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Query: UMLS:C0277787 (stigma)
 13,352 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The molecular mechanisms responsible for postpollination changes in floral scent emission were investigated in snapdragon cv Maryland True Pink and petunia cv Mitchell flowers using a volatile ester, methylbenzoate, one of the major scent compounds emitted by these flowers, as an example. In both species, a 70 to 75% pollination-induced decrease in methylbenzoate emission begins only after pollen tubes reach the ovary, a process that takes between 35 and 40 h in snapdragon and approximately 32 h in petunia. This postpollination decrease in emission is not triggered by pollen deposition on the stigma. Petunia and snapdragon both synthesize methylbenzoate from benzoic acid and S-adenosyl-l-methionine (SAM); however, they use different mechanisms to downregulate its production after pollination. In petunia, expression of the gene responsible for methylbenzoate synthesis is suppressed by ethylene. In snapdragon, the decrease in methylbenzoate emission is the result of a decrease in both S-adenosyl-l-methionine:benzoic acid carboxyl methyltransferase (BAMT) activity and the ratio of SAM to S-adenosyl-l-homocysteine ("methylation index") after pollination, although the BAMT gene also is sensitive to ethylene.
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PMID:Regulation of methylbenzoate emission after pollination in snapdragon and petunia flowers. 1463 Sep 69

S-glycoproteins, i.e. stigma glycoproteins that are heritable in correlation with S allele in self-incompatible Brassica species, were apparently purified for three S alleles in B. oleracea. From SDS gel electrophoresis, the estimated molecular weight for two of the S-glycoproteins was 57,000. The other S-glycoprotein was considered to be heterogeneous with molecular weights of 60,000 and 65,000. Distinct differences in amino acid content were found; in general, cysteine, methionine and histidine were low, and serine, glutamate, glycine, leucine, arginine and aspartate were high and variable between the S-glycoproteins. Differences in the isoelectric point were mainly attributed to the amino acid composition of each S-glycoprotein.
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PMID:Comparative Studies on S-Glycoproteins Purified from Different S-Genotypes in Self-Incompatible BRASSICA Species I. Purification and Chemical Properties. 1724 74

De-novo synthesis of the S-allele-specific glycoproteins of Brassica oleracea is demonstrated in stigmas at different developmental stages. Excised stigmas incorporate (14)C-labeled amino acids into their S-glycoproteins early in development and before the self-incompatibility response is acquired, but the rate of synthesis accelerates prior to anthesis, resulting in the accumulation of high levels of the S-glycoproteins in the stigma and coinciding with the acquisition of the pollen-stigma incompatibility response. Since the self-compatible and self-incompatible zones of developing inflorescences are very sharply delineated, a threshold quantity of S-glycoproteins appears to be critical for the onset of self-incompatibility. Incorporation experiments in which [(35S)methionine was applied to intact stigma surfaces indicate that the papillae are the main sites of synthesis of the S-specific glycoproteins.
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PMID:Biosynthesis of glycoproteins involved in the pollen-stigma interaction of incompatibility in developing flowers of Brassica oleracea L. 2424 Sep 63