Journal Article

Role of light and jasmonic acid signaling in regulating foliar phloem cell wall ingrowth development

Combs, Andrew F, Adams, William W, Amiard, Véronique, Demmig-Adams, Barbara, Mueh, Kristine E, Turgeon, Robert

2007

Overview

Phloem cells adjacent to sieve elements can possess wall invaginations. The role of light and jasmonic acid signaling in wall ingrowth development was examined in pea companion cells (CCs), Arabidopsis thaliana phloem parenchyma cells (PCs), and in Senecio vulgaris (with ingrowths in both cell types). Features characterized included wall ingrowths (from electron microscopic images), foliar vein density and photosynthetic capacity. In Arabidopsis, wall ingrowths were bulky compared with finger-like invaginations in pea and S. vulgaris. Relative to low light (LL), wall invagination in both CCs and PCs was greater in high light (HL). Treatment with methyl jasmonate in LL had no effect on CCs, but increased PC wall ingrowths. LL-to-HL transfer resulted in significantly less wall ingrowth in the fad7-1 fad8-1 (jasmonate-deficient) Arabidopsis mutant relative to the wild type. These results suggest that chloroplast oxidative status, via chloroplast-derived jasmonates, may modulate phloem structure and function. While CC wall ingrowths facilitate phloem loading by expanding the membrane area available for active uptake, one can speculate that phloem PC ingrowths may have two potential roles: to increase the efflux of sugars and/or protons into the apoplast to augment phloem loading; and/or to protect the phloem against pathogens and/or insects.

• Publisher: Oxford, UK : Blackwell Publishing Ltd,Blackwell Science,Blackwell Publishing Ltd
• Subject: Acetates / Acetates - metabolism / apoplast / Arabidopsis / Arabidopsis - cytology / Arabidopsis - growth & development / Arabidopsis - metabolism / Arabidopsis thaliana / Cell Wall / Cell Wall - metabolism / Cell Wall - ultrastructure / Cell walls / chloroplasts / companion cells / Cyclopentanes / Cyclopentanes - metabolism / cytology / electron microscopy / growth & development / insects / jasmonic acid / jasmonic acid (JA) / Light / metabolism / methyl jasmonate / mutants / Mutation / oxylipin / Oxylipins / Parenchyma / parenchyma (plant tissue) / Pathogens / Peas / Phloem / Phloem - cytology / Phloem - ultrastructure / Phloem companion cells / phloem loading / phloem parenchyma cells / Photosynthesis / Pisum sativum - cytology / Pisum sativum - growth & development / Pisum sativum - metabolism / Plant cells / plant defense / Plant Leaves / Plant Leaves - cytology / Plant Leaves - metabolism / Plant veins / Plants / protons / Senecio / Senecio - cytology / Senecio - growth & development / Senecio - metabolism / Senecio vulgaris / Sieve elements / Signal Transduction / sugars / transfer cells / ultrastructure / wall ingrowths