Pollen sterility

The small population resulted from several difficulties which were Inherent in King Midas it was pollen sterile and the plant had low vigor. It was necessary to identify a susceptible Inbred line which could be used in genetic studies. A survey of available genetic material resulted in the acquisition of G60, a pink flowered mite-susceptible line. In addition, the survey indicated that a highly resistant line, G54, satisfied the criteria for genetic studies it was used to replace G71, the original resistant parent. 

The theme of this book is not a reformulation of theoretical physics, but an attempt to identify the theoretical ideas fundamental to chemistry and recast them in more familiar style. There is no doubt but, that the chemist of this century will have to be familiar with the concepts that appear to be new, even alien, at present. The philosophy that inspires this work is that specialization in science is detrimental in the long term. Specialization may well stimulate productivity in the short term, but this productivity becomes sterile in the absence of innovation, that depends on cross-pollenation, or the adoption of new theoretical models. 

To germinate lily pollen, spread 20 mg g fresh weight lots onto the surface of 10-mL sterile SYB (46,47) or Dickinson s (48) media in sterile Petri dishes. 

In many plant species compatible pollen tubes grow directly down inside the style as a bundle of long smooth tubes with bright callose plugs. Only in female sterile plants of Oenothera mut. brevistylis was branching of pollen tubes found in the style and ovary (7). 

Another problem is the direction of pollen tube growth, which should be considered as tropism, related to attraction by the fertile ovules. Many observations of pollen tubes in the fluorescence microscope supported this suggestion—pollen tubes pass by the sterile ovules and grow in the direction of the fertile ones. The number of ovules penetrated by a pollen tube is correlated with the number of developing seeds, which supports the hypothesis about interaction (attraction) between the ovule and pollen tube (1,2,5). 

Napoli, C.A. et al., White anther A Petunia mutant that abolishes pollen flavonol accumulation, induces male sterility, and is complemented by a chalcone synthase transgene, Plant Physiol, 120, 615, 1999. 

These standards can be met by adding male sterility traits to control pollen flow to avoid outcrossing. Some plant species that have enclosed flower structures would represent good candidates. A crop like corn, which is a wind-pollinated crop, can have tassels removed manually, and sterile varieties can be made to contain the pollen (Shama and Peterson, 2004). 

The viability of seeds produced by S. divinorum is questionable. It is apparently a self-sterile plant which will produce seed only when cross-pollinated (1). Valdes pollinated fourteen flowers and four produced seeds. Unfortunately, the seeds viability could not be assessed as they were accidentally killed when a growth chamber overheated (1). Generally, this plant is reproduced by cuttings. It is a diploid species (N=l 1) whose pollen grains are not as viable as those of other Salvia species. Out of 3027 pollen grains, Reisfield found that 53% aborted, although this fact alone does not explain why the plants do not set seed in Mexico (16). Even when 5. divinorum is hand pollinated, only 2 to 3 percent of the nutlets fully mature (8). 

Pollen grains from FAA-preserved flowers on wild and greenhouse-grown plants were analyzed for cytoplasm stainability. Sterile or aborted pollen grains did not take up the cotton blue-lactophenol stain, and were also conspicuous by their shrunken size and shriveled form. 

In order to obtain hybrid seeds, self-pollination and pollination by a sibling plant must be avoided. It is sought to develop a female parental line accepting pollen from other lines (cross-pollination), without reproduction of its own line. This can be achieved directly through emasculation, i.e., elimination of the pollenbearing organ, usually at the expense of large labor requirements. Other methods can be used to induce male sterility. 

Cytoplasmic Male Sterility. Unfortunately, large-scale mechanical emasculation cannot be applied to all crops of interest. In wheat, for example, the pollen-bearing anthers and female stigmas lay side by side within each floret of a spikelet. Removal of anthers with small, hand-held instruments obviously has utility only for small-scale hybridization experiments. Nevertheless, by crossing a female parent endowed with cytoplasmic male sterility with a male parent that has fertility-restoring genes, one can achieve hybrid wheat seed production. This technology, however, has limitations compared to... 

Pollen Screening for Disease Resistance Using Phytotoxins. A liquid shake culture was made using a 4 1 (V-8 juice glass distilled water) medium. The pH was adjusted to 5.8, and the medium sterilized at 121°C for 15 min. Two hundred and fifty ml of medium in 500 ml Erlenmeyer flasks was inoculated with Fusarium and Verticillium races supplied by Dr. Ken Kimball, Moran Seed Co., Davis, CA, and shaken for 7 days at 24°C. The medium was then centrifuged at 1000 rpm to separate out the mass of spores and filaments. The filtrate was run through a... 

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