Hypergravity stimulus enhances primary xylem development and decreases mechanical properties of secondary cell walls in inflorescence stems of Arabidopsis thaliana
Hypergravity stimulus enhances primary xylem development and decreases mechanical properties of secondary cell walls in inflorescence stems of Arabidopsis thaliana
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DOI：
10.1093/aob/mcl055
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发表时间：
2006-06-01
期刊：
影响因子：
4.2
通讯作者：
Kamisaka, Seiichiro
中科院分区：
文献类型：
--
作者：
Nakabayashi, Izumi;Karahara, Ichirou;Kamisaka, Seiichiro
中心点背景和目的木质部在加强植物体内起着重要作用。过去对杨树张力木和斜生李树干木质部形成的研究表明，重力条件的变化影响木质部导管的形态和力学性质。本研究旨在研究超重力刺激对阿拉伯花序茎初生木质部导管形态和发育的影响以及对分离的次生壁制剂力学性能的影响。中心点方法在光学显微镜下观察了300g超重力处理24 h后生长3~5d的拟南芥植株花序茎的初级木质部的形态，并观察了用酶消化法从花序茎中分离的次生细胞壁制剂(主要由次生木质部元素组成)的延展性。用机械感受器阻断剂氯化Gd处理植物，以测试机械感受器在超重反应中的作用。中心点关键结果每木质部中的次生木质部元素的数量、次生厚度的表观厚度和花序茎中的次生木质部元素的横截面积都随着超重的增加而增加。氯化Gd抑制了超重力对次生加厚和次生木质部分子横截面积增加的影响，但不能抑制超重力对次生加厚和次生木质部分子数量增加的影响。次生细胞壁制备的延伸性随超重力的变化而降低。结论超重力刺激促进了次生木质部的发育，降低了次生细胞壁的延伸性，机械感受器可能参与了这一过程。
center dot Background and Aims The xylem plays an important role in strengthening plant bodies. Past studies on xylem formation in tension woods in poplar and also in clinorotated Prunus tree stems lead to the suggestion that changes in the gravitational conditions affect morphology and mechanical properties of xylem vessels. The aim of this study was to examine effects of hypergravity stimulus on morphology and development of primary xylem vessels and on mechanical properties of isolated secondary wall preparations in inflorescence stems of arabidopsis.center dot Methods Morphology of primary xylem was examined under a light microscope on cross-sections of inflorescence stems of arabidopsis plants, which had been grown for 3-5 d after exposure to hypergravity at 300 g for 24 h. Extensibility of secondary cell wall preparation, isolated from inflorescence stems by enzyme digestion of primary cell wall components (mainly composed of metaxylem elements), was examined. Plants were treated with gadolinium chloride, a blocker of mechanoreceptors, to test the involvement of mechanoreceptors in the responses to hypergravity.center dot Key Results Number of metaxylem elements per xylem, apparent thickness of the secondary thickenings, and cross-section area of metaxylem elements in inflorescence stems increased in response to hypergravity. Gadolinium chloride suppressed the effect of hypergravity on the increase both in the thickness of secondary thickenings and in the cross-section area of metaxylem elements, while it did not suppress the effect of hypergravity on the increase in the number of metaxylem elements. Extensibility of secondary cell wall preparation decreased in response to hypergravity. Gadolinium chloride suppressed the effect of hypergravity on cell wall extensibility.center dot Conclusions Hypergravity stimulus promotes metaxylem development and decreases extensibility of secondary cell walls, and mechanoreceptors were suggested to be involved in these processes.