EVALUATION OF TUBER-BEARING SOLANUM SPECIES FOR SYMPTOMOLOGY, AS DIAGNOSTIC HOSTS, AND SOURCES OF IMMUNITY TO POTATO-VIRUS-Y NECROTIC STRAIN (PVYN)

A total of 258 Plant Introductions (PI) belonging to 69 Solanum specie s were evaluated in the greenhouse for their reaction to the tobacco v einal necrosis strain of potato virus Y (PVYN). One hundred and thirty -one (50.7%) of the PI accessions produced mosaic symptoms ranging fro m mild to severe. Local lesion and veinal necrosis symptoms were obser ved in 19 PI accessions (7.3%) and a variety of other symptoms were ob served in another 11 PI accessions (4.2%). Only 97 PI accessions (37.5 %) were symptomless carriers of PVYN. PI accession 473505 of S. sparsi pilum and PI accession 498021 of S. brachycarpum developed local lesio ns and veinal necrosis with PVYN, but necrotic spots and mosaic with P VYO. Common mechanically-transmitted potato viruses A, S, M, and X did not interfere with PVY symptom development in S. sparsipilum and S. b rachycarpum. Thus, PI 473505 and PI 498021 can be used as indicator pl ants for specific identification of PVYN. PI accession 472819 of S. ch acoense developed local lesions with systemic spread in PVYO, but with out systemic spread in PVYN. Thus, this can be used as a differential host plant for PVY strains. Two PI accessions of S. stolonferum, PI 16 0372 and 161171 were immune to PVYN.