Characterization of polypeptides synthesized by mRNA isolated from pollen

Total RNA and polysomes extracted from maize pollen were translated in vitro in the rabbit reticulocyte lysate system. Protein products were separated on 1 and 2 dimensional SDS-PAGE gels, and protein profiles compared. Pollen from 35 inbred cultivars and 8 hybrids was collected and stored at -70 C. As a control for environmental variability, samples of Oh43 were collected at various times during the growing season (1983 and 1984). A series of pollen storage experiments was also undertaken. Pollen was collected and stored at 4 C in the dark for up to 8 days.

Translation products from total RNA separated on SDS-PAGE gels show 20 distinct bands for one-dimensional and 80-100 spots for two-dimensional separations. The size classes range from 94Kd to 14Kd with two major groups of proteins at 43 and 32 Kd. Unlabeled pollen proteins, stained with Coomassie blue, show a similar spread of size classes with major bands at 32, 38, 43 and 50 Kd. The polypeptides for translation products of free and bound polysomes show similar banding patterns with some qualitative and quantitative differences. A comparison of translation product patterns from both total mRNA and polysomes shows at least 24 spots in common, 17 of which are major spots. Total mRNA and free polysome patterns show at least 17 spots in common, 8 of which are most prominent.

A comparison of polypeptide patterns from samples of Oh43 monitored at weekly intervals over the growing season show no quantitative or qualitative differences on 1D or 2D gels. Preliminary comparison of polypeptide patterns from inbreds and hybrids shows no significant differences at the 1D level. Cold storage of pollen at 4 C shows deterioration of mRNA in Oh43 after 8 days of storage but very little deterioration of mRNA in SC after 6 days.

M. J. Dunlop and D. B. Walden

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors.

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