Overexpression of poplar cellulase accelerates growth and disturbs the closing movements of leaves in sengon
Overexpression of poplar cellulase accelerates growth and disturbs the closing movements of leaves in sengon
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DOI：
10.1104/pp.108.116970
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发表时间：
2008-06-01
期刊：
影响因子：
7.4
通讯作者：
Hayashi, Takahisa
中科院分区：
文献类型：
--
作者：
Hartati, Sri;Sudarmonowati, Enny;Hayashi, Takahisa
本研究利用根癌农杆菌法，在热带豆科植物赤杨中高效表达了白杨纤维素酶(PaPopCel1)。PaPopCel1过表达增加了叶片较大的茎的长度和宽度，表现出比野生型叶片略高的绿色密度。与野生型植物相比，转基因植物上的叶片对在日落时关闭得更慢。然而，当每种基因的主脉被切除并放在纸巾上时，转基因植物的叶片比野生型植物的叶片关闭得更快。根据细胞壁的碳水化合物分析，转基因植物的叶片含有较少的壁结合型木葡聚糖。木葡聚糖酶活性的原位检测表明，尽管转基因植株比野生型植株含有较少的完整木葡聚糖，但整个木葡聚糖的掺入发生在附着在主脉上的小叶柄枕的薄壁细胞(运动细胞)中，这可能是为了收紧管壁。这些观察结果支持这样一种假设，即杨树纤维素酶攻击纤维素微纤维的准晶位置，使木葡聚糖插层松散，导致不可逆壁修饰。这一过程可能是为什么杨树纤维素酶的过度表达既促进了植物的生长，又通过改变植物叶片的闭合运动来扰乱植物的生物钟的原因。
In this study, poplar (Populus alba) cellulase (PaPopCel1) was overexpressed in a tropical Leguminosae tree, sengon (Paraserianthes falcataria), by the Agrobacterium tumefaciens method. PaPopCel1 overexpression increased the length and width of stems with larger leaves, which showed a moderately higher density of green color than leaves of the wild type. The pairs of leaves on the transgenic plants closed more slowly during sunset than those on the wild-type plants. When main veins from each genotype were excised and placed on a paper towel, however, the leaves of the transgenic plants closed more rapidly than those of the wildtype plant. Based on carbohydrate analyses of cell walls, the leaves of the transgenic plants contained less wall-bound xyloglucan than those of the wild-type plants. In situ xyloglucan endotransglucosylase activity showed that the incorporation of whole xyloglucan, potentially for wall tightening, occurred in the parenchyma cells (motor cells) of the petiolule pulvinus attached to the main vein, although the transgenic plant incorporated less whole xyloglucan than the wild-type plant. These observations support the hypothesis that the paracrystalline sites of cellulose microfibrils are attacked by poplar cellulase, which loosens xyloglucan intercalation, resulting in an irreversible wall modification. This process could be the reason why the overexpression of poplar cellulase both promotes plant growth and disturbs the biological clock of the plant by altering the closing movements of the leaves of the plant.