Characterization of AhLea-3 and its enhancement of salt tolerance in transgenic peanut plants

BACKGROUND: Late embryogenesis abundant (LEA) proteins were reported to be related to adversity stress and drought tolerance. Lea-3 from Arachis hypogaea L. (AhLea-3) was previously found to be related to salt tolerance according to the result of transcriptome profiling and digital gene expression analysis. So, AhLea-3 was cloned and the salt tolerance was validated by transgenic peanut plants. RESULTS: AhLea-3 was isolated from M34, a salt-resistant mutant of peanut, with its cDNA as the template. AhLea-3 contains one intron and two extrons, and the full-length cDNA sequence contains 303 bp. AhLea3 was ligated to pCAMBIA1301 to obtain the overexpression vector pCAMBIA1301-AhLea-3, which was then transferred into peanut variety Huayu23. The expression level of AhLea-3, as determined by qRTPCR analysis, was >10 times higher in transgenic than in non-transgenic plants. Five days after they were irrigated with 250 mM NaCl, the transgenic plants showed less severe leaf wilting, higher activities of antioxidant enzymes (superoxide dismutase, peroxidase, and catalase), and lower malonic dialdehyde content than non-transgenic plants. Relative to non-transgenic plants, the transgenic plants had a higher photosynthetic net rate, stomatal conductance, and transpiration rate, and a lower intercellular CO2 concentration after salt stress treatment (250 mM NaCl). CONCLUSIONS: These results indicate that overexpression of AhLea-3 increased the salt tolerance of transgenic peanut plants. AhLea-3 might become a useful gene resource for the variety breeding of salinity tolerance in peanut.

The effect of three plant bioregulators on pollen germination, pollen tube growth and fruit set in almond [Prunus dulcis (Mill.) D.A. Webb] cvs. Non Pareil and Carmel

Background In commercial almond [Prunus dulcis (Mill.) D.A. Webb] orchards in Chile, the percentage of fruit set is low and commonly reaches 5–30%. As almond trees bloom during a cool period and also suffer from self-incompatibility, any factor that can improve pollination, pollen germination and pollen tube growth or extend the effective pollination period, such as the application of plant bioregulators (PBRs), should be beneficial for fruit production. Results Three plant bioregulators (PBRs): brassinolide (BL), gibberellic acid (GA3) and kinetin (KN) were evaluated for pollen germination and pollen tube growth in vitro, as well as for fruit set in almond cultivars Non Pareil and Carmel, in central Chile, during the 2013 and 2014 seasons. For pollen germination in vitro, the BL concentration of 10 mg L- 1 had the highest value in Non Pareil (97.7%), after 4 h germination in 2014 growing season (the control was 90.9%). KN at a concentration of 50 µL L- 1 induced the longest pollen tube growth of 1243.4 µm in Carmel after 8 h germination in 2013 (the control was 917.7 µm). In Non Pareil, the highest percentage of fruit set (31.0%) was achieved in 2014 by spraying during bloom at pink bud stage with KN at 50 µL L- 1 (the control was 16.7%). Conclusions A significant favorable effect of the tested PBRs was observed in pollen germination and pollen tube growth in vitro, as well as on fruit set in Non Pareil and Carmel almonds.

Histological analysis of pollen-pistil interactions in sour passion fruit plants (Passiflora edulis Sims)

The success of sexual plant reproduction is directly influenced by specific interactions between the pollen and pistil. Light, fluorescence and scanning electron microscopy techniques were used to evaluate the steps of pollination in sour passion fruit plants (Passiflora edulis Sims). In the compatible interaction, pollen tubes grow through stigma projections towards the ovary. The pollen grain surface was found to be spheroidal and to consist of heteroreticulate exine with six colpi. Furthermore, analysis in vivo of pollen-pistil interactions indicated that stigmas of flowers 24 hours before anthesis are unable to discriminate compatible (genetically unrelated) and incompatible (genetically related) pollen grains. Taken together, these results provide insight into the cellular mechanisms underlying pollination in passion fruit plants.

