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Hiroshi Tobe - One of the best experts on this subject based on the ideXlab platform.

  • mode of Pollen Tube Growth in pistils of ticodendron incognitum ticodendraceae fagales and the evolution of chalazogamy
    Botanical Journal of the Linnean Society, 2008
    Co-Authors: Akiko Sogo, Hiroshi Tobe
    Abstract:

    Ticodendron incognitum is the sole species of the Ticodendraceae, which was established as a new family in the Fagales less than 20 years ago. Considering the diverse modes of Pollen Tube Growth observed in other Fagales, we investigated the Growth of Pollen Tubes in the pistil of Ticodendron. At the time of pollination, T. incognitum had four immature ovules in a bilocular ovary, thus exhibiting delayed fertilization, as in other Fagales. During the period when fertilization was delayed, Pollen Tube Growth in the pistil was intermittent, consisting of five steps associated with development of the ovules and embryo sacs. Four cessation sites occurred: in the style, in the tissue of the upper part of the ovary, inside and outside of the funicle and at the chalaza. A single Pollen Tube eventually reaches a mature embryo sac through the chalaza in one of the four ovules. While both delayed fertilization and intermittent Pollen Tube Growth play a role in male and female gametophyte selection, as in other Fagales, the five-step process of Pollen Tube Growth through the chalaza (i.e. chalazogamy) is characteristic of lineages of the Casuarinaceae, Ticodendraceae and Betulaceae (the latter with the loss of one step). © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 157, 621–631.

  • delayed fertilization and Pollen Tube Growth in pistils of fagus japonica fagaceae
    American Journal of Botany, 2006
    Co-Authors: Akiko Sogo, Hiroshi Tobe
    Abstract:

    In contrast to most angiosperms, in which fertilization occurs 1 or 2 days after pollination, in some plant orders, including the Fagales, fertilization is delayed from 4 days to more than 1 year, raising questions regarding why fertilization is delayed and where and how Pollen Tubes remain in the pistil during the delay. To answer these questions, we investigated Pollen-Tube Growth in pistils of Fagus japonica (Fagaceae), which are tricarpellate and have six ovules, using light, fluorescence, and scanning electron microscopy. The ovules were immature at the time of pollination and required 5 weeks to become fully developed. During this 5 weeks, Pollen Tubes grew from the stigma to the embryo sac in association with the development of ovules and intermittently in three steps with two Growth-cessation sites, i.e., on the funicle and near the micropyle. The number of Pollen Tubes was gradually reduced from many to one at the two Growth-cessation sites, and fertilization occurred in one ovule that apparently developed earlier than the others in the pistil. Thus, delayed fertilization plays an important role in gametophyte competition and selection leading to nonrandom fertilization. Intermittent Pollen-Tube Growth is also likely widespread in angiosperms because it is known in other Fagales and an unrelated order Garryales.

  • mode of Pollen Tube Growth in pistils of myrica rubra myricaceae a comparison with related families
    Annals of Botany, 2006
    Co-Authors: Akiko Sogo, Hiroshi Tobe
    Abstract:

    • Background and Aims It is generally known that fertilization is delayed for more than a few weeks after pollination in Fagales. Recent studies showed that, during that period, Pollen Tubes grew in pistils in close association with the development of the ovule in a five-step process in Casuarina (Casuarinaceae) and a four-step process in Alnus (Betulaceae). The number of Pollen Tubes was reduced from many to one, a fact suggesting that delayed fertilization plays a role for gametophyte selection. Myrica (Myricaceae) also shows delayed fertilization for >2 weeks after pollination, but nothing is known of how Pollen Tubes grow in the pistil during that period. • Methods Pollen-Tube Growth and the development of the ovule in pistils was investigated by fluorescent and scanning electron microscopy and analysis of microtome sections of the pistils. • Key Results Developmental study of the Pollen-Tube Growth in the pistil of M. rubra showed that the tip of the Pollen Tube was branched or lay in a zigzag pattern in the upper space of the ovarian locule or near the tip of the integument, and subsequently was swollen on the nucellar surface. Such morphological changes indicate that the Pollen-Tube Growth was temporarily arrested before fertilization. The Pollen-Tube Growth in M. rubra can therefore be summarized as occurring in three steps: (1) from the stigma to the ovarian locule; (2) from the ovarian locule to the nucellar surface; and (3) from the nucellar surface to the embryo sac. • Conclusion Myrica differs from other families in that the Pollen Tubes arrest their Growth on the nucellar surface, probably digesting nutrient from nucellar cells. There is little information on five other families of Fagales. An extensive study is needed to better understand the diversity and function of the mode of Pollen-Tube Growth within the order.

