Aryana Libris

Author : Herrmann Doris
Title : Characterisation of Genetic Diversity and Molecular Dissection of Seed Yield and Persistence in Swiss Mattenklee
Year : 2006

Link download : Herrmann_Doris_-_Characterisation_of_Genetic_Diversity_and_Molecular_Dissection_of_Seed_Yield_and_Persistence_in_Swiss_Mattenklee.zip

Summary. Red clover (Trifolium pratense L.) is an important component of permanent pastures and meadows as well as of grass-clover leys in temperate regions. Mattenklee landraces, i.e. persistent and locally adapted Swiss red clover landraces, and wild red clover populations may present particularly valuable genetic resources. However, landraces and wild populations are poorly characterised and the genetic origin of Mattenklee is largely unknown. Although through the last decades red clover cultivars improved for traits such as forage yield or disease resistance have been developed, cultivars often suffer from low seed yield and persistence. These two complex traits are influenced by many components, may be negatively correlated and have therefore proven to be difficult to improve. Molecular markers may help to rapidly characterise genetic resources. In addition, the development of markers closely linked to seed yield and persistence may help to complement and speed up traditional breeding procedures. The first objective of this thesis was to determine genetic diversity and distinctness of Mattenklee landraces and wild clover populations and to investigate the potential ancestry of Mattenklee. The second objective was to identify quantitative trait loci (QTLs) for seed yield and persistence for the future development of molecular markers to apply in marker assisted breeding and to detect alternative traits linked to the target traits, which are easier to score, thus allowing for improved selection of seed yield and persistence. In the first part of the project, eight Mattenklee landraces, eight Mattenklee cultivars and three field clover cultivars were characterised using 24 individual plants and amplified fragment length polymorphism (AFLP) markers. Furthermore, an optimised bulking strategy using AFLP markers and two bulked samples per population consisting of twenty plants each was applied to characterise 120 populations of six different red clover groups (Mattenklee landraces, Mattenklee cultivars, Swiss wild clover populations, field clover cultivars, Dutch wild clover populations and Dutch landraces). The results of these two studies revealed Mattenklee landraces as a distinct group showing a high genetic diversity, which was clearly higher than diversity of Mattenklee and field clover cultivars. The investigations based on bulked samples showed that Swiss wild clover populations are a highly diverse and distinct group, which was clearly separated from all other red clover groups. This separation emphasises that the ancestry of red clover landraces is primarily found in introduced germplasm rather than in natural wild clover populations. Mattenklee landraces and Swiss wild clover populations represent distinct and diverse genetic resources for the improvement of red clover cultivars and for conservation and restoration of diversity. ...