Genetic changes accompanying the domestication of Pisum sativum: is there a common genetic basis to the 'domestication syndrome' for legumes?

Abstract

Background and aims: The changes that occur during the domestication of crops such as maize and common bean appear to be controlled by relatively few genes. This study investigates the genetic basis of domestication in pea (Pisum sativum) and compares the genes involved with those determined to be important in common bean domestication.

Methods: Quantitative trait loci and classical genetic analysis are used to investigate and identify the genes modified at three stages of the domestication process. Five recombinant inbred populations involving crosses between different lines representing different stages are examined.

Key results: A minimum of 15 known genes, in addition to a relatively few major quantitative trait loci, are identified as being critical to the domestication process. These genes control traits such as pod dehiscence, seed dormancy, seed size and other seed quality characters, stem height, root mass, and harvest index. Several of the genes have pleiotropic effects that in species possessing a more rudimentary genetic characterization might have been interpreted as clusters of genes. Very little evidence for gene clustering was found in pea. When compared with common bean, pea has used a different set of genes to produce the same or similar phenotypic changes.

Conclusions: Similar to results for common bean, relatively few genes appear to have been modified during the domestication of pea. However, the genes involved are different, and there does not appear to be a common genetic basis to 'domestication syndrome' in the Fabaceae.

Fig. 1.

Photograph of pea pods with considerable growth of undifferentiated tissue (neoplasms) caused by expression of the Np allele. Such expression usually occurs only when plants are grown in the glasshouse. In the field, Np expression is suppressed except under specific conditions such as bruchid infestation.

Fig. 2.

The linkage groups of Pisum sativum (n = 7). Symbols and relative positions of loci and QTLs influencing morphological or physiological changes occurring during the domestication of the species are given in large print to the right of the respective linkage group. Anchor markers are shown in small print along the linkage groups. An asterisk following a locus symbol indicates that the locus had pleiotropic effects on several traits modified during domestication of pea.