Abstract
Tomato hypocotyl elongation is a consequence of active cell division and
expansion, both of which require precisely regulated cell cycle
progression. Little is known about the function of APC/C regulators in
cell cycle progression during hypocotyl growth. Here, we isolated and
characterized the positive and negative APC/C regulators, SlCCS52and SlUVI4 genes in tomato. We probed SlUVI4 andSlCCS52B roles in tomato hypocotyl elongation via modulating cell
cycle progression. Light especially blue light represses the
transcription of SlUVI4 and SlCCS52B to inhibit the
hypocotyl elongation through the suppression of endoreduplication. MS
basal salts and sugar both improve SlUVI4 and SlCCS52Btranscription to enhance hypocotyl length via the promotion of
endoreduplication. Hypocotyl elongation enhanced by heat might require
auxin-induced repression of SlUVI4 transcription. Salt
inhibits hypocotyl elongation possibly through ethylene-mediated
modulation of SlUVI4 and SlCCS52B transcription. Genetic
studies reveal that tomato deletion mutant of SlUVI4 and
overexpression plants of SlCCS52B in Arabidopsis both exhibit
shorter hypocotyl with enhanced endoreduplication. Thus, our results
suggest that APC/C activities stimulated by SlCCS52 genes
requires SlUVI4 -meidated inhibitory machinery to reorchestrate
cell cycle progression and facilitate hypocotyl elongation.
Keywords: Tomato, hypocotyl elongation, UVI4, CCS52, APC/C,
cell cycle, light quality, heat, salt, plant hormones.