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Plants with increased protein, methionine and starch level and decreased glycoalkaloid content

The data from mRNA analysis suggest the developmental regulation of 14-3-3 isoform expressions in potato plants. To test 14-3-3 protein function transgenic potato plants under-expressing 14-3-3 isoforms were analysed. The transgenic plants showed a decrease in tuber number and an increase in tuber size; an increase in the fresh weight of tubers was detected.

The repressed plants showed significant increases in nitrate reductase (NR) activity. The increase in NR activity resulted in a significant decrease in nitrate level and increase in protein content. The level of sucrose phosphate synthase and starch synthase activities is also significantly increased in all the 14-3-3 under-expressed transgenes, and remarkably, the increase in enzyme activity is accompanied by respective changes in sucrose and starch levels in the tubers. In opposite the key enzymes of tyrosine metabolism are decreased upon 14-3-3 repression and resulted in catecholamine content reduction. The decrease in catecholamine content in transgenic tubers might be also responsible for starch increase in these plants.

The significant increase in ethylene content, which follows methionine level, was also found. The substantial increase of ethylene level in the repressed forms might explain the significant shortening of the vegetation period of the analyzed transgenic plants.

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51-148 WROC³AW
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