Lei Yaogeng, Hannoufa Abdelali, Yu Peiqiang
Department of Animal and Poultry Science, College of Agriculture and Bioresources, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK S7N5A8, Canada.
London Research and Development Centre, Agriculture and Agri-Food Canada, 1391 Sandford Street, London, ON N5V 4T3, Canada.
Anim Nutr. 2023 Mar 9;14:79-87. doi: 10.1016/j.aninu.2023.02.010. eCollection 2023 Sep.
Alfalfa ( L.) is a legume forage that is widely cultivated owing to its high biomass yield and favorable nutrient values. However, alfalfa contains relatively high lignin, which limits its utilization. Downregulation of two transcriptional factors, Transparent Testa8 () and Homeobox12 (), has been proposed to reduce lignin content in alfalfa. Therefore, silencing of (i) and i) in alfalfa was achieved by RNAi technology. The objective of this project was to determine effect of gene modification through silencing of and genes in alfalfa plants on lignin and phenolic content, bioenergic value, nutrient supply from rumen degradable and undegradable fractions, and in vitro ammonia production in response to the silencing of and genes in alfalfa. All gene silenced alfalfa plants (5 i and 11 i) were grown under greenhouse conditions with wild type as a control. Samples were analyzed for bioactive compounds, degradation fractions, truly digestible nutrients, energetic values and in vitro ammonia productions in ruminant systems. Furthermore, relationships between physiochemical, metabolic and fermentation characteristics and molecular spectral parameters were determined using vibrational molecular spectroscopy. Results showed that the i had higher lignin, while i had higher phenolics. Both silenced genotypes had higher rumen slowly degraded carbohydrate fractions and truly digestible neutral detergent fiber, but lower rumen degradable protein fractions. Moreover, the i had lower truly digestible crude protein, energetic values and ammonia production compared with other silenced genotypes. In addition, in relation to the nutritive values of alfalfa, structural carbohydrate parameters were negatively correlated, whereas alpha/beta ratio in protein structure was positively correlated. Furthermore, good predictions were obtained for degradation of protein and carbohydrate fractions and energy values from molecular spectral parameters. In conclusion, silencing of the and genes decreased protein availability and increased fiber availability. Silencing of the gene also increased lignin and decreased energy and rumen ammonia production. Moreover, nutritional alterations were closely correlated with molecular spectral parameters. Therefore, gene modification through silencing the and genes in alfalfa influenced physiochemical, metabolic and fermentation characteristics.
紫花苜蓿（Medicago sativa L.）是一种豆科牧草，因其生物量产量高且营养价值良好而被广泛种植。然而，紫花苜蓿含有相对较高的木质素，这限制了其利用。有人提出下调两个转录因子，即透明种皮8（Transparent Testa8，TT8）和同源异型盒12（Homeobox12，HB12），以降低紫花苜蓿中的木质素含量。因此，通过RNA干扰技术实现了紫花苜蓿中TT8和HB12基因的沉默。本项目的目的是确定在紫花苜蓿植株中通过沉默TT8和HB12基因进行基因修饰对木质素和酚类含量、生物能量值、瘤胃可降解和不可降解部分的养分供应以及响应紫花苜蓿中TT8和HB12基因沉默的体外氨产生的影响。所有基因沉默的紫花苜蓿植株（5个TT8-RNAi和11个HB12-RNAi）在温室条件下生长，以野生型作为对照。对样品进行了反刍动物系统中生物活性化合物、降解部分、真正可消化养分、能量值和体外氨产生的分析。此外，使用振动分子光谱法确定了理化、代谢和发酵特性与分子光谱参数之间的关系。结果表明，TT8-RNAi具有较高的木质素，而HB12-RNAi具有较高的酚类物质。两种沉默基因型均具有较高的瘤胃缓慢降解碳水化合物部分和真正可消化的中性洗涤纤维，但瘤胃可降解蛋白质部分较低。此外，与其他沉默基因型相比，TT8-RNAi具有较低的真正可消化粗蛋白、能量值和氨产生。此外，就紫花苜蓿的营养价值而言，结构碳水化合物参数呈负相关，而蛋白质结构中的α/β比率呈正相关。此外，从分子光谱参数对蛋白质和碳水化合物部分的降解以及能量值获得了良好的预测。总之，TT8和HB12基因的沉默降低了蛋白质的可利用性并增加了纤维的可利用性。TT8基因的沉默还增加了木质素含量并降低了能量和瘤胃氨产生。此外，营养改变与分子光谱参数密切相关。因此，通过沉默紫花苜蓿中的TT8和HB12基因进行基因修饰影响了理化、代谢和发酵特性。
