Journal Article

Effects of photo and thermo cycles on flowering time in barley: a genetical phenomics approach

I. Karsai, P. Szűcs, B. Kőszegi, P.M. Hayes, A. Casas, Z. Bedő and O. Veisz

in Journal of Experimental Botany

Published on behalf of Society for Experimental Biology

Volume 59, issue 10, pages 2707-2715
Published in print July 2008 | ISSN: 0022-0957
Published online June 2008 | e-ISSN: 1460-2431 | DOI: http://dx.doi.org/10.1093/jxb/ern131

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The effects of synchronous photo (16 h daylength) and thermo (2 °C daily fluctuation) cycles on flowering time were compared with constant light and temperature treatments using two barley mapping populations derived from the facultative cultivar ‘Dicktoo’. The ‘Dicktoo’בMorex’ (spring) population (DM) segregates for functional differences in alleles of candidate genes for VRN-H1, VRN-H3, PPD-H1, and PPD-H2. The first two loci are associated with the vernalization response and the latter two with photoperiod sensitivity. The ‘Dicktoo’בKompolti korai’ (winter) population (DK) has a known functional polymorphism only at VRN-H2, a locus associated with vernalization sensitivity. Flowering time in both populations was accelerated when there was no fluctuating factor in the environment and was delayed to the greatest extent with the application of synchronous photo and thermo cycles. Alleles at VRN-H1, VRN-H2, PPD-H1, and PPD-H2—and their interactions—were found to be significant determinants of the increase/decrease in days to flower. Under synchronous photo and thermo cycles, plants with the Dicktoo (recessive) VRN-H1 allele flowered significantly later than those with the Kompolti korai (recessive) or Morex (dominant) VRN-H1 alleles. The Dicktoo VRN-H1 allele, together with the late-flowering allele at PPD-H1 and PPD-H2, led to the greatest delay. The application of synchronous photo and thermo cycles changed the epistatic interaction between VRN-H2 and VRN-H1: plants with Dicktoo type VRN-H1 flowered late, regardless of the allele phase at VRN-H2. Our results are novel in demonstrating the large effects of minor variations in environmental signals on flowering time: for example, a 2 °C thermo cycle caused a delay in flowering time of 70 d as compared to a constant temperature.

Keywords: BM5A; Hordeum vulgare; HvFT1; HvFT3; HvPRR7; ZCCT-H

Journal Article.  5714 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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