Establishment of the nuclear stock (pre-base) of the V. vinifera genus through phytosanitary selection in the Republic of Moldova

Abstract

Diseases caused by phytopathogenic viruses, phytoplasmas, and bacterial cancer significantly reduce both the quantity and quality of the production, as well as influence the plants' longevity since they affect grapevines systemically, meaning that the infected tissues remain diseased throughout their lives. Adequate strategies to restrict the production and distribution of infected stocks focus on improving the cultural health (phytosanitary selection and sanitation) and certifying planting material, as combating chronic diseases through agrotechnical or chemical measures is not efficient. Phytosanitary selection is a crucial element in enhancing productivity and structural quality by eliminating diseased individuals and selecting plants that are less susceptible to diseases. This study aims to establish a nuclear stock (pre-base) of the V. vinifera genus through phytosanitary selection. The research involved visual observation, biotype testing, sanitation, and in vitro culture to obtain grapevine clones free from viruses, phytoplasmas, and crown gall disease from 14 table grape varieties and 19 wine grape varieties. The test results revealed a widespread distribution of diseases of virotic etiology and bacterial cancer in asymptomatic form, including grapevine fleck (15-65%), A. vitis (26-44%), GLRaV-1 (8-26%), GLRaV-3 (7-39%). To sanitize the selected material after testing, thermotherapy was applied at t0 510C for 45 minutes. Thanks to the in vitro method, 7300 phytosanitary grapevine clones from local, European, and new selection varieties were multiplied, leading to the establishment of the nuclear stock. This marks the first step in the process of transferring viticulture in the Republic of Moldova based on certified planting material.