Search Results

You are looking at 1 - 10 of 10 items for

  • Author or Editor: W.V. Baird x
  • Refine by Access: All x
Clear All Modify Search
Free access

X. Zhang, B.B. Rhodes, W.V. Baird, H.T. Skorupska, and W.C. Bridges

juvenile albino (ja) is a spontaneous mutant, first observed in 1992. Hypocotyls, new young leaves, shoot tips, tendrils, and flowers on the main shoot of the ja mutant are all albino during early spring and late fall. The interior of the albino leaves gradually become green, while the margins remain albino. Fruit rind color of the mutant is variegated. Growth of the ja mutant is severely impaired in the early spring and late fall. However, the mutant grows almost normal in the summer, and produces fruits of almost normal size. Genetic analysis of F1, F2, and BC1 populations derived from the ja mutant showed that ja mutant is inherited as a single, recessive, nuclear gene. The segregation ratios in the F2 and BC1 progenies derived from the cross between the previously reported dg virescent mutant and the ja mutant indicated that both are inherited independently. Experiments with temperature (3–5C vs. 20–22C at night), day length (8 vs. 15 h), and red and/or far-red light (15 vs. 0 min) at the end of an 8-h day were performed to investigate the regulation of ja trait expression. Temperature and red/far-red light had no differential effect on mutant and wild-type plants. However, significantly increased fresh weight and chlorophyll content were observed in the ja mutant over the wild-type when grown under long-day conditions. In addition, chlorophyll synthesis or accumulation in the mutant is severely impaired under short-day conditions. To our knowledge, this is the only virescent mutant in Cucurbitaceae whose expression is regulated by day length.

Free access

X.P. Zhang, B.B. Rhodes, W.V. Baird, H.T. Skorupska, and W.C. Bridges

Hybrid seed production can be facilitated by using male sterility coupled with a seedling marker. This research was initiated to combine the ms male sterility and dg delayed-green seedling marker into watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] lines. Male-sterile plants of the male-sterile line G17AB were crossed with plants of delayed-green breeding line Pale90, which has yellow cotyledons and pale-green, newly developed, true leaves. The double-recessive recombinants, male sterile and delayed green, from the F2 population were backcrossed to the male-fertile plants of G17AB. The pedigree method was used for selection in the progenies. The segregation ratios obtained from F2 and BC1F2 populations suggest that the male-sterile and delayed-green traits are inherited independently and that delayed green is inherited as a single recessive nuclear gene. Two male-sterile watermelon lines with delayed-green seedling marker have been developed. These lines will provide a convenient way to introduce male sterility and the delayed-green seedling marker into various genetic backgrounds. These two lines can be used for testing the efficiency of a new, hybrid, watermelon, seed production system.

Free access

X.P. Zhang, B.B. Rhodes, W.V. Baird, W.C. Bridges, and H.T. Skorupska

This research was conducted to develop genic male-sterile lines of watermelon (Citrullus lanatus Matsum & Nakai) homozygous for the juvenile albino (ja) seedling marker. Male-sterile plants (msms) of the genic male-sterile line G17AB were crossed with a Dixielee plant that was heterozygous for the ja locus. Male-fertile, juvenile albino recombinants of the F2 progeny were self-pollinated, resulting in F3 progeny. The male-sterile normal green recombinants of the F2 progeny were crossed with an F1 hybrid plant with genotype MsmsJaja, and three populations (93JMSB-1, -2, and -3) were obtained from these crosses. Juvenile albino recombinants were confined to 93JMSB-1. Of the juvenile albino plants of 93JMSB-1, male-sterile plants were sib-crossed with male-fertile plants, resulting in 93JMSB-1-1. Progeny of 93JMSB-1-1 was homozygous for ja and segregated for ms in a 127 male-sterile: 128 male-fertile ratio, fitting a 1:1 ratio. The male-sterile juvenile albino plants of F3 were crossed with male-fertile juvenile albino plants of 93JMSB-1, resulting in 93JMSF3-1 and -2. Plants 93JMSF3-1 and -2 were homozygous for ja but segregated for ms at 10 male-sterile: 13 male-fertile and 15 male-sterile: 19 male-fertile for 93JMSF3-1 and 93JMSF3-2, respectively, fitting the 1:1 ratio. These three genic male-sterile lines with the ja seedling marker provide valuable germplasm for introducing ms and ja genes into diverse genetic backgrounds and for studying cross-pollination and gene flow in watermelon populations.

Free access

X.P. Zhang, B.B. Rhodes, W.V. Baird, H.T. Skorupska, and W.C. Bridges

Juvenile albino, gene symbol ja, is a spontaneous virescent mutant, first observed in `Dixielee' and an F2 population of `G17AB' (msms) × `Dixielee' in 1992. Hypocotyls, new young leaves, shoot tips, tendrils and flowers on the main shoot of the ja mutant are all albino during early spring. The interior portions of albino leaves gradually become green, while the margins remain albino. Fruit rind color of the mutant is variegated. Growth of the ja mutant is severely impaired in the early spring. However, the mutant grows at a rate comparable to wild-type in the summer, and produces fruit of almost normal size. Genetic analysis of F1, F2, and BC1 populations derived from the ja mutant showed that the gene for the ja mutant is inherited as a single, recessive, nuclear gene. Segregation ratios in the F2 and BC1 progenies derived from the cross between the previously reported delayed green virescent mutant and the ja mutant indicate independent inheritance of the genes dg and ja. Temperature and red/far-red light had no differential effect on mutant and the wild-type plants. An increase of daylength from 8 to 15 hours increased fresh weight and chlorophyll content more in the ja mutant than in the wild-type. The mutant had a higher chlorophyll a: b ratio than the wild-type under long days. Chlorophyll synthesis or accumulation in the mutant is severely impaired under short days. This is the only virescent mutant in the family Cucurbitaceae whose expression is regulated by daylength.

