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Loss of floral repressor function adapts rice to higher latitudes in Europe.

Gómez-Ariza J, Galbiati F, Goretti D, Brambilla V, Shrestha R, Pappolla A, Courtois B, Fornara F - J. Exp. Bot. (2015)

Bottom Line: Pyramiding of mutations is frequently observed in European germplasm, but single mutations are sufficient to adapt rice to flower at higher latitudes.Expression of Ehd1 is increased in varieties showing reduced or Hd1 expression under natural long days, as well as in single hd1 mutants in isogenic backgrounds.These data indicate that loss of repressor genes has been a key strategy to expand rice cultivation to Europe, and that Ehd1 is a central node integrating floral repressive signals.

View Article: PubMed Central - PubMed

Affiliation: University of Milan, Department of Biosciences, Via Celoria 26, 20133 Milan, Italy.

No MeSH data available.


Diurnal patterns of Hd3a and RFT1 mRNA expression in Italian varieties under SD and LD. (A) Diurnal quantification of Hd3a mRNA expression under SD. (B) Diurnal quantification of RFT1 mRNA expression under SD. (C) Diurnal quantification of Hd3a mRNA expression under LD. (D) Diurnal quantification of RFT1 mRNA expression under LD. Quantification of expression levels was determined in Volano, Sant’Andrea and Augusto compared to Nipponbare. Bars on top indicate day (white) or night (black). ZT indicates hours from dawn (Zeitgeber). Ubiquitin (Ubq) was used to normalize gene expression levels.
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Figure 3: Diurnal patterns of Hd3a and RFT1 mRNA expression in Italian varieties under SD and LD. (A) Diurnal quantification of Hd3a mRNA expression under SD. (B) Diurnal quantification of RFT1 mRNA expression under SD. (C) Diurnal quantification of Hd3a mRNA expression under LD. (D) Diurnal quantification of RFT1 mRNA expression under LD. Quantification of expression levels was determined in Volano, Sant’Andrea and Augusto compared to Nipponbare. Bars on top indicate day (white) or night (black). ZT indicates hours from dawn (Zeitgeber). Ubiquitin (Ubq) was used to normalize gene expression levels.

Mentions: It has been previously demonstrated that under SD conditions RFT1 expression was lower compared to Hd3a in wild type plants. Further reduction of its expression by RNAi caused no delay of flowering, indicating that RFT1 is not contributing to flowering promotion under SD (Komiya et al., 2008). In Italian varieties, the correlation between heading dates and RFT1 expression was higher than with Hd3a expression at two time points under continuous SD (Table 2). Expression of upstream regulators of the florigens was poorly correlated to heading dates (Supplementary Table S4). Therefore, the diurnal mRNA expression profiles of Hd3a and RFT1 were determined under both LD and SD. In addition to Nipponbare, which shows a high PS index, three Italian varieties with a low PS index were selected for this experiment, regardless of genotype. Hd3a was induced in all varieties to levels similar to those observed in Nipponbare (Fig. 3A). Additionally, high levels of RFT1 expression in the three Italian varieties (Fig. 3B) were observed, indicating that RFT1 transcription was strongly de-repressed under SD and exceeded that of Nipponbare. Plants grown under LD showed induction of Hd3a and RFT1 transcription (Fig. 3C, D). The overall expression levels of RFT1 were higher under SD than under LD (Fig. 3B, D). In Italian varieties, de-repression of Hd3a and RFT1 transcription occurs under both long and short photoperiods in the morning, differently from the normal day length-induced peak in the evening in Nipponbare. Induction of RFT1 expression is not only a consequence of activation by the LD pathway but rather the result of its transcriptional de-repression in the background of varieties adapted to northern latitudes.


Loss of floral repressor function adapts rice to higher latitudes in Europe.

Gómez-Ariza J, Galbiati F, Goretti D, Brambilla V, Shrestha R, Pappolla A, Courtois B, Fornara F - J. Exp. Bot. (2015)

Diurnal patterns of Hd3a and RFT1 mRNA expression in Italian varieties under SD and LD. (A) Diurnal quantification of Hd3a mRNA expression under SD. (B) Diurnal quantification of RFT1 mRNA expression under SD. (C) Diurnal quantification of Hd3a mRNA expression under LD. (D) Diurnal quantification of RFT1 mRNA expression under LD. Quantification of expression levels was determined in Volano, Sant’Andrea and Augusto compared to Nipponbare. Bars on top indicate day (white) or night (black). ZT indicates hours from dawn (Zeitgeber). Ubiquitin (Ubq) was used to normalize gene expression levels.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
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getmorefigures.php?uid=PMC4378634&req=5

Figure 3: Diurnal patterns of Hd3a and RFT1 mRNA expression in Italian varieties under SD and LD. (A) Diurnal quantification of Hd3a mRNA expression under SD. (B) Diurnal quantification of RFT1 mRNA expression under SD. (C) Diurnal quantification of Hd3a mRNA expression under LD. (D) Diurnal quantification of RFT1 mRNA expression under LD. Quantification of expression levels was determined in Volano, Sant’Andrea and Augusto compared to Nipponbare. Bars on top indicate day (white) or night (black). ZT indicates hours from dawn (Zeitgeber). Ubiquitin (Ubq) was used to normalize gene expression levels.
Mentions: It has been previously demonstrated that under SD conditions RFT1 expression was lower compared to Hd3a in wild type plants. Further reduction of its expression by RNAi caused no delay of flowering, indicating that RFT1 is not contributing to flowering promotion under SD (Komiya et al., 2008). In Italian varieties, the correlation between heading dates and RFT1 expression was higher than with Hd3a expression at two time points under continuous SD (Table 2). Expression of upstream regulators of the florigens was poorly correlated to heading dates (Supplementary Table S4). Therefore, the diurnal mRNA expression profiles of Hd3a and RFT1 were determined under both LD and SD. In addition to Nipponbare, which shows a high PS index, three Italian varieties with a low PS index were selected for this experiment, regardless of genotype. Hd3a was induced in all varieties to levels similar to those observed in Nipponbare (Fig. 3A). Additionally, high levels of RFT1 expression in the three Italian varieties (Fig. 3B) were observed, indicating that RFT1 transcription was strongly de-repressed under SD and exceeded that of Nipponbare. Plants grown under LD showed induction of Hd3a and RFT1 transcription (Fig. 3C, D). The overall expression levels of RFT1 were higher under SD than under LD (Fig. 3B, D). In Italian varieties, de-repression of Hd3a and RFT1 transcription occurs under both long and short photoperiods in the morning, differently from the normal day length-induced peak in the evening in Nipponbare. Induction of RFT1 expression is not only a consequence of activation by the LD pathway but rather the result of its transcriptional de-repression in the background of varieties adapted to northern latitudes.

Bottom Line: Pyramiding of mutations is frequently observed in European germplasm, but single mutations are sufficient to adapt rice to flower at higher latitudes.Expression of Ehd1 is increased in varieties showing reduced or Hd1 expression under natural long days, as well as in single hd1 mutants in isogenic backgrounds.These data indicate that loss of repressor genes has been a key strategy to expand rice cultivation to Europe, and that Ehd1 is a central node integrating floral repressive signals.

View Article: PubMed Central - PubMed

Affiliation: University of Milan, Department of Biosciences, Via Celoria 26, 20133 Milan, Italy.

No MeSH data available.