02460naa a2200265 a 450000100080000000500110000800800410001910000170006024501640007726000090024152016230025065000330187365000160190665000100192265000220193265300110195465300240196565300320198965300190202165300120204065300320205270000140208470000170209877300790211510829292012-06-26       2004    bl uuuu     u00u1 u    #d1 aMEHTA, Y. R.  aMolecular and pathogenic variability of Pyrenophora tritici-repentis isolates causing tan spot of wheat in the State of Paraná, Brazil.h[electronic resource]  c2004  aGenetic variability of 40 Pyrenophora tritici-repentis (Ptr) isolates collected from several wheat cultivars/lines grown in 12 different regions of the state of Paraná, during 1996-2000, was assessed by pathological and molecular analyses. Out of the 40 isolates, only 17 sporulated and hence only these were used for pathological studies, whereas all 40 isolates were used for molecular analyses and phytotoxin sensitivity test. One of the 17 isolates was non-pathogenic to wheat. Virulence test conducted on six wheat cultivars against the other 16 Ptr isolates, revealed a very low cultivar x isolate interaction indicating that the isolates differed in aggressiveness and a low possibility of existence of different races. The sensitivity of the cultivars to the culture filtrate was not always correlated with susceptibility to the pathogen. All the 38 commercially grown wheat cultivars showed compatible reaction to the Ptr isolates. However, some cultivars differed in their level of resistance. When amplification products obtained with primers ITS4 and ITS5 were digested with five restriction enzymes, similar banding patterns were observed for all the isolates. ERIC and REP-PCR data were combined to construct a dendrogram which revealed three groups at 80% similarity, however, 90% of the isolates formed a single group, and were compatible with the results obtained in virulence test. The results indicate that Ptr on wheat in the State of Paraná is genetically uniform, implying that screening wheat germplasm for resistance to this disease need not involve a wide range of isolates of this pathogen.  aPyrenophora tritici-repentis  aAgricultura  aTrigo  aTriticum Aestivum  aBrasil  aCultivares de trigo  aDrechslera tritici-repentis  aMancha amarela  aParaná  aSensibilidade à fitotoxina1 aMEHTA, A.1 aRIEDE, C. R.  tSumma Phytopathologica, Botucatugv. 30, n. 4, p. 436-444, Oct./Dec. 2004.