Morfologia e viabilidade de grãos de pólen de acessos silvestres de abacaxi / Morphology and viability of pollen grains from wild varieties of pineapple

O objetivo do trabalho foi avaliar a viabilidade de grãos de pólen de acessos silvestres de abacaxi mediante a percentagem de germinação in vitro, crescimento do tubo polínico em duas temperaturas de incubação e uso de carmim acético. Além disso, o trabalho busca reconhecer os padrões da morfologia polínica de algumas variedades de abacaxi. Foram utilizadas amostras de pólen coletadas de seis acessos de abacaxi: Silvestre-25, I-26/803 (Ananas macrodontes), Igor (A. comosus var. erectifolius), Ananás Santo Amaro, FRF-22 e FRF-32 (A. comosus var. bracteatus). Os grãos de pólen foram inoculados em meio de cultura contendo 10 por cento de sacarose, 0,01 por cento H3BO3, 0,01 por cento KNO3, 0,03 por cento Ca(NO3)2.4H2O, solidificado com 1 por cento de ágar e pH ajustado para 6,5. Foram testadas as temperaturas de incubação de 25°C e 30°C. A viabilidade do pólen foi avaliada pela coloração com carmim acético a 2 por cento. Todas as variedades de A. comosus apresentaram grãos de pólen de tamanho médio, simetria radial, âmbito ovalado a esferoidal, 2-porados, subprolatos, exina eutectada, reticulada, heterobrocada, lumens variando de arredondados a poligonais, sem granulações, com exceção dos dois acessos de A. macrodontes que apresentaram tamanho grande. Melhores taxas de germinação foram obtidas para A. macrodontes em comparação com o erectifolius e bracteatus. A maioria dos acessos apresentou viabilidade com carmim acético acima de 76 por cento.

The aim of this research was to evaluate the pollen grains viability from accessions of wild pineapple using in vitro pollen germination and the growth of the polinic tube in two different temperatures and acetic carmine. In addition, the study aimed to recognize the pattern of pollen morphology of some pineapple varieties. Samples from six pineapple's accessions: Silvestre-25, I-26/803 (Ananas macrodontes), Igor (A. comosus var. erectifolius), Ananás Santo Amaro, FRF-22 and FRF-32 (A. comosus var. bracteatus) were used. The pollen grains were inoculated onto medium culture containing 10 percent of sucrose, 0.01 percent H3BO3, 0.01 percent KNO3, 0.03 percent Ca(NO3)2.4H2O, solidified with 1 percent agar and pH adjusted to 6.5. Two incubation temperatures, 25°C e 30°C were evaluated. Pollen viability was evaluated by staining with 2 percent acetic carmine. All varieties of A. comosus showed pollen grains of medium size, radial symmetry, oval to spheroidal, ambit 2-porate, subprolate, exine eutectic, reticulate, heterobrochate, lumens ranging from polygonal to rounded, grain-free, except for two accessions of A. macrodontes that showed big size. The best germination rates were obtained for A. macrodontes when compared to erectifolius and bracteatus. The majority of accessions presented pollen viability higher than 76 percent using the acetic carmine technique.

Viabilidade in vitro de grãos de pólen de bananeira sob diferentes concentrações de ácido bórico e sacarose / In vitro viability of banana pollen grain under different concentrations of boric acid and sucrose

Neste trabalho, objetivou-se avaliar a germinação do grão de pólen e o comprimento do tubo polínico das bananeiras diplóides M53, 8987-01 e 9197-03, Calcutá, Lidi e 86B79-12. O delineamento utilizado foi inteiramente casualizado com cinco doses de sacarose (0, 5, 10, 15, 20 por cento) e seis concentrações de ácido bórico (0, 100, 200, 300, 400 e 500 Mg L-1) com quatro repetições. Foram utilizados grãos de pólen retirados da inflorescência masculina dos diplóides Musa acuminata (AA). O pólen foi distribuído em placas de Petri, contendo o seguinte meio de cultura: 1,27 mM de Ca(NO3)2.2H2O, 0,87 mM de MgSO4.7H2O, 0,99 mM de KNO3, 0,7 por cento de ágar com pH ajustado para 7,0, variando as concentrações de sacarose e de ácido bórico. As avaliações foram realizadas 24 horas após a distribuição do pólen no meio de cultura. O meio de cultura padrão para germinação de grãos de pólen suplementado com 15 por cento de sacarose proporcionou uma maior percentagem de germinação para os diplóides de bananeira avaliados. A concentração de ácido bórico adicionado ao meio de cultura para a germinação de grãos de pólen de bananeira diplóide é dependente do genótipo.

