Mokshina Natalia, Gorshkova Tatyana, Deyholos Michael K
Kazan Institute of Biochemistry and Biophysics, Russian Academy of Sciences, Kazan, Russia.
Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
PLoS One. 2014 Jun 11;9(2):e97949. doi: 10.1371/journal.pone.0097949. eCollection 2014.
Plant chitinases (EC 3.2.1.14) and chitinase-like (CTL) proteins have diverse functions including cell wall biosynthesis and disease resistance. We analyzed the expression of 34 chitinase and chitinase-like genes of flax (collectively referred to as LusCTLs), belonging to glycoside hydrolase family 19 (GH19). Analysis of the transcript expression patterns of LusCTLs in the stem and other tissues identified three transcripts (LusCTL19, LusCTL20, LusCTL21) that were highly enriched in developing bast fibers, which form cellulose-rich gelatinous-type cell walls. The same three genes had low relative expression in tissues with primary cell walls and in xylem, which forms a xylan type of secondary cell wall. Phylogenetic analysis of the LusCTLs identified a flax-specific sub-group that was not represented in any of other genomes queried. To provide further context for the gene expression analysis, we also conducted phylogenetic and expression analysis of the cellulose synthase (CESA) family genes of flax, and found that expression of secondary wall-type LusCESAs (LusCESA4, LusCESA7 and LusCESA8) was correlated with the expression of two LusCTLs (LusCTL1, LusCTL2) that were the most highly enriched in xylem. The expression of LusCTL19, LusCTL20, and LusCTL21 was not correlated with that of any CESA subgroup. These results defined a distinct type of CTLs that may have novel functions specific to the development of the gelatinous (G-type) cellulosic walls.
植物几丁质酶（EC 3.2.1.14）和类几丁质酶（CTL）蛋白具有多种功能，包括细胞壁生物合成和抗病性。我们分析了亚麻中属于糖苷水解酶家族19（GH19）的34个几丁质酶和类几丁质酶基因（统称为LusCTLs）的表达情况。对LusCTLs在茎和其他组织中的转录表达模式分析发现，有三个转录本（LusCTL19、LusCTL20、LusCTL21）在发育中的韧皮纤维中高度富集，韧皮纤维形成富含纤维素的凝胶状细胞壁。同样的这三个基因在具有初生细胞壁的组织和形成木聚糖型次生细胞壁的木质部中相对表达较低。对LusCTLs的系统发育分析确定了一个亚麻特有的亚组，在所查询的任何其他基因组中均未出现。为了给基因表达分析提供更多背景信息，我们还对亚麻的纤维素合酶（CESA）家族基因进行了系统发育和表达分析，发现次生壁型LusCESAs（LusCESA4、LusCESA7和LusCESA8）的表达与在木质部中富集程度最高的两个LusCTLs（LusCTL1、LusCTL2）的表达相关。LusCTL19、LusCTL20和LusCTL21的表达与任何CESA亚组的表达均不相关。这些结果定义了一种独特类型的CTLs，它们可能具有与凝胶状（G型）纤维素壁发育相关的新功能。
