CSIC-Misión Biológica de Galicia, Grupo de Genética y Mejora de Maíz, Apartado 28, 36080 Pontevedra, Spain.
Phytochemistry. 2012 Nov;83:43-50. doi: 10.1016/j.phytochem.2012.07.026. Epub 2012 Aug 30.
Cross-linking of grass cell wall components through diferulates (DFAs) has a marked impact on cell wall properties. However, results of genetic selection for DFA concentration have not been reported for any grass species. We report here the results of direct selection for ester-linked DFA concentration in maize stalk pith tissues and the associated changes in cell wall composition and biodegradability. After two cycles of divergent selection, maize populations selected for higher total DFA (DFAT) content (CHs) had 16% higher DFAT concentrations than populations selected for lower DFAT content (CLs). These significant DFA concentration gains suggest that DFA deposition in maize pith parenchyma cell walls is a highly heritable trait that is genetically regulated and can be modified trough conventional breeding. Maize populations selected for higher DFAT had 13% less glucose and 10% lower total cell wall concentration than CLs, suggesting that increased cross-linking of feruloylated arabinoxylans results in repacking of the matrix and possibly in thinner and firmer cell walls. Divergent selection affected esterified DFAT and monomeric ferulate ether cross link concentrations differently, supporting the hypothesis that the biosynthesis of these cell wall components are separately regulated. As expected, a more higher DFA ester cross-coupled arabinoxylan network had an effect on rumen cell wall degradability (CLs showed 12% higher 24-h total polysaccharide degradability than CHs). Interestingly, 8-8-coupled DFAs, previously associated with cell wall strength, were the best predictors of pith cell wall degradability (negative impact). Thus, further research on the involvement of these specific DFA regioisomers in limiting cell wall biodegradability is encouraged.
通过 diferulates（DFAs）交联草细胞壁成分对细胞壁特性有显著影响。然而，尚未有任何草种的 DFA 浓度遗传选择结果的报道。我们在此报告了在玉米茎髓组织中直接选择酯键连接的 DFA 浓度以及相关的细胞壁成分和生物降解性变化的结果。经过两轮分歧选择，选择更高总 DFA（DFAT）含量（CHs）的玉米群体比选择更低 DFAT 含量的群体（CLs）的 DFAT 浓度高 16%。这些显著的 DFA 浓度增益表明，DFA 在玉米髓质薄壁细胞壁中的沉积是一个高度可遗传的性状，受遗传调控，可以通过传统的育种进行修饰。选择更高 DFAT 的玉米群体比 CLs 群体的葡萄糖含量低 13%，总细胞壁浓度低 10%，这表明阿魏酰阿拉伯木聚糖的交联增加导致基质的重新包装，可能导致细胞壁更薄更坚固。分歧选择对酯化的 DFAT 和单体阿魏酸醚交叉链接浓度的影响不同，这支持了这些细胞壁成分的生物合成分别受到调控的假说。正如预期的那样，更高的 DFA 酯交叉偶联阿拉伯木聚糖网络对瘤胃细胞壁降解性有影响（CLs 的 24 小时总多糖降解率比 CHs 高 12%）。有趣的是，与细胞壁强度相关的 8-8 偶联的 DFA 是髓质细胞壁降解性的最佳预测因子（负面影响）。因此，鼓励进一步研究这些特定的 DFA 区域异构体在限制细胞壁生物降解性方面的作用。
