Defense Responses in Aspen with Altered Pectin Methylesterase Activity Reveal the Hormonal Inducers of Tyloses

TY - JOUR

T1 - Defense Responses in Aspen with Altered Pectin Methylesterase Activity Reveal the Hormonal Inducers of Tyloses

AU - Lesniewska, Joanna

AU - Ohman, David

AU - Krzeslowska, Magdalena

AU - Kushwah, Sunita

AU - Barciszewska-Pacak, Maria

AU - Kleczkowski, Leszek A.

AU - Sundberg, Bjorn

AU - Moritz, Thomas

AU - Mellerowicz, Ewa J.

PY - 2017/2

Y1 - 2017/2

N2 - Tyloses are ingrowths of parenchyma cells into the lumen of embolized xylem vessels, thereby protecting the remaining xylem from pathogens. They are found in heartwood, sapwood, and in abscission zones and can be induced by various stresses, but their molecular triggers are unknown. Here, we report that down-regulation of PECTIN METHYLESTERASE1 (PtxtPME1) in aspen (Populus tremula × tremuloides) triggers the formation of tyloses and activation of oxidative stress. We tested whether any of the oxidative stress-related hormones could induce tyloses in intact plantlets grown in sterile culture. Jasmonates, including jasmonic acid (JA) and methyl jasmonate, induced the formation of tyloses, whereas treatments with salicylic acid (SA) and 1-aminocyclopropane-1- carboxylic acid (ACC) were ineffective. SA abolished the induction of tyloses by JA, whereas ACC was synergistic with JA. The ability of ACC to stimulate tyloses formation when combined with JA depended on ethylene (ET) signaling, as shown by a decrease in the response in ET-insensitive plants.Measurements of internal ACC and JA concentrations in wild-type and ET-insensitive plants treated simultaneously with these two compounds indicated that ACC and JA regulate each other’s concentration in an ET-dependent manner. The findings indicate that jasmonates acting synergistically with ethylene are the key molecular triggers of tyloses.

AB - Tyloses are ingrowths of parenchyma cells into the lumen of embolized xylem vessels, thereby protecting the remaining xylem from pathogens. They are found in heartwood, sapwood, and in abscission zones and can be induced by various stresses, but their molecular triggers are unknown. Here, we report that down-regulation of PECTIN METHYLESTERASE1 (PtxtPME1) in aspen (Populus tremula × tremuloides) triggers the formation of tyloses and activation of oxidative stress. We tested whether any of the oxidative stress-related hormones could induce tyloses in intact plantlets grown in sterile culture. Jasmonates, including jasmonic acid (JA) and methyl jasmonate, induced the formation of tyloses, whereas treatments with salicylic acid (SA) and 1-aminocyclopropane-1- carboxylic acid (ACC) were ineffective. SA abolished the induction of tyloses by JA, whereas ACC was synergistic with JA. The ability of ACC to stimulate tyloses formation when combined with JA depended on ethylene (ET) signaling, as shown by a decrease in the response in ET-insensitive plants.Measurements of internal ACC and JA concentrations in wild-type and ET-insensitive plants treated simultaneously with these two compounds indicated that ACC and JA regulate each other’s concentration in an ET-dependent manner. The findings indicate that jasmonates acting synergistically with ethylene are the key molecular triggers of tyloses.

U2 - 10.1104/pp.16.01443

DO - 10.1104/pp.16.01443

M3 - Journal article

SN - 0032-0889

VL - 173

SP - 1409

EP - 1419

JO - Plant Physiology

JF - Plant Physiology

IS - 2

ER -