Fasciclin-like arabinogalactan proteins: specialization for stem biomechanics and cell wall architecture in Arabidopsis and Eucalyptus
Fasciclin-like arabinogalactan proteins: specialization for stem biomechanics and cell wall architecture in Arabidopsis and Eucalyptus
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DOI：
10.1111/j.1365-313x.2010.04181.x
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发表时间：
2010-05-01
期刊：
影响因子：
7.2
通讯作者：
Southerton, Simon G.
中科院分区：
文献类型：
--
作者：
MacMillan, Colleen P.;Mansfield, Shawn D.;Southerton, Simon G.
古老的细胞粘附成束蛋白（FAS）结构域存在于细菌、真菌、藻类、昆虫和动物中，并且存在于高等植物中的成束蛋白样阿拉伯半乳聚糖蛋白（FLAs）大家族中。含脂肪酸合成酶的蛋白质在昆虫、藻类和脊椎动物中的功能作用已经确定;然而，各种高等植物脂肪酸合成酶的生物学功能尚不清楚。一些FLAs的表达已经与拟南芥茎中次生壁纤维素合成的开始相关，并且还与树木的茎和分支中的木材形成相关，这表明在植物茎中的生物学作用。我们研究了FLAs是否有助于植物茎生物力学。使用系统发育，转录丰度和启动子-GUS融合分析，我们确定了一个保守的子集的单一FAS结构域FLAs（A组FLAs）在桉树和拟南芥，具有特定的和高转录丰度的茎，特别是在干细胞进行二次壁沉积，系统发育的保守性似乎延伸到其他双子叶植物和单子叶植物。基因功能分析表明，拟南芥T-DNA敲除双突变体茎改变了茎的生物力学与降低拉伸强度和降低拉伸弹性模量，以及改变细胞壁结构和组成，增加纤维素微纤丝角和减少阿拉伯糖，半乳糖和纤维素含量。使用材料工程的概念，我们与这些FLAs的细胞壁成分与干生物力学的影响。我们的研究结果表明，一个子集的单一FAS域FLAs有助于植物茎强度通过影响纤维素沉积，和茎弹性模量通过影响细胞壁基质的完整性。
P>The ancient cell adhesion fasciclin (FAS) domain is found in bacteria, fungi, algae, insects and animals, and occurs in a large family of fasciclin-like arabinogalactan proteins (FLAs) in higher plants. Functional roles for FAS-containing proteins have been determined for insects, algae and vertebrates; however, the biological functions of the various higher-plant FLAs are not clear. Expression of some FLAs has been correlated with the onset of secondary-wall cellulose synthesis in Arabidopsis stems, and also with wood formation in the stems and branches of trees, suggesting a biological role in plant stems. We examined whether FLAs contribute to plant stem biomechanics. Using phylogenetic, transcript abundance and promoter-GUS fusion analyses, we identified a conserved subset of single FAS domain FLAs (group A FLAs) in Eucalyptus and Arabidopsis that have specific and high transcript abundance in stems, particularly in stem cells undergoing secondary-wall deposition, and that the phylogenetic conservation appears to extend to other dicots and monocots. Gene-function analyses revealed that Arabidopsis T-DNA knockout double mutant stems had altered stem biomechanics with reduced tensile strength and a reduced tensile modulus of elasticity, as well as altered cell-wall architecture and composition, with increased cellulose microfibril angle and reduced arabinose, galactose and cellulose content. Using materials engineering concepts, we relate the effects of these FLAs on cell-wall composition with stem biomechanics. Our results suggest that a subset of single FAS domain FLAs contributes to plant stem strength by affecting cellulose deposition, and to the stem modulus of elasticity by affecting the integrity of the cell-wall matrix.