Eight distinct cellulose synthase catalytic subunit genes from Betula luminifera are associated with primary and secondary cell wall biosynthesis
Eight distinct cellulose synthase catalytic subunit genes from Betula luminifera are associated with primary and secondary cell wall biosynthesis
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来自光皮桦的八个不同的纤维素合酶催化亚基基因与初生和次生细胞壁生物合成相关
DOI：
10.1007/s10570-014-0261-z
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发表时间：
2014-08-01
期刊：
影响因子：
5.7
通讯作者：
Lin, Erpei
中科院分区：
文献类型：
--
作者：
Huang, Huahong;Jiang, Cheng;Lin, Erpei
纤维素是植物细胞壁的重要组成部分，是决定木材质量的主要因素。纤维素合成酶（CESA）由CESA基因家族编码，是纤维素生物合成的重要催化剂。通过转录组测序，从白桦中分离到8个全长CesA cdna。预测的蛋白包含985 - 1103个氨基酸，与毛杨相应的pticesa具有85 - 92%的同源性。每种蛋白均含有植物CESA蛋白的典型基序。系统发育分析表明，BlCESA1、BlCESA3和BlCESA4属于与次级细胞壁合成相关的3个分支，BlCESA2、BlCESA5、BlCESA6、BlCESA7和BlCESA8属于与原代细胞壁合成相关的3个分支。定量反转录PCR和原位mRNA杂交表明，BlCesA1、BlCesA3和BlCesA4转录本在木质素化茎的木质部最为丰富，并且在激素和蔗糖处理下具有相似的表达模式。因此，这三个基因编码的蛋白可能是次级壁CesA复合物的亚基。然而，BlCesA1、BlCesA3和BlCesA4在机械应力下的表达模式不同。这3个基因在张力木中的表达量明显高于对照木，但在对缘木中的表达模式不同，说明这3个基因在次生壁形成过程中发挥着不同的作用。BlCesA2、BlCesA5、BlCesA6和BlCesA7主要在叶片和韧皮部表达。与BlCesA6最相似的BlCesA8在叶片、韧皮部和形成层均有强烈表达。有趣的是，这两个基因在激素、蔗糖和弯曲处理下表现出不同的表达模式。因此，除了原代细胞壁的生物合成外，BlCesA8可能还有其他功能。
Cellulose, a significant proportion of the plant cell wall, is the main determining factor of the wood qualities of a timber tree. Cellulose synthase (CESA), an essential catalyst for cellulose biosynthesis, is encoded by the CesA gene family. We isolated eight full-length CesA cDNAs from Betula luminifera on the basis of transcriptome sequencing. The predicted proteins comprised 985–1,103 amino acids, sharing 85–92 % identity with the corresponding PtiCESAs from Populus trichocarpa. Each protein contained typical motifs of plant CESA proteins. Phylogenetic analysis showed that BlCESA1, BlCESA3 and BlCESA4 belonged to three clades linked to secondary cell wall synthesis, and BlCESA2, BlCESA5, BlCESA6, BlCESA7 and BlCESA8 belonged to three clades associated with primary cell wall synthesis. Quantitative reverse transcription PCR and in situ mRNA hybridization indicated that transcripts of BlCesA1, BlCesA3 and BlCesA4 were most abundant in the xylem of the lignified stem and had similar expression patterns when treated with hormones and sucrose. Thus, the proteins encoded by these three genes might be subunits of the secondary wall CesA complex. However, the expression patterns of BlCesA1, BlCesA3 and BlCesA4 were different in response to mechanical stress. These three genes showed much higher expression levels in the tension wood than in the control, and they showed different expression patterns in the opposite wood, suggesting that these genes play different roles during secondary wall formation. BlCesA2, BlCesA5, BlCesA6 and BlCesA7 were predominantly expressed in the leaf and phloem. BlCesA8, which is most similar to BlCesA6, was strongly expressed in the leaf, phloem and cambium. Interestingly, these two genes showed distinct expression patterns when treated with hormones, sucrose and bending. Thus, in addition to biosynthesis of the primary cell wall, BlCesA8 might have other functions.