Although the root system is indispensable for absorption of nutrients and water, it is poorly studied in maize owing to the difficulties of direct measurement of roots. Here, 103 maize lines were used to compare root architectures under well-watered and water-stressed conditions. Significant genetic variation, with medium to high heritability and significant correlations, was observed for root traits. Total root length (TRL) and total root surface area (TSA) had high phenotypical diversity, and TRL was positively correlated with TSA, root volume, and root forks. The first two principal components explained 94.01% and 91.15% of total root variation in well-watered and water-stressed conditions, respectively. Thus, TRL and TSA, major contributors to root variation, can be used as favorable selection criteria at the seedling stage. We found that stiff stalk and non-stiff stalk groups (temperate backgrounds) showed relatively higher mean values for root morphological diversity than the TST group (tropical/subtropical background). Of the tested lines, 7, 42, 45, and 9 were classified as drought sensitive, moderately sensitive, moderately drought tolerant, and highly drought tolerant, respectively. Seven of the 9 extremely drought tolerant lines were from the TST group, suggesting that TST germplasms harbor valuable genetic resources for drought tolerance that could be used in breeding to improve abiotic stress tolerance in maize.

The objective of this experiment was to observe the allele frequency and genotype distribution of some 9p21 SNPs in the Anhui Han population, and to study its relationship with the susceptibility to ischemic stroke. For this purpose, a collection of 992 patients with ischemic stroke confirmed and hospitalized in our hospital from October 2017 to October 2020 were used as the IS case group, and 951 normal people who had a healthy physical examination in the physical examination center of our hospital during the same period were selected as the control group. After informed consent, cubital venous blood of all subjects was collected, and epidemiological data of the subjects were collected; the rs2383206, rs2383207, rs10757274, and rs1333049 on chromosome 9p21 as the sites to be tested, using Sequenom Mass Array system for genotyping, using Haploview4.2 software to calculate whether the genotype distribution meets Hardy-Weinberg equilibrium. Results showed that there were no significant differences between the two groups in gender, age, and smoking history. There are significant differences in the levels of hypertension, diabetes and hyperlipidemia, total cholesterol, triglycerides, HDL-C and apolipoprotein A1 between the two groups of study subjects. The genotype frequencies of the participating populations were in a balanced state. The results of the association analysis between SNPs and IS susceptibility showed that rs2383207, rs10757274, rs1333049 and rs2383206 are the susceptibility sites of ischemic stroke. It concluded that in Anhui, China, the inheritance of chromosome 9p21 region is associated with ischemic stroke.