Systemic infection with potato virus Y-NTN alters the structure and activity of the shoot apical meristem in a susceptible potato cultivar

Stem nodes of the potato virus Y-NTN (PVYNTN) susceptible potato cultivar ( Solanum tuberosum cv. "Igor") were studied to investigate whether alteratio ns in shoot morphology caused by infection with PVYNTN are related to chang es in structure and activity of the shoot apical meristem. The PVYNTN cause s severe disease symptoms known as the potato tuber necrotic ringspot disea se (PTNRD) in susceptible potato plants grown in the field. Although in ste m node culture the symptoms are mildly expressed, in systemically PVYNTN-in fected plants the shoot height stem diameter, number of leaves and the tota l 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 d ue 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 s howing that the infection of potato plants with PVYNTN leads to alterations in the shoot apical meristem structure and mitotic activity. These changes are, in turn, reflected in altered overall morphology of the infected plan t. (C) 2000 Academic Press.