) 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
Hsiang-I Lee and Michael J. Havey
Derek W. Barchenger, Joseph I. Said, Yang Zhang, Mingzhou Song, Franchesca A. Ortega, Yeasong Ha, Byoung-Cheorl Kang, and Paul W. Bosland
for marker-assisted selection to introduce an Rf gene into novel germplasm ( Lin et al., 2015 ). More recently, the Co1Mod1 marker ( Jo et al., 2016 ) has been found to have similar applicability. Inheritance of restoration-of-fertility in chile
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
Bingqiang Wei, Lanlan Wang, Paul W. Bosland, Gaoyuan Zhang, and Ru Zhang
). 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
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
Josiah Raymer, Mack Thetford, and Debbie L. Miller
building foredunes. More often, seacoast marshelder is found in combination with one or more dune-building grasses ( Woodhouse, 1982 ). Seacoast marshelder is used for dune restoration and stabilization projects ( Craig, 1991 ) and has also been identified
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 Gökçe, John McCallum, Yutaka Sato, and Michael J. Havey
Cytoplasmic-genic male sterility (CMS) is used to produce hybrid onion (Allium cepa L.) seed. For the most widely used source of onion CMS, male sterility is conditioned by the interaction of the male-sterile (S) cytoplasm and the homozygous recessive genotype at a nuclear male-fertility restoration locus (Ms). Maintainer lines are used to seed propagate male-sterile lines, possess normal (N) male-fertile cytoplasm, and are homozyous recessive at the Ms locus. Due to the biennial nature of onion, it takes 4 to 8 years of crossing and scoring of progeny phenotypes to establish if maintainer lines can be extracted from an uncharacterized population or family. Identification of nuclear markers tightly linked to the Ms locus would allow for molecular-facilitated selection of maintainer lines. We evaluated testcross progenies from a segregating family for nuclear restoration of male fertility over at least three environments. Although segregations in the F2 family fit the expected 1:2:1 ratio (P = 0.973), the proportion of male-sterile testcross progenies showed significant (P < 0.01) year effects and it is therefore imperative to score male-fertility restoration over environments. Too many male-sterile testcross progenies were often observed, indicating that the dominant allele conditioning male-fertility restoration for S cytoplasm may not show complete penetrance. Segregations of amplified fragment length polymorphisms and restriction fragment length polymorphisms (RFLPs) revealed RFLPs flanking the Ms locus at 0.9 and 8.6 cM. An onion cDNA showing highly significant homology to the aldehyde dehydrogenase conditioned by the rf2 locus of maize was identified and mapped to linkage group I, independent of the Ms locus. A sample of commercial onion germplasm was evaluated for putative allelic diversity at the RFLP loci linked to Ms. The genomic region corresponding to the cDNA (AOB272) revealing the closest RFLP to Ms was sequenced to reveal numerous single nucleotide polymorphisms. Single-stranded conformational polymorphisms and single nucleotide extensions were developed that revealed genomic variation at AOB272-EcoRI. The use of these molecular markers to select maintainer lines in onion is discussed.