Phytochromes mainly function in photoau- totrophic organisms to adjust growth in response to fluctuating light signals. The different isoforms of plant phytochromes often display both conserved and divergent roles, pr...Phytochromes mainly function in photoau- totrophic 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 fine-tune 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 develop- ment as long as NaPHYBI was functional; whereas silencing the expression of NaPHYB1 alone strongly altered flowering time and leaf morphology. Thecontribution 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 phyto- chrome-silenced lines, combined with sequence and transcript accumulation independent functional analysis, suggest the diversification of the phytochromes, and a dominant role of NaPHYB1 and NaPHYB2 in N. attenuata＇s vegetative and reproductive development.展开更多
基金supported by European Research Council advanced grant Clockwork Green (293926) to ITBthe Global Research Lab program (2012055546) from the National Research Foundation of Korea+2 种基金Institute for Basic Science (IBS-R021-D1)Human Frontier Science Program (RGP0002/2012)the Max Planck Society
文摘Phytochromes mainly function in photoau- totrophic 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 fine-tune 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 develop- ment as long as NaPHYBI was functional; whereas silencing the expression of NaPHYB1 alone strongly altered flowering time and leaf morphology. Thecontribution 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 phyto- chrome-silenced lines, combined with sequence and transcript accumulation independent functional analysis, suggest the diversification of the phytochromes, and a dominant role of NaPHYB1 and NaPHYB2 in N. attenuata＇s vegetative and reproductive development.
