Evaluation on Fusarium crown rot resistance and agronomic traits of wheat near-isogenic lines

Fusarium crown rot (FCR) caused by species of Fusarium fungus is a global soil-borne disease of wheat. Increasing results indicate frequent controversy between seedling and adult plant resistance to FCR. To understand relationships between FCR resistance and agronomic traits in seedling and adult wheat (Triticum aestivum L.) plants, we developed 193 near-isogenic lines (NILs) and evaluated FCR severity during seedling and adult plant-growth stages. Agronomic traits such as plant height, thousand-kernel weight (TKW), and the composition of vernalization and dwarf genes were analyzed. An FCR disease index (DI) for the seedling stage did not correlate with that of the adult. Adult plant DI correlates extremely, significantly, and negatively with plant height and TKW. Adult FCR severity did not correlate with allelic variations of vernalization genes Vrn-A1 and Vrn-D1. The dwarfing gene Rht-D1b significantly reduced plant height and increased FCR severity. This study shows that the growth and development of wheat can affect its resistance to FCR. The correlation between FCR severity and plant height suggests that it should be feasible to enhance FCR resistance in wheat cultivars through the manipulation of dwarfing genes. Several phenotypically different lines of FCR severity were identified for subsequent gene mining and resistance mechanism analysis.