Sucrose synthase affects carbon partitioning to increase cellulose production and altered cell wall ultrastructure
Sucrose synthase affects carbon partitioning to increase cellulose production and altered cell wall ultrastructure
复制标题
DOI：
10.1073/pnas.0900188106
复制
发表时间：
2009-08-04
影响因子：
11.1
通讯作者：
Mansfield, Shawn D.
中科院分区：
文献类型：
--
作者：
Coleman, Heather D.;Yan, Jimmy;Mansfield, Shawn D.
利用2个启动子控制陆地棉蔗糖合成酶基因（Gossypium hirsutum sucrose synthase，SuSy）在银白杨×大齿杨（Populus alba x grandidentata）中的高效表达。RNA转录本丰度，酶活性，细胞壁成分和可溶性碳水化合物的分析表明，在转基因株系的显着变化。所有品系在木质部发育过程中都表现出显著增加的SuSy酶活性。这种活性表现在所有品系中单位干重的次生细胞壁纤维素含量改变，比对照水平增加2%至6%，而不影响植物生长。纤维素浓度的升高与细胞壁结晶度的增加有关，但不改变次生壁微纤丝角。这一发现表明，所观察到的结晶度的增加是改变碳分配纤维素生物合成的功能，而不是张力木材形成的结果。此外，在转基因株系中增加的纤维素沉积导致木质部次生细胞壁变厚，从而提高木材密度。这些研究结果清楚地表明，SuSy是白杨库强度的关键调节因子，并表明SuSy与纤维素合成和次生壁形成密切相关。
Overexpression of the Gossypium hirsutum sucrose synthase (SuSy) gene under the control of 2 promoters was examined in hybrid poplar (Populus alba x grandidentata). Analysis of RNA transcript abundance, enzyme activity, cell wall composition, and soluble carbohydrates revealed significant changes in the transgenic lines. All lines showed significantly increased SuSy enzyme activity in developing xylem. This activity manifested in altered secondary cell wall cellulose content per dry weight in all lines, with increases of 2% to 6% over control levels, without influencing plant growth. The elevated concentration of cellulose was associated with an increase in cell wall crystallinity but did not alter secondary wall microfibril angle. This finding suggests that the observed increase in crystallinity is a function of altered carbon partitioning to cellulose biosynthesis rather than the result of tension wood formation. Furthermore, the augmented deposition of cellulose in the transgenic lines resulted in thicker xylem secondary cell wall and consequently improved wood density. These findings clearly implicate SuSy as a key regulator of sink strength in poplar trees and demonstrate the tight association of SuSy with cellulose synthesis and secondary wall formation.