Genetic analysis for high temperature tolerance in bread wheat

Heat stress, characterised by a trend in average temperature increase during anthesis and grain filling, leads to forced maturity is one of the major constraints of wheat production in arid and, semiarid regions of the world. This study examined the nature and magnitude of gene action for yield and its contributing characters and some important heat tolerant parameters in bread wheat ( Triticum aestivum l em. thell) to determine breeding strategies for future breeding programmes. Twelve lines and four testers were crossed in an L x T mating design. The 48 crosses and their parents were raised under normal (21, November 2002) and late sown (1, January 2003) seasons at the Experimental Farm of Rajasthan College of Agriculture, Udaipur in India. Lines K\u2019sona, DWR 195, C 306 and K 9708 were found to be good combiners for different heat tolerant parameters along with grain yield. Combinations of Raj 3077 x Kailash under normal (E1) and late sown (E2), C 306 x PBN 51 (E1) and C 306 x HD 2189 (E2) for grain yield; had high sca effect. The crosses viz., K 9708 x PBN 51 for proline content and heat injury, DWR 195 with HD 2189, and C 306 with Kailash for heat injury had desirable significant sca effects. The other crosses, HD 2329 x Kailash for pollen viability, and Raj 3765 x Kailash for chlorophyll content, were the best specific combiners. Parents like C 306, K\u2019sona, DWR 195, K 9708, Raj 3077, PBN 51 and Kailash could be utilised in multiple crossing programmes and further biparental matting for selection of high yielding progenies for heat tolerance.Le stress d\ufb \ue0 la chaleur, caract\ue9ris\ue9 par une tendance \ue0 l\u2019augmentation de la temp\ue9rature moyenne au cours de l\u2019anth\ue9sis et du remplissage de grains, et conduisant \ue0 la maturation forc\ue9e est une des contraintes majeures \ue0 la production du bl\ue9 dans des r\ue9gions arides et semi arides du monde. Cette \ue9tude a examin\ue9 la nature et la magnitude de l\u2019action de g\ue8nes de rendement et ses caract\ue8res contributifs ainsi que quelques param\ue8tres importants de tol\ue9rance dans le bl\ue9 patissier ( Triticum aestivum ) afin de d\ue9terminer des strat\ue9gies d\u2019am\ue9lioration pour des programmes futures d\u2019am\ue9lioration. Douze lign\ue9es et quatre testeurs \ue9taient crois\ue9s en dispositf L x T. Les 48 croisements et leurs parents \ue9taient plant\ue9s en saisons normale (21, November 2002) et tardive (1, January 2003) \ue0 la ferme exp\ue9rimentale du coll\ue8ge d\u2019Agriculture de Rajasthan, Udaipur en Inde. Les lign\ue9es K\u2019sona, DWR 195, C 306 et K 9708 \ue9taient jug\ue9es de bons combinants pour diff\ue9rents param\ue8tres de tol\ue9rance \ue0 la chaleur avec un bon redement en grains. Les combinaisons de Raj 3077 x Kailash en saison normale (E1) et plant\ue9es tardivement (E2), C 306 x PBN 51 (E1) et C 306 x HD 2189 (E2) pour rendement en grain avaient un effet sca \ue9lev\ue9.Les croisements telque K 9708 x PBN 51 avec for proline content and heat injury, DWR 195 avec HD 2189, etC 306 avec Kailash pour dommage de la chaleur avaient d\u2019effects sca significatifs. Les autres croisements, HD 2329 x Kailash pour variabilit\ue9 de pollen, et Raj 3765 x Kailash pour contenu chlorophyllien, \ue9taient les meilleurs combinants sp\ue9cifiques. Les parents dont C 306, K\u2019sona, DWR 195, K 9708, Raj 3077, PBN 51 et Kailash pourraient \ueatre utilis\ue9s dans de multiples programmes de croisement et autres couvertures biparentales pour la s\ue9lection de prog\ue9nies \ue0 rendement \ue9lev\ue9 avec tol\ue9rance \ue0 la chaleur

A genome-wide gene-environment interaction study of breast cancer risk for women of European ancestry

