Genetic Relationship among Sweetpea Cultivars and Related Species by AFLP Analysis

Abstract

Sweetpea (Lathyrus odoratus L.) is an important ornamental crop belonging to the Fabaceae family. In Japan, commercial cut flower production under forced culture has flourished, but few cultivars are bred exclusively for cut flower forced culture. In order to obtain knowledge for the selection of breeding materials, we elucidated the genetic relationships among eighty-seven sweetpea cultivars and two related species using the amplified fragment length polymorphisms (AFLP). Sweetpea cultivars were grouped into two clusters. Cluster I consisted of four cultivars, including a wild cultivar, ‘Cupani’ and cultivars established from spontaneous mutation or natural hybridization, such as ‘Cupid’ and ‘Painted Lady’. The biggest cluster, cluster II, consisted of eighty-three sweetpea cultivars. No distinct subcluster shared common morphological or ecological characteristics, such as tendril-less, plant type, or flowering habit in cluster II. The distinct genetic differentiation among cultivars highly seems to reflect sweetpea breeding history originating in the United Kingdom 300 years ago using limited genetic resources. Thus, hybridization with genetically distinct, exotic resources may contribute to the development of sweetpea cultivars.