  • Intermittent Pollen-Tube Growth in pistils of alders (Alnus)
    Proceedings of the National Academy of Sciences of the United States of America, 2005
    Co-Authors: Akiko Sogo, Hiroshi Tobe
    Abstract:

    In alders, where fertilization occurs ≈8 weeks after pollination, the Pollen Tube (male gametophyte) grows intermittently in four steps in close association with the development of the ovary and its ovules. Pollen Tubes stop growing in the style, at the ovarian locule, and at the chalaza (ovule), before reaching an embryo sac for fertilization. At the stage when the ovary develops an ovule primordium in each of the two locules, many Pollen Tubes germinate on the stigma, and a few of them reach the style, where they remain for ≈7 weeks. Thereafter, a single Tube resumes growing; with a short stop in the upper space of the ovarian locule, it reaches the older of the two ovules when it has developed a two-nucleate embryo sac. Except in the last step, where the Tube grows from the chalaza to an embryo sac (female gametophyte), an eight-nucleate mature embryo sac is not necessary for Pollen-Tube guidance in the pistil. Although the intermittent Pollen-Tube Growth appears to play an important role in the selection of a single Pollen Tube from many and one ovule from two, its detection provides insight into the study of the mechanism of Pollen-Tube guidance.

  • intermittent Pollen Tube Growth in fagales especially in alders alms sieboldiana
    Plant Morphology, 2005
    Co-Authors: Akiko Sogo, Hiroshi Tobe
    Abstract:

    Summary: In Fagales, the ovary is still immature when Pollen is delivered to the stigma and the fertilization occurs more than one month after pollination. Developmental study of the Pollen-Tube Growth in the pistil of three species(Casuarina equisetifolia, Alnus sieboldiana and Myrica rubra)in Fagales showed that the Pollen Tube grows intermittently in close association with the development of the ovary and ovules. At the stage when the ovary develops an ovule primordium, many Pollen Tubes germinated on the stigma and reached the style, where they remain for several weeks in Casuarina and Alnus. The Pollen-Tube Growth to the style proceeds irrespective of ovules and embryo sac. Thereafter, the Pollen Tube resumes growing to the ovary with an immature ovule(s)(megaspore tetrad stage in Casuarina and Alnus and megaspore mother cell stage in Myrica). In these species, the Pollen Tube reaches the ovule with immature embryo sac. Except in the last step, where the Tube grows from the tissue of ovule(the chalaza or the nucellus)to an embryo sac, a mature embryo sac is not necessary for Pollen-Tube guidance in the pistil. While the intermittent Pollen-Tube Growth appears to play an important role in the selection of a single Pollen Tube from many and one ovule from two(in Casuarina and Alnus), its detection provides insight into a study of the mechanism of Pollen-Tube guidance.

Peter K Hepler - One of the best experts on this subject based on the ideXlab platform.

