Pollen germination

Experiment 2. Effects of terpenoid allelochemicals on pollen germination The effects of the terpenoids found in many allelopathically active plants are dependent on the concentration of the active matter (Fig. 4). Linalool, cymol, citral, gaillardine and austricine excreted by many flowers, stimulated the pollen germination upto 10 7-1()" M concentrations and depress in higher ones. Rodriguez et.al (1976) described the biological effects of some sesquiterpene lactones, which are allelochemicals. 

Experiment 3. Fluorescence and pollen germination at binding of allelochemicals with cytoskeleton and organelles... 

Martin, F. W. (1970). Pollen germination on foreign stigmas. Bulletin of the Torrey Botanical Club 97 1-6. 

Fig. 3. Lightmicroscope radioautographs ofintact tubes from pollen germinated 4 h in a medium containing [14C]-proline with or without the proline analogue, azetidine-2-carboxylic acid (AZC). A = 1.0 mM AZC, B = 0.1 mM AZC, C = 0.01 mM AZC, D = 0.001 mM AZC, E = Control. From Dashek and Mills (50), with permission. 

Taylor LP, Hepler PK. Pollen germination and tube growth. Anna Rev Plant Physiol Plant Mol Biol 1997 48 461-491. 

Feder, W. A. Reduction in tobacco pollen germination and tube elongation, induced by low levels of ozone. Science 160 1122, 1968. 

There is evidence that ozone is a radiomimetic gas. Ozone affects pollen germination in some spedes and thus may directly affect yield. 

Alternative hypotheses for pollen pigments hold that flavonoids are involved in pollen-style incompatibility relationships via pollen germination, or else serve as growth regulators for pollen tube development. Certain flavonoids have also been postulated to ameliorate the effects of heat stress during fertilization. 

Flavonoids are not always essential signal molecules in mycorrhizal symbioses, however various other phenolic acids can elicit similar effects. " Compounds that actively promote the growth of AMF (i.e., kaempferol, quercetin, and myricetin) " are also required for pollen germination and growth of the germ tube. " " Thus, these compounds may have some general effect on cell elongation.It has been concluded that flavonoids stimulate, but are not essential for mycorrhiza formation. 

Further resolution of the problem was obtained by studying pollen germination and tube growth through styles of hand-pollinated flowers. Of 39 styles observed, 13 (33%) had four or more pollen tubes that traversed the entire length of the style, reaching the ovary. Three or more pollen tubes reached the ovary in almost one half the styles observed. Of the 20 styles in which four or more pollen grains or tubes were observable at all, 14 had three or more pollen tubes that reached the ovary. Also, no difference was noted between the self- and supposed cross-pollinations. 

Variations of the life cycle occur. For example, a process called apomixis leads to asexual formation of seed.469 In many plants, including maize, separate flowers form the ovule and the pollen. This is one mechanism for avoiding inbreeding.470 In many plants systems of self-incompatibility have evolved.471 In some, e.g., Arabidopsis and other crucifers, pollen germination is disrupted unless it falls on a stigma possessing a different allele-specific receptor. In other cases development of the pollen tube is disrupted at a later stage. In maize and in more than 150 other... 

Effect of Prebloom Treatment on Pollen Germinability and Fruit Development... 

KGA3 on pollen germinability was studied, using the hanging-drop procedure as described by Olmo (22), and on development of the fruit, including the number of hard seeds per berry, determined by cutting berries open with a razor blade. Small shot berries that failed to soften or color were not counted. 

Guyon V, Astwood J, Garner E, Dunker K, Taylor LP. 2000. Isolation and characterization of cDNAs expressed in the early stages of flavonol-induced pollen germination in petunia. Plant Physiol 123 699-710. 

Hodgkin, T., Lyon, G.D. Inhibition of Solanum pollen germination in vitro by the phytoalexin rishitin. Ann Bot 1979 44 253-255. 

As pointed out above, bioassay choice is extremely important since different sensitivities and different responses are observed that are dependent on the bioassay specimen. For example, comparison of four bioassay methods for detection of destruxin B, a host-specific toxin produced by Alternaria brassicae, indicated a lack of rapid electrolyte leakage and insensitivity of host protoplasts. However, leaf and pollen bioassays were sensitive to low toxin levels. Pollen germination was the most rapid, sensitive and quantitative bioassay for the toxin. Significant inhibition of Brassica campestris pollen germination and pollen tube growth occurred only 30 min after incubation with 2.5 pg mL 1, and 7.5 pg mL 1 caused total inhibition.3... 

Feder, W. A., Reduction in Tobacco Pollen Germination and Tube Elonga-... 

Sulzbach, C. W., Pack, M. R., Effect of Fluoride on Pollen Germination and Pollen Tube Elongation, Phytopathol. (1971) 61, 913. 

C-Methylene-MI (MMO) is one of several MI antagonists that produce morphological modifications in Schizosaccharomyces pombe, a fission yeast with an absolute requirement for MI (Schopfer et al., 1969). When this epoxide is injected into rats, MIOase is inactivated and necrotic lesions develop in the kidneys. Simultaneous administration of MI prevents enzyme inactivation and reduces cytotoxicity (Weinhold and Anderson, 1967). The epoxide also represses pollen germination, inhibits pollen tube elongation, and delays seed germination (Chen et al., 1977 Maiti and Loewus, 1978a,b). 

QS, like those of other plants, store proteins in the embryo to provide nutrients for growth and development (Herman and Larkins, 1999). In the food area, proteins stored in seeds are the source of the proteins consumed directly as food by humans (Shewry et al., 1995). Stored proteins provide building blocks for rapid growth upon seed and pollen germination (Herman and Larkins, 1999). Osborne (1924) introduced a classification of plant proteins based on their solubility in a series of solvents, such as albumins in water, and globulins in saline. 

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