增强宿主免疫力是降低鸡发病率的有效途径。异嗜性粒细胞与淋巴细胞比率（H/L）与鸟类的抗病性有关。具有不同H/L表型的鸡只表现出抗病性的差异。然而，H/L作为免疫功能指标的有效性仍需进一步分析。本研究构建了H/L定向选育系（京星黄鸡），该品系已培育了12个世代。我们比较了异嗜性粒细胞的功能，并结合统计学分析方法来探索与H/L相关的候选基因和调控途径。与非选择系（NS）相比，从H/L选择系（G12）分离的异嗜性粒细胞的氧化爆发功能较强（P=0.044）。基于全基因组选择性清除分析，选择系第九世代（G9，n=92）相比于非选择系（NS，n=92），有22.44 Mb基因组区域受到选择，注释到300个蛋白编码基因。其中，包含与细胞内受体信号通路相关的解旋酶C结构域1（IFIH1）和moesin（MSN）诱导的干扰素，与白细胞趋化性负调节相关的C-C基序趋化因子受体6（CCR6），二肽基肽酶4（DPP4）和溶血补体（HC）以及与肌动蛋白细胞骨架组织相关的紧密连接蛋白1（TJP1）等基因。此外，基于全基因组关联分析（GWAS），还鉴定出了45个indels与H/L相关，共注释到29个蛋白编码基因。北京油鸡肝脏转录组验证发现，蛋白酪氨酸磷酸酶非受体5型（PTPN5）（r=0.75，P=0.033）和氧甾醇结合蛋白5（OSBPL5）（r=0.89，P=0.0027）基因的表达量与H/L呈正相关。与高H/L组相比，北京油鸡低H/L组PTPN5和OSBPL5的表达量较低（P<0.05）。OSBPL5基因上indel位点 5_13108985（P=3.85E-06）的A/A等位基因频率从NS到G5和G9逐渐增加，且A/A个体的H/L低于杂合子A/ATCT（P=4.28E-04）和纯合ATCT/ATCT个体（P=3.40E-05）。以上结果表明，H/L经过定向选育，异嗜性粒细胞的氧化爆发功能增强，基因组22.44 Mb区域受到定向选择。另外PTPN5和OSBPL5基因被鉴定为H/L相关候选基因。这些发现揭示了H/L与免疫相关的复杂遗传机制，基于H/L进行遗传选育有助于提高鸡的免疫力。

本研究比较H/L选育群体和非选育群体的基因组数据和沙门氏菌感染后的脾脏转录组数据，旨在鉴定H/L选育过程中参与脾脏抗菌能力的关键基因。在选择系第10代，从H/L选育系和对照系分别选取41只和31只个体采集外周血样本提取DNA，并基于55K SNP芯片进行基因分型进行选择信号分析；分别选取选育系和对照系群体于7日龄进行鼠伤寒沙门氏菌（ST）感染试验，感染后3d测定肝组织载菌量和血液溶菌酶含量，同时采集脾脏组织（N=9）进行转录组分析；结合选择信号和脾脏转录组结果共同鉴定脾脏中参与沙门氏菌抵抗的候选基因。结果表明，与对照系群体相比，H/L选育群体对鼠伤寒沙门氏菌的抗性更强（P<0.05）。在选育系和对照系之间，鉴定的分化基因主要参与TGF-β信号通路、FoxO信号通路和沙门氏菌感染通路。对所有鉴定得到的脾脏差异表达基因（DEGs）的分析结果表明，沙门氏菌感染途径涉及的G蛋白偶联受体（GPCR）和胰岛素样生长因子（IGF-I）信号通路被显著富集（p<0.01）。基于DEGs和Fst（Fixation index）的综合分析鉴定了参与沙门氏菌感染途径的候选基因，如GPR39、NTRK2和ANXA1。广泛的基因组变化显示了在鸡群中免疫反应的多基因遗传基础。许多与免疫防御功能相关的基因在H/L选育和对照系中差异表达，选育系群体对沙门氏菌表现出更强的抗性。该研究确定了在用ST攻击后易感鸡和抗性鸡中差异表达的基因和通路，以更好地了解宿主对ST感染的免疫抗性。本研究利用动物模型（H/L定向选育系和对照系）的基因组数据和脾脏转录组数据进行了系统性的研究，解析了H/L定向选育后脾脏影响沙门氏菌抗性的分子机制。

Potassium (K) deficiency is one of the major abiotic stresses which has drastically influenced maize growth and yield around the world. However, the physiological mechanism of K deficiency tolerance is not yet fully understood. To identify the differences of root morphology, physiology and endogenous hormones at different growing stages, two maize inbred lines 90-21-3 (tolerance to K deficiency) and D937 (sensitive to K deficiency) were cultivated in the long-term K fertilizer experimental pool under high potassium (+K) and low potassium (–K) treatments. The results indicated that the root length, volume and surface area of 90-21-3 were significantly higher than those of D937 under –K treatment at different growing stages. It was noteworthy that the lateral roots of 90-21-3 were dramatically higher than those of D937 at tasselling and flowering stage under –K treatment. Meanwhile, the values of superoxide dismutase (SOD) and oxidizing force of 90-21-3 were apparently higher than those of D937, whereas malondialdehyde (MDA) content of D937 was obviously increased. Compared with +K treatment, the indole-3-acetic acid (IAA) content of 90-21-3 was largely increased under –K treatment, whereas it was sharply decreased in D937. On the contrary, abscisic acid (ABA) content of 90-21-3 was slightly increased, but that of D937 was significantly increased. The zeatin riboside (ZR) content of 90-21-3 was significantly decreased, while that of D937 was relatively increased. These results indicated that the endogenous hormones were stimulated in 90-21-3 to adjust lateral root development and to maintain the physiology function thereby alleviating K deficiency.