  • Pollen Tube Growth oscillations and intracellular calcium levels are reversibly modulated by actin polymerization
    Plant Physiology, 2008
    Co-Authors: Luis Cardenas, Alenka Lovywheeler, Joseph G Kunkel, Peter K Hepler
    Abstract:

    Prevention of actin polymerization with low concentrations of latrunculin B (Lat-B; 2 nm) exerts a profound inhibitory effect on Pollen Tube Growth. Using flow-through chambers, we show that Growth retardation starts after 10 min treatment with 2 nm Lat-B, and by 15 to 20 min reaches a basal rate of 0.1 to 0.2 μm/s, during which the Pollen Tube exhibits relatively few oscillations. If treated for 30 min, complete stoppage of Growth can occur. Studies on the intracellular Ca2+ concentration indicate that the tip-focused gradient declines in parallel with the inhibition of Growth. Tubes exhibiting nonoscillating Growth display a similarly reduced and nonoscillating Ca2+ gradient. Studies on the pH gradient indicate that Lat-B eliminates the acidic domain at the extreme apex, and causes the alkaline band to move more closely to the tip. Removing Lat-B and returning the cells to control medium reverses these effects. Phalloidin staining of F-actin reveals that 2 nm Lat-B degrades the cortical fringe; it also disorganizes the microfilaments in the shank causing the longitudinally oriented elements to be disposed in swirls. Cytoplasmic streaming continues under these conditions, however the clear zone is obliterated with all organelles moving into and through the extreme apex of the Tube. We suggest that actin polymerization promotes Pollen Tube Growth through extension of the cortical actin fringe, which serves as a track to target cell wall vesicles to preferred exocytotic sites on the plasma membrane.

  • pectin methylesterase a regulator of Pollen Tube Growth
    Plant Physiology, 2005
    Co-Authors: Maurice Bosch, Alice Y. Cheung, Peter K Hepler
    Abstract:

    The apical wall of growing Pollen Tubes must be strong enough to withstand the internal turgor pressure, but plastic enough to allow the incorporation of new membrane and cell wall material to support polarized tip Growth. These essential rheological properties appear to be controlled by pectins, which constitute the principal component of the apical cell wall. Pectins are secreted as methylesters and subsequently deesterified by the enzyme pectin methylesterase (PME) in a process that exposes acidic residues. These carboxyls can be cross-linked by calcium, which structurally rigidifies the cell wall. Here, we examine the role of PME in cell elongation and the regulation of its secretion and enzymatic activity. Application of an exogenous PME induces thickening of the apical cell wall and inhibits Pollen Tube Growth. Screening a Nicotiana tabacum Pollen cDNA library yielded a Pollen-specific PME, NtPPME1, containing a pre-region and a pro-region. Expression studies with green fluorescent protein fusion proteins show that the pro-region participates in the correct targeting of the mature PME. Results from in vitro Growth analysis and immunolocalization studies using antipectin antibodies (JIM5 and JIM7) provide support for the idea that the pro-region acts as an intracellular inhibitor of PME activity, thereby preventing premature deesterification of pectins. In addition to providing experimental data that help resolve the significance and function of the pro-region, our results give insight into the mechanism by which PME and its pro-region regulate the cell wall dynamics of growing Pollen Tubes.

  • control of Pollen Tube Growth role of ion gradients and fluxes
    New Phytologist, 2003
    Co-Authors: Terena L Holdawayclarke, Peter K Hepler
    Abstract:

    Contents Summary  000 I. Introduction  000 II. Ion gradients and flux patterns  000 III. Oscillations  000 IV. The need for a Ca2+ store  000 V. Intracellular targets for Ion activity  000 VI. Extracellular targets for ions: the cell wall  000 VII. Ions in navigation  000 VIII. Role of ions in self-incompatibility  000 IX. The plasma membrane; site of global coordination and control  000 X. A model for Pollen Tube Growth  000 IX. Conclusions  000 Acknowledgements  000 References  000 Summary Pollen Tube Growth attracts our attention as a model system for studying cell elongation in plants. The process is fast, it is confined to the tip of the Tube, and it is crucial for sexual reproduction in plants. In the enclosed review we focus on the control of Pollen Tube Growth, giving special attention to the role of ions, especially calcium and protons. During the last decade technical advances have made it possible to detect localized intracellular gradients, and extracellular fluxes of calcium and protons in the apical domain. Other ions, notably potassium and chloride, are also receiving attention. An important development has been the realization that Pollen Tube Growth oscillates in rate; in addition, the ion gradients and fluxes oscillate in magnitude. Although all the ionic oscillations show the same period as that of the Growth rate, with the exception of extracellular chloride efflux, they are not in phase with Growth. Considerable effort is devoted to the elucidation of these different phase relationships, with the view that a hierarchical order may provide clues about those events that are primary vs. secondary in Growth control. Attention is also given to the targets for the ions, for example, the secretory system, the cytoskeleton, the cell wall, in an attempt to provide a global understanding of Pollen Tube Growth.