Free access

Zhen-Xiang Lu, G.L. Reighard, W.V. Baird, and A.G. Abbott

Cluster analyses of 20 peach rootstocks by 40 RAPD markers produced a dendrogram of genetic relationship in good agreement with their putative pedigrees. BY520-9, BY520-8, SL1089, and SL1090, which are selections derived from a common ancestor, clustered together, with the normalized average distance (NAD) ranging from 0.20 to 0.55. Similarly, the clustering of Lovell with Halford and Boone County with Harrow Blood, whose respective NADs were 0.19 and 0.22, implied a high degree of genetic relatedness between each pair of genotypes. Okinawa and Yunnan, both introduced from eastern Asia, tied in a close group (NAD = 0.63) and share relatively similar phenotypes. The first major bifurcation in the dendrogram divided the 20 rootstocks into two groups. One group (Lovell, Halford, Montclar, Bailey, Harrow Blood, Boone County, Tennessee Natural, and GF 305) is susceptible to root-knot nematodes, whereas the second group (BY520-9, BY520-8, SL1089, SL1090, Higama, Nemaguard, Flordaguard, Yunnan, Okinawa, and Nemared), with the exception of Rubira and Siberian C, is tolerant or resistant.

Free access

Zhen-Xiang Lu, G.L. Reighard, W.V. Baird, A.G. Abbott, and S. Rajapakse

Eighteen peach rootstock cultivars, most of Prunus persica (L.) Batsch, were screened for diagnostic random amplified polymorphic DNA (RAPD) markers using synthetic decamer oligonucleotide primers. Twenty of the 80 primers were informative, and 40 amplified DNA bands from the informative primers were selected as RAPD markers. Based on combined banding patterns, all 18 rootstock cultivars were identified with only six of the 20 informative primers. Cluster analysis of the 18 peach rootstock cultivars using 40 RAPD markers produced a dendrogram of genetic relatedness in good agreement with their putative pedigrees. The first major bifurcation in the dendrogram divided these rootstock cultivars into two groups according to their resistance or susceptibility to root-knot nematodes [Meloidogyne incognita (Kofoid and White) Chitwood and M. javanica (Treub) Chitwood].

Free access

Bryon Sosinski, W.V. Baird, S. Rajapakse, R.E. Ballard, and A.G. Abbott

We have developed a highly saturated genetic linkage map in peach (diploid, 2n = 16) using two separate crosses. The first population consists of 48 randomly selected F2 individuals which were generated by selfing an F1 from the cross of `New Jersey Pillar' x KV 77119. This progeny set exhibits segregation for gross morphological traits including: canopy shape, fruit flesh color, and flower petal color, size, and number. The second population contains 48 F2 progeny derived from the cross of `Suncrest' x `Bailey'. These progeny segregate for quality traits such as fruit diameter, weight, flesh color, cling vs. free stone, soluble solids, pH of juice extract, and fruit developmental period. Nine linkage groups were identified in the first cross, which cover 590 cM of the genome. In the second cross, eight linkage groups were found that contain several significant chromosomal intervals contributing to fruit quality characteristics by QTL analysis. Anchor loci present in both maps were used to join the linkage groups to create a single combined map of the peach genome. Physical mapping is currently underway to assign the each linkage group to the appropriate chromosome.

Free access

W.V. Baird, R.E. Ballard, S. Rajapakse, and A.G. Abbott

Free access

S. Rajapakse, L. E. Belthoff, R. E. Ballard, R. Scorza, W.V. Baird, R. Monet, and A. G. Abbott

We have constructed a genetic linkage map of peach consisting of RFLP, RAPD, and morphological markers, based on 78 F2 individuals derived from the self-fertilization of four F1 individuals originating from a cross between `New Jersey Pillar' and KV 77119. This progeny set was chosen because parental genotypes exhibit variation in canopy shape, fruit flesh color, and flower petal color, size, and number. The segregation of 81 markers comprised of RFLP, RAPD and morphological loci was analyzed. Low copy genomic and cDNA probes were used in the RFLP analysis. The current genetic map for the WV family contains 57 markers assigned to 9 linkage groups, which cover 520 cM of the peach nuclear genome. The average distance between two adjacent markers was 9 cM. Linkage was detected between Pillar (Pi) and double flowers (Dl). RFLP markers loosely linked to Pi, flesh color (Y), and white flower (W) loci were found. Twenty-four markers remain unassigned.

Free access

L. Eldredge, R. Ballard, W.V. Baird, A. Abbott, P. Morgens, A. Callahan, R. Scorza, and R. Monet

Peach [Prunus persica (L.) Batsch.] is considered the best genetically characterized species of the genus Prunus. We therefore used it as a model in our study of the genome organization in Prunus by means of restriction fragment length polymorphisms (RPLPs). Initial results indicated that 60% of cloned DNA sequences examined occur at low copy number within the peach genome. After selecting and examining these sequences, polymorphisms sufficient for RPLP mapping were found. We determined that ≫33% of our cDNA clones and 20% of our genomic clones detected RPLPs among peach cultivars. Analysis of RPLP segregation in two families, both of which segregate for known morphological characters, revealed segregation in 12 RFLP markers for one family and 16 for the other. Although we have not detected linkage between RFLP and morphological markers, preliminary analyses indicate possible linkage between two RPLP markers.