). In this study, two progenies, constructed from the hybridization of CMS line 8A with restorer lines R1 and R2, analyzed the inheritance mechanisms of fertility restoration for CMS in pepper by the joint segregation analysis method. The aims of this
Bingqiang Wei, Lanlan Wang, Paul W. Bosland, Gaoyuan Zhang, and Ru Zhang
Hsiang-I Lee and Michael J. Havey
) cytoplasm with the homozygous recessive genotype at one nuclear male fertility restoration locus ( Ms ) ( Jones and Clarke, 1943 ). Breeders work to eliminate the dominant allele at Ms from populations to ensure stable expression of male sterility and
Derek W. Barchenger, Joseph I. Said, Yang Zhang, Mingzhou Song, Franchesca A. Ortega, Yeasong Ha, Byoung-Cheorl Kang, and Paul W. Bosland
linkage groups ( Min et al., 2009 ) have also been reported to control the phenotype. Furthermore, partial fertility restoration has been reported ( Lee, 2001 ; Lee and Park, 2008 ) with multiple haplotypes in existence ( Min et al., 2008 ). Liu et al
Michael J. Havey
( Ms ) controls male-fertility restoration; a dominant allele at Ms conditions male fertility, whereas plants homozygous-recessive at Ms are male-sterile ( Jones and Clarke, 1943 ). Plants possessing normal (N) cytoplasm are always male
The primary source (S cytoplasm) of cytoplasmic-genic male sterility (CMS) used to produce hybrid-onion (Allium cepa L.) seed traces back to a single plant identified in 1925 in Davis, California. Many open-pollinated populations also possess this cytoplasm, creating an undesirable state of cytoplasmic uniformity. Transfer of cytoplasms from related species into cultivated populations may produce new sources of CMS. In an attempt to diversify the cytoplasms conditioning male sterility, the cytoplasm of Allium galanthum Kar. et Kir. was backcrossed for seven generations to bulb-onion populations. The flowers of galanthum-cytoplasmic populations possess upwardly curved perianth and filaments with no anthers, making identification of male-sterile plants easier than for either S- or T-cytoplasmic male-sterile onion plants. Mean seed yield per bulb of the galanthum-cytoplasmic populations was measured in cages using blue-bottle flies (Calliphora erythrocephala Meig.) as pollinators and was not significantly different from one of two S-cytoplasmic male-sterile F1 lines, a T-cytoplasmic male-sterile inbred line, or N-cytoplasmic male-fertile lines. Male-sterile lines possessing either the S or galanthum cytoplasm were each crossed with populations known to be homozygous dominant and recessive at the nuclear locus conditioning male-fertility restoration of S cytoplasm and progenies were scored for male-fertility restoration. Nuclear restorers of male fertility for S cytoplasm did not condition male fertility for the galanthum-cytoplasmic populations. It is intended that these galanthum-cytoplasmic onion populations be used as an alternative male-sterile cytoplasm for the diversification of hybrid onion seed production.
Chunsheng Lu and Mark Bridgen
An interspecific hybrid of Alstroemeria aurea × Alstroemeria caryophyllaea was rescued by immature ovule culture and was completely sterile. To restore the fertility of the hybrid, young, vigorous shoots and buds were treated aseptically with three colchicine levels (0.2, 0.4, and 0.6% in DMSO solution) at four treatment durations (6, 12, 18, and 24 hours), before being cultured onto a shoot regeneration medium for regrowth and development. The growth and development of all treated shoots were retarded by the colchicine. New shoots were regenerated from 61% of the surviving cultures after one month. The degree of recovery was not significantly different among treatments, although the highest concentration (0.6%) and the longest time treatment (24 hours) resulted in some morphological abnormalities. Cultures with newly regenerated shoots/buds were able to initiate roots and, eventually, sixty plantlets were transplanted into the greenhouse after acclimatization. Cytological examination of the root tip cells of the plantlets indicated that tetraploids (2n=4x=32) as well as aneuploids plants were generated from the colchicine treatment, whereas all plants from the control were diploids (2n=2x=16). Details explaining cytological changes and the fertility of the colchiploids will be presented.
Sergio Melgar and Michael J. Havey
one nuclear male-fertility-restoration locus ( Ms ) ( Jones and Clarke, 1943 ). Male-fertile plants possess normal (N) male-fertile cytoplasm or male-sterile (S) cytoplasm with a dominant allele at Ms . Male-sterile plants (S msms ) can be seed
Michael J. Havey and Sunggil Kim
homozygous recessive genotype at one nuclear male-fertility restoration ( Ms ) locus. A dominant allele at Ms conditions male fertility for plants possessing S cytoplasm. Jones and Davis (1944) recognized that male-sterile plants ( S msms ) can be seed
Ali Fuat Gokce and Michael J. Havey
Cytoplasmic-genic male sterility (CMS) is used to produce hybrid onion seed. For the most widely used source of CMS in onion, male sterility is conditioned by the interaction of sterile (S) cytoplasm and the homozygous recessive genotype at a single nuclear male-fertility restoration locus (Ms). Maintainer lines used to seed-propagate male-sterile lines possess normal fertile (N) cytoplasm and the homozyous recessive genotype at the Ms locus. Presently, it takes 4 to 8 years to establish if maintainer lines can be extracted from an uncharacterized population or family. We previously developed a PCR marker useful to distinguish N and S cytoplasms of onion. To tag the nuclear male-fertility restoration locus (Ms), we evaluated segregation at Ms over at least three environments. Segregations of AFLPs, RAPDs, and RFLPs revealed molecular markers flanking the Ms locus. We are working to convert these linked molecular markers to nonradioactive PCR-based detection. The organellar and nuclear markers were used to select plants from open-pollinated onion populations and determine if the number of test-crosses required to identify maintaining genotypes.
David A. Dierig, Pernell M. Tomasi, and Dennis T. Ray
Lesquerella fendleri (Gray) Wats. (lesquerella, Brassicaceae), native to the southwestern United States, is a potentially useful industrial oilseed crop. The seed oil contains hydroxy fatty acids, similar to castor (Ricinus communis L.) seed oil. The unique properties of the oil, along with coproducts, allow additional applications that would not compete with castor oil. Plants with vestigial anthers (male-sterile) were discovered in a greenhouse-grown, nonselected population in 1993. The inheritance of the trait was investigated through four crop seasons. Crosses were made among male-sterile and male-fertile plants from an open pollinated population, thus, they were heterozygous for many traits. Statistical analysis indicated that male sterility is expressed as a result of two nonlinked nuclear genes with epistatic relations and different cytoplasms, which cause partial or total fertility restoration. These ratios fit a 13:3 epistatic ratio, indicating that male sterility is controlled by homozygous recessive alleles at one locus in combination with at least one dominant allele at the second locus, i.e., ms1ms1 Ms2_. Some cross results were skewed in favor of fertile phenotypes presumably due to cytoplasmic effects causing partial fertility restoration. Male-sterile lines could be used for hybrid development and this information will be helpful in implementing a strategy for hybrid development. Hybrid plants and higher yields will enhance the potential for commercialization of this new alternative crop.