Proceedings of the XLV Italian Society of Agricultural Genetics - SIGA Annual Congress

Salsomaggiore Terme, Italy - 26/29 September, 2001

ISBN 88-900622-1-5

Poster Abstract

VARIATION OF ALFALFA MOSAIC VIRUS (AMV) SYMPTOMS IN LUCERNE GERMPLASM

PECETTI L., ROMANI M., PIANO E.

Istituto Sperimentale per le Colture Foraggere, Viale Piacenza 29, 26900 Lodi

aphid, Alfalfa Mosaic Virus (AMV), germplasm, lucerne, Medicago sativa L. complex

The Alfalfa Mosaic Virus (AMV) is a widespread pathogen on lucerne. In the third year of growth, the percentage of plants with symptoms caused by AMV under natural conditions was recorded on 14 genotypes belonging to different taxonomic groups within the Medicago sativa complex (subspp. sativa, falcata, ´ varia, and hybrids among different taxa), as also indicated by their different flower colour. The genotypes, all characterised by deep-set crown, were also morphologically diversified and categorised into four models, varying in growth habit and vigour. Significant differences were found among models and genotypes; the two most erect and vigorous models had, on average, higher percentage of plants with symptoms (> 80%) than the very prostrate and rhizomatous model (< 15%). Genotypes ranged between 1.4% and 97.6% of plants with symptoms. Such a variation appeared to be related with differences in flower colour and, hence, taxonomic origin of the germplasm: the mean frequency of plants with symptoms in purple-flowered genotypes (typically of subsp. sativa) was 70.7% versus 24.6% in genotypes with other flower colours. The two genotypes with the highest percentage (> 95%) and the two with the lowest (< 10%) were again evaluated in the next year and confirmed the sharp differences in symptoms already observed. In addition, a strong relationship was evidenced between the presence of plants with symptoms in a plot and aphid infestation in the same plot.