Dataset Information

Conifer R2R3-MYB transcription factors: sequence analyses and gene expression in wood-forming tissues of white spruce (Picea glauca).

ABSTRACT: BACKGROUND: Several members of the R2R3-MYB family of transcription factors act as regulators of lignin and phenylpropanoid metabolism during wood formation in angiosperm and gymnosperm plants. The angiosperm Arabidopsis has over one hundred R2R3-MYBs genes; however, only a few members of this family have been discovered in gymnosperms. RESULTS: We isolated and characterised full-length cDNAs encoding R2R3-MYB genes from the gymnosperms white spruce, Picea glauca (13 sequences), and loblolly pine, Pinus taeda L. (five sequences). Sequence similarities and phylogenetic analyses placed the spruce and pine sequences in diverse subgroups of the large R2R3-MYB family, although several of the sequences clustered closely together. We searched the highly variable C-terminal region of diverse plant MYBs for conserved amino acid sequences and identified 20 motifs in the spruce MYBs, nine of which have not previously been reported and three of which are specific to conifers. The number and length of the introns in spruce MYB genes varied significantly, but their positions were well conserved relative to angiosperm MYB genes. Quantitative RTPCR of MYB genes transcript abundance in root and stem tissues revealed diverse expression patterns; three MYB genes were preferentially expressed in secondary xylem, whereas others were preferentially expressed in phloem or were ubiquitous. The MYB genes expressed in xylem, and three others, were up-regulated in the compression wood of leaning trees within 76 hours of induction. CONCLUSION: Our survey of 18 conifer R2R3-MYB genes clearly showed a gene family structure similar to that of Arabidopsis. Three of the sequences are likely to play a role in lignin metabolism and/or wood formation in gymnosperm trees, including a close homolog of the loblolly pine PtMYB4, shown to regulate lignin biosynthesis in transgenic tobacco.

SUBMITTER: Bedon F

PROVIDER: S-EPMC1851958 | biostudies-literature | 2007

REPOSITORIES: biostudies-literature

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Conifer R2R3-MYB transcription factors: sequence analyses and gene expression in wood-forming tissues of white spruce (Picea glauca).

Bedon Frank F Grima-Pettenati Jacqueline J Mackay John J

BMC plant biology 20070330

<h4>Background</h4>Several members of the R2R3-MYB family of transcription factors act as regulators of lignin and phenylpropanoid metabolism during wood formation in angiosperm and gymnosperm plants. The angiosperm Arabidopsis has over one hundred R2R3-MYBs genes; however, only a few members of this family have been discovered in gymnosperms.<h4>Results</h4>We isolated and characterised full-length cDNAs encoding R2R3-MYB genes from the gymnosperms white spruce, Picea glauca (13 sequences), and ...[more]

PMID: 17397551

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Project description:Tree improvement programs select genotypes for faster growth, at both early and late stages, to increase yields over unimproved material, and the improvement is frequently attributed to genetic control in growth parameters among genotypes. Underutilized genetic variability among genotypes also has the potential to ensure future gains are possible. However, the genetic variation in growth, physiology and hormone control among genotypes generated from different breeding strategies has not been well characterized in conifers. We assessed growth, biomass, gas exchange, gene expression and hormone levels in white spruce seedlings obtained from three different breeding strategies (controlled crosses, polymix pollination, open pollination) using parents grafted into a clonal seed orchard in Alberta, Canada. A pedigree-based best linear unbiased prediction (ABLUP) mixed model was implemented to quantify variability and narrow-sense heritability for target traits and the levels of several hormones and expression of gibberellin-related genes in apical internodes were also determined. Over the first 2-years of development, the estimated heritabilities for height, volume, total dry biomass, above ground dry biomass, root:shoot ratio and root length, varied between 0.10 and 0.21, with height having the highest value. The ABLUP values showed large genetic variability in growth and physiology traits both between families from different breeding strategies, and within families. The principal component analysis showed that developmental and hormonal traits explained 44.2% and 29.4% of the total phenotypic variation between the three different breeding strategies and two growth groups. In general, controlled crosses from the fast growth group showed the best apical growth, with more accumulation of indole-3-acetic acid, abscisic acid, phaseic acid, and a 4-fold greater gene expression of PgGA3ox1 in genotypes from controlled crosses versus those from open pollination, but in some cases, open-pollination from the fast and slow growth groups showed the best root development, higher water use efficiency (iWUE and δ13C) and more accumulation of zeatin and isopentenyladenosine. In conclusion, tree domestication can lead to trade-offs between growth, carbon allocation, photosynthesis, hormone levels and gene expression, and we encourage the use of this phenotypic variation identified in improved and unimproved trees to advance white spruce tree improvement programs.

Dataset Information

Conifer R2R3-MYB transcription factors: sequence analyses and gene expression in wood-forming tissues of white spruce (Picea glauca).

Publications

Conifer R2R3-MYB transcription factors: sequence analyses and gene expression in wood-forming tissues of white spruce (Picea glauca).

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