Environmental control of branching in petunia.
Plants alter their development in response to changes in their environment. This responsiveness has proven to be a successful evolutionary trait. Here, we tested the hypothesis that two key environmental factors, light and nutrition, are integrated within the axillary bud to promote or suppress the growth of the bud into a branch. Using petunia (Petunia hybrida) as a model for vegetative branching, we manipulated both light quality (as crowding and the red-to-far-red light ratio) and phosphate availability, such that the axillary bud at node 7 varied from deeply dormant to rapidly growing. In conjunction with the phenotypic characterization, we also monitored the state of the strigolactone (SL) pathway by quantifying SL-related gene transcripts. Mutants in the SL pathway inhibit but do not abolish the branching response to these environmental signals, and neither signal is dominant over the other, suggesting that the regulation of branching in response to the environment is complex. We have isolated three new putatively SL-related TCP (for Teosinte branched1, Cycloidia, and Proliferating cell factor) genes from petunia, and have identified that these TCP-type transcription factors may have roles in the SL signaling pathway both before and after the reception of the SL signal at the bud. We show that the abundance of the receptor transcript is regulated by light quality, such that axillary buds growing in added far-red light have greatly increased receptor transcript abundance. This suggests a mechanism whereby the impact of any SL signal reaching an axillary bud is modulated by the responsiveness of these cells to the signal.
New Zealand Institute for Plant and Food Research, Limited, Sandringham, Auckland 1025, New Zealand.
Revel S M
http://orcid.org/0000-0001-5238-7604
RS
Drummond
New Zealand Institute for Plant and Food Research, Limited, Sandringham, Auckland 1025, New Zealand.
Bart J
http://orcid.org/0000-0002-5871-2831
BJ
Janssen
New Zealand Institute for Plant and Food Research, Limited, Sandringham, Auckland 1025, New Zealand.
Zhiwei
http://orcid.org/0000-0002-7605-9768
Z
Luo
New Zealand Institute for Plant and Food Research, Limited, Sandringham, Auckland 1025, New Zealand.
Carla
C
Oplaat
New Zealand Institute for Plant and Food Research, Limited, Sandringham, Auckland 1025, New Zealand.
Susan E
http://orcid.org/0000-0001-5035-5190
SE
Ledger
New Zealand Institute for Plant and Food Research, Limited, Sandringham, Auckland 1025, New Zealand.
Mark W
MW
Wohlers
New Zealand Institute for Plant and Food Research, Limited, Sandringham, Auckland 1025, New Zealand kimberley.snowden@plantandfood.co.nz.
Kimberley C
http://orcid.org/0000-0001-9640-4015
KC
Snowden
D053898:Biosynthetic Pathways / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D018076:DNA, Complementary / Q000235:genetics; D004777:Environment; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000528:radiation effects; D017343:Genes, Plant; D008027:Light; D008969:Molecular Sequence Data; D009024:Morphogenesis / Q000187:drug effects / Q000528:radiation effects; D032306:Petunia / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000528:radiation effects; D010758:Phosphorus / Q000494:pharmacology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D018547:Plant Stems / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D025341:Principal Component Analysis; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000528:radiation effects; D014157:Transcription Factors / Q000378:metabolism
D018076:DNA, Complementary; D010940:Plant Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D010758:Phosphorus