The Chilean genus Leucocoryne has exceptional qualities as an ornamental plant that is being developed through breeding. Little is known about the origin of its genetic variation for flower phenotype. Our hypothesis is that, despite having a perfect flower, Leucocoryne has an outbreeding behavior due to self-incompatibility. Greenhouse studies were conducted to study self-incompatibility. In 2000, one species L. purpurea Gay. and two distinct populations Leucocoryne sp. Pichicuy and Leucocoryne sp. Chigualoco were used, whereas in 2001, L. coquimbensis F. Phil. and Leucocoryne sp. Alcones and Leucocoryne sp. Talinay were added. Field studies were carried out in 2001 at La Campana (lat. 29°S, Valparaíso Region, Chile) and Bosque de Fray Jorge (lat. 33°S, Coquimbo Region, Chile) National Parks with L. ixioides Lindley and L. purpurea, respectively. The index of self-genetic incompatibility (ISI) was measured as the average number of seeds per fruit produced by self-pollination divided by the average number of seeds per fruit produced from cross-pollination. The average ISI values for 2000 and 2001 were 0.08 and 0.06, respectively, meaning that Leucocoryne is largely self-incompatible. In the field seed set was compared between flowers that were isolated from insects and those that were not. None of the isolated flowers produced seeds, instead nonisolated flowers produced an average of 29 seeds per fruit at La Campana and 56 at Bosque de Fray Jorge. Leucocoryne's self-incompatibility and outcrossing behavior plus its capacity to fix any genotype via asexual reproduction, most likely contribute to its large variation for flower color, shape, size, design, and aroma. Due to Leucocoryne's reproductive behavior it would be difficult to breed for homozygous inbreds and pure hybrid cultivars
Abstract
‘Matou’ wentan (pummelo) is usually seedless in Taiwan. However, about 8% of the fruits on the market are seedy. In controlled pollination tests, ‘Matou’ was self-incompatible and highly parthenocarpic. Seedy fruits in commercial orchards are apparently from pollination by trees of other cultivars such as ‘Liucheng’ (C. sinensis Osb.), ‘Ponkan’ (C. ponkan Tan.), and especially ‘Paiyu’ and ‘Hwungyu’ (C grandis). Seedy fruits of ‘Matou’ wentan could be prevented by excluding other citrus cultivars from the orchard.
Abstract
Peach (Prunus persica Batsch. ‘Lovell’) seedlings and ‘Marianna 2624’ plum (P. cerasifera Ehrh. X P. munsoniana Wight & Hedr.?) cuttings were budded with ‘Fay Elberta’ peach and ‘Marianna 2624’. Of the 4 combinations only ‘Fay Elberta’/‘Marianna 2624’ showed foliar symptoms indicative of graft incompatibility; those trees budded in mid-March appeared abnormal by early August. Prunasin, the only cyanogenic glycoside detected in both species, accumulated in young scion bark of ‘Marianna 2624’ and peach to nearly equal levels. Amounts of prunasin in leaves and bark of ‘Fay Elberta’ on peach were usually greater than in those on plum. The level in the scion bark of ‘Marianna 2624’ was similar on both rootstocks. In late summer, the quantity of the glucoside in peach scion bark rose above that in corresponding plum bark; however, the prunasin concentration in both leaves and scion bark of ‘Fay Elberta’/‘Marianna 2624’ trees was not correlated with the severity of incompatibility symptoms. The prunasin level in the plum rootstock bark immediately below or 18 cm from the union was unaffected by the scion species or by signs of ill-health in the peach top. Although the rootstock was shown capable of affecting the accumulation of prunasin in scion tissues, the stability of the level of this glucoside in the peach/plum combination suggests that cyanogenesis is not closely linked with their incompatibility.
Techniques are described to determine whether embryos are formed in ovules of incompatible crosses between Ornithogalum (L.) plants, and to rescue embryos in cases where the development of embryos is halted following fertilization. By using Herr's clearing liquid, it can be ascertained within 5 hours whether hybrid embryos have been formed. Such embryos can be rescued by culturing them in ovulo on basal medium containing 70 g sucrose/liter and no added growth regulators. The embryos' requirement for sucrose changes as they develop; therefore, cultured ovules are transferred after 14 days to a medium containing 10 g sucrose/liter, where germination occurs.
Abstract
Two rabbiteye blueberry (Vaccinium ashei Reade) cultivars Beckyblue and its open-pollinated progeny Aliceblue, both of which are known to be highly male- and female-fertile, were self-pollinated, reciprocally cross-pollinated, and pollinated with pollen from a third cultivar, Climax, which is not closely related to the other two. Fruit set percentage on ‘Aliceblue’ and ‘Beckyblue’ averaged 65% when ‘Climax’ was the pollen parent and < 1% when the cultivars were self-pollinated. Reciprocal crosses of ‘Beckyblue’ and ‘Aliceblue’ averaged 24% set, indicating a high degree of cross-incompatibility. There was no effect of pollen parent on berry fresh weight, although seed weight and seed number were reduced by self-pollination or pollination by the related cultivar.
