Search

The fungus Pyrenophora teres causing disease symptoms similar to P. tritici-repentis was recently detected on wheat in Argentina. After confirmation by molecular studies the pathogen was identified as P. teres f. maculata, part of a complex of leaf spots that affect wheat and other cereal crops. The objective of this work was to characterize the virulence and identify QTL conferring resistance to two isolates of P. teres f. maculata (Ptm) in a collection of 110 spring wheat genotypes previously assembled for association mapping and genotyped with 2836 DArT markers. Two isolates of Ptm (PT2047 and PT2050) were used in field experiments. To find marker-trait associations (MTAs) a mixed linear model implemented in TASSEL 5.1 software was used. Considerable phenotypic variation in disease severity was observed at the seedling and adult stages, and some accessions were resistant to both isolates over 2 years. Twelve MTAs identified with nine markers were significantly associated with resistance. The nine markers were distributed over seven chromosomal regions on 6 of the 21 wheat chromosomes. These QTL were novel since this is the first study to identify genomic regions associated with resistance to Ptm in wheat. Wheat genotypes with moderate to high levels of resistance to P. teres f. maculata were identified and will be useful in breeding programs. [ABSTRACT FROM AUTHOR]

Tan spot caused by Pyrenophora tritici-repentis (Died.) Drechs. (anamorph Drechslera tritici-repentis (Died.) Shoem.) is one of the most important wheat diseases. The aim of this work was to generate information about variability of the resistance to tan spot in a population of spring wheat genotypes. Field experiments were carried out in 2014 at the Experimental Station Julio Hirs chhorn, National University of La Plata. The experimental design was a split-plot with two replications. The main plots were two isolates of P. tritici-repentis. Subplots were 110 spring wheat genotypes. Severity evaluation was performed in seedlings as the area affected with necrosis and chlorosis. Genotypes and isolates significanlty influenced the disease severity. Los Hornos isolate was more aggressive than Gualeguaychú isolate . Severity ranged between 18,4% to 78,7%. Some genotypes showed better performance against one of the isolates. The high variability in resistance to tan spot found could be used in breeding to improve the resistance to the disease. [ABSTRACT FROM AUTHOR]

The present study was designed to determine the effects of inoculations of foliar disease pathogens with different nutritional habits: Pyrenophora tritici-repentis (necrothroph -PTR-) and Puccinia triticina (biotroph -LR-) on the physiological components of biomass generation, like absorbed photosynthetic active radiation (APAR) and radiation use efficiency (RUE), and on the yield production in wheat. Field experiments were carried out in 2012-2013 at FCAyF-UNLP using a split-split-plot design with three replications. The main plots were the pathogen inoculations. Subplots were inoculation treatments: 1- Without inoculation, 2- Low dose of spores concentration inoculation, 3- High dose of spores concentration. Ten cultivars were the sub-subplots. Foliar diseases decreasedbiomass production mainly explained by reductions in green leaf area, healthy area duration and reductionson APAR, showing higher declines under PTR inoculations. A detrimental effect in the RUE was detected at LR inoculations, which could be associated with the nutritional habit of the pathogen. [ABSTRACT FROM AUTHOR]