White and UV light effects on cell nuclei in the aurea genotype of Lycopersicum esculentum L.
The effects of white light and UV light on chromosome endoreduplication, chromatin conformation and RNA synthesis were analysed in the hypocotyl cortical cylinder of the cv UC-105 of tomato and its isogenic mutant aurea, deficient in photoactive phytochrome A at the etiolated stage. Short white light or UV irradiations were administered to 4-day-old seedlings grown in the dark. White light had no effect on the mean ploidy level in the cv UC-105, but it increased the ploidy level in the aurea mutant. This is explained by hypothesizing that phytochrome inhibits endoreduplication, while cryptochrome stimulates it. UV light produced a higher ploidy in both genotypes, possibly because of residual action of cryptochrome at this wavelength or of specific UV-responsive photoreceptor. White light or UV light transiently increased heterochromatin amounts in the diploid nuclei of cv UC-105, and produced higher levels of RNA transcription than continuous dark. It is suggested that these responses were mediated by phytochrome, because they were lacking in the aurea mutant.
Dipartimento di Biologia delle Piante Agrarie dell'Università, Pisa, Italy.
A
A
Cavallini
L
L
Natali
R
R
Tonfoni
G
G
Cionini
B
B
Lercari
D002467:Cell Nucleus / Q000502:physiology / Q000528:radiation effects*; D002843:Chromatin / Q000502:physiology / Q000528:radiation effects; D002875:Chromosomes / Q000502:physiology / Q000528:radiation effects*; D004247:DNA / Q000096:biosynthesis / Q000528:radiation effects; D005838:Genotype; D008027:Light; D018551:Solanum lycopersicum / Q000502:physiology*; D009154:Mutation / Q000235:genetics; D010834:Phytochrome / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D011003:Ploidies; D012313:RNA / Q000096:biosynthesis / Q000528:radiation effects; D014466:Ultraviolet Rays
D002843:Chromatin; D010834:Phytochrome; D012313:RNA; D004247:DNA