Self-incompatibility (SI) is the inability of otherwise fertile gametes to produce viable zygotes upon self-fertilization. The S locus of chromosome 1 in Lycopersicon is thought to be the main controlling factor in SI. However, the significance of other chromosome segments in the control of SI or the effect of a foreign genetic background on the S locus has not been thoroughly explored. In addition, the relationship between SI and wider interspecific crossing barriers remains unclear. Using DNA and protein markers for chromosome 1, we have created a series of backcross lines that contain either 1) the SI locus and flanking chromosome region from a SI species in a SC species background or 2) the same chromosome region from a SC species in a SI species background. The reproductive behavior of these plants will be discussed.
The existence of self-incompatibility (SI) was demonstrated in `Britton' and `Rose' Easter cactus (Rhipsalidopsis). In a full diallel cross among five clones, 18 out of 20 outcrosses resulted in 68% to 100% fruit set, whereas reciprocal crosses between two of the clones and all five self-pollinations failed to set fruit. Pollen tube growth was greatly inhibited in styles of selfed pistils, but there was no evidence of pollen tube inhibition in compatibly crossed pistils. Easter cactus exhibited characteristics typically found in sporophytic SI systems (trinucleate pollen, papillate stigmas, and scant stigmatic exudate) together with those associated with gametophytic SI systems (stylar inhibition of pollen tube growth and absence of reciprocal differences in outcrosses). Additional experiments were performed to determine the effects of bud pollinations, growth regulators (BA, GA3, and NAAm), and high temperatures (0- to 48-h exposure at 40C) on the SI response. Heat treatments were more effective than either bud pollinations or growth regulators in overcoming SI, and yielded an average of 7.2 viable seeds per treated flower when plants were incubated for 12 h at 40C and selfed immediately after incubation. Isozyme analysis of the S0 parent and putative S1 progeny confirmed that selfing had occurred following heat treatments. Using S1 progeny in breeding programs may extend the flower color range and lead to a greater diversity in other plant characteristics than presently exists in cultivated germplasm. Chemical names used: N-(phenylmethyl)-1H-purin-6-amine [benzyladenine (BA)], gibberellic acid (GA3), and α-naphthaleneacetamide (NAAm).
Abstract
Compatibly- and incompatibly-pollinated detached styles of Lilium longiflorum were incubated for various time periods at 39°, 31°, 24°, 19° and 12.5°C to elucidate the effect of high and low temperatures on the self-incompatibility reaction. High temperatures during pollen tube growth prevented the incompatibility reaction, as incompatible pollen tubes reached lengths similar to those of campatible tubes in styles incubated at 39° and 31°C. Between 12 and 24 hr post-pollination the rate of compatible tube growth at 24°C (room temp) doubled while the rate of incompatible tubes continued unchanged. Incompatible pollen tube growth decelerated after 2 days at 19°C resulting in a significant difference between compatible and incompatible tube length 3 days after pollination. In styles incubated at 12.5°C the lengths of compatible and incompatible pollen tubes did not differ significantly until 6 days after pollination when incompatible tubes were shorter. The self-incompatibility reaction occurred at low temperatures, for growth of incompatible tubes was restricted to lengths typical of those grown at room temperature.
Abstract
Investigation of pollen grain germination and retention on the stigma, and pollen tube frequency in the style following compatible (cross) and incompatible (self) pollinations in ‘Nonpareil’ almond [Prunus dulcis (Mill.) D.A. Webb Syn. Prunus amygdalus Batsch.J revealed that rejection of incompatible male gametophytes occurs on the stigma as well as in the style. Self-pollinations are characterized by lower pollen grain retention on the stigma, reduced and delayed pollen germination, and, where pollen germination had occurred, a low frequency of pollen tubes growing through the style. Pollen tube growth slowed greatly after the tubes entered the ovarian locule before they reached the ovule.
In order to characterize the self-incompatibility system in Theobroma cacao, the levels of ethylene, indole-3-acetic acid (IAA), and abscisic acid (ABA) were determined after pollination with compatible and incompatible pollen and in unpollinated flowers. Pollen tube growth rates after incompatible and compatible pollinations were identical, and the majority of the pollen tubes reached the ovules between 12 and 20 hours after pollination. ABA levels rose in incompatibly pollinated flowers, and fell in compatibly pollinated flowers, prior to pollen tube—ovule contact. Ethylene evolution remained stable in compatibly pollinated flowers and rose in incompatibly pollinated flowers. IAA concentrations increased in compatibly pollinated flowers, and remained stable in incompatibly pollinated flowers after pollination and subsequent to pollen tube—ovule contact.