Michaels Scott D, Bezerra Isabel C, Amasino Richard M
Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA.
Proc Natl Acad Sci U S A. 2004 Mar 2;101(9):3281-5. doi: 10.1073/pnas.0306778101. Epub 2004 Feb 18.
In temperate climates, the prolonged cold temperature of winter serves as a seasonal landmark for winter-annual and biennial plants. In these plants, flowering is blocked before winter. In Arabidopsis thaliana, natural variation in the FRIGIDA (FRI) gene is a major determinate of the rapid-cycling vs. winter-annual flowering habits. In winter-annual accessions of Arabidopsis, FRI activity blocks flowering through the up-regulation of the floral inhibitor FLOWERING LOCUS C (FLC). Most rapid-flowering accessions, in contrast, contain null alleles of FRI. By performing a mutant screen in a winter-annual strain, we have identified a locus, FRIGIDA LIKE 1 (FRL1), that is specifically required for the up-regulation of FLC by FRI. Cloning of FRL1 revealed a gene with a predicted protein sequence that is 23% identical to FRI. Despite sequence similarity, FRI and FRL1 do not have redundant functions. FRI and FRL1 belong to a seven-member gene family in Arabidopsis, and FRI, FRL1, and at least one additional family member, FRIGIDA LIKE 2 (FRL2), are in a clade of this family that is required for the winter-annual habit in Arabidopsis.
在温带气候中，冬季持续的低温是一年生和二年生植物的季节性标志。在这些植物中，冬季前开花受到抑制。在拟南芥中，FRIGIDA（FRI）基因的自然变异是决定快速循环与一年生开花习性的主要因素。在拟南芥的一年生类型中，FRI活性通过上调开花抑制因子FLOWERING LOCUS C（FLC）来阻止开花。相比之下，大多数快速开花类型含有FRI的无效等位基因。通过在一年生品系中进行突变体筛选，我们鉴定出一个位点，FRIGIDA LIKE 1（FRL1），它是FRI上调FLC所特需的。FRL1的克隆揭示了一个基因，其预测的蛋白质序列与FRI有23%的同一性。尽管序列相似，但FRI和FRL1没有冗余功能。FRI和FRL1属于拟南芥中的一个七成员基因家族，并且FRI、FRL1和至少一个其他家族成员FRIGIDA LIKE 2（FRL2）属于该家族中拟南芥一年生习性所需的一个进化枝。
