Phi thickenings in Brassica oleracea roots are induced by osmotic stress and mechanical effects, both involving jasmonic acid. (22nd October 2021)

• Record Type: Journal Article
• Authors: Aleamotuʻa, Maketalena; Baker, Jaime K; McCurdy, David W; Collings, David A
• Editors: Vissenberg, Kris
• Is Part Of: Journal of experimental botany. Volume 73:Number 3(2022)
• Page Start: 756
• Page End: 769
• Publication Date: 2021-10-22
• Subjects: Brassica oleracea -- jasmonic acid -- mechanical stress -- osmoprotectants -- osmotic stress -- phi thickenings -- plant hormones -- salt stress -- secondary cell wall -- signalling pathways; Botany -- Periodicals; Botany, Experimental -- Periodicals; Plant physiology -- Periodicals; 580
• DOI: 10.1093/jxb/erab468
• Languages: English
• ISSNs: 0022-0957

Abstract

Abstract: Phi thickenings are peculiar secondary cell wall thickenings found in radial walls of cortical cells in plant roots. However, while thickenings are widespread in the plant kingdom, research into their development has been lacking. Here, we describe a simple system for rapid induction of phi thickenings in primary roots of Brassica. Four-day-old seedlings were transferred from control agar plates to new plates containing increased levels of osmotica. Phi thickening development occurred within a narrow region of the differentiation zone proportional to osmolarity, with cellulose deposition and lignification starting after 12h and 15h, respectively. However, osmoprotectants not only failed to induce phi thickenings, but inhibited induction when tested in combination with thickening-inducing osmotica. An independent, biomechanical pathway exists regulating phi thickening induction, with root growth rates and substrate texture being important factors in determining thickening induction. Phi thickening development is also controlled by stress-related plant hormones, most notably jasmonic acid, but also abscisic acid. Our research not only provides the first understanding of the developmental pathways controlling phi thickening induction, but also provides tools with which the functions of these enigmatic structures might be clarified. Abstract : Phi thickenings, single bands of secondary cell wall deposited in root cortical cells, are induced by both osmotic stress and biomechanical effects in Brassica roots through pathways involving jasmonic acid.