Petrova Anna, Kozlova Liudmila, Gorshkov Oleg, Nazipova Alsu, Ageeva Marina, Gorshkova Tatyana
Laboratory of Plant Cell Growth Mechanisms, Kazan Institute of Biochemistry and Biophysics, Federal Research Center Kazan Scientific Center of Russian Academy of Sciences, Kazan, Russia.
Microscopy Cabinet, Kazan Institute of Biochemistry and Biophysics, Federal Research Center Kazan Scientific Center of Russian Academy of Sciences, Kazan, Russia.
Front Plant Sci. 2021 Apr 6;12:660375. doi: 10.3389/fpls.2021.660375. eCollection 2021.
In the fibers of many plant species after the formation of secondary cell walls, cellulose-enriched cell wall layers (often named G-layers or tertiary cell walls) are deposited which are important in many physiological situations. Flax ( L.) phloem fibers constitutively develop tertiary cell walls during normal plant growth. During the gravitropic response after plant inclination, the deposition of a cellulose-enriched cell wall layer is induced in xylem fibers on one side of the stem, providing a system similar to that of tension wood in angiosperm trees. Atomic force microscopy (AFM), immunochemistry, and transcriptomic analyses demonstrated that the G-layer induced in flax xylem fibers was similar to the constitutively formed tertiary cell wall of bast (phloem) fibers but different from the secondary cell wall. The tertiary cell walls, independent of tissue of origin and inducibility, were twice as stiff as the secondary cell walls. In the gravitropic response, the tertiary cell wall deposition rate in xylem was higher than that of the secondary cell wall. Rhamnogalacturonan I (RG-I) with galactan side chains was a prominent component in cellulose-rich layers of both phloem and xylem flax fibers. Transcriptomic events underlying G-layer deposition in phloem and xylem fibers had much in common. At the induction of tertiary cell wall deposition, several genes for rhamnosyltransferases of the GT106 family were activated in xylem samples. The same genes were expressed in the isolated phloem fibers depositing the tertiary cell wall. The comparison of transcriptomes in fibers with both inducible and constitutive tertiary cell wall deposition and xylem tissues that formed the secondary cell walls is an effective system that revealed important molecular players involved in the formation of cellulose-enriched cell walls.
在许多植物物种的纤维中，次生细胞壁形成后，会沉积富含纤维素的细胞壁层（通常称为G层或三生细胞壁），这在许多生理情况下都很重要。亚麻（亚麻属）韧皮纤维在正常植物生长过程中会组成型地发育三生细胞壁。在植物倾斜后的向重力性反应中，茎一侧的木质部纤维会诱导沉积一层富含纤维素的细胞壁层，形成一个与被子植物树木中张力木相似的系统。原子力显微镜（AFM）、免疫化学和转录组分析表明，亚麻木质部纤维中诱导形成的G层与韧皮（韧皮部）纤维组成型形成的三生细胞壁相似，但与次生细胞壁不同。三生细胞壁，无论其起源组织和诱导性如何，其硬度是次生细胞壁的两倍。在向重力性反应中，木质部中三生细胞壁的沉积速率高于次生细胞壁。带有半乳聚糖侧链的鼠李半乳糖醛酸聚糖I（RG-I）是亚麻韧皮部和木质部纤维富含纤维素层中的主要成分。韧皮部和木质部纤维中G层沉积背后的转录组事件有很多共同之处。在三生细胞壁沉积诱导时，GT106家族的几个鼠李糖基转移酶基因在木质部样本中被激活。同样的基因在沉积三生细胞壁的分离韧皮纤维中也有表达。比较具有诱导型和组成型三生细胞壁沉积的纤维以及形成次生细胞壁的木质部组织的转录组，是一个有效的系统，揭示了参与富含纤维素细胞壁形成的重要分子参与者。
