Lignin deposition and associated changes in anatomy, enzyme activity, gene expression, and ruminal degradability in stems of tall fescue at different developmental stages
Lignin deposition and associated changes in anatomy, enzyme activity, gene expression, and ruminal degradability in stems of tall fescue at different developmental stages
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DOI：
10.1021/jf020516x
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发表时间：
2002-09-25
影响因子：
6.1
通讯作者：
Wang, ZY
中科院分区：
文献类型：
--
作者：
Chen, L;Auh, C;Wang, ZY
以高羊茅（FestucaarundinaceaSchreb）为材料，在3个生育期和3个伸长期对茎组织进行取样。解剖学分析表明，愈创木基（G）和丁香基（S）木质素在植物发育过程中的沉积和木质素厚壁组织环的形成。从伸长期到生殖期，克拉森木质素含量急剧增加。气相色谱-质谱联用分析表明，随着茎的发育，S木质素含量和S/G比值逐渐增加，对羟基苯基（H）和G木质素含量逐渐减少，S木质素含量和S/G比值从茎的上部节间向基部节间逐渐增加，而G和H木质素含量逐渐减少。O-甲基转移酶相对活性在茎发育过程中增加，并与茎的木质化过程平行。在发展过程中的酶活性的模式与底物的选择，最高的活动时看到的底物是咖啡醛和5-羟基阿魏酸，和最低的活动时看到的咖啡酸和5-羟基松柏醇被用作底物。咖啡酸O-甲基转移酶和肉桂醇脱氢酶基因的表达量在茎伸长期增加，在生殖生长期保持较高水平。植物发育过程中的解剖、代谢和分子水平的变化与木质化和降解密切相关。这项研究提供了一个完整的图片的分子和化学事件，伴随着木质素沉积和瘤胃降解率的变化。
Stem tissues of tall fescue (Festuca arundinacea Schreb) were sampled at three elongation stages and three reproductive stages. Anatomical analysis showed the deposition of guaiacyl (G) and syringyl (S) lignin during plant development and the formation of a lignified sclerenchyma ring. A dramatic increase in Klason lignin content was found from elongation stage to reproductive stage. Lignin composition analyzed by gas chromatography- mass spectrometry revealed that S lignin content and S/G ratio increased with stem development but contents of p-hydroxyphenyl (H) and G lignins decreased, during the same period S lignin content and S/G ratio also increased from the younger upper internode down to the older basal internode of the stem, but G and H lignin decreased in parallel. Relative O-methyltransferase activities increased during stem development and in parallel with the lignification process of stem. The pattern of enzyme activity during development varied with the choice of substrate with highest activities seen when substrates were caffeoylaldehyde and 5-hydroxyferulic acid, and lowest activities were seen when caffeic acid and 5 hydroxyconiferyl alcohol were used as substrates. The expression of caffeic acid O-methyltransferase and cinnamyl alcohol dehydrogenase genes increased during the stem elongation stage and remained at high levels during the reproductive stages. The changes at anatomical, metabolic, and molecular levels during plant development were closely associated with lignification and degradability. This study provides an integrated picture of the molecular and chemical events that accompany changes in lignin deposition and ruminal degradability.