Potato CONSTANS is involved in photoperiodic tuberization in a graft‐transmissible manner

Abstract

CONSTANS (CO) is involved in the photoperiodic control of plant developmental processes, including flowering in several species and seasonal growth cessation and bud set in trees. It has been proposed that CO could also affect the day-length regulation of tuber induction in Solanum tuberosum (potato), a plant of great agricultural relevance. To address this question, we examined the role of CO in potato. A potato CO-like gene, StCO, was identified and found to be highly similar to a previously reported potato gene of unknown function. Potato plants overexpressing StCO tuberized later than wild-type plants under a weakly inductive photoperiod. StCO silencing promoted tuberization under both repressive and weakly inductive photoperiods, but did not have any effect under strongly inductive short days, demonstrating that StCO represses tuberization in a photoperiod-dependent manner. The effect of StCO on tuber induction was transmitted through grafts. In addition, StCO affected the mRNA levels of StBEL5 - a tuberization promoter, the mRNA of which moves long distances in potato plants - and StFT/StSP6A, a protein highly similar to FLOWERING LOCUS T (FT), which is a key component of systemic flowering signals in other species. We also found that StFT/StSP6A transcript levels correlate with the induction of tuber formation in wild-type plants. These results show that StCO plays an important role in photoperiodic tuberization and, together with the recent demonstration that StFT/StSP6A promotes tuberization, indicate that the CO/FT module participates in controlling this process. Moreover, they support the notion that StCO is involved in the expression of long-distance regulatory signals in potato, as CO does in other species.

CIRCADIAN CLOCK ASSOCIATED1 (CCA1) and the Circadian Control of Stomatal Aperture

“…Together, our results show that the external coincidence photoperiod pathway that is known to control plant development, such as reproductive development, bud dormancy, and tuberization on a seasonal level (Böhlenius et al, 2006;González-Schain et al, 2012;Suárez-López et al, 2001) also regulates daily responses in Arabidopsis. It has been suggested that promoting stomatal opening and increasing photosynthesis (Ando et al, 2013) prior to flowering can be beneficial to plants; Figure 7.…”

Genome-wide analysis reveals phytohormone action during cassava storage root initiation

“…The diminishing of AGL20 might lead to inhibition of root elongation and induction of phase transition into storage stage (Achard et al 2007;Fleet and Sun 2005). In potato, common regulatory pathways and homologous genes (CO, SOC1 and FT) were conserved between the flowering and tuberization processes (González-Schain et al 2012;Rodriguez-Falcon et al 2006). IbMADS and AGL20-like (DV037991) were SR initiation factors that responded to CK, were involved in auxin-mediated initial thickening of the SR and were downregulated in SR (Ku et al 2008;McGregor 2006;Noh et al 2010;You et al 2003).…”

The Multiple Signals That Control Tuber Formation

“…In a study on native CO genes of potato, StCO also functioned in a repressive manner in tuberization in potato (González-Schain et al, 2012). Overexpression lines of StCO tuberized later than wild-type plants, whereas silencing StCO expression promoted tuberization under both repressive and weakly inductive photoperiod conditions.…”