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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.


Heading dates and photoperiod sensitivity of 16 temperate japonica varieties cultivated in Italy and Nipponbare. (A) Days from germination to heading were scored under natural long days (NLD) in Milan, artificial long days (LD) and artificial short days (SD). (B) Photoperiod sensitivity index of the same varieties as in (A).
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Figure 1: Heading dates and photoperiod sensitivity of 16 temperate japonica varieties cultivated in Italy and Nipponbare. (A) Days from germination to heading were scored under natural long days (NLD) in Milan, artificial long days (LD) and artificial short days (SD). (B) Photoperiod sensitivity index of the same varieties as in (A).

Mentions: Artificial selection has expanded rice cultivation from tropical Asia to higher latitudes in Europe, partly by influencing the capacity of plants to flower under long days. To address the molecular mechanisms involved, a working panel composed of 16 temperate japonica varieties cultivated in Italy (mini-panel) was selected to be representative of the diversity of heading dates observed under natural field conditions (Fig. 1). The mini-panel and Nipponbare were grown under constant LD (16 hours light) and SD (10 hours light) in growth chambers, and under natural long day conditions (NLD) in Milan (~45°N). All varieties flowered earlier under SD conditions compared to LD conditions, and the response to distinct photoperiods showed large variation (Fig. 1A). Most varieties flowered at similar times under NLD and LD, indicating that photoperiodic flowering was similarly promoted both under constant and varying day lengths. Flowering of Thaibonnet, Balilla and Nipponbare was delayed under LD compared to NLD, indicating that these varieties could discriminate between different long photoperiods and that continuous LD of 16h caused stronger floral repression. Based on heading dates under LD and SD, we calculated a photoperiod sensitivity index (PS). All varieties tested showed reduced PS compared to Nipponbare (Fig. 1B), and some varieties, including Augusto and Sant’Andrea, were almost completely insensitive and flowered at the same time regardless of day length (Fig. 1A). These data indicate that flowering of mini-panel varieties can be promoted by SD but not repressed under LD and NLD compared to Nipponbare. Their capacity to discriminate between different day lengths is therefore impaired.


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)

Heading dates and photoperiod sensitivity of 16 temperate japonica varieties cultivated in Italy and Nipponbare. (A) Days from germination to heading were scored under natural long days (NLD) in Milan, artificial long days (LD) and artificial short days (SD). (B) Photoperiod sensitivity index of the same varieties as in (A).
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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

Figure 1: Heading dates and photoperiod sensitivity of 16 temperate japonica varieties cultivated in Italy and Nipponbare. (A) Days from germination to heading were scored under natural long days (NLD) in Milan, artificial long days (LD) and artificial short days (SD). (B) Photoperiod sensitivity index of the same varieties as in (A).
Mentions: Artificial selection has expanded rice cultivation from tropical Asia to higher latitudes in Europe, partly by influencing the capacity of plants to flower under long days. To address the molecular mechanisms involved, a working panel composed of 16 temperate japonica varieties cultivated in Italy (mini-panel) was selected to be representative of the diversity of heading dates observed under natural field conditions (Fig. 1). The mini-panel and Nipponbare were grown under constant LD (16 hours light) and SD (10 hours light) in growth chambers, and under natural long day conditions (NLD) in Milan (~45°N). All varieties flowered earlier under SD conditions compared to LD conditions, and the response to distinct photoperiods showed large variation (Fig. 1A). Most varieties flowered at similar times under NLD and LD, indicating that photoperiodic flowering was similarly promoted both under constant and varying day lengths. Flowering of Thaibonnet, Balilla and Nipponbare was delayed under LD compared to NLD, indicating that these varieties could discriminate between different long photoperiods and that continuous LD of 16h caused stronger floral repression. Based on heading dates under LD and SD, we calculated a photoperiod sensitivity index (PS). All varieties tested showed reduced PS compared to Nipponbare (Fig. 1B), and some varieties, including Augusto and Sant’Andrea, were almost completely insensitive and flowered at the same time regardless of day length (Fig. 1A). These data indicate that flowering of mini-panel varieties can be promoted by SD but not repressed under LD and NLD compared to Nipponbare. Their capacity to discriminate between different day lengths is therefore impaired.

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.