Crown Rot Resistance Assessed Using Single Chromosome Substitution Lines And Its Relation With Fusarium Head Blight And Mycotoxin In Durum Wheat

Wheat Fusarium head blight (FHB), caused mainly by Fusarium graminearum and Fusarium culmorum, is a serious disease problem. The resistance resource to FHB , however, is very Poor. Compared with the common wheat (2n=6x=42), durum wheat (2n=4x=28) is more susceptible to this disease. The three sets of Langdon-Triticum dicoccoides (LDN-DIC) disomic chromosome substitution lines were inoculated by CR, and the second set of substitution line was inoculated by FHB. Consequently, the gene responsible for to resistant to FHB and inhibition of mycotoxin production waspreliminary localization. Main research results are followed :1. Inoculating the second set of chromosome substitution line to find the identification of chromosome responsible for FHB and mycotoxin productionUSDA geneticist Steven Xu produced a set of lines [LDN (PI481521)]. Each line had a different pair of chromosome from PI481521 substituted for the corresponding Langdon durum chromosomes. The purpose of this study was to determine if any of the LDN (PI481521) lines showed useful level of resistance of FHB. We test these lines for response by inoculating with Fusarium graminearum in the greenhouse. Inoculation was accomplished via the single spikelet method .In the test, some lines differed significantly. Two lines, LDN (PI481521-3A) and LDN (PI481521-7B), were consistently less susceptible and another two, LDN (PI481521-2A) and LDN (PI481521-6A), were more susceptible than the parent Langdon durum, which itself showed an intermediate FHB reaction. Also, these inoculated spikelets were detected by using Beacon Analytical Systems DON plate kit to analysis the mycotoxin .The results showed two lines LDN (PI481521-3A) and LDN (PI481521-7B) were the lowest amount of mycotoxin. Among the substitution lines, so there is a strong correlation between FHB severity and Don contents. Consequently, the genes responsible for to resistant to FHB and inhibition of mycotoxin production were preliminary localization.2. Inoculating three sets of chromosome substitution lines to analysis their reaction to CR infectionAs part of our effort to address the wheat CR problem, we analyzed three sets of Langdon-Triticum dicoccoides (LDN-DIC) disomic chromosome substitution lines. This analysis found highly significant difference among these lines in their reactions to CR infection. CR reaction is clearly quantitatively inherited as several of the substitution lines in each of the three sets showed altered responses to CR infection, some with improved while others with reduced resistance. Substituting any of the Langdon chromosomes by the three different donors failed to consistently improve CR resistance. The responses of a particular line for a given Langdon chromosome varies depend on the different donor genotypes. This suggests that the three donor genotypes have different genes conferring CR resistance, and those genes conferring super-susceptibility may not exist in durum wheat.3. Compared the CR resistance lines to FHB resistance linesThe results above showed the most CR resistant lines are not those with the best resistance to Fusarium head blight, confirming that, although can be caused by the same pathogens, these two diseases are controlled by different genes.