0000000000240037
AUTHOR
Nathalie Charpentier
Grapevine fruit set: Physiology of the abscission zone
Effects of ethylene and of 'anti-ethylene' compounds on the floral pedicel abscission zone in grapevines were analysed via a laboratory model consisting of isolated flowers held in Petri dishes. Our model permitted precise determination of abscission and enabled us to test a range of physiologically-active compounds including ethylene precursors, and antagonists of ethylene action. For example, a precursor of ethylene, 1-aminocyclopropane-l-carboxylic acid, had the same effect as ethylene in promoting abscission. Conversely, an inhibition of ethylene action by silver thiosulfate or an inhibition of ethylene synthesis by amino-oxyacetic acid both strongly inhibited abscission zone function. …
Genetic lesions associated with Muller's ratchet in an RNA virus
The molecular basis of Muller's ratchet has been investigated using the important animal pathogen foot-and-mouth disease virus (FMDV). Clones from two FMDV populations were subjected to serial plaque transfers (repeated bottleneck events) on host BHK-21 cells. Relative fitness losses were documented in 11 out of 19 clones tested. Small fitness gains were observed in three clones. One viral clone attained an extremely low plating efficiency, suggesting that accumulation of deleterious mutations had driven the virus near extinction. Nucleotide sequence analysis revealed unique genetic lesions in multiply transferred clones that had never been seen in FMDVs isolated in nature or subjected to m…