How cells and tissues of Daphnopsis fasciculata (Thymelaeaceae) react to the leaf-mining habit of Phyllocnistis hemera (Lepidoptera: Gracillariidae).

Abstract

Plant cell and tissue responses to the attack of mining herbivores may be diagnosed by anatomical and histochemical analyses, herein investigated regarding the mining activity of Phyllocnistis hemera larvae in the leaf lamina of Daphnopsis fasciculata. The larva enters the leaf lamina through the adaxial epidermis, and feeds on palisade parenchyma cells. A healing tissue is produced after the larva passes, and its cells are reactive to histochemical tests for lignins and pectins. At first, the leaf mine is composed of a channel that is limited by palisade parenchyma cell wall fragments. Later, it is filled with a regenerative tissue constituted by isodiametric cells recruited from the spongy parenchyma, which fills up the mine channel. The cells differentiated inside the mine, regenerated the damage caused to leaf tissues, and may isolate the mine from the entrance of pathogens. Daphnopsis fasciculata is capable of reconstructing mesophyll tissues, which involves the totipotency of parenchyma cells and enables an important strategy for plant recovering after the attack of mining parasites.