  • actin polymerization is essential for Pollen Tube Growth
    Molecular Biology of the Cell, 2001
    Co-Authors: Luis Vidali, Sylvester T Mckenna, Peter K Hepler
    Abstract:

    Actin microfilaments, which are prominent in Pollen Tubes, have been implicated in the Growth process; however, their mechanism of action is not well understood. In the present work we have used profilin and DNAse I injections, as well as latrunculin B and cytochalasin D treatments, under quantitatively controlled conditions, to perturb actin microfilament structure and assembly in an attempt to answer this question. We found that a ∼50% increase in the total profilin pool was necessary to half-maximally inhibit Pollen Tube Growth, whereas a ∼100% increase was necessary for half-maximal inhibition of cytoplasmic streaming. DNAse I showed a similar inhibitory activity but with a threefold more pronounced effect on Growth than streaming. Latrunculin B, at only 1–4 nM in the Growth medium, has a similar proportion of inhibition of Growth over streaming to that of profilin. The fact that tip Growth is more sensitive than streaming to the inhibitory substances and that there is no correlation between streaming and Growth rates suggests that tip Growth requires actin assembly in a process independent of cytoplasmic streaming.

  • actin polymerization is essential for Pollen Tube Growth
    Molecular Biology of the Cell, 2001
    Co-Authors: Luis Vidali, Sylvester T Mckenna, Peter K Hepler
    Abstract:

    Actin microfilaments, which are prominent in Pollen Tubes, have been implicated in the Growth process; however, their mechanism of action is not well understood. In the present work we have used profilin and DNAse I injections, as well as latrunculin B and cytochalasin D treatments, under quantitatively controlled conditions, to perturb actin microfilament structure and assembly in an attempt to answer this question. We found that a approximately 50% increase in the total profilin pool was necessary to half-maximally inhibit Pollen Tube Growth, whereas a approximately 100% increase was necessary for half-maximal inhibition of cytoplasmic streaming. DNAse I showed a similar inhibitory activity but with a threefold more pronounced effect on Growth than streaming. Latrunculin B, at only 1--4 nM in the Growth medium, has a similar proportion of inhibition of Growth over streaming to that of profilin. The fact that tip Growth is more sensitive than streaming to the inhibitory substances and that there is no correlation between streaming and Growth rates suggests that tip Growth requires actin assembly in a process independent of cytoplasmic streaming.

Akiko Sogo - One of the best experts on this subject based on the ideXlab platform.

  • mode of Pollen Tube Growth in pistils of ticodendron incognitum ticodendraceae fagales and the evolution of chalazogamy
    Botanical Journal of the Linnean Society, 2008
    Co-Authors: Akiko Sogo, Hiroshi Tobe
    Abstract:

    Ticodendron incognitum is the sole species of the Ticodendraceae, which was established as a new family in the Fagales less than 20 years ago. Considering the diverse modes of Pollen Tube Growth observed in other Fagales, we investigated the Growth of Pollen Tubes in the pistil of Ticodendron. At the time of pollination, T. incognitum had four immature ovules in a bilocular ovary, thus exhibiting delayed fertilization, as in other Fagales. During the period when fertilization was delayed, Pollen Tube Growth in the pistil was intermittent, consisting of five steps associated with development of the ovules and embryo sacs. Four cessation sites occurred: in the style, in the tissue of the upper part of the ovary, inside and outside of the funicle and at the chalaza. A single Pollen Tube eventually reaches a mature embryo sac through the chalaza in one of the four ovules. While both delayed fertilization and intermittent Pollen Tube Growth play a role in male and female gametophyte selection, as in other Fagales, the five-step process of Pollen Tube Growth through the chalaza (i.e. chalazogamy) is characteristic of lineages of the Casuarinaceae, Ticodendraceae and Betulaceae (the latter with the loss of one step). © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 157, 621–631.

