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Alfalfa Mosaic Virus Transmission to Seed Through Alfalfa Gametes and Longevity in Alfalfa Seed. F. I. Frosheiser, Research Plant Pathologist, North Central Region, ARS, USDA, Department of Plant Pathology, University of Minnesota, St. Paul 55101; Phytopathology 64:102-105. Accepted for publication 26 July 1973. DOI: 10.1094/Phyto-64-102.

Direct assay of alfalfa seed on Phaseolus vulgaris ‘Bountiful’ plants was as effective as seedling assay on bean to detect alfalfa mosaic virus (AMV) in alfalfa (Medicago sativa) seeds. AMV was transmitted to alfalfa seeds at a much higher frequency through male gametes (pollen) than through females gametes (ovules). The transmission frequency through pollen in all tests ranged from 0.5 to 26.5% and transmission through the ovules ranged from 0 to 9.5%. Transmission through both pollen and ovules was much less at a constant temp of 29 ± 1 C than at 18 ± 2 C or 24 ± 2 C. Transmission at alternating temp of 29 C and 22 C was greater than at 29 C but less than at 18 C and 24 C constant. AMV seed transmission differed considerably among AMV strains and in different tests, and somewhat among alfalfa clones. The percentage of virus-infected seeds was not reduced significantly in a seed lot containing about 20% infected seeds after storage for 5 yr at –18 C, 4 C, or 21-27 C. The percentage of infected seeds in two commercial seed lot samples, stored under refregeration for 4 yr, also was not reduced appreciably.