毛白杨纤维素合酶基因PtCesA_4的克隆、表达及单核苷酸多态性分析

组合利用生物信息学和RT-PCR方法,首次从毛白杨未成熟木质部cDNA中分离出PtCesA4cDNA全长,并进行测序和序列分析,结果表明克隆的毛白杨PtCesA4 cDNA片段总长为3 757 bp,基因内部含有完整的开放阅读框架,大小为3 129 bp,可编码长度为1 042个氨基酸残基的蛋白质,所推导的蛋白质氨基酸序列与拟南芥AtCesA4、水稻OsCesA,和火炬松PtCesA2的蛋白质氨基酸序列同源性分别为80.3%,78.9%和75.6%.组织特异性Realtime-PCR结果显示,PtCesA4基因在杨树根、茎、叶片和顶端分生组织中均有表达,但其表达模式却不同:PtCesA4在成熟叶片、未成熟木质部和成熟木质部中表达丰度最高,在根部和顶端分生组织表达丰度中等,在树皮和韧皮部有少量表达,在形成层中表达丰度最低.在此基础上,组合利用MEGA3.1和DnaSP4.50.4软件对毛白杨40株基因型个体的PtCesA4序列进行比对和分析,检测到153个单核苷酸多态性(sinsh nueleotide polymorphism,SNP)位点,SNP频率为1/35 bp,多样性指数π/0.005 02.其中51个是常见SNPs,102个为罕见SNPs.在这些SNPs中,有118个属于转换,35个属于颠换.在外显子区域,共检测到69个SNP位点,其中59个为同义突变,10个为错义突变.对PtCesA4基因内SNPs进行的连锁不平衡分析结果显示,随着核苷酸序列长度的增加,SNPs的连锁不平衡在基因内部迅速衰退,因此,在毛白杨中,基于PtCesA4基因的连锁不平衡作图是可行的,而基于整个杨树基因组的连锁不平衡作图是不可行的.也是不必要的.研究结果为毛白杨PtCesA4基因的连锁不平衡作图及其基因辅助毛白杨木材纤维性状的分子育种提供了理论依据.

Isolation,Expression and Single Nucleotide Polymorphisms Analysis of Cellulose Synthase gene (PtCesA_4) from Populus tomentosa

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 Arabido...