Salicylic acid regulates flowering time and links defence responses and reproductive development.

Flowering relies on signaling networks that integrate endogenous and external cues. Normally, plants flower at a particular season, reflecting day length and/or temperature cues. However, plants can surpass this seasonal regulation and show precocious flowering under stress environmental conditions. Here, we show that UV-C light stress activates the transition to flowering in Arabidopsis thaliana through salicylic acid (SA). Moreover, SA also regulates flowering time in non-stressed plants, as SA-deficient plants are late flowering. The regulation of flowering time by SA seems to involve the photoperiod and autonomous pathways, but it does not require the function of the flowering time genes CONSTANS (CO), FCA, or FLOWERING LOCUS C (FLC).