Banana nectar as a medium for testing pollen viability and germination in Musa

A quick and reliable method for evaluating pollen quality is essential in a breeding program, especially in a crop such as banana that is characterized by high male and female sterility. In this study the germination and viability of banana pollen was evaluated in a sucrose solution and diluted banana nectar. Twenty banana accessions were used to evaluate pollen germination in the two media after 3 and 24 h. Nineteen genotypes (95%) showed significantly higher pollen germination potential (PGP) in diluted nectar than in 3% sucrose solution. The accession TMB2x 8075 - 7 showed no significant pollen germination in nectar and sucrose. Eleven genotypes (55%) showed significant increase in pollen germination by increasing the time of incubation whereas pollen germination for nine genotypes (45%) was not affected by increase in incubation time. Nectar from different banana clones influenced pollen germination suggesting a genotype effect for pollen germination in Musa

Glutathione synthesis is essential for pollen germination in vitro

BACKGROUND: The antioxidant glutathione fulfills many important roles during plant development, growth and defense in the sporophyte, however the role of this important molecule in the gametophyte generation is largely unclear. Bioinformatic data indicate that critical control enzymes are negligibly transcribed in pollen and sperm cells. Therefore, we decided to investigate the role of glutathione synthesis for pollen germination in vitro in Arabidopsis thaliana accession Col-0 and in the glutathione deficient mutant pad2-1 and link it with glutathione status on the subcellular level. RESULTS: The depletion of glutathione by buthionine sulfoximine (BSO), an inhibitor of glutathione synthesis, reduced pollen germination rates to 2-5% compared to 71% germination in wildtype controls. The application of reduced glutathione (GSH), together with BSO, restored pollen germination and glutathione contents to control values, demonstrating that inhibition of glutathione synthesis is responsible for the decrease of pollen germination in vitro. The addition of indole-3-acetic acid (IAA) to media containing BSO restored pollen germination to control values, which demonstrated that glutathione depletion in pollen grains triggered disturbances in auxin metabolism which led to inhibition of pollen germination. CONCLUSIONS: This study demonstrates that glutathione synthesis is essential for pollen germination in vitro and that glutathione depletion and auxin metabolism are linked in pollen germination and early elongation of the pollen tube, as IAA addition rescues glutathione deficient pollen

Exploration of Limonium interspecific breeding possibility : a thesis presented in partial fulfilment of the requirement for the degree of Master of Science in Plant Science at Massey University, Palmerston North, New Zealand

Interspecific crossability was investigated in the genus Limonium (Plumbaginaceae). Six Limonium species were chosen for this study, five of which are dimorphic and L.perigrinum which is monomorphic. Ovary, ovule and embryo development was investigated, as were in vitro pollen germination and pollen tube growth. Unilateral incompatibility was observed in 8 interspecific combinations. A high frequency of interspecific crossability was observed between L.perezii X L.sinuatum and L.sinense X L.aureum. Pollen tubes were frequently observed penetrating the ovules in these crosses. Pollen tube growth that terminated in the styles or was restricted to the stigmas was found in some Limonium interspecific crosses. Abnormalities of pollen tube growth in the interspecific crosses included heavy callose deposits at the tips of pollen tubes; pollen tube branching and pollen tube growing in the wrong direction. Embryo, ovule and ovary development was studied with L.perezii plants following conspecific pollination. Three distinct groupings of florets can be recognised at the basis of their post-pollination growth and development. Twenty-six percent of conspecific pollinated florets showed no ovary and ovule growth. No embryo was found in this group. In eleven percent of florets, ovaries and ovules grew up to Day 12 after pollination and then shrivelled. No embryo was ever found in this group. Sixty-three percent florets produced embryos following conspecific pollination and developed normally. The viability of Limonium pollen was assessed with Alexander's stain and fluorochromatic reaction (FCR) stain. Optimal conditions for in vitro L.perezii pollen germination and tube growth were established. Poly-ethylene glycol and filter paper supports were of particular significance. In vitro pollen germination rate of about 40% was achieved. Plant growth regulators (IAA, GA 3 and ethylene), some minerals (manganese sulphate, copper sulphate) and prehydration treatment were used in experiments to improve pollen germination and tube growth. None of these factors, however, had positive effect on either pollen germination or tube growth. It was found that while L.perezii pollen tube growth tolerates a wide range of temperature, there is an optimum between 20°C-25°C

