Systemic infection with potato virus YNTNalters the structure and activity of the shoot apical meristem in a susceptible potato cultivar

Stem nodes of the potato virus Y^NTN(PVY^NTN) susceptible potato cultivar (Solanum tuberosum cv. “Igor”) were studied to investigate whether alterations in shoot morphology caused by infection with PVY^NTNare related to changes in structure and activity of the shoot apical meristem. The PVY^NTNcauses severe disease symptoms known as the potato tuber necrotic ringspot disease (PTNRD) in susceptible potato plants grown in the field. Although in stem node culture the symptoms are mildly expressed, in systemically PVY^NTN-infected plants the shoot height stem diameter, number of leaves and the total leaf area were lower than in the healthy control plants at day 18 and 35 of culture. Histological analysis of the longitudinal sections of the shoot tip revealed that the infected plants had smaller shoot apical meristems due primarily to a lower cell number in different meristem zones. One of the most affected zones of the apical shoot meristem was the peripheral zone, the region in which leaf primordia are induced. The data is consistent in showing that the infection of potato plants with PVY^NTNleads to alterations in the shoot apical meristem structure and mitotic activity. These changes are, in turn, reflected in altered overall morphology of the infected plant.