Background Genome-wide studies of gene–environment interactions (G×E) may identify variants associated with disease risk in conjunction with lifestyle/environmental exposures. We conducted a genome-wide G×E analysis of ~ 7.6 million common variants and seven lifestyle/environmental risk factors for breast cancer risk overall and for estrogen receptor positive (ER +) breast cancer. Methods Analyses were conducted using 72,285 breast cancer cases and 80,354 controls of European ancestry from the Breast Cancer Association Consortium. Gene–environment interactions were evaluated using standard unconditional logistic regression models and likelihood ratio tests for breast cancer risk overall and for ER + breast cancer. Bayesian False Discovery Probability was employed to assess the noteworthiness of each SNP-risk factor pairs. Results Assuming a 1 × 10–5 prior probability of a true association for each SNP-risk factor pairs and a Bayesian False Discovery Probability < 15%, we identified two independent SNP-risk factor pairs: rs80018847(9p13)-LINGO2 and adult height in association with overall breast cancer risk (ORint = 0.94, 95% CI 0.92–0.96), and rs4770552(13q12)-SPATA13 and age at menarche for ER + breast cancer risk (ORint = 0.91, 95% CI 0.88–0.94). Conclusions Overall, the contribution of G×E interactions to the heritability of breast cancer is very small. At the population level, multiplicative G×E interactions do not make an important contribution to risk prediction in breast cancer

Physical activity, sedentary time and breast cancer risk: a Mendelian randomisation study

Objectives: Physical inactivity and sedentary behaviour are associated with higher breast cancer risk in observational studies, but ascribing causality is difficult. Mendelian randomisation (MR) assesses causality by simulating randomised trial groups using genotype. We assessed whether lifelong physical activity or sedentary time, assessed using genotype, may be causally associated with breast cancer risk overall, pre/post-menopause, and by case-groups defined by tumour characteristics. Methods: We performed two-sample inverse-variance-weighted MR using individual-level Breast Cancer Association Consortium case-control data from 130 957 European-ancestry women (69 838 invasive cases), and published UK Biobank data (n=91 105–377 234). Genetic instruments were single nucleotide polymorphisms (SNPs) associated in UK Biobank with wrist-worn accelerometer-measured overall physical activity (nsnps=5) or sedentary time (nsnps=6), or accelerometer-measured (nsnps=1) or self-reported (nsnps=5) vigorous physical activity. Results: Greater genetically-predicted overall activity was associated with lower breast cancer overall risk (OR=0.59; 95% confidence interval (CI) 0.42 to 0.83 per-standard deviation (SD;~8 milligravities acceleration)) and for most case-groups. Genetically-predicted vigorous activity was associated with lower risk of pre/perimenopausal breast cancer (OR=0.62; 95% CI 0.45 to 0.87,≥3 vs. 0 self-reported days/week), with consistent estimates for most case-groups. Greater genetically-predicted sedentary time was associated with higher hormone-receptor-negative tumour risk (OR=1.77; 95% CI 1.07 to 2.92 per-SD (~7% time spent sedentary)), with elevated estimates for most case-groups. Results were robust to sensitivity analyses examining pleiotropy (including weighted-median-MR, MR-Egger). Conclusion: Our study provides strong evidence that greater overall physical activity, greater vigorous activity, and lower sedentary time are likely to reduce breast cancer risk. More widespread adoption of active lifestyles may reduce the burden from the most common cancer in women

Effect of intermating on genetic variability and character association in aromatic Rice (Oryza sativa L.)

Biparental mating (BIP) attempted in the F2 of a cross of P-1460 × P-1121 revealed that, the biparental progenies had better mean performance as compared to F3 progenies for all the characters studied. In general, the lower limits of the range decreased for all the characters in the biparental progenies widening the variability. The variation created on account of biparental mating was found to be heritable as seen from increase in heritability estimates and genetic advance as per cent of mean. Highest value of genetic and phenotypic coefficient of variation were recorded for yield / plant (34.00 and 35.21) followed by No. of spikelet’s / panicle (22.05 and 23.26). Test weight (g) and panicles / m2exhibited high heritability and genetic advance (% as mean). The correlation coefficient in biparental progenies are generally of higher magnitude than in F3 populations. Traits like, panicles/m2, Spikelet’s/ panicle, panicle length, test weight (g) and days to maturity showed significant correlation with yield / plant in biparental progenies. It was also observed that, the non-significant negative association between panicles/m2 with yield / plant (g) in F3 changed to positive and significant in BIP population. Similarly, non-significant positive association between days to 50% flowering, spikelet’s / panicle, panicle length (g) and test weight with yield / plant in F3 got changed to positive and significant in BIP populations. These results indicated that intermating in F2 was quite effective to break undesirable linkage

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Stability Analysis in Six-row Barley Genotypes for Grain Yield in Multi-environmental Trails Using Eberhart and Russel (1966)

