Photoperiodic control of seasonal growth is mediated by ABA acting on cell-cell communication

TLDR

Seasonal cycles of growth and dormancy enable perennial plants to survive winter, with the dormant period in aspen trees resulting from loss of access to growth‑promoting signals. Dormancy is triggered when abscisic acid blocks symplastic intercellular communication through plasmodesmata, preventing growth‑promoting signals from reaching the meristem. The study shows that photoperiodic control of dormancy in hybrid aspen is mechanistically distinct from autumnal growth cessation, as ABA‑mediated blockage of plasmodesmata communication prevents growth‑promoting signals from accessing the meristem and thereby disallows precocious growth.

Abstract

In temperate and boreal ecosystems, seasonal cycles of growth and dormancy allow perennial plants to adapt to winter conditions. We show, in hybrid aspen trees, that photoperiodic regulation of dormancy is mechanistically distinct from autumnal growth cessation. Dormancy sets in when symplastic intercellular communication through plasmodesmata is blocked by a process dependent on the phytohormone abscisic acid. The communication blockage prevents growth-promoting signals from accessing the meristem. Thus, precocious growth is disallowed during dormancy. The dormant period, which supports robust survival of the aspen tree in winter, is due to loss of access to growth-promoting signals.