Occurrence and virulence of<i>Puccinia recondita</i>in Canada in 1985

Samborski, D. J.

doi:10.1080/07060668609501782

Cited by 6 publications

(1 citation statement)

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“…The effectiveness of Lr12 against the majority of local leaf rust pathotypes can probably be ascribed to the fact that Lr12 has not been deliberately used in wheat breeding in South Africa. Virulence to Lr 12 has, however, been reported from elsewhere (Samborski, 1983;1986;Stoyanov, 1987;Singh & Gupta, 1992;Park & McIntosh, 1994;McIntosh, Wellings & Park, 1995), emphasizing the nondurability of the gene when exposed singly in commercial cultivars.…”

Section: Discussionmentioning

confidence: 98%

Assessment of macroscopic components of leaf rust resistance in wheat genotypes containing Lr12 and Lr13

Bender

Pretorius

Spies

1997

South African Journal of Plant and Soil

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Monogenic resistance in wheat (Triticum aestivum L.) to leaf rust, caused by Puccinia recondita Rob. ex. Desm. f. sp. tritici, h•as generally not been durable. Durable resistance, as well as an improved expression of resistance, have been associated with Lrgene combinations. In this study, the assumption that Lr12 and Lr13 may interact to condition improved resistance to leaf rust, was investigated. Four Thatcher (T c) x RL6011 F3 lines (13/12-3, 13/12-9, 13/12-19 and 13/12-40), homozygous for both Lr13 and Lr12, were selected and their leaf rust resistance compared with the parents (CT263 [=TcLr13] and RL6011 [=TcLr12]), the single gene lines Tc/13-22 and TC/12-16, and Thatcher. In addition to infection type studies in seedlings and adult plants, lines were compared according to macroscopic components of resistance, as well as disease ratings in the field. Flag leaf infection type studies showed that Lr12 is effective against most pathotypes of P. recondita f. sp. tritici occurring in South Africa. Conversely, Lr13 is ineffective against the dominant pathotypes, implying that the gene has no value as a monogenic source of resistance. Based on the fact that several pathotypes are avirulent to these genes, they should be manipulated with relative ease in local breeding programmes directed at utilizing these sources in combination with other Lr genes. Infection types on the flag leaves of lines carrying both Lr12 and Lr13 often displayed chlorosis and necrosis. These ratings on primary and flag leaves, as well as the quantitative components latent period, uredium density and uredium size, did not indicate clear differences between the digenic lines and the most resistant parent. In the absence of a pathotype virulent to both genes, the combination lines were resistant in the field. Data obtained were not conclusive in suggesting pronounced resistance enhancement due to combining Lr12 with Lr13. Enkelgeen-weerstand in koring (Tn"ticum aestivum L.) teen blaarroes, veroorsaak deur die swam Puccinia recondita Rob. ex. Desm. f. sp. tritici, is dikwels nie volhoubaar nie. Meer standhoudende weerstand, asook verbeterde vlakke van weerstand, kan verkry word deur weerstandsgene te kombineer. In hierdie studie is die aanname ondersoek dat die interaksie tussen Lr12 en Lr13 verhoogde weerstand teen blaarroes tot gevolg kan he. Vier F31yne in die genetiese agtergrond van Thatcher (Tc) (13/12-3,13/12-9,13/12-19 en 13/12-40), homosigoties vir beide Lr12 en Lr13, is geselekteer en met die ouers (CT263 [=TcLr13] en RL6011 [=TcLr12]), die enkelgeenlyne Tc/13-22 en Tc/12-16, en Thatcher vergelyk ten opsigte van blaarroesbestandheid. Behalwe vir die bepaling van infeksietipes, is makroskopiese weerstandskomponente gekwantifiseer en siekteramings in die veld gedoen. Vlagblaarinfeksietipes het getoon dat Lr12 effektief is teen meeste Suid-Afrikaanse patotipes van P. recondita f. sp. tritici. Die dominante patotipes is virulent tot Lr13. Die voorkoms van verskeie avirulente patotipes beteken dat die gene met refatiewe gemak in plaaslike...

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