Genotype Main Effect Research Articles

Assessment of repeatability and representativeness of testing sites for provitamin a maize in savanna agro-ecologies of Nigeria

Identification of ideal testing sites for selection of superior maize (Zea mays L.) germplam is vital to the success of a maize breeding programme. Sixteen provitamin A maize genotypes were evaluated at seven locations in savanna agro-ecologies of Nigeria for 3 yr to assess the representativeness, discriminating ability, and repeatability of the testing sites and to identify ideal testing sites for selection of superior maize germplasm. Location, year, and their interaction effects were significant for grain yield and mostmeasured traits while genotype and genotype ´x year interactive effects were significant for grain yield. The genotype main effects plus genotype ´x environment interaction (GGE) biplot analysis revealed PVA SYN-18 F2 as the highest-yielding and most stable genotype across environments. The GGE biplot identified Zaria, Saminaka, and Kaboji as the most discriminating locations. Also, the biplot identified Kaboji, Batsari, Saminaka, and Zaria as the most repeatable locations. Zaria and Saminaka, being among the most discriminating, representative and repeatable locations, were considered as the core testing sites for selection of superior maize genotypes for release and commercialization. The core testing sites identified in this study should facilitate the identification of stable and high-yielding maize germplasm adaptable to the savannas agro-ecologies of Nigeria.

The behavioral effects of gestational and lactational benzo[a]pyrene exposure vary by sex and genotype in mice with differences at the Ahr and Cyp1a2 loci

Benzo[a]pyrene (BaP) is a polycyclic aromatic hydrocarbon (PAH) and known carcinogen in the Top 10 on the United States' list of priority pollutants. Humans are exposed through a variety of sources including tobacco smoke, grilled foods and fossil fuel combustion. Recent studies of children exposed to higher levels of PAHs during pregnancy and early life have identified numerous adverse effects on the brain and behavior that persist into school age and adolescence. Our studies were designed to look for genotype and sex differences in susceptibility to gestational and lactational exposure to BaP using a mouse model with allelic differences in the aryl hydrocarbon receptor and the xenobiotic metabolizing enzyme CYP1A2. Pregnant dams were exposed to 10 mg/kg/day of BaP in corn oil-soaked cereal or the corn oil vehicle alone from gestational day 10 until weaning at postnatal day 25. Neurobehavioral testing began at P60 using one male and one female per litter. We found main effects of sex, genotype and treatment as well as significant gene x treatment and sex x treatment interactions. BaP-treated female mice had shorter latencies to fall in the Rotarod test. BaP-treated high-affinity AhrbCyp1a2(−/−) mice had greater impairments in Morris water maze. Interestingly, poor-affinity AhrdCyp1a2(−/−) mice also had deficits in spatial learning and memory regardless of treatment. We believe our findings provide future directions in identifying human populations at highest risk of early life BaP exposure, because our model mimics known human variation in our genes of interest. Our studies also highlight the value of testing both males and females in all neurobehavioral studies.

Yield stability and test location representativeness in foxtail millet [Setaria italica (L.) Beauv.] genotypes

Development of a crop variety with high grain yield and stability in test locations is an important part of crop breeding program. Thirteen foxtail millet genotypes were evaluated in randomized complete block design with three replications in Jumla and Dolakha, Nepal from April to August in three consecutive years 2017, 2018, and 2019. The objective of this study was to analyze grain yield stability and adaptability of foxtail millet genotypes applying genotype main effect plus genotype by environment interaction (GGE) biplot analysis. The results showed that grain yields were significantly (P<0.05) affected by the environment (E), genotype (G), and their interaction (G×E). The genotype HUMLA-163 had regression coefficient equal to unity (b=1.01), thus this genotype had average adaptation to all environments whereas HUMLA-213 (b=1.18) and HUMLA-252 (b=1.19) had regression coefficients greater than unity, thus these genotypes were more adapted to favorable environments. GGE biplot showed that HUMLA-163 was more stable and adaptive genotype. Thus, genotype HUMLA-163 is recommended for release as a variety to improve foxtail millet production in hilly region of Nepal.

Comparative study on the stability and adaptability of different models to develop a high-yield inbred line from landrace rice varieties

Multilocation trials are important in plant breeding carried out in the field of agronomy. A combination of agronomy and plant breeding is needed to improve plant characteristics and stability testing before releasing new varieties. A single stability analysis method may not be sufficiently representative to determine the performance of genotypes across environments, which sometimes lead to wrong decisions about genotype stability. The objective of this study was to estimate yield potential, adaptability, and stability of superior lines resulting from inbred landraces based on parametric and nonparametric, and a genotype main effect G × E interaction (GGE) biplot. Fourteen inbred lines from Bengkulu landrace rice varieties were evaluated in five environments from January 2019 to November 2020. The experiment was conducted using a complete randomized block design with two replications. The results showed that the highest yield grouping based on the G × E heat-map, genotypes G13(BKL4-B1-268-10), G10(BKL2-B3-264-6), G7(BKL1-B3-261-3), and G5(BKL1-B1-259-1), was found in Sungai Serut. There was a strong positive correlation (r = 1.00) between the mean yield (Yi) and YSi, S2di and Di, and Wi2 and StabVar. Meanwhile, the genotype occurred in the top third of the ranks (TOP) had a positive correlation of 0.78, indicating a suitable stability parameter to identify high-yield genotypes. There were four consistently stable lines based on parametric and nonparametric stability analyses: G10(BKL2-B3-264-6), G7(BKL1-B3-261-3), G13(BKL4-B1-268-10), and G5(BKL1-B1-259-1). The GGE approach methods showed consistent stability, and lines G13(BKL4-B1-268-10), G10(BKL2-B3-264-6), G5(BKL1-B1-259-1), G7(BKL1-B3-261-3), and G6(BKL1-B2-260-2) had high-yield potential, wide adaptability, and stability, and are recommended for further testing as candidates for new varieties.

