Production of 2n Pollen and Further Characterization of the Calyx Carpellaris (cc) Trait in the Pea1

Abstract

Many genes are known to affect floral development in the pea (Pisum sativum L.), but few of these traits have been extensively studied. Flower abnormalities that confer self‐sterility may be of interest to the breeder for the purpose of facilitating outcrossing because the pea is highly self‐pollinated in North American environments. Among th mutants affecting self‐fertilization, the structural steriles are generally male and female fertile; but structural malformations inhibit transfer of pollen to the stigma of the same flower. A structurally sterile mutant of spontaneous origin was observed in the line X1415 and was provided to us by L. G. Cruger, Del Monte Corp. A study was undertaken to describe its floral anatomy and cause of sterility and to determinites inheritance and possible linkage. Flowers of the mutant are carpelloid with extra gynoeciad ifferentiated from the calyx and androecium and exhibit reduced male and female fertility. The corolla is reduced or absent. The mutant produces varying amounts of 2n pollen via parallel spindles during Meiosis II. 4× ✕ 2× crosses are difficult, but possible. F2 segregation of three marker genes in sexually derived tetraploids showed tetrasomic inheritance. The mutant is allelic to calyx carpellaris (cc) in the G.10B line and probably is the same gene. The mutant is conditioned by homozygous recessive alleles at a single locus; and linkage was demonstrated among the cc, r, tl, and coch loci. The gene order is r‐tl‐cc‐coch on Chromosome 7. Under field conditions, 13% of the structurally sterile F2 plants set pods with an average of 1.6 pods per plant. The progeny were mostly the result of self‐fertilization, but at least one‐third were the result of outcrossing.