  • delayed fertilization and Pollen Tube Growth in pistils of fagus japonica fagaceae
    American Journal of Botany, 2006
    Co-Authors: Akiko Sogo, Hiroshi Tobe
    Abstract:

    In contrast to most angiosperms, in which fertilization occurs 1 or 2 days after pollination, in some plant orders, including the Fagales, fertilization is delayed from 4 days to more than 1 year, raising questions regarding why fertilization is delayed and where and how Pollen Tubes remain in the pistil during the delay. To answer these questions, we investigated Pollen-Tube Growth in pistils of Fagus japonica (Fagaceae), which are tricarpellate and have six ovules, using light, fluorescence, and scanning electron microscopy. The ovules were immature at the time of pollination and required 5 weeks to become fully developed. During this 5 weeks, Pollen Tubes grew from the stigma to the embryo sac in association with the development of ovules and intermittently in three steps with two Growth-cessation sites, i.e., on the funicle and near the micropyle. The number of Pollen Tubes was gradually reduced from many to one at the two Growth-cessation sites, and fertilization occurred in one ovule that apparently developed earlier than the others in the pistil. Thus, delayed fertilization plays an important role in gametophyte competition and selection leading to nonrandom fertilization. Intermittent Pollen-Tube Growth is also likely widespread in angiosperms because it is known in other Fagales and an unrelated order Garryales.

  • mode of Pollen Tube Growth in pistils of myrica rubra myricaceae a comparison with related families
    Annals of Botany, 2006
    Co-Authors: Akiko Sogo, Hiroshi Tobe
    Abstract:

    • Background and Aims It is generally known that fertilization is delayed for more than a few weeks after pollination in Fagales. Recent studies showed that, during that period, Pollen Tubes grew in pistils in close association with the development of the ovule in a five-step process in Casuarina (Casuarinaceae) and a four-step process in Alnus (Betulaceae). The number of Pollen Tubes was reduced from many to one, a fact suggesting that delayed fertilization plays a role for gametophyte selection. Myrica (Myricaceae) also shows delayed fertilization for >2 weeks after pollination, but nothing is known of how Pollen Tubes grow in the pistil during that period. • Methods Pollen-Tube Growth and the development of the ovule in pistils was investigated by fluorescent and scanning electron microscopy and analysis of microtome sections of the pistils. • Key Results Developmental study of the Pollen-Tube Growth in the pistil of M. rubra showed that the tip of the Pollen Tube was branched or lay in a zigzag pattern in the upper space of the ovarian locule or near the tip of the integument, and subsequently was swollen on the nucellar surface. Such morphological changes indicate that the Pollen-Tube Growth was temporarily arrested before fertilization. The Pollen-Tube Growth in M. rubra can therefore be summarized as occurring in three steps: (1) from the stigma to the ovarian locule; (2) from the ovarian locule to the nucellar surface; and (3) from the nucellar surface to the embryo sac. • Conclusion Myrica differs from other families in that the Pollen Tubes arrest their Growth on the nucellar surface, probably digesting nutrient from nucellar cells. There is little information on five other families of Fagales. An extensive study is needed to better understand the diversity and function of the mode of Pollen-Tube Growth within the order.

  • Intermittent Pollen-Tube Growth in pistils of alders (Alnus)
    Proceedings of the National Academy of Sciences of the United States of America, 2005
    Co-Authors: Akiko Sogo, Hiroshi Tobe
    Abstract:

