Bulked segregant analysis to detect quantitative trait loci (QTL) related to heat tolerance at grain filling rate in wheat using simple sequence repeat (SSR) markers

The grain-filling rate (GFR) plays an important role in determining grain yield. An F2 population of wheat was developed from a cross between the 2 wheat cultivars, Ksu106 (heat-tolerant) and Yecora Rojo (heat-sensitive). The parents and 205 F2 plants were planted on the 20th of January during the winter season of 2009 to evaluate heat tolerance during the grain-filling period. The sowing date in the present investigation represents the heat stress conditions in Saudi Arabia. Bulked – segregant analyses (BSA) was used in conjunction with simple sequence repeats (SSR) analysis to find markers linked to genes of heat tolerance. Composite interval mapping was used for mapping quantitative trait loci (QTL). The results reveal that 12 SSR markers: Wmc24, Wmc168, Wmc326, Xgwm30, Xgwm456, Wmc25, Wmc44, Wmc94, Wmc161, Wmc273, Wmc327 and Xgwm566 were linked to GFR by QTLs analysis of the F2 population. The results show that regression analysis for the relationship between the 12 markers and the phenotypes of F2 individuals were highly significant. The results demonstrate that SSR markers combined with bulked segregant analysis could be used to identify molecular markers linked to the grain filling rate as an indicator for heat tolerance in wheat.Keywords: Grain filling rate, QTL analysis, SSR marker, whea

Identification of new SSR markers linked to leaf chlorophyll content, flag leaf senescence and cell membrane stability traits in wheat under water stressed condition

Segregating F4 families from the cross between drought sensitive (Yecora Rojo) and drought tolerant (Pavon 76) genotypes were made to identify SSR markers linked to leaf chlorophyll content, flag leaf senescence and cell membrane stability traits in wheat (Triticum aestivum L.) under water-stressed condition and to map quantitative trait locus (QTL) for the three physiological traits. The parents and 150 F4 families were evaluated phenotypically for drought tolerance using two irrigation treatments (2500 and 7500 m3/ha). Using 400 SSR primers tested for polymorphism in testing parental and F4 families genotypes, the results revealed that QTL for leaf chlorophyll content, flag leaf senescence and cell membrane stability traits were associated with 12, 5 and 12 SSR markers, respectively and explained phenotypic variation ranged from 6 to 42%. The SSR markers for physiological traits had genetic distances ranged from 12.5 to 25.5 cM. These SSR markers can be further used in breeding programs for drought tolerance in wheat

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

Analysis of diversity using simple sequence repeat (SSR): distinctions between original Parmentiera cereifera tree and somaclones

Abstract Background The possibility of culturing Parmentiera cereifera in vitro was tested. Shoot tips and lateral buds were cultured in three media that were based on Murashige and Skoog (MS) but supplemented with different types and concentrations of growth regulators. Thirty-eight simple sequence repeat (SSR) primers were used to assess the genetic stability of the regenerated plantlets. Results Lateral buds recorded the highest significant mean values for shoot, root length, and the number of leaves when cultured in MS + 1.2 mg/l of 6-benzylaminopurine (BAP) + 1.5 g/l of activated charcoal. Seeds were also grown in different media. The best results were obtained with MS basal medium. The resulting shoots were rooted in MS medium, with 1.5 g/l of activated charcoal. Regenerated plants were acclimatized in the greenhouse. The 38 SSR primers produced 63 scorable bands ranging from 1 to 3, with an average of 1.68 per primer. Fifty-five monomorphic bands were obtained that ranged from 0 to 3, with an average of 1.45 per primer. The coefficient of similarity matrix ranged from 0.92 to 1.0, with an average of 97.4. Dendrogram generated using the SSR data tended to group the in vitro plants with the mother plant into two major clusters. The first cluster contained 19 in vitro plants with the mother plant and consisted of 4 subgroups. The second cluster contained in vitro plants, P-15, which had the lowest genetic similarity (92%) with the mother plant. Conclusions The results revealed the increase in the degree of similarity between the tested plants in the SSR analyses. Therefore, micropropagation is a safe mode for multiplication of true-to-type plants of P. cereifera

Identification of new microsatellite marker linked to the grain filling rate as indicator for heat tolerance genes in F 2 wheat population

Abstract The objective of this study was to estimate inheritance of the grain filling rate as indicator for heat tolerant genes. The minimum number of genes for the trait in bread wheat was also assessed by combining quantitative genetic estimates and SSR marker analyses. Two cultivars, Debra (heat-tolerant) and Yecora Rojo (heat-sensitive) crossed and F 1 and F 2 populations generated. The parents, F 1 and 162 F 2 plants were planted in winter season 2009 to evaluate heat tolerance during the grain-filling period. The sowing date in the present investigation represents the heat stress conditions in Saudi Arabia. The minimum number of genes or factors controlling heat tolerance was estimated (1.5) and the broad sense heritability was estimated as 47.7 %. The results revealed that three SSR markers; Xgwm132, Xgwm577 and Xgwm617 were linked to grain filling rate (GFR) by quantitative trait loci (QTL) analysis of the F 2 population. The results showed that regression analysis for the relationship between the three markers (Xgwm132, Xgwm577 and Xgwm617) and the phenotypes of F 2 plants were highly significant and the coefficients of determination (R 2 ) were 0.07, 0.25 and 0.03, respectively. This indicates that these three markers were associated with the grain filling rate as indicator for heat tolerant genes. The adjusted R 2 values suggested that the Xgwm132, Xgwm577 and Xgwm617 accounted for 7%, 25% and 3% of the total phenotypic variation of heat tolerance in the F 2 population, respectively. The results demonstrated that SSR markers, combined with bulked segregant analysis, could be used to identify molecular markers linked to the grain filling rate as indicator for heat tolerance in wheat

Assessment of the salt tolerance of wheat genotypes during the germination stage based on germination ability parameters and associated SSR markers

Although the germination stage accounts for a very short period of a plant’s life cycle, it involves numerous mechanisms and multistage processes that potentially differ among genotypes under salt stress. Therefore, we hypothesized that the parameters controlling the water uptake pattern and α-amylase activity during the seed germination process could be helpful for assessment the salt tolerance of wheat genotypes at the early growth stage. Genotypic differences in the germination ability parameters and α-amylase activity were assessed for seven wheat cultivars under normal and salt stress conditions at the molecular marker level using 30 simple sequence repeat (SSR) markers linked to salt tolerance. Results found that genotypic variations in the water uptake pattern were appeared at the late stage of phase II under both salinity levels and more obviously during phase III. Genotypic variations were observed in the germination time (GT), which was delayed by increasing salinity levels. The α-amylase activity and GT were positively and negatively correlated, respectively, with each time of water uptake rate. Significant correlation (r = 0.49, P = 0.026) was observed between similarity coefficients of germination ability parameters and SSR data based on the Mantel test. Among the 24 SSR markers, which showed polymorphism, Cdf 9, Cdf 46, Cdf 49, Wmc 503, and Gwm 312 were associated with almost germination ability parameters (R2 ranged from 0.43 to 0.95). Therefore, based on the molecular marker-phenotypic trait association at germination stage, assessment of salt tolerance in many wheat genotypes in a relatively short time could be conceivable