Expression of multi-copy flavonoid pathway genes coincides with anthocyanin, flavonol and flavan-3-ol accumulation of grapevine

The biosynthetic pathways of main grape flavonoids: anthocyanins, flavonols, and flavan-3-ols, hold in common the early step enzymes of biosynthetic pathway: chalcone synthase (CHS), chalcone isomerase (CHI), and flavanone 3-hydroxylase (F3H), the genes of which are multi-copied in the grape genome. The ratios of mRNA levels of the three Chss (Chs1, Chs2, and Chs3), as well as those of the two Chis (Chi1 and Chi2) and those of the two F3hs (F3h1 and F3h2), were different among organs, even though no organ-specificity was observed in the strictest sense. Multiple regression analysis demonstrated that the transcription of particular genes significantly coincided with the biosynthesis of a particular flavonoid: the transcription of Chi2 coincided with flavan-3-ol; Chs1, Chs2, F3h1, and F3h2 with flavonol; and Chs2, Chs3, and F3h2 with anthocyanin biosynthesis. Thus, the transcription of these multi-copy genes is likely induced differently for the biosyntheses of anthocyanins, flavonols, and flavan-3-ols.

Effects of abscisic acid treatment and night temperatures on anthocyanin composition in Pinot noir grapes

Potted Pinot noir grapevines were grown under continuous high temperature (30 °C) or low night (15 °C) and high day (30 °C) temperatures after veraison. Half of the total number of clusters of each vine was sprayed with 250 ppm abscisic acid (ABA) at veraison. Anthocyanin accumulation in berry skins grown under high night temperatures was lower than that in berries grown under low night temperatures. HPLC analysis showed that the ratios of delphinidin-3-glucoside, cyanidin-3-glucoside and petunidin-3-glucoside to the total anthocyanin content were greatly reduced under high night temperatures. ABA treatment enhanced anthocyanin accumulation under high night temperatures to almost the same level as under low night temperatures; the ratio of each anthocyanin to the total anthocyanin, however, was not affected by ABA treatment.

Nuclear spin-lattice relaxation in ferrimagnetic clusters and chains: A contrast between zero and one dimensions

Motivated by ferrimagnetic oligonuclear and chain compounds synthesized by Caneschi et al., both of which consist of alternating manganese(II) ions and nitronyl-nitroxide radicals, we calculate the nuclear spin-lattice relaxation rate 1/T_1 employing a recently developed modified spin-wave theory. 1/T_1 as a function of temperature drastically varies with the location of probe nuclei in both clusters and chains, though the relaxation time scale is much larger in zero dimension than in one dimension. 1/T_1 as a function of an applied field in long chains forms a striking contrast to that in finite clusters, diverging with decreasing field like inverse square root at low temperatures and logarithmically at high temperatures.Comment: to be published in Phys. Rev. B 68 August 01 (2003