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This study simultaneously considered the phylogeny, fatty acid binding ability, and fungal toxicity of a large number of monocot nonspecific lipid transfer proteins (ns-LTP). Nine novel full-length wheat ns-LTP1 clones, all possessing coding sequences of 348 bp, isolated from abiotic- and biotic-stressed cDNA libraries from aerial tissues, exhibited highly conserved coding regions with 78 to 99 and 71 to 100% identity at the nucleotide and amino acid levels, respectively. Phylogenetic analyses revealed two major ns-LTP families in wheat. Eight wheat ns-LTP genes from different clades were cloned into the expression vector pPICZalpha and transformed into Pichia pastoris. Sodium dodecyl sulfate polyacrylamide gel electrophoresis, Western blotting, and in vitro lipid binding activity assay confirmed that the eight ns-LTP were all successfully expressed and capable of in vitro binding fatty acid molecules. A comparative in vitro study on the toxicity of eight wheat ns-LTP to mycelium growth or spore germination of eight wheat pathogens and three nonwheat pathogens revealed differential toxicities among different ns-LTP. Values indicating 50% inhibition of fungal growth or spore germination of three selected ns-LTP against six fungi ranged from 1 to 7 microM. In vitro lipid-binding activity of ns-LTP was not correlated with their antifungal activity. Using the fluorescent probe SYTOX Green as an indicator of fungal membrane integrity, the in vitro toxicity of wheat ns-LTP was associated with alteration in permeability of fungal membranes.

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Current western Canadian hard red spring wheat cultivars and their progenitors, inoculated with a composite of Tilletia tritici and T. laevis races, were grown at Lethbridge from 1989 to 1991 and the percentage infection was determined. This study also examined cultivar × environment interaction effects. Ancestral cultivars, such as Red Calcutta 33, Marquis, Thatcher, and their descendants, Canthatch, Park, Neepawa, Manitou, and Cadet, exhibited intermediate levels of bunt resistance. Cultivars including the cultivar Hope in their ancestry, such as Redman, Chris, Katepwa, Columbus, Reward, and Lancer, were highly resistant. Analysis of the environment × cultivar interaction indicated that bunt infection levels in Hope, Redman, and Columbus were stable over environments, but infection which varied according to environment was observed for Katepwa and Reward. The reduction of a number of cultivars including Neepawa, Thatcher, Kenya Farmer, Fortuna, Cadet, and Chris, was unstable across environment. Mexican semi-dwarf cultivars, such as Tobari 66, Potem 70, Cajeme 71, Ciano 67, Sonora 64, Inia 66, and the Canadian cultivars HY320, BW 90, and Laura, were highly susceptible. In general, the level of infection in these cultivars was uniform across environments. The nature of resistance in Canadian cultivars, the high infection levels of some Canadian cultivars and their Mexican semi-dwarf ancestors, and the variation in stability of infection levels of some cultivars across environments are discussed. Key words: Triticum aestivum, semi-dwarf, stability analysis, genotype × environment interactions