The genetic basis of stomatal conductance (g s ), net photosynthetic rate (P N ), and transpiration rate (E) was explored by using a wheat doubled haploid population from a cross of Hanxuan10 and Lumai 14. The above three traits were evaluated in wheat flag leaves at 10, 20, 30 days after anthesis under drought stress (DS) and well-watered (WW), and quantitative trait loci (QTL) were analyzed. Expression of the traits during the grain filling stage showed downward trends under both conditions, but expression of three phenotypes were stronger under WW than those under DS. Extremely significant positive correlations were established among the traits at all growth stages under both conditions. A total of 18 additive QTLs for those traits were identified on 10 chromosomes. Among them, two batches of nine additive QTLs were associated with the target traits under DS and WW, respectively. Two additive QTLs for gs and E, two for g s and P N , six for g s , P N , and E clustered at the same or near the region (colocation) of chromosomes 4A, 2B, and 7B, respectively. This provided genetic basis for close phenotype correlations among g s , P N , and E. Furthermore, QTLs for g s , P N , and E near Xgwm577 and Xgwm611 located on 7B chromosome were linked to previously reported QTLs regulating a SPAD value and the chlorophyll a/b ratio under dark-induced condition. This finding indicated that these QTLs on 7B chromosome might be involved in the process of wheat leaf senescence.

Delayed senescence, or stay-green, contributes to a longer grain-filling period and has been regarded as a desirable characteristic for the production of a number of crops including wheat. In the present study, in order to identify quantitative trait loci (QTLs) for traits related to the progression of wheat flag leaf senescence, green leaf area duration (GLAD) of a doubled haploid (DH) population, derived from two winter wheat varieties Hanxuan10 and Lumai14, was visually estimated under two water conditions and was recorded at 3-day intervals from 10 days after anthesis to physiological maturity using a 0-9 scale. According to GLAD, parameters related to the progression of senescence of DH lines and their parents were estimated by the Gompertz statistical model. Based on the model parameters, DH lines were categorized into three groups under drought stress and four groups under well-watered conditions. A total of 24 additive QTLs and 23 pairs of epistatic QTLs for parameters related to the progression of senescence were identified on 18 chromosomes, except for 3B, 1D and 6D. Of the QTLs detected, 14 and 10 additive QTLs were associated with the investigated traits under drought stress and well-watered conditions, respectively. Furthermore, 4, 7, 6, 2 and 2 additive QTLs for traits related to progression of senescence were clustered around the same or similar regions of chromosomes 1A, 1B, 5A, 5B and 7A, respectively. The present data provided the genetic basis for high phenotypic correlations among traits related to the progression of wheat flag leaf senescence. In addition, 17 loci were co-located or linked with previously reported QTLs regulating chlorophyll fluorescence, high-light-induced photo-oxidation, or heat stress and dark-induced senescence. The marker Xwmc336 on chromosome 1A, responsible for the onset and end times of leaf senescence, the time to maximum rate of senescence, the time to reach 75% senescence and chlorophyll content under drought stress may be helpful for marker-assisted selection breeding of wheat.

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The photosynthesis of wheat glumes makes important contributions to the yield. Stomata play a crucial role in regulating photosynthesis and transpiration in plants. However, the genetic base of wheat glume stomata is not fully understood. In this study, stomatal length (SL), stomatal width (SW), stomatal density (SD), potential conductance index (PCI) of stomata, stomatal area (SA), and stomatal relative area (SRA) were measured in different parts of wheat glumes from a doubled haploid (DH) population and their parents. Quantitative trait loci (QTLs) of these traits were anchored on a high-density genetic linkage map of the DH population. A total of 61 QTLs for stoma-related traits were mapped onto 16 chromosomes, and each one accounted for 3.63 to 19.02% of the phenotypic variations. Two QTL hotspots were detected in two marker intervals, AX-109400932∼AX-110985652 and AX-108972184∼AX-108752564, on chromosome 6A. Five possibly candidate genes (TraesCS6A02G105400, TraesCS6A02G106400, TraesCS6A02G115100, TraesCS6A02G115400, and TraesCS6A02G116200) for stoma-related traits of wheat glumes were screened out , according to their predicted expression levels in wheat glumes or spikes. The expression of these genes may be induced by a variety of abiotic stresses. These findings provide insights for cloning and functional characterization of stoma-related candidate genes in wheat glumes.

Background: Catheter malfunction is a common complication of peritoneal dialysis (PD). This study aimed to retrospectively analyze the risk factors and management of catheter malfunction in urgent-start PD.Methods: Patients who underwent urgent-start PD were divided into catheter-malfunction and control groups. Baseline demographic and laboratory data of the two groups were compared, and the risk factors for catheter malfunction were analyzed. Primary outcome measure was catheter survival, and the secondary outcomes were surgical complications and malfunction treatment.Results: Total of 700 patients was analyzed, among whom 143 (20.4%) experienced catheter malfunctions, specifically catheter migration (96, 67.1%), omental wrapping (36, 25.2%), and migration plus omental wrapping (11, 7.7%). Catheter survival time in the malfunction group (202.5 ± 479.4 days) was significantly shorter than that in the control group (1295.3 ± 637.0 days) (P < 0.001). Multivariate analysis revealed higher body mass index [hazard ratio (HR), 1.061; 95% confidence intervals (CI), 1.010–1.115; P = 0.018], lower surgeon count (HR, 1.083; 95% CI, 1.032–1.136; P = 0.001), and higher serum potassium (HR, 1.231; 95% CI, 1.041–1.494; P = 0.036) as independent risk factors for catheter malfunction, while older age (HR, 0.976, 95% CI, 0.962–0.991; P = 0.002) and colonic dialysis (HR, 0.384; 95% CI, 0.254–0.581; P < 0.001) as protective factors. Further subgroup analysis revealed a shorter catheter survival time in patients with younger age ( ≤ 40 years), higher serum potassium levels (≥5 mmol/L), while a longer catheter survival time in patients with colonic dialysis. PD tube and subcutaneous tunnel preservation was successful in 41 out of 44 patients with omental wrapping. All patients had good post-incision prognoses.Conclusions: Urgent-start PD is safe and effective for unplanned PD patients. Adequate pre-operative colonic dialysis and serum potassium level control are conducive in preventing catheter malfunction. Conservative treatment is effective in managing catheter migration alone, while preservation of the PD tube and the subcutaneous tunnel is effective for omental wrapping.