Enhancing host immunity is an effective way to reduce morbidity in chickens.  Heterophil to lymphocyte ratio (H/L) is associated with host disease resistance in birds.  Chickens with different H/L levels show different disease resistances.  However, the utility of the H/L as an indicator of immune function needs to be further analyzed.  In this study, a H/L directional breeding chicken line (Jingxing yellow chicken) was constructed, which has been bred for 12 generations.  We compared the function of heterophils, and combined statistical analysis to explore the candidate genes and pathways related to H/L.  The oxidative burst function of the heterophils isolated from the H/L selection line (G12) was increased (P=0.044) compared to the non-selection line (NS).  The 22.44 Mb genomic regions which annotated 300 protein-coding genes were selected in the genome of G9 (n=92) compared to NS (n=92) based on a genome-wide selective sweep.  Several selective regions were identified containing genes like interferon induced with helicase C domain 1 (IFIH1) and moesin (MSN) associated with the intracellular receptor signaling pathway, C–C motif chemokine receptor 6 (CCR6), dipeptidyl peptidase 4 (DPP4) and hemolytic complement (HC) associated with the negative regulation of leukocyte chemotaxis and tight junction protein 1 (TJP1) associated with actin cytoskeleton organization.  In addition, 45 genome-wide significant indels containing 29 protein-coding genes were also identified as associated with the H/L based on genome-wide association study (GWAS).  The expression of protein tyrosine phosphatase non-receptor type 5 (PTPN5) (r=0.75, P=0.033) and oxysterol binding protein like 5 (OSBPL5) (r=0.89, P=0.0027) were positively correlated with H/L.  Compared to the high H/L group, the expressions of PTPN5 and OSBPL5 were decreased (P<0.05) in the low H/L group of Beijing you chicken.  The A/A allelic frequency of indel 5_13108985 (P=3.85E–06) within OSBPL5 gradually increased from the NS to G5 and G9, and the individuals with A/A exhibited lower H/L than individuals with heterozygote A/ATCT (P=4.28E–04) and homozygous ATCT/ATCT (P=3.40E–05).  Above results indicated oxidative burst function of heterophils were enhanced, and 22.44 Mb genomic regions were selected with the directional selection of H/L.  In addition, PTPN5 and OSBPL5 genes were identified as H/L-related candidate genes.  These findings revealed the complex genetic mechanism of H/L related to immunity and will allow selection for improving chicken immunity based on the H/L

Salmonella is one of the most common food-borne pathogens and its resistance in chicken can be improved through genetic selection.  The heterophils/lymphocytes (H/L) ratio in the blood reflects the immune system status of chicken.  We compared the genome data and spleen transcriptomes between the H/L ratio-selected and non-selected chickens, after Salmonella infection, aiming to identify the key genes participating in the antibacterial activity in the spleen.  The results revealed that, the selected population had stronger (P<0.05) liver resistance to Salmonella typhimurium (ST) than the non-selected population.  In the selected and non-selected lines, the identified differentiation genes encode proteins involved in biological processes or metabolic pathways that included the TGF-beta signaling pathway, FoxO signaling pathway, and Salmonella infection pathway.  The results of the analysis of all identified differentially expressed genes (DEGs) of spleen revealed that the G protein-coupled receptor (GPCR) and insulin-like growth factor (IGF-I) signaling pathways were involved in the Salmonella infection pathway.  Integrated analysis of DEGs and F_ST (fixation index), identified candidate genes involved in Salmonella infection pathway, such as GPR39, NTRK2, and ANXA1.  The extensive genomic changes highlight the polygenic genetic of the immune response in these chicken populations.  Numerous genes related to the immune performance are differentially expressed in the selected and non-selected lines and the selected lines has a higher resistance to Salmonella. 

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.