93905, USA.
Department of Plant Pathology, University of California, Davis, c/o Sam Farr United States Crop Improvement and Protection Research Center, Salinas, CA, 93905, USA.
BMC Plant Biol. 2024 Jul 29;24(1):717. doi: 10.1186/s12870-024-05399-5.
Sclerotinia spp. are generalist fungal pathogens, infecting over 700 plant hosts worldwide, including major crops. While host resistance is the most sustainable and cost-effective method for disease management, complete resistance to Sclerotinia diseases is rare. We recently identified soft basal stem as a potential susceptibility factor to Sclerotinia minor infection in lettuce (Lactuca sativa) under greenhouse conditions.
Analysis of stem and root cell wall composition in five L. sativa and one L. serriola accessions with varying growth habits and S. minor resistance levels revealed strong association between hemicellulose constituents, lignin polymers, disease phenotypes, and basal stem mechanical strength. Accessions resistant to basal stem degradation consistently exhibited higher levels of syringyl, guaiacyl, and xylose, but lower levels of fucose in stems. These findings suggest that stem cell wall polymers recalcitrant to breakdown by lignocellulolytic enzymes may contribute to stem strength-mediated resistance against S. minor.
The lignin content, particularly guaiacyl and syringyl, along with xylose could potentially serve as biomarkers for identifying more resistant lettuce accessions and breeding lines. Basal stem degradation by S. minor was influenced by localized microenvironment conditions around the stem base of the plants.
核盘菌属是一种真菌病原体，能感染全世界 700 多种植物宿主，包括主要作物。虽然利用宿主抗性是管理疾病最具可持续性和成本效益的方法，但对核盘菌病的完全抗性很少见。我们最近在温室条件下发现，生菜（Lactuca sativa）的软基茎是对小核盘菌感染的潜在易感性因素。
对五个生菜和一个生菜属不同生长习性和小核盘菌抗性水平的品系的茎和根细胞壁成分进行分析，发现半纤维素成分、木质素聚合物、疾病表型和基茎机械强度之间存在很强的相关性。对基茎降解有抗性的品系在茎中始终表现出较高水平的丁香基、愈创木基和木糖，但糠醛水平较低。这些发现表明，木质素细胞壁聚合物对木质纤维素酶的分解具有抗性，可能有助于基茎强度介导对小核盘菌的抗性。
木质素含量，特别是愈创木基和丁香基，以及木糖，可能可以作为鉴定更具抗性的生菜品系和育种群的生物标志物。小核盘菌对基茎的降解受到植物基茎周围局部微环境条件的影响。
