Histochemistry of lignin and suberin deposition in boundary layers formed after wounding in various plant species and organs

Abstract

Wound responses in a variety of injured plant tissues were assessed using conventional lignin tests and fluorescence techniques for suberin detection in tissues present at the time of wounding. The tissue assessed included twigs of four conifer species, barley and cherry foliage, fern rachis, potato tuber, carrot root, musksmelon cotyledons, and cucumber hypocotyl. Apple leaves infected by a leaf spotting fungus (Botryosphaeria obtusa) were also examined. All tissues, except barley and apple foliage and fern rachis, formed a morphologically distinct lignosuberized boundary layer from cells present at the time of wounding. The boundary layer consisted initially of cells with lignified walls which with time developed suberin lamellae. In the fern rachis, the boundary layer was suberized in the absence of lignin. In the wounded barley and infected apple foliage, neither lignin nor suberin was detected histochemically.