Implementation of marker assisted breeding in triticale

[摘要] ENGLISH ABSTRACT: Research into markers for the detection of genetic diversity and cultivar identification hasbecome an important component of the genetic improvement of crops. However, the incorporationof marker assisted selection (MAS) as a tool for the identification and characterizationof breeding material has not been fully implemented in the breeding of springtriticale at Stellenbosch University's Plant Breeding laboratory (SU-PBL). The presentstudy served as a case study in order to achieve this.The first part of the study concerned the detection of genetic diversity in 101 newlysourced triticale cultivars, from a USDA germplasm bank, together with five local controlcultivars, in order to identify possible crossing parents. Eight SSR markers, including fivederived from rye and three from wheat, and five agronomic characteristics were used toassess diversity. In seedling screening the foreign cultivars showed resistance towards thestem rust isolate used, but were mostly susceptible to the leaf rust isolate. Out of the 8SSR markers tested, 7 markers were polymorphic and revealed 140 alleles varying from 12to 26 with an average of 17.5 alleles per locus. The observed polymorphic informationcontent (PIC) value ranged from 0.39 to 0.88 with an average of 0.70, indicative of thegood discriminatory ability of the SSR markers. The data revealed that the South Africancultivars were genetically closely related to cultivars from the USA and Canada.The second part of the study focused on the introgression of a blue aleurone layer gene(Ba), carried by a wheat cultivar, 'Cltr1202STR', and purple pericarp genes (Pp1; Pp3)also carried by a wheat cultivar, 'Amethyst', into a triticale background. Unfortunately theintrogression of the purple pericarp genes failed. Two lines containing the blue aleuronelayer, 11T023 and 11T028, were however successfully created. Molecular typing of theselines with SSR markers were able to show that BC4F1 line 11T023 (Ba) B was geneticallysimilar to the recurrent parent 'Agbeacon'; and that the BC4F1 11T028 line (Ba) A wasclosest to the 'US2007' recurrent parent.The study illustrated that MAS was a reliable tool for detecting genetic diversity in newlysourced germplasm, and assisted in making a backcross breeding effort more effective.The data generated from MAS could therefore clearly assist in making the SU-PBL breedingprogram more effective by moving, better informed, decision making toward data based partly on the genotype, thereby minimizing the risks associated with purely phenotypicbased decisions.

[发布机构] Stellenbosch University