The current study aimed to determine the phenotypic stability for grain yield per plant under three distinct environmental conditions using fifteen parental lines and three testers with 45 crosses (30 single crosses and 15 three-way crosses) of six-row barley in three replications using Randomized Block Design. Eberhart and Russell (1966) developed the modal to examine stability. The mean sum of squares due to genotype and environment wassquares due to genotype and environment were found to be significant for grain yield per plant, which showed the differential effect of environment on genotypes. For grain yield per plant, it was also observed that the mean sum square resulting from the climate + (G x E) interaction, E (linear), and G x E (linear) was significant. With a non-significant deviation from regression (S2di=0) and regression coefficient near unity (bi=1), the genotypes BG 959, BG 105 x RD 2508, PL 751 x RD 2508, DWRB 137 x RD 3005, and RD 2035 x F1 exhibited higher grain yield than the population mean. These genotypes were the most stable and desirable under variable environmental conditions. These genotypes could be used as donors in regular breeding programs to improve barley grain yield

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http://www.indianjournals.com/ijor.aspx?target=ijor:ijws&volume=48&issue=2&article=012An experiment consisting of five establishment techniques in rice-wheat cropping sequence with different combinations of conventional tillage (CT), zero-tillage (ZT) and minimum tillage (MT) viz. (CT-CT, ZT-CT, CT-ZT, ZT-ZT and MT-ZT) was conducted during 2003–2007 at the farm of a farmer in Haryana on a larger plot size of 0.4 ha under each treatment. During first year, grain yield of wheat did not differ significantly among different treatments but during 2004–05 to 2007–08, grain yield of wheat in ZT method of planting was either higher or at par with conventional ploughed method of planting but CT transplanting of rice was significantly more than ZT transplanted treatments except during first year when rains were very good at transplanting time. Weed dynamics after 4 years revealed that in rice crop, weed density of Echinochloa colona, E. crusgalli, Leptochloa chinensis, Cyperus spp. and broad-leaf weeds such as Ammania baccifera and Eclipta alba was more when rice was transplanted under ZT or MT conditions but in wheat, weed density of grassy weed Phalaris minor was less under ZT-ZT or MT-ZT treatments. After 4 years of continuous ZT in both rice and wheat crops, weed flora changed in favour of broad-leaf weeds. Bulk density of soil did not vary after 5 years of ZT-ZT conditions. Soil temperature of root zone in wheat crop planted under ZT conditions was more (0.7–1.7 OC) in first week of February and less (2.1-.3.8 OC) in first week of April as compared to conventional CT-CT practice of rice and wheat crops resulting in more grain yield of wheat due to temperature moderation and also due to a bit addition of organic matter in ZT conditions. Grain yield of rice planted under ZT or MT conditions was less mostly due to more weed infestation and it also consumed 4.8–184% more water as compared to CT method of puddle transplanted rice.Not Availabl

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Physical activity, sedentary time and breast cancer risk: a Mendelian randomisation study

Objectives Physical inactivity and sedentary behaviour are associated with higher breast cancer risk in observational studies, but ascribing causality is difficult. Mendelian randomisation (MR) assesses causality by simulating randomised trial groups using genotype. We assessed whether lifelong physical activity or sedentary time, assessed using genotype, may be causally associated with breast cancer risk overall, pre/post-menopause, and by case-groups defined by tumour characteristics.Methods We performed two-sample inverse-variance-weighted MR using individual-level Breast Cancer Association Consortium case-control data from 130 957 European-ancestry women (69 838 invasive cases), and published UK Biobank data (n=91 105-377 234). Genetic instruments were single nucleotide polymorphisms (SNPs) associated in UK Biobank with wrist-worn accelerometer-measured overall physical activity (n(snps)=5) or sedentary time (n(snps)=6), or accelerometer-measured (n(snps)=1) or self-reported (n(snps)=5) vigorous physical activity.Results Greater genetically-predicted overall activity was associated with lower breast cancer overall risk (OR=0.59; 95% confidence interval (CI) 0.42 to 0.83 per-standard deviation (SD;similar to 8 milligravities acceleration)) and for most case-groups. Genetically-predicted vigorous activity was associated with lower risk of pre/perimenopausal breast cancer (OR=0.62; 95% CI 0.45 to 0.87,>= 3 vs. 0 self-reported days/week), with consistent estimates for most case-groups. Greater genetically-predicted sedentary time was associated with higher hormone-receptor-negative tumour risk (OR=1.77; 95% CI 1.07 to 2.92 per-SD (similar to 7% time spent sedentary)), with elevated estimates for most case-groups. Results were robust to sensitivity analyses examining pleiotropy (including weighted-median-MR, MR-Egger).Conclusion Our study provides strong evidence that greater overall physical activity, greater vigorous activity, and lower sedentary time are likely to reduce breast cancer risk. More widespread adoption of active lifestyles may reduce the burden from the most common cancer in women.Genome Instability and Cance