DISPLAYING SINK-SOURCE FLUX IN PHYLLOXERATED GRAPEVINES BY MICROSCOPIC TECHNIQUES
Grape phylloxera (Daktulosphaira vitifoliae Fitch, Homoptera: Phylloxeridae) is a serious global pest that feeds on roots and leaves of susceptible grapevine varieties of Vitis ssp. These insects induce feeding sites in both, roots and leaves of grapevine. So-called nodosities are induced within the meristematic zone of the grape root tips, whereas leaf-galls are formed on leaves. Both feeding sites change dramatically the uptake and transportation of water, minerals and assimilates within these tissues. The aim of this work was to provide evidence that nodosities and/or leaf-galls induced in grapevine (Vitis berlandieri × Vitis riparia) activate sink tissue to increase phloem flow and symplastically transfer sucrose towards the feeding insects. To do that we used fluorescent dye carboxyfluorescein diacetate (CFDA) as a marker of sucrose phloem transport as well as symplastic phloem unloading. We hypothesize that the CFDA applied on cut leaf petiole will be either (1) transported into root towards nodosities, (2) remain in the shoot and accumulate in leaf-galls or (3) spread in the plant towards nodosities and leaf-galls if both induced. Our results show a strong and specific symplastic flux from the phloem to phylloxera-induced feeding sites in grapevine (nodosities and/or leaf-galls).
Wieczorek , K., Hensler , S. and Forneck, A. 2014. DISPLAYING SINK-SOURCE FLUX IN PHYLLOXERATED GRAPEVINES BY MICROSCOPIC TECHNIQUES. Acta Hort. (ISHS) 1045:29-32
Daktulosphaira vitifoliae, symplastic sucrose transport, CFDA, carboxyfluorescein diacetate