Pollen Germination in vitro

Pollen germination in vitro is a reliable method to test the pollen viability. It also addresses many basic questions in sexual reproduction and particularly useful in wide hybridization. Many pollen germination medium ranging from simple sugars to complex one having vitamins, growth regulators, etc. in addition to various minerals have been standardized to germinate pollen artificially. The different media, successful pollen germination methods, procedures from pollen germination studies with wheat, rye, brinjal, pigeonpea and its wild relatives are discussed

Effects of therapeutants and temperature on pollen germination, pollen tube growth and fruit set in fruit crops : a thesis presented in partial fulfilment of the requirements for the degree of Master of Horticultural Science at Massey University

This study involved assessments of therapeutant effects on pollination and fruit set; of temperature effects on pollen germination and pollen tube growth in apples, peaches and kiwifruits; of flowerage effects on pollen germination and pollen tube growth in kiwifruit styles; and of hand pollination effects on fruit set, fruit weight and seed numbers per fruit in kiwifruit vines. From the point of view of their in vitro effects on pollen germination therapeutants can be listed in order of decreasing inhibitory effect as follows: (a) for apples - mancozeb plus dinocap, triforine, dichlofluanid, bupirimate, bayleton, citowett R captan and mancozeb; (b) for peaches - triforine, vinclozoline, streptomycin plus triforine, mancozeb, captafol, iprodione, dichlofluanid, streptomycin and benomyl; and (c) for kiwifruits - dichlofluanid, captan and vinclozoline. However, it appeared that while in vitro a therapeutant was very inhibitory, the application of a spray to anthers in an intact flower did not affect the germination of pollen subsequently released by those anthers. Fungicides proven to be toxic to pollen in vitro did not necessarily produce similarly toxic effects in vivo. Reasons for such varying effects of fungicides on pollen germination and pollen tube growth in vitro and in vivo are suggested. At 24 hours after pollination the number of pollen tubes growing more than 1/2 the style length of kiwifruit (Hayward) flowers one to two days old were 38% and 27% higher than in flowers less than one day old and more than three days old respectively. In apples 5 sprays of either bayleton or captan, 3 sprays of either of the therapeutants mancozeb, mancozeb plus dinocap, and triforine and a wetting agent citowett R applied during bloom period caused no effect in fruit set in Golden Delicious trees; and 3 bupirimate sprays during bloom period had no effect on the fruit set in Splendour trees. In peaches 6 sprays of either captafol, or benomyl or iprodione, 5 sprays of either mancozeb or vinclozoline or streptomycin or triforine during bloom period caused no effect on fruit set in Golden Queen trees. Three sprays of streptomycin or dichlofluanid caused no effect but 3 sprays of triforine, triforine plus streptomycin or of ethephon caused 50%, 70% and 90% reduction in fruit set in Red Haven peach trees. In kiwifruits 3 sprays of either dichlofluanid, captan or vinclozoline reduced seed numbers per fruit by 37% but did not affect fruit set or fruit weight. Thus in vitro and in vivo studies were useful in determining therapeutant effects on pollen but did not necessarily provide information on their effects on fruit set in apple, peach and kiwifruit and on fruit weight and seed numbers per fruit in kiwifruit. The germination of both apple and peach pollen was higher at 24°C than at 16°C, 20°C, 28°C and at 32°C. After 18 hours incubation pollen tubes were longer at 28°C and at 32°C than at 16°C, 20°C and 24°C. In vivo studies with kiwifruit (Matua) pollen showed that pollen germination at 14°C, 18°C, 22°C and 26°C did not differ significantly. Temperatures both higher and lower than the temperature range 18 to 22°C were found to be inhibitory to pollen tube growth in kiwifruit (Hayward) styles. Hand pollination of flowers did not influence percentage fruit set but increased fruit weight and seed numbers per fruit in kiwifruit (Hayward) vines. Because fruit weight was positively correlated with seed number per fruit in fruits from both bee pollinated and bee plus hand pollinated flower clusters, supplementary pollination may play an important role in the production of fruit in kiwifruit orchards

Flowering and pollination studies with European plum (Prunus domestica L.) cultivars

