Initiation of a pre-breeding programme for enhancing genetic resistance against wheat rust

[摘要] ENGLISH ABSTRACT: Plant diseases are among the major causes of food insecurity. In South Africa the wheat fungaldiseases including stem rust caused by Puccinia graminis f. sp. tritici, leaf rust caused by P.triticina and stripe rust caused by P. striiformis f. sp. tritici are the most important. Geneticresistance is a viable way of protecting wheat crops against the wheat rusts, especially cultivarscarrying multiple genes that confer durable resistance. In order to breed for multi-gene resistance aneffective breeding strategy that allows for selecting multiple resistance genes and other desirabletraits needs to be devised.The aim of this study was to identify a number of genotypes with combinations of different rustresistance genes, good grain yield and end-use quality out of an existing pre-breeding populationand thereby identify superior parents. In order to achieve the stated aim the following objectiveshave been identified: identify wheat lines through marker-assisted selection (MAS) carrying thegene complexes, Sr31/Lr26/Yr9, Lr24/Sr24, Lr37/Sr38/Yr17, Lr34/Yr18 and Sr2; to develop inbredlines to evaluate selected lines under field trials.From the initial subset of 64 lines, 60 were chosen and advanced to the doubled haploid (DH) phaseand seed multiplication. The 60 lines either carried one or more of the three rust resistance genecomplexes. The genes that were the most prominent were Sr31/Lr26/Yr9 and Lr24/Sr24. Theselected lines were incorporated into a DH seed multiplication phase. After 4 cycles of seedincreases and preliminary field evaluation during multiplication, 15 lines were chosen and subjectedto multi-location field trails.The extensive multi-location field trails carried out in this study aided in identifying genotypes fromthe 15 MS-MARS lines with good adaptability and stability in regards to yield and baking quality.An important observation was that the molecular markers employed to indentify quality locicorrelated well with the genes encoding the HMW-GS 5, 10 and 12 as observed with the Agilent©2100 Bioanalyzer.In future studies the lines which performed the best could be re-introduced into the existing MSMARSpre-breeding programme of the Stellenbosch University's Plant Breeding Laboratory (SUPBL).The frequencies of desired alleles could be increased in this manner. Since the majority ofthese characteristics are influenced by quantitatively inherited alleles, using these lines as recurrent parents will increase the frequencies of these alleles in the existing SU-PBL pre-breedingpopulation.

[发布机构] Stellenbosch University