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Title: Genetic studies of wide crosses between cultivated pea species, and the domestication of Pisum abyssinicum
Author: Holden, David
ISNI:       0000 0004 2687 2712
Awarding Body: University of East Anglia
Current Institution: University of East Anglia
Date of Award: 2009
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Genetic maps were produced from wide crosses between the garden pea Pisum sativum and the cultivated species P. abyssinicum, cultivation of which is confmed to North-east Africa and Yemen. Crosses were made in two directions: with P. abyssinicum as the female parent in ll2202 (P. abyssinicum) x ll2822 (P. sativum), and as the male parent in Kite (P. sativum) x ll2 (P. abyssinicum). Parallel linkage maps were produced for the two populations. 454 markers were mapped in the ll2202 x ll2822 F7 population, and 252 in the Kite x ll2 F6 population, using predominantly SSR (simple sequence repeat) and SSAP (sequence-specific amplification polymorphism) markers. 152 markers are shared between linkage maps; this figure represents more than 50% of the mapped markers derived from the primer combinations that were used on both populations. A number of novel loci were associated with segregating traits derived from both cross parents. Analysis in the ll2202 x ll2822 population found strong partial resistance to infection by downy mildew (Peronospora viciae f. sp.pisi), in which 52% of trait variance was explained by a single locus on linkage group I. This source of resistance is derived from the P. sativum parent. Significant segregation distortion affected approximately half of the markers used in the linkage maps; segregation ratios were found to be biased in favour of maternal alleles in both populations, which may represent a fonn of partial reproductive isolation between P. abyssinicum and P. sativum. Combined with observed transgressive segregation of domestication traits in the wide crosses, this suggests that these taxa do not have a shared domestication history.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available