Races of Puccinia triticina detected on wheat in Zimbabwe, Zambia and Malawi and regional germplasm responses uri icon

abstract

  • To identify races of Puccinia triticina in southern Africa, samples of infected wheat leaves obtained from Zimbabwe, Zambia and Malawi were analysed at the University of the Free State, Bloemfontein and the Agricultural Research Council-Small Grain Institute, Bethlehem, South Africa (SA). Four races were identified from 63 isolates obtained during 2011-2013. Using the North American notation, these races coded to MCDS (74.6 %), TCPS (12.7 %), FBPT (6.3 %) and SCDS (6.3 %). MCDS and TCPS occurred in both Zimbabwe and Zambia whereas FBPT and SCDS were only detected in Zimbabwe and Malawi, respectively. Three of these races (MCDS, FPBT and SCDS) are also known in SA. SSR analysis of races detected in southern Africa suggested that MCDS and FPBT are more closely related to CCPS (3SA45), a race identified in SA in 2009. Occurrence of similar races across southern Africa indicates migration of inoculum between countries, and highlights the need for each country to monitor and share information on virulence changes in the region. In seedling tests, over 72 % of Zimbabwean commercial cultivars were susceptible to race TCPS which occurred in both Zimbabwe and Zambia. To predict occurrence of adult plant resistance (APR) in these cultivars, they were tested for the presence of gene Lr34 which confers durable resistance to multiple fungal pathogens. Only three cultivars were positive for this gene suggesting that most of the current Zimbabwean commercial cultivars may be susceptible to leaf rust both as seedlings and adult plants, assuming the absence of other APR genes. Three cultivars and 15 breeding lines, all highly resistant as seedlings across races, carried Lr19. One line contained Lr19 and Lr34. It is suggested that sources of race nonspecific resistance genes be included in wheat breeding programs in Zimbabwe.

publication date

  • 2015
  • 2015