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Scientia Silvae Sinicae ›› 2009, Vol. 12 ›› Issue (5): 1-10.doi: 10.11707/j.1001-7488.20090501

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Isolation，Expression and Single Nucleotide Polymorphisms Analysis of Cellulose Synthase gene (PtCesA4) from Populus tomentosa

Xu Baohua1,2,Yang Xiaohui1.2,Li Bailian1,2,3,Zhang Zhiyi1.2,Zhang Deqiang1.2   

  1. (1.Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of Ministry of Education，Beijing Forestry University Beijing 100083； 2. National Engineering Laboratory for Tree Breeding，Beijing Forestry University Beijing 100083； 3.Department of Forestry， North Carolina State University North Carolina State 27695-8203)
  • Received:2008-12-19 Revised:1900-01-01 Online:2009-05-25 Published:2009-05-25

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Abstract:

The cellulose synthase gene(CesA) plays a key role in regulating cellulose biosynthesis during the wood formation. In this study, a full-length cDNA clone encoding PtCesA4 was isolated from the cDNA prepared from immature xylem zone of Populus tomentosa with the biological informatics and RT-PCR. The cDNA was 3 757 bp in length with an open reading frame (ORF) which would be capable to encode a protein of 1 042 AA. The deduced protein sequence of the PtCesA4 shared 80.3％, 78.9％ and 75.6% identity with Arabidopsis thaliana AtCesA4, Oryza sativa OsCesA1 and Pinus taeda PtCesA2, respectively. Realtime-PCR indicated that PtCesA4 transcripts had their mRNA products expressed in roots, stems, leaves and apical shoot meristems, but their expressions were differential in the different tissues. The PtCesA4 transcripts were the most abundant mRNA products in mature leaf, immature and mature xylem, with medium expression in root and apical shoot meristems, with some expression in the bark and phloem, but a lowest-abundance was detected in cambium. The genomic sequences of PtCesA4 in 40 individuals were aligned, compared and analyzed using the software MEGA3.1 and DnaSP4.50.7. A total of 153 single nucleotide polymorphisms (SNPs) were detected and the frequency and diversity of SNPs were 1/35 bp and 0.005 02, respectively. Among them, 51 were common SNPs and 102 were rare SNPs. There were 118 and 35 mutation types of transition and transversion, respectively. There were 69 SNPs detected in the coding regions of PtCesA4, of which 59 were silent mutations and 10 were missense mutations. The linkage disequilibrium of SNPs in the PtCesA4 was analyzed and the result showed that LD declines rapidly within the gene regions of PtCesA4 with the length increase. It suggested that wide LD mapping in Populus genome might not be feasible and not be necessary, but LD mapping based on PtCesA4 gene could be particularly useful in breeding programs of forest trees. The results, therefore, provided the important genetic foundation for associated with PtCesA4gene and gene-assisted breeding of new germplasms with desirable wood fiber traits in P. tomentosa.

Key words: Populus tomentosa, lignocellulose, cellulose synthase, single nucleotide polymorphisms