Ranade SS, Abrahamsson S, Niemi J, García-Gil MR
Pinus taeda cDNA Microarray as a Tool for Candidate Gene Identification for Local Red/Far-Red Light Adaptive Response in Pinus sylvestris
American Journal of Plant Sciences, 2013:4, 479-493

Abstract
Light quality response is a vital environmental cue regulating plant development. Conifers, like angiosperms, respond to the changes in light quality including the level of red (R) and far-red (FR) light, which follows a latitudinal cline. R and FR wavelengths form a significant component of the entire plant life cycle, including the initial developmental stages such as seed germination, cotyledon expansion and hypocotyl elongation. With an aim to identify differentially ex- pressed candidate genes, which would provide a clue regarding genes involved in the local adaptive response in Scots pine (Pinus sylvestris) with reference to red/far-red light; we performed a global expression analysis of Scots pine hy- pocotyls grown under two light treatments, continuous R (cR) and continuous FR (cFR) light; using Pinus taeda cDNA microarrays on bulked hypocotyl tissues from different individuals, which represented different genotypes. This ex- periment was performed with the seeds collected from northern part of Sweden (Ylinen, 68°N). Interestingly, gene ex- pression pattern with reference to cryptochrome1, a blue light photoreceptor, was relatively high under cFR as com- pared to cR light treatment. Additionally, the microarray data analysis also revealed expression of 405 genes which was enhanced under cR light treatment; while the expression of 239 genes was enhanced under the cFR light treatment. Dif- ferentially expressed genes were re-annotated using Blast2GO tool. These results indicated that cR light acts as pro- moting factor whereas cFR antagonises the effect in most of the processes like C/N metabolism, photosynthesis and cell wall metabolism which is in accordance with former findings in Arabidopsis. We propose cryptochrome1 as a strong candidate gene to study the adaptive cline response under R and FR light in Scots pine as it shows a differential expres- sion under the two light conditions.

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