Genetics of stripe rust (Puccinia striiformis Westend.) resistance in the sort white spring wheat, Owens

Abstract

Stripe rust (yellow rust), caused by Puccinia striiformis Westend. is a major disease of wheat and barley, particularly in cool, moist growing seasons. The Canadian soft white spring wheat, Owens, is known to possess resistance to the stripe rust race SRC 4-84. The aim of this project was to study the genetics of resistance in Owens. Several Kenyan wheat cultivars were also tested for their response to the Canadian stripe rust races. The cultivar Owens posesses one, homozygous dominant gene for seedling resistance against SRC 4-84. This gene is not Yrl, Yr3a, Yr3b, Yr3c, Yr4a, Yr4b, Yr5, Yr6, Yr7, Yr8 or YrlO. It is unlikely to be Yr9 or Yr15, as neither gene is indicated in the Owens pedigree. The remaining, untested seedling genes are Yr2 and YrA. It is also possible that the resistance in Owens is conferred by a gene that has not been described. The yellow rust differential cultivar Hybrid 46 exhibits a recessive resistance to race SRC 4-84, which is either being conferred by Yr3b or a previously undescribed gene in this cultivar. Eight Kenyan lines (Kenya Chiriku, Kenya Mlembe, Kenya Popo, Kenya Kulungu, Kenya Nyumbu, Pasa, Kwale, Paa) were resistant to the Canadian stripe rust race SRC 4-84. Based on already published data and the findings of this study, it was determined that the effective resistance in Kenya Kulungu against race SRC 4-84 is being conferred by Yr3b or a previously unidentified gene. Low levels of residual resistance were detected in seven, older cultivars (Kenya Tembo, Kenya Swara, Kenya Leopard, Kenya Page, Bounty, Romany, Africa Mayo).