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In situ localisation of maize streak virus in susceptible cultivar and a resistant line

Bigarré L., Granier M., Reynaud B., Nicole M., Peterschmitt M.. 1997. In : 1st International Maize Streak Disease Symposium, Hazyview, South Africa, September 9th - 11th 1997. s.l. : s.n., 1 p.. Maize Streak Disease Symposium. 1, 1997-09-09/1997-09-11, Hazyview (Afrique du Sud).

Distribution of maize streak virus (La Reunion strain) was studied in leaf tissues of a susceptible cultivar and a partially resistant line of maize, using immunocytochemistry. The phenotype ofresistance is expressed as a decrease in the streak density and width on the leaves; the infected plants show an aImost normal yield compared to healthy ones. In susceptible plants, large arrays (inclusions) of virions were detected inmost of the cellular types including bundle sheath, mesophyll, phloemand epiderm, and only in the chlorotic areas. Large amounts ofvirus could aIso be observed in sorne nucleuses of the resistant plant, but the density of the viral inclusions in the tissues was fur lower than for the susceptible plant. Moreover, the viral inclusions could be found inthe mesophyll indicating that the virus can move fromthe phloemto the surrounding tissues and that the virus can accomplish a complete cycle once ina cell. The difference between both types ofplants seems to be the number of cells able to replicate the virus inlarge amounts. This could result from a delay inthe first steps ofthe replication and propagation ofthe virus inthe tissues as it is established that the older the tissues are, the less permissive they are for the viral replication process. It is proposed that the resistance affects the replication ofthe virus in the early steps ofviral multiplication inthe stem apex, a crucial regionfor this process. This hypothesis is presently tested by detection of the replicative furms by in situ hybridization in this region in the two types of plants. (Texte intégral)
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