大豆孢囊线虫（Soybean cyst nematode, SCN; Heterodera glycines）是世界范围内最具破坏性的大豆病原物之一。研究大豆-SCN互作机制对提出新的病害防控策略、培育抗大豆孢囊线虫病的大豆新品种具有重要实践意义。SCN侵染可诱导大豆的多个差异基因上调或下调表达。然而，差异基因表达变化的调控机制在很大程度上仍未被探索。N⁶ -甲基腺苷（m⁶A）甲基化是最广泛存在的mRNA修饰之一，在植物响应病原物侵染过程中发挥重要的转录重编程的调控作用。然而，在大豆对SCN的亲和性和非亲和性反应中是否也存在m⁶A甲基化对差异基因的表达调控作用尚未明确。为此，本研究首先明确了大豆品种Williams 82 对SCN race 3具有敏感性（亲和性反应），但对SCN_T（大豆孢囊线虫烟草群体）存在非寄主抗性（非亲和性反应）；其次通过液相色谱-串联质谱法检测了m⁶A/A比率。结果表明，与亲和性反应相比，m⁶A甲基化整体水平在非亲和性反应中显著升高；在此基础上，通过N⁶-甲基腺苷(m⁶A)全转录组比较了大豆对SCN的亲和性和非亲和性反应的差异。在非亲和性反应中，差异修饰m⁶A峰（differentially modified m⁶A peaks, DMPs）和差异表达基因（differentially expressed genes, DEGs）的数量均显著增多；在亲和反应和非亲和反应中，分别存在133和194个差异表达基因的m⁶A甲基化修饰水平也表现出差异显著性 (我们将这些基因称为DMDs)。亲和反应中的DMDs显著富集在玉米素生物合成、植物-病原互作、糖酵解/糖异生和醚脂质代谢途径，且与植物-病原互作途径相关的DMDs表达量下调最多；而与SCN_T侵染的非亲和反应中仅叶酸生物合成通路被显著富集，且该通路的DMDs表达量上调最多。综上所述，本研究首次明确了大豆-SCN互作中存在m⁶A甲基化修饰，且m⁶A全转录组在大豆和SCN的亲和和非亲和反应中存在差异。研究结果为大豆-SCN的非寄主抗性反应在转录后修饰水平上的调控机制提供了新的见解，对提高大豆抗SCN育种有重要应用价值。

本研究利用RNA测序技术，分析和比较了SA处理前后梨果实的转录表达谱。在SA处理12 h和24 h后，分别有159个和419个基因表达水平发生显著改变。在这些差异表达基因（Differentially expressed genes，DEGs）中，有125个基因在2个处理时间点均存在差异表达，被鉴定为可能与SA调控果实成熟衰老有关的候选基因。这些DEGs主要与植物激素的生物合成与代谢、细胞壁代谢与修饰、抗氧化系统和衰老相关转录因子等有关。此外，通过实时定量PCR（qRT-PCR）进一步验证了SA处理后梨果实中几种候选DEGs的表达。本研究有助于加深对SA调控梨果实成熟衰老综合机制的认识。

Two experiments were conducted to determine the effects of fiber level from alfalfa meal and sampling time on the apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of amino acids (AA) in growing pigs. A total of 24 ileal-cannulated pigs (Duroc×(Large White×Landrace) with body weight (21.4±1.5) kg) were randomly allotted to 4 treatments. The pigs were provided a corn-soybean meal diet or a diet containing 5, 10 or 20% of alfalfa meal during two 10-d experimental periods. The AID of AA was measured. Six ileal-cannulated pigs were fed a protein-free diet in order to estimate the endogenous protein losses and SID of AA. Ileal AA digestibility was not affected by inclusion of 5 or 10% alfalfa meal in the diet (P>0.05). The AID of His, Lys, Met, Phe, Thr, Val, Ala, Asp, Cys, Gly, Pro, Ser and Tyr reduced by 2.0–6.8% with the addition level of alfalfa meal (linear, P<0.05). The SID of His, Lys, Ser, Thr and Tyr decreased by 2.2–4.3% as the level of alfalfa meal in the diet increased (linear, P<0.05). The AID and SID of AA were not affected by the sampling time (P>0.05). A multiple linear regression analysis, taking into account both the soluble and insoluble fiber content in the diets, explained more than 36% of variation in SID of Ser and Thr (P<0.05). In conclusion, the corn-soybean meal diet containing 10% of alfalfa meal did not affect ileal AA digestion. The AID and SID of AA were similar between two sampling times. Increasing the concentration of total dietary fiber from 12.3 to 21.4% by adding graded levels of alfalfa meal (0–20%) to a corn-soybean meal control diet induced a linear reduction in AID and SID of most AA. Soluble and insoluble fibers from alfalfa meal have differential roles in the AA digestion, which may help explain the variation observed in the SID of partial AA. These findings would provide important information for dietary fiber level and composition related to AA digestion.

The fiber level and composition have an important effect on nutrient digestibility of swine diets. Little information is known about the effects of fiber level and composition from alfalfa meal on nutrient digestibility of fattening pigs fed a corn-soybean meal-based diet. The objective of this experiment was to determine the effects of alfalfa fiber on the growth performance, intestinal nutrient flow and apparent total tract digestibility (ATTD) of nutrients in fattening pigs. 24 barrows (Duroc×(Large White×Landrace), body weight=(60.6±0.7) kg) were randomly allotted to 4 treatments with 6 replicates of 1 pig per replicate. The pigs were provided a control diet or a diet containing 5, 10 or 20% of alfalfa meal during a 14-d experiment period. Average daily gain (ADG) and the ATTD of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and gross energy (GE) reduced linearly as the level of alfalfa meal in the diet increased (P<0.01). The total tract flow of DM, OM, CP, NDF, ADF, and GE increased with the increase in dietary alfalfa (linear, P<0.05). Growth performance and nutrient digestion were not affected by inclusion of 5% alfalfa meal in the diet (P>0.05). A multiple linear regression analysis, taking into account both soluble and insoluble fiber intake, explained approximately 70% of the variation in the ATTD of DM, OM, NDF, and GE (P<0.01). In conclusion, alfalfa meal should be limited to less than 5% of the diet in fattening pigs to maximize growth performance and nutrient digestion. Soluble and insoluble fiber from alfalfa meal has the differential roles in nutrient digestion, which may help explain the main variation observed in nutrient digestibility. These findings suggest that knowledge of specific fiber components is necessary to accurately predict the effects of dietary fiber on nutrient digestibility.