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.
X.P. Zhang, B.B. Rhodes, W.V. Baird, H.T. Skorupska, and W.C. Bridges
Qi Zhang, August C. Gabert, and James R. Baggett
A new sterile mutant designated pollen sterile (PS) found in pickling cucumber (Cucumis sativus L.) is characterized by normal corolla in staminate and pistillate flowers, normal fertility in the female, and absence of pollen in otherwise normal-appearing staminate flowers. All F1 plants from PS × male fertile (MF) sib-matings were MF, and F2 progeny segregated 3 MF: 1 PS. Sib-matings of PS segregates with sister MF segregates produced either 1 MF: 1 PS ratios or all normal plants. Thus, PS is controlled by a single recessive gene. The PS gene is not allelic to apetalous (ap), but was shown to be allelic to male sterile-2 (ms-2) and is designated ms-2 PS. It was not possible to determine possible allelic relationships between ms-2 PS and ms-1 because of strong male and female sterility of the available ms-1 material. F1 generations from gynoecious-PS and monoecious-PS crossed with monoecious, gynoecious (silver-ion treated), and hermaphroditic parents produced no PS plants and sex types did not influence PS levels in F2 progenies, indicating it is not possible to maintain the PS mutants through crosses with different cucumber sex types. It was not possible to change the expression of PS by applying cytokinin, IAA, or GA3, and there were no changes in response to temperature and fertilizer treatment. Unlike gynoecy, which is responsive to some external factors, PS is unresponsive. The results suggest that the use of PS in cucumber F1 hybrid seed production is not practical. Chemical names used: indole acetic acid (IAA), gibberellin (GA3).
Neil O. Anderson and Peter D. Ascher
Chrysanthemum [Dendranthema ×grandiflora Tzvelv. (syn. Chrysanthemum ×morifolium Ramat.)] breeding programs have been selecting for reduced expression of self-incompatibility (via pseudo-self-compatibility) to create inbred families with selected genotypes to serve as parents for F1 hybrid chrysanthemum seed production. However, it is not known to what extent inbreeding is affecting fertility in this outcrossing, heterozygous species. The objective of this research was to assess male/female fertility changes (gain/loss) in successive inbred generations of chrysanthemums. Pseudo-self-compatible chrysanthemum parents (n = 41 inbred, noninbred, and recombinant inbred) were chosen for fertility analyses. As many as three generations of inbreds (I1, I2, and I3) from self-pollinations were created using rapid generation cycling. Female and male fertility levels of the parents and all derived inbred populations were assessed using outcross seed set and pollen stainability, respectively. Average seed set ranges were 0.3% to 96.1% (inbred parents), 24.5% to 38.5% (noninbred parents), and 0.9% to 85.1% (recombinant inbred parents); these began decreasing in the I1 and continued to decline steadily into the I3. Statistically significant (P < 0.05) decreases in seed set occurred in n = 23 (56.1%) inbred families; the remaining inbred families had similar or higher fertility than the parents. Pollen stainability was >50% for the parents, but began declining in some inbred families as inbreeding progressed. Fertility reductions were attributed to inbreeding depression. Lack of significant fertility losses in other inbred families demonstrates the opportunity of selection of fertile inbred parents for use in hybrid seed production.
Daniel J. Cantliffe
hybrid seed production and plant germplasm conservation. The reader has an opportunity to get information, packed into 796 pages, in almost any area related to seeds. The contributing authors to Dr. Basra's book are excellent and well known for their
Sergio Melgar and Michael J. Havey
propagated by crossing with maintainer plants (N msms ), and subsequently used for hybrid seed production. S cytoplasm of onion traces back to a single male-sterile plant ( Jones 1937 ) and is an alien cytoplasm introgressed in antiquity into onion ( Havey
Richard J. Henny and J. Chen
their native tropical habitats, propagated, and sold as ornamentals. Plant breeding research to induce Aglaonema flowering ( Henny, 1983 ) and to control pollination ( Henny, 1985 ) made hybrid seed production protocols available. These breeding
Liwang Liu, Guang Liu, Yiqin Gong, Wenhao Dai, Yan Wang, Fanmin Yu, and Yunying Ren
showed reduced heat and cold tolerance. Thus, hybrid purity from the GOT was calculated to be 96.7%. Seed contamination is always a concern in hybrid seed production of cabbage. In this study, nine of the 210 F 1 hybrids generated the FPS markers only
Randy G. Gardner and Dilip R. Panthee
crossed with indeterminate lines because of its segregation for the ms-10, aa gene combination for male sterility linked to the green stem seedling marker, which comes from NC 2C ( Gardner, 1993 ). Male sterility greatly facilitates hybrid seed
Cecil T. Pounders, Hamidou F. Sakhanokho, and Leopold M. Nyochembeng
traits identified in FB08-59 and FB08-163 make them ideal parents for development of inbred lines with high levels of environmental stress tolerance to serve as parents for F 1 hybrid seed production. Fig. 1. ( A ) Begonia cucullata ; ( B ) Begonia
Randy G. Gardner and Dilip R. Panthee
-temperature fruit set. ‘Plum Regal’ has been tested for organic production by growers and performed well under severe conditions for late blight in western North Carolina in 2009. Hybrid seed production for ‘Plum Regal’ is facilitated by the ms-10 gene for male