    In alders, where fertilization occurs ≈8 weeks after pollination, the Pollen Tube (male gametophyte) grows intermittently in four steps in close association with the development of the ovary and its ovules. Pollen Tubes stop growing in the style, at the ovarian locule, and at the chalaza (ovule), before reaching an embryo sac for fertilization. At the stage when the ovary develops an ovule primordium in each of the two locules, many Pollen Tubes germinate on the stigma, and a few of them reach the style, where they remain for ≈7 weeks. Thereafter, a single Tube resumes growing; with a short stop in the upper space of the ovarian locule, it reaches the older of the two ovules when it has developed a two-nucleate embryo sac. Except in the last step, where the Tube grows from the chalaza to an embryo sac (female gametophyte), an eight-nucleate mature embryo sac is not necessary for Pollen-Tube guidance in the pistil. Although the intermittent Pollen-Tube Growth appears to play an important role in the selection of a single Pollen Tube from many and one ovule from two, its detection provides insight into the study of the mechanism of Pollen-Tube guidance.

  • intermittent Pollen Tube Growth in fagales especially in alders alms sieboldiana
    Plant Morphology, 2005
    Co-Authors: Akiko Sogo, Hiroshi Tobe
    Abstract:

    Summary: In Fagales, the ovary is still immature when Pollen is delivered to the stigma and the fertilization occurs more than one month after pollination. Developmental study of the Pollen-Tube Growth in the pistil of three species(Casuarina equisetifolia, Alnus sieboldiana and Myrica rubra)in Fagales showed that the Pollen Tube grows intermittently in close association with the development of the ovary and ovules. At the stage when the ovary develops an ovule primordium, many Pollen Tubes germinated on the stigma and reached the style, where they remain for several weeks in Casuarina and Alnus. The Pollen-Tube Growth to the style proceeds irrespective of ovules and embryo sac. Thereafter, the Pollen Tube resumes growing to the ovary with an immature ovule(s)(megaspore tetrad stage in Casuarina and Alnus and megaspore mother cell stage in Myrica). In these species, the Pollen Tube reaches the ovule with immature embryo sac. Except in the last step, where the Tube grows from the tissue of ovule(the chalaza or the nucellus)to an embryo sac, a mature embryo sac is not necessary for Pollen-Tube guidance in the pistil. While the intermittent Pollen-Tube Growth appears to play an important role in the selection of a single Pollen Tube from many and one ovule from two(in Casuarina and Alnus), its detection provides insight into a study of the mechanism of Pollen-Tube guidance.

Scott W Armbruster - One of the best experts on this subject based on the ideXlab platform.

  • Pollen Tube Growth rates in collinsia heterophylla plantaginaceae one donor crosses reveal heritability but no effect on sporophytic offspring fitness
    Annals of Botany, 2009
    Co-Authors: Asa Lankinen, Johanne Maad, Scott W Armbruster
    Abstract:

    Evolutionary change in response to natural selection will occur only if a trait confers a selective advantage and there is heritable variation. Positive connections between Pollen traits and fitness have been found, but few studies of heritability have been conducted, and they have yielded conflicting results. To understand better the evolutionary significance of Pollen competition and its potential role in sexual selection, the heritability of Pollen Tube-Growth rate and the relationship between this trait and sporophytic offspring fitness were investigated in Collinsia heterophylla. Because the question being asked was if female function benefited from obtaining genetically superior fathers by enhancing Pollen competition, one-donor (per flower) crosses were used in order to exclude confounding effects of post-fertilization competition/allocation caused by multiple paternity. Each recipient plant was crossed with an average of five Pollen donors. Pollen-Tube Growth rate and sporophytic traits were measured in both generations. Pollen-Tube Growth rate in vitro differed among donors, and the differences were correlated with in vivo Growth rate averaged over two to four maternal plants. Pollen-Tube Growth rate showed significant narrow-sense heritability and evolvability in a father-offspring regression. However, this Pollen trait did not correlate significantly with sporophytic-offspring fitness. These results suggest that Pollen-Tube Growth rate can respond to selection via male function. The data presented here do not provide any support for the hypothesis that intense Pollen competition enhances maternal plant fitness through increased paternity by higher-quality sporophytic fathers, although this advantage cannot be ruled out. These data are, however, consistent with the hypothesis that Pollen competition is itself selectively advantageous, through both male and female function, by reducing the genetic load among successful gametophytic fathers (Pollen), and reducing inbreeding depression associated with self-pollination in plants with mix-mating systems.

