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

Abstract

HighlightAllelic variants of floral repressor genes have been artificially selected to reduce sensitivity to photoperiod of rice varieties cultivated in Europe, allowing cultivation of a tropical species at higher latitudes.

Antagonistic Transcription Factor Complexes Modulate the Floral Transition in Rice

“…This observation suggests the existence of a mechanism that downregulates their expression upon commitment to flowering and that could possibly depend on Ehd1, encoding a common upstream promoter of Hd3a and RFT1 expression (Goretti et al, 2017;Ogiso-Tanaka et al, 2013;Gómez-Ariza et al, 2015). Under our growing conditions, expression of the florigens reached a peak ;12 to 15 d after shifting plants from LD to SD (Galbiati et al, 2016).…”

“…However, transcription of RFT1 can be induced also under long days (LDs), and its floral promotive activity under these conditions contributes to the facultative nature of the photoperiodic flowering response of rice (Gómez-Ariza et al, 2015;Komiya et al, 2009).…”

“…Since seasonal expression of the rice florigens is transient and is strongly reduced upon completion of the floral transition, a plausible biological role for this autoregulatory loop could be to switch off transcription of the florigens upon floral commitment. Alternatively (or in parallel), it could fine-tune the production of Hd3a and RFT1 during photoperiodic induction (Gómez-Ariza et al, 2015;Ogiso-Tanaka et al, 2013). More data will be required to distinguish between these possibilities and validate them, but it is clear that reproductive commitment requires a tight balance between flowering promoting and repressive complexes, whose equilibrium could be controlled by modulating the expression levels of distinct bZIPs by developmental or environmental factors (Tang et al, 2016;Wu et al, 2014;Zhang et al, 2016) or by controlling their activity through phosphorylation (Kagaya et al, 2002;Choi et al, 2005;Furihata et al, 2006).…”

“…All primers used in RT-qPCR experiments have an annealing temperature of 60°C. For quantification of transcripts of Hd3a and RFT1 endogenous mRNAs, Ehd1, OsMADS14, OsMADS15, and UBQ, we used primers described by Galbiati et al (2016) and Gómez-Ariza et al (2015). All other primers used in this study are listed in Supplemental Table 1.…”

Effects ofHd2in the presence of the photoperiod-insensitive functional allele ofHd1in rice

“…Loss-of-function variants for genes controlling PS has been known to be the most important resource for japonica rice in northern cultivation regions to successfully reproduce under NLD conditions in a short summer period (Takahashi and Shimamoto, 2011; Wei et al, 2012; Fujino et al, 2013; Kim et al, 2013; Koo et al, 2013; Gómez-Ariza et al, 2015). At the same time, little knowledge has been accumulated for the genetic basis underlying the photoperiod-insensitive character of early-season indica rice cultivars in Southern China which also require successful reproduction under NLD conditions in summer thus sufficient time could be provided for late-season cropping.…”