Traditionally, Chinese indigenous cattle is geographically widespread.  The present study analyzed based on genome-wide variants to evaluate the genetic background among 157 individuals from four representative indigenous cattle breeds of Hubei Province of China: Yiling yellow cattle (YL), Bashan cattle (BS), Wuling cattle (WL), Zaobei cattle (ZB), and 21 individuals of Qinchuan cattle (QC) from the nearby Shanxi Province of China.  Linkage disequilibrium (LD) analysis showed the LD of YL was the lowest (r2=0.32) when the distance between markers was approximately 2 kb.  Principle component analysis (PCA), and neighbor-joining (NJ)-tree revealed a separation of Yiling yellow cattle from other geographic nearby local cattle breeds.  In PCA plot, the YL and QC groups were segregated as expected; moreover, YL individuals clustered  together more obviously.  In the NJ-tree, the YL group formed an independent branch and BS, WL, ZB groups were mixed.  We then used the FST statistic approach to reveal long-term selection sweep of YL and other 4 cattle breeds.  According to the selective sweep, we identified the unique pathways of YL, associated with production traits.  Based on the results, it can be proposed that YL has its unique genetic characteristics of excellence resource, and it is an indispensable cattle breed in China.   

In order to understand the response of nitrate metabolism in seedlings of oilseed rape (Brassica napus L.) to low oxygen stress (LOS), two cultivars were studied at different light, LOS time and exogenous nitrate concentrations under hydroponic stress. Results show that N-uptake and dry matter of rape seedlings were decreased after LOS stress while nitrate accumulation (NA) under LOS was induced by darkness. Nitrate accumulation peaked at 3 d while root activity (RA, defined as dehydrogenase activity) decreased with prolonged waterlogging exposure. Exogenous nitrate significantly elevated NA and RA. Tungstate (TS) and LOS inhibited nitrate reductase (NR) activity while NR transcription and activity were enhanced by exogenous nitrate. Low oxygen stress stimulated the activity of superoxide dismutase (SOD) and peroxidase (POD) slightly, but inhibited that of catalase (CAT). B. napus L. Zhongshuang 10 (ZS10), a LOS tolerant cultivar, displayed smaller decrease upon dry matter under LOS, higher NA in darkness and lower NA in light than B. napus L. Ganlan CC (GAC), a LOS sensitive variety. ZS10 had lower NA and higher RA after waterlogging and exogenous nitrate treatment, and higher NR activity under TS inhibition than GAC, but the activity of antioxidant enzymes did not change under LOS. The results indicate that nitrate metabolism involved tolerance of rape seedlings to LOS, with lower accumulation and higher reduction of nitrate being related to higher LOS tolerance of rape seedlings exposed to waterlogging.