Vijaya Gopal Kakani - One of the best experts on this subject based on the ideXlab platform.

  • differences in in vitro Pollen germination and Pollen Tube Growth of cotton cultivars in response to high temperature
    Annals of Botany, 2005
    Co-Authors: Vijaya Gopal Kakani, K R Reddy, Sailaja Koti, T P Wallace, P V V Prasad, V R Reddy, Duli Zhao
    Abstract:

    � Background and Aims High-temperature environments with >30 � C during flowering reduce boll retention and yield in cotton. Therefore, identification of cotton cultivars with high-temperature tolerance would be beneficial in both current and future climates. � Methods Response to temperature (10‐45 � Ca t 5 � C intervals) of Pollen germination and Pollen Tube Growth was quantified, and their relationship to cell membrane thermostability was studied in 12 cultivars. A principal component analysis was carried out to classify the genotypes for temperature tolerance. � Key Results Pollen germination and Pollen Tube length of the cultivars ranged from 20 to 60 % and 411 to 903 mm, respectively. A modified bilinear model best described the response to temperature of Pollen germination and Pollen Tube length. Cultivar variation existed for cardinal temperatures (Tmin, Topt and Tmax) of Pollen germination percentage and Pollen Tube Growth. Mean cardinal temperatures calculated from the bilinear model for the 12 cultivars were 15� 0, 31� 8 and 43� 3 � C for Pollen germination and 11� 9, 28� 6 and 42� 9 � C for Pollen Tube length. No significant correlations were found between Pollen parameters and leaf membrane thermostability. Cultivars were classified into four groups based on principal component analysis. � Conclusions Based on principal component analysis, it is concluded that higher Pollen germination percentages and longer Pollen Tubes under optimum conditions and with optimum temperatures above 32 � C for Pollen

  • response of in vitro Pollen germination and Pollen Tube Growth of groundnut arachis hypogaea l genotypes to temperature
    Plant Cell and Environment, 2002
    Co-Authors: Vijaya Gopal Kakani, P V V Prasad, P Q Craufurd, T R Wheeler
    Abstract:

    Air temperatures of greater than 35 °C are frequently encountered in groundnut-growing regions, especially in the semi-arid tropics. Such extreme temperatures are likely to increase in frequency under future predicted climates. High air temperatures result in failure of peg and pod set due to lower Pollen viability. The response of Pollen germination and Pollen Tube Growth to temperature was quantified in order to identify differences in Pollen tolerance to temperature among 21 groundnut genotypes. Plants were grown from sowing to harvest in a poly-tunnel under an optimum temperature of 28/22 °C (day/night). Pollen was collected at anther dehiscence and was exposed to temperatures from 10° to 47·5 °C at 2·5 °C intervals. The results showed that a modified bilinear model most accurately described the response to temperature of percentage Pollen germination and maximum Pollen Tube length. Genotypes were found to range from most tolerant to most susceptible based on both Pollen characters and membrane thermostability. Mean cardinal temperatures (Tmin, Topt and Tmax) averaged over 21 genotypes were 14·1, 30·1 and 43·0 °C for percentage Pollen germination and 14·6, 34·4 and 43·4 °C for maximum Pollen Tube length. The genotypes 55-437, ICG 1236, TMV 2 and ICGS 11 can be grouped as tolerant to high temperature and genotypes Kadiri 3, ICGV 92116 and ICGV 92118 as susceptible genotypes, based on the cardinal temperatures. The principal component analysis identified maximum percentage Pollen germination and Pollen Tube length of the genotypes, and Tmax for the two processes as the most important Pollen parameters in describing a genotypic tolerance to high temperature. The Tmin and Topt for Pollen germination and Tube Growth, rate of Pollen Tube Growth were less predictive in discriminating genotypes for high temperature tolerance. Genotypic differences in heat tolerance-based on Pollen response were poorly related (R2 = 0·334, P = 0·006) to relative injury as determined by membrane thermostability.