TY - JOUR T1 - Soil salinity inhibits plant shade avoidance JF - bioRxiv DO - 10.1101/289124 SP - 289124 AU - Scott Hayes AU - Adrian Louis Tween AU - Kasper van Gelderen AU - Michel de Vries AU - Salomé Prat AU - Robert. C. Schuurink AU - Christa Testerink AU - Ronald Pierik Y1 - 2018/01/01 UR - http://biorxiv.org/content/early/2018/03/27/289124.abstract N2 - Global food production is set to keep increasing despite a predicted decrease in total arable land [1]. To achieve higher production, denser planting will be required on increasingly degraded soils. When grown in dense stands, crops elongate and raise their leaves in an effort to reach sunlight, a process termed shade-avoidance [2]. Shade is perceived by a reduction in the ratio of red (R) to (FR) light and results in the stabilisation of a class of transcription factors known as PHYTOCHROME INTERACTING FACTORs (PIFs) [3,4]. PIFs activate the expression of auxin biosynthesis genes [4,5] and enhance auxin sensitivity [6], which promotes cell wall loosening and drives elongation growth. Despite our molecular understanding of shade-induced growth, little is known about how this developmental programme is integrated with other environmental factors.Here we demonstrate that low levels of NaCl in soil strongly impair the ability of plants to respond to shade. This block is dependent upon abscisic acid (ABA) signalling and the canonical ABA signalling pathway. Low R:FR light enhances the expression of a positive regulator of the brassinosteroid (BR) signalling pathway, BRASSINOSTEROID SIGNALLING KINASE 5 (BSK5). We found that ABA inhibits BSK5 up-regulation and interferes with GSK3-like kinase inactivation by the BR pathway, thus leading to a suppression of PIF function. By demonstrating a link between the ABA and BR-signalling pathways this study provides an important step forward in our understanding of how environmental cues are integrated into plant development. ER -