ausblenden:
Schlagwörter:
-
Zusammenfassung:
Phytochromes mainly function in photoautotrophic organisms to adjust
growth in response to fluctuating light signals. The different isoforms of plant
phytochromes often display both conserved and divergent roles, presumably to finetune
plant responses to environmental signals and optimize fitness. Here we describe
the distinct, yet partially redundant, roles of phytochromes NaPHYA, NaPHYB1 and
NaPHYB2 in a wild tobacco species, Nicotiana attenuata using RNAi-silenced
phytochrome lines. Consistent with results reported from other species, silencing the
expression of NaPHYA or NaPHYB2 in N. attenuata had mild or no influence on plant
development as long as NaPHYB1 was functional; whereas silencing the expression of
NaPHYB1 alone strongly altered flowering time and leaf morphology. The contribution
of NaPHYB2 became significant only in the absence of NaPHYB1; plants silenced for
both NaPHYB1 and NaPHYB2 largely skipped the rosette-stage of growth to rapidly
produce long, slender stalks that bore flowers early: hallmarks of the shade-avoidance
responses. The phenotyping of phytochrome-silenced lines, combined with sequence
and transcript accumulation analysis, suggest the independent functional diversification
of the phytochromes, and a dominant role of NaPHYB1 and NaPHYB2 in N. attenuata’s
vegetative and reproductive development.