The objective of this work was to evaluate the germination of pollen grain and pollen tube length of banana diploids (M53, 8987-01 e 9197-03, Calcutta, Lidi and 86B79-12). Five concentrations of sucrose (0, 5, 10, 15 and 20 percent) and six concentrations of boric acid (0, 100, 200, 300, 400 and 500 mg L-1) were used, in a completely randomized experimental design, with four replicates. The pollen was distributed in Petri dishes containing the following culture medium: 1.27 mM Ca(NO3)2.2H2O, 0.87 mM MgSO4.7H2O, 0.99 mM KNO3, and 0.7 percent agar; pH adjusted to 7.0, varying the sucrose and boric acid concentrations. The evaluations were performed 24 hours after the distribution of the pollen in the culture medium. The standard culture medium for germination of pollen grains with 15 percent sucrose provided the highest germination percentage for the banana diploids. The concentration of boric acid added to the culture medium for pollen grain germination of diploid banana is dependent on the genotype.

Ultrastructural features of Mimulus aurantiacus (Scrophulariaceae) pollen tubes in vivo

The aim of this study is to give information on ultrastructure of in vivo pollen tubes of Mimulus aurantiacus which were collected from the Botanical Garden of the University of California at Berkeley. Materials were prepared according to electron microscopy methods and examined under Zeiss electron microscope. Four zones were examined in the pollen tubes of Mimulus aurantiacus. APICAL ZONE: Mitochondria, smooth endoplasmic reticulum, rough endoplasmic reticulum, dictyosomes and secretory vesicles were observed. SUBAPICAL ZONE: This area contained abundant rough endoplasmic reticulum and occasionally some smooth endoplasmic reticulum. The polysomes, mitochondria, proplastids that contain starch, small vacuoles and a few lipid bodies were detected. NUCLEAR ZONE: Both generative and vegetative cell nuclei lie in this zone. The vegetative cell nucleus was large and long. Rough endoplasmic reticulum, mitochondria, ribosomes, dictyosomes, and amyloplasts that are rich of starch were observed. VACUOLATION AND PLUG FORMATION ZONE: Cytoplasm of the tubes was full of large vacuoles. Few organelles such as mitochondria, dictyosome and rough endoplasmic reticulum were detected along their periphery.

O objetivo deste estudo é informar sobre a ultraestrutura de tubos de pólen de Mimulus aurantiacus in vivo coletados no "Botanical Garden" da Universidade da Califórnia em Berkeley. O material foi preparado de acordo com os métodos de microscopia eletrônica e examinado em microscópio eletrônico Zeiss. Quatro zonas dos tubos de pólen de Mimulus aurantiacus foram examinadas. ZONA APICAL: foram observados mitocôndrias, retículo endoplasmático liso; retículo endoplasmático rugoso, dictiossomos e vesículas secretoras. ZONA SUBAPICAL: esta área continha retículo endoplasmático rugoso em abundância e, ocasionalmente, algum retículo endoplasmático liso. Foram detectados polissomos, mitocôndrias, proplastídeos que contêm amido, pequenos vacúolos e alguns corpos lipídicos. ZONA NUCLEAR: nesta área, existem tanto núcleos de células geradoras como vegetativas. O núcleo de célula vegetativa é grande e longo. Foram observados retículo endoplasmático rugoso, mitocôndria, ribossomos, dictiossomos e amiloplastos ricos em amido. ZONA DE VACUOLIZAÇÃO E DE FORMAÇÃO DE "PLUG": o citoplasma dos tubos estava cheio de grandes vacúolos. Algumas organelas como mitocôndria, dictiossomo e retículo endoplasmático rugoso foram detectadas em toda a periferia desta área.