One of the most important factors affecting the financial outcome of commercial fruit growing is the success of pollination and fertilization, which in turn are dependent on weather conditions, activity of pollinators and the compatibility and overlap in flowering of the cultivars. Before introducing new cultivars, it is obviously important to know the compatibility and flowering characteristics of the genotypes. In order to find out these attributes of seven new and four established plum cultivars, pollen germination tests, hand pollinations and flowering phenology observations were carried out. ‘Prosser 84’ had 70% pollen germination. ‘Opal’ had just 3%, probably due to aged pollen. ‘Anna Späth’ flowered over a short period (13 days) and ‘1468’ and ‘DCA BO 46’ over long (19 days) periods; the overlap of all cultivars was relatively good. With ‘1468’, ‘Victory’, ‘Anna Späth’ and ‘Prosser 84’ flowering intensity varied between years, ‘Jubileum’, ‘V70032’, ‘Tita’ and ‘DCA BO 46’ flowered regularly, the others were intermediate. ‘1468’ and ‘WJ 65’ flowered early, ‘Prosser 84’ and ‘DCA BO 46’ late and the rest fell in between. ‘Victoria’ proved to be self-fertile, ‘Jubileum’, ‘V70032’ and ‘1468’ semi self-fertile. Fruit set percentages after June drop of all crosses were rather low; varying between 0 and 28%. With ‘Tita’, fruit drop occurred approximately two weeks later than with the other cultivar

Effects of boron and gibberellic acid on in vitro pollen germination of pistachio (Pistacia vera L.)

This study was conducted on male pistachio cultivars which consisted of Uygur, Atli, Kaska, Sengel and Kavak to study the influence of boron and gibberellin on pollen germination in vitro. Pollen was sown in germination media that included 20% sucrose, 10, 25, 50, 75 and 100 ppm boric acid (H3BO3) and gibberellic acid (GA3), separately. It was found that pollen germination for all cultivars were greatly reduced with increased GA3 concentration in the germination medium and reached the lowest value at the 100 ppm GA3 whereas germination was decreased up to 25 ppm in H3BO3 and gradually increased again to 100 ppm. With the mediums of boric acid and gibberellic acid ranging from 0 - 100 ppm, the amount and pattern of response in pollen germinability varied among cultivars considerably. Pollen germination was severely inhibited by GA3 and slightly promoted by boron. The results suggest that gibberellic acid had adverse effects on pollen germination of pistachio.Key words: Pistachio, Pistacia vera, in vitro, pollen germination, boron, gibberellic acid

Kanamycin resistance during in vitro development of pollen from transgenic tomato plants

Effects of kanamycin on pollen germination and tube growth of pollen from non-transformed plants and from transgenic tomato plants containing a chimaeric kanamycin resistance gene were determined. Germination of pollen was not affected by the addition of kanamycin to the medium in both genotypes. Kanamycin, however, severely affected tube growth of pollen from non-transformed plants, while pollen from plants containing the chimaeric gene were less sensitive and produced significantly longer tubes at kanamycin concentrations between 200-400 mg l-1. Apparently, this resistance for kanamycin correlates with the expression of the chimaeric gene during male gametophytic development.

The pollen receptor kinase LePRK2 mediates growth-promoting signals and positively regulates pollen germination and tube growth

In flowering plants, the process of pollen germination and tube growth is required for successful fertilization. A pollen receptor kinase from tomato (Solanum lycopersicum), LePRK2, has been implicated in signaling during pollen germination and tube growth as well as in mediating pollen (tube)-pistil communication. Here we show that reduced expression of LePRK2 affects four aspects of pollen germination and tube growth. First, the percentage of pollen that germinates is reduced, and the time window for competence to germinate is also shorter. Second, the pollen tube growth rate is reduced both in vitro and in the pistil. Third, tip-localized superoxide production by pollen tubes cannot be increased by exogenous calcium ions. Fourth, pollen tubes have defects in responses to style extract component (STIL), an extracellular growth-promoting signal from the pistil. Pollen tubes transiently overexpressing LePRK2-fluorescent protein fusions had slightly wider tips, whereas pollen tubes coexpressing LePRK2 and its cytoplasmic partner protein KPP (a Rop-GEF) had much wider tips. Together these results show that LePRK2 positively regulates pollen germination and tube growth and is involved in transducing responses to extracellular growth-promoting signals.Fil: Zhang, Dong. Chinese Academy of Sciences; República de ChinaFil: Wengier, Diego Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisiología, Biología Molecular y Celular. Laboratorio de Fisiología y Biología Molecular; Argentina. University of California at Berkeley; Estados UnidosFil: Shuai, Bin. University of California at Berkeley; Estados UnidosFil: Gui, Cai Ping. Chinese Academy of Sciences; República de ChinaFil: Muschietti, Jorge Prometeo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisiología, Biología Molecular y Celular. Laboratorio de Fisiología y Biología Molecular; ArgentinaFil: McCormick, Sheila. University of California at Berkeley; Estados UnidosFil: Tang, Wei Hua. Chinese Academy of Sciences; República de China. University of California at Berkeley; Estados Unido