Environmental and auxin regulation of wood formation involves members of the Aux/IAA gene family in hybrid aspen.
Indole acetic acid (IAA/auxin) profoundly affects wood formation but the molecular mechanism of auxin action in this process remains poorly understood. We have cloned cDNAs for eight members of the Aux/IAA gene family from hybrid aspen (Populus tremula L. x Populus tremuloides Michx.) that encode potential mediators of the auxin signal transduction pathway. These genes designated as PttIAA1-PttIAA8 are auxin inducible but differ in their requirement of de novo protein synthesis for auxin induction. The auxin induction of the PttIAA genes is also developmentally controlled as evidenced by the loss of their auxin inducibility during leaf maturation. The PttIAA genes are differentially expressed in the cell types of a developmental gradient comprising the wood-forming tissues. Interestingly, the expression of the PttIAA genes is downregulated during transition of the active cambium into dormancy, a process in which meristematic cells of the cambium lose their sensitivity to auxin. Auxin-regulated developmental reprogramming of wood formation during the induction of tension wood is accompanied by changes in the expression of PttIAA genes. The distinct tissue-specific expression patterns of the auxin inducible PttIAA genes in the cambial region together with the change in expression during dormancy transition and tension wood formation suggest a role for these genes in mediating cambial responses to auxin and xylem development.
Moyle
Richard
R
Umeå Plant Science Centre, Swedish University of Agricultural Sciences, Department of Forest Genetics and Plant Physiology, 90183 Umeå, Sweden.
Schrader
Jarmo
J
Stenberg
Anneli
A
Olsson
Olof
O
Saxena
Sangeeta
S
Sandberg
Göran
G
Bhalerao
Rishikesh P
RP
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics; D001696:Biomechanical Phenomena; D003001:Cloning, Molecular; D004777:Environment; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006823:Hybrid Vigor / Q000235:genetics; D007210:Indoleacetic Acids / Q000494:pharmacology*; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics; D010937:Plant Growth Regulators / Q000494:pharmacology; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D031308:Salicaceae / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D017386:Sequence Homology, Amino Acid
D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D010940:Plant Proteins; C030737:indoleacetic acid