The rhythmic expression of genes controlling flowering time in southern and northern populations of invasive Ambrosia artemisiifolia.

Aims Flowering time has been suggested to be an important adaptive trait during the dispersal of invasive species, and identifying the molecular mechanisms underlying flowering time may provide insight into the local adaptation during the process of invasion. Here, we conducted a preliminary exploration on the genetic basis of the differentiation of flowering time in Ambrosia artemisiifolia. Methods Using relative real-time fluorescent quantitative polymerase chain reaction, we investigated the expression levels of eight floweringrelated genes, including AP1, FT, SOC1, CRY2, FKF1, GI, CO2 and SPY, in leaves and flowers at different time points in individuals from northern Beijing and southern Wuhan populations that exhibit significant differences in flowering times to identify any rhythmic changes in gene expression and their association with differential flowering times. Important Findings The differentiation of flowering time in the A. artemisiifolia populations was closely associated with five genes involved in flowering pathways. The floral pathway integrators FT and SOC1 and floral meristem identity gene AP1 exhibited increased expression during flowering. The photoreceptor CRY2 in the light-dependent pathway and the SPY gene in the gibberellin pathway displayed specific expression patterns over time. In earlier-flowering Beijing plants, CRY2 expression was lower and SPY expression was higher than in Wuhan plants. The expression patterns of these five genes suggest a molecular basis for the differentiation of flowering time in A. artemisiifolia. [ABSTRACT FROM AUTHOR]