Project start: 10.07.2017
Project end: 31.03.2019
Sponsor: Development agency for agribusiness

Phytoplasmas (Candidatus Phytoplasma) are cell wall-less plant-pathogenic bacteria which can colonize the phloem of more than 700 plant species including many economically important crops. They cause a wide range of symptoms that vary depending on the phytoplasma strain, their host plant, and environmental factors, and usually include yellowing of leaves, proliferation of shoots and stunting. In grapevine (Vitis vinifera) phytoplasmas cause diseases referred to as grapevine yellows. In other fruit trees like apple (Malus domestica) they cause apple proliferation and in pear (Pyrus) they lead to pear decline. Phytoplasmas are spread by phloem-feeding insect vectors, grafting, or vegetative propagation of infected plants. Control strategies for phytoplasmas currently rely only on preventing their spread, as there are no effective chemical plant protection products against phytoplasmas. In addition, phytoplasma diseases have long incubation periods of up to several months before symptoms can be observed. Therefore, this project aims to develop a fast and reliable molecular detection method for phytoplasmas based on LAMP and TaqMan assays, respectively, to be used in the production of vegetatively propagated crops like grapevine, apple, or pear.

Project start: 01.03.2013
Project end: 31.12.2016
Sponsor: Federal Ministry of Food and Agriculture

Rubus stunt is considered the most important phytoplasmosis on raspberries and can cause yield losses of up to 100%. With the diagnostic methods available so far, latently infected but also symptomatic plants are not detected properly. In addition, potential vectors and possible transmission routes are unknown. The aim of the project is to develop a highly sensitive and rapid molecular on-site test system for the early diagnosis of this phytoplasmosis. In addition, findings on the species spectrum of potential vectors and further transmission routes are to be obtained, which will serve as a basis for the development of targeted and timely control measures. The development of a molecular method for the diagnosis of Rubus stunt will follow the establishment of an on-site sampling protocol based on TaqMan probes, LAMP assays and label-free detection. Investigations on the species spectrum and phenology of potential vectors, further transmission routes, the susceptibility of raspberry cultivars as well as on targeted control measures are to be carried out in a raspberry propagation farm or in yielding plants. Based on this, management strategies for the propagation and cultivation of raspberries will be developed. Finally, the methods developed for molecular phytoplasma diagnostics are to be validated under field conditions and transferred to other crops for the detection of phytoplasmas.