|Lopes Leite, Daniela - HORT DEPT UNIV WI MADISON|
Submitted to: Journal of American Society of Horticulture Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 29, 1998
Publication Date: N/A
Interpretive Summary: Hybrid leek offers numerous advantages to growers, including significantly greater yield, greater uniformity, and combination of disease resistances. However, a major obstacle to the production of hybrid leek is a system of male sterility. The leek inflorescence contains hundreds of flowers with male and female parts functioning at the same time. Large-scale emasculation is not practical. Cytoplasmic male sterility (CMS) is known in many crops and commonly used to produce hybrid seed. CMS is conditioned by DNA housed in the mitochondria and is maternally transmitted. Genetic analyses of mitochondrial DNA has revealed differences among the mitochondria of male-sterile and male-fertile plants. In this study, we evaluated for differences in the mitochondrial and chloroplast DNAs among populations of leek and its closely related relatives kurrat and great-headed garlic. Research is continuing as populations possessing unique mitochondrial DNA were identified and are being evaluated for male sterility.
Technical Abstract: Hybrid leek (Allium ampeloprasum L. var. porrum) is more uniform and higher yielding than open-pollinated cultivars. Leek has perfect flowers and a male-sterility system is required to produce hybrid seed. A genic male-sterile plant has been identified and is asexually propagated as the female parent of leek hybrids. A system of cytoplasmic male sterility (CMS) in leek would be a cheaper alternative to the high cost of asexually propagating female plants for hybrid production. CMS systems are used to produce hybrid bulb onion, bunching onion, and chive, but no CMS system has been identified in leek. Restriction fragment length polymorphisms (RFLPs) in the chloroplast and mitochondrial genome have correlated with CMS in many crops. We undertook Southern analyses of the chloroplast and mitochondrial DNAs to identify polymorphisms among the organellar genomes of 60 accessions of cultivated A. ampeloprasum. No polymorphisms were detected in the chloroplast genome of leek and kurrat. Three accessions of leek and one of kurrat possessed polymorphisms for seven mitochondrial probe-enzyme combinations. Great-headed garlic differed from leek and kurrat for six polymorphisms in the chloroplast genome and for many mitochondrial probe-enzyme combinations. The 45s rDNA of great-headed garlic differed from kurrat and leek at six restriction-enzyme sites. We identified individual leek plants possessing mitochondrial polymorphisms and will establish if polymorphic cytoplasms correlate with the expression of CMS.