A Cross-species Transcriptional Profile Analysis of Heartwood Formation in Black Walnut
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- Huang, Z., Tsai, CJ., Harding, S.A. et al. Plant Mol Biol Rep (2010) 28: 222. doi:10.1007/s11105-009-0144-x
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The value of black walnut (Juglans nigra L.) is determined by the quality and quantity of darkly colored heartwood in its stem. We are exploring the regulation of heartwood production by identifying genes associated with the transition from sapwood to heartwood. We analyzed microarray data from a cross-species hybridization where black walnut cDNA was probed using a 7K gene aspen array. Results showed that only about 17% (1,253 vs 7K) of the probes in the microarray hybridized with genes from black walnut. Genes showing differential abundance in response to time change and developmental stage in the stem were identified and investigated. Eleven genes were identified as upregulated only in the transition zone (TZ) or interior sapwood of a tree harvested in fall; 55 genes were upregulated only in the TZs of trees harvested in summer; 74 genes were upregulated in the TZ of trees harvested in summer and in fall. Most of these genes were classified as “no hits”, but some, such as the orthologs of Arabidopsis genes At2g14900 and At3g04710, were putatively related to cell rescue and defense. Genes related to other functional classifications such as signal transduction, metabolism, and protein fate and synthesis were also identified in this experiment. Overall, these analyses provide insight into the mechanism regulating heartwood formation in black walnut.