Abstract

The objective of this work was to evaluate the effect of the presence of 2N^VS translocation on the inheritance of wheat resistance to head blast, in F₂ segregating lines from two biparental crosses. The IPF 86766 and 'Santa Fe' genotypes were used as female parents (both 2N^VS carriers), and 'BRS 404', as the common male parent (non 2N^VS carrier). Using a mixture of three isolates of Pyricularia oryzae Triticum, wheat spikes and rachises were evaluated for bleaching severity at five (%BS_5dpi) and seven days post-inoculation (%BS_7dpi), as well as for the number of infection points (IPR) and pathogen sporulation (SPO). Chi-square analyses showed that segregation follows a 3:1 Mendelian hypothesis, with a major locus with a dominant allele: %BS_7dpi for IPF 86766 × 'BRS 404' and IPR for 'Santa Fe' x 'BRS 404'. Therefore, this is the first known study to show that the 2N^VS translocation responsible for resistance to head blast is a major locus with a dominant allele. In a controlled environment, 'BRS 404' shows bleaching severity and SPO similar with those occurring on IPF 86766 and 'Santa Fe'.

Index terms:
Magnaporthe oryzae ; Triticum aestivum ; genetic resistance; rainfed farming; wheat blast