Genetische Analysen für eine markergestützte Verbesserung der Trockenstresstoleranz von Winterackerbohnen

Abstract

In this analysis, aiming to prepare for marker-assisted selection of drought tolerance in autumn sown faba bean (Vicia faba L.), 196 winter-type and four spring-type inbred lines were genotyped. Physiological traits such as spad, membrane stability index, leaf water content, total content of soluble sugars as well as proline and glycine betaine accumulation were assessed in control and stress treatments. 40 out of 196 inbred lines were pheno-typed in the field to elucidate correlations between physiological traits and field-assessed traits, such as yield. Rain-Out-Shelters were used in Göttingen and Groß Lüsewitz in 2010/2011, 2012 and 2012/2013. Chemical desiccation with potassium iodide solution was used to test such indirect means of drought stress simulation. Yet, no trustworthy relations were found between drought and desiccation induced stress symptoms. Furthermore, no clear correlations were proven between physiological traits and field-based drought stress results. Using a mapping population of 101 RIL a genetic map comprising 1451 molecular markers, 12 linkage groups and a total length of 1633.2 cM was constructed. Five of these linkage groups were identified as fragments. The seven remaining ones were indirectly assigned to the six chromosomes of faba bean via SNP-markers, e.g. linkage group one and four repre-sent one shared linkage group. Mapped markers were selected upon their segregation pat-tern in the A-set – comprising 189 of the phenotyped 196 winter-type inbred lines – and used in association analysis of physiological traits. Linkage disequilibrium between 323 610 marker pairs was compared to their map distance. Decay of linkage disequilibrium is shown to be reduced by recombination during genetic material’s development. Using 1322 molecular markers in association mapping, six QTL for physiological traits were identified. One QTL each for absolute difference in glycine betaine content between con-troll and stress treatment and glycine betaine in control treatment were found. Further, four markers were identified to be related to absolute difference in proline content be-tween stress and control treatment. Yet, the QTL identified cannot be recommended for marker-assisted selection on drought stress tolerance as traits’ relevance could not be veri-fied in the field. In a next step, inbred lines could be field-phenotyped in naturally drought prone environments using multiple years and locations. Such results could be used for fur-ther evaluation of the above mentioned physiological traits.