Down-regulation of an anionic peroxidase in transgenic aspen and its effect on lignin characteristics
Down-regulation of an anionic peroxidase in transgenic aspen and its effect on lignin characteristics
复制标题
DOI：
10.1007/s10265-003-0087-5
复制
发表时间：
2003-06-01
影响因子：
2.8
通讯作者：
Morohoshi, N
中科院分区：
文献类型：
--
作者：
Li, YH;Kajita, S;Morohoshi, N
人们普遍认为过氧化物酶催化木质素生物合成的最后一步。在这项研究中，为了研究阴离子过氧化物酶基因 prxA3a 的表达如何与植物组织中的木质化相关，我们生产了转基因烟草植物，该植物含有与 prxA3a 启动子融合的 β-葡萄糖醛酸酶 (GUS) 基因。 GUS活性的组织化学染色表明prxA3a启动子主要在干组织的木质化细胞中具有活性。此外，为了检查抑制 prxA3a 表达的效果，我们将反义 prxA3a 基因构建体转移到原始宿主杂交白杨 (Populus sieboldii x P gradidentata) 中，置于 prxA3a 基因原始启动子的控制下。获得并表征了 11 株转化的白杨树，并通过 PCR 和 Southern 印迹分析在所有这些品系中证实了反义构建体的稳定整合。酶活性测定表明，大多数转基因品系中的总过氧化物酶活性和酸性过氧化物酶活性均低于对照植物。此外，过氧化物酶活性的降低与木质素含量降低和木质素成分改变有关。过氧化物酶活性降低最高的转基因品系表现出较高的紫丁香基/香草醛(S/V)比率和较低的S+V产量，这主要是因为V单位数量减少。因此，我们的结果表明prxA3a参与木质部组织的木质化，并且阴离子过氧化物酶的下调改变了杂交白杨中的木质素含量和组成。
It is generally accepted that peroxidases catalyze the final step in the biosynthesis of lignin. In this study, to examine how expression of prxA3a, a gene for an anionic peroxidase, might be related to lignification in plant tissues, we produced transgenic tobacco plants that harbored a gene for beta-glucuronidase (GUS) fused to the prxA3a promoter. Histochemical staining for GUS activity indicated that the prxA3a promoter was active mainly in the lignifying cells of stem tissues. Further, to examine the effects of suppressing the expression of prxA3a, we transferred an antisense prxA3a gene construct into the original host, hybrid aspen (Populus sieboldii x P gradidentata), under the control of the original promoter of the prxA3a gene. Eleven transformed aspens were obtained and characterized, and the stable integration of the antisense construct was confirmed by PCR and Southern blotting analysis in all these lines. Assays of enzymatic activity showed that both total peroxidase activity and acidic peroxidase activity were lower in most transgenic lines than in the control plants. In addition, the reduction of peroxidase activity was associated with lower lignin content and modified lignin composition. Transgenic lines with the highest reduction of peroxidase activity displayed a higher syringyl/vanillin (S/V) ratio and a lower S + V yield, mainly because of a decreased amount of V units. Thus, our results indicate that prxA3a is involved in the lignification of xylem tissue and that the down-regulation of anionic peroxidase alters both lignin content and composition in hybrid aspen.