A study on genotype × environment interactions for the multiple traits of maize hybrids in China

AbstractThe correct interpretation of the adaptability and stability of maize (Zea mays L.) hybrids in different ecological environments is very important for plant breeders. Additive main effect and multiplicative interaction model and genotype main effects and genotype × environment interaction biplot are the two most popular methods in the analysis of genotype × environment interaction in multienvironment trials. We conducted an experiment designed to examine and evaluate the adaptability and stability of four agronomic traits of 19 tested maize genotypes in two consecutive growth cycles across seven provinces including 37 locations using a randomized completely block design with three replicates. The combined ANOVA for all traits showed that the effect of genotype, environment, and genotype × environment interaction were significant at 0.1% probability levels. In order to evaluate multiple agronomic traits more accurately, multitrait stability index (MTSI) as an emerging selection method based on mean performance and stability was adopted. Agronomic trait grain yield (GY) was positively correlated with grain weight per ear and growth period. In addition, it was also found that GY and bar tip length showed obvious negative correlation. The MTSI is very helpful for breeders who hope to select mean performance and stability based on a variety of agronomic traits because it provides a convenient selection process while taking into account the relevant results of the traits.

Molecular variability and salinity effects on growth characters and antioxidant enzymes activity in Egyptian barley genotypes

To evaluate the response of ten barley genotypes to high yield potency and constant performance under normal and saline soil conditions this study was carried out. All agronomic studied traits were significantly decreased due to saline stress. The main genotypic effect and genotype by environment interaction (GGE) biplot analysis revealed that Lines 6, 4, 8 and Giza-123 were the highest in the productivity and more tolerant to saline stress. Results of SSI indicated that, some genotypes were considered to be the highly tolerant for the studied traits. Also, the physiological response of barley leaves to salinity indicated that the activities of antioxidant defense enzymes were changed in equal with the increased salt concentrations in tolerant genotypes. Under gradual salt stress intensity, Lines 3, 5 and 6 showed highly increase in their peroxidase (POD), catalase (CAT) and polyphenol oxidase (POX) effectiveness associated with a significant altitude in their germination rate especially at 10 dsm−1 of NaCl. All genotypes recorded a significant excess in their activities under mild salt stress concentration (10 dsm−1 of NaCl) followed by a strong reduction in POD and CAT activities at sharp stress (14 dsm−1 of NaCl). While POX activity showed higher increase at14 dsm−1 of NaCl as compared to 10 dsm−1 of NaCl and control treatments. Molecular analysis showed that a total of 90 different loci with an average of 12.86 loci per RAPD primer were amplified from different barley genotypes in the three different systems, single, double and triple-RAPD, out of them, 77 loci (85.56%) were found to be polymorphic. The total percentages of polymorphism were decreased with increasing the number of primer combinations which recorded 91.67, 82.35 and 62.50% of polymorphism in the single, double and triple-RAPD systems, respectively, indicating that single-RAPD technique showed the highest percentage of polymorphism (91.67).

Productivity of Newly Released Common Bean (Phaseolus vulgaris L.) Varieties Under Sole Cropping and Intercropping With Maize (Zea mays L.)

Intercropping maize (Zea mays L.) with common bean (Phaseolus vulgaris L.) is one of the predominant farming practices in eastern and southern Africa (ESA) for effective use of resources and continuous household food supply. The productivity of sole or intercropped crops is subject to variety, location, year, and their interaction. Therefore, the objective of this study was to determine the productivity of newly released common bean varieties NUA45 and SER83 under sole cropping and intercropping with a maize hybrid variety SC672 as a guide to large-scale production. Experiments were conducted at Chitedze Agricultural Research Station (13.85°S; 33.38°E) and Linthipe Extension Planning Area (12.06°S; 33.25°E) in 2019 and 2020 in Malawi using a factorial arrangement laid out in a randomized complete block design (RCBD) with four replications. The numbers of pods per plant (NPP) and seeds per pod (NSP), grain yield (GYD), and 100-seed weight were collected for common bean included, while GYD was recorded for maize. The main effects for genotype, location, year, and intercropping system were significant (p < 0.05) for GYD in common bean. The effects of the year and cropping system and location by intercropping system interaction were significant for maize GYD. The maize yield did not vary between sole cropped and intercropped systems. The total land equivalent ratios (LERs) for NUA45 and SER83 were 1.59 and 1.77, respectively. The LER-values showed a significant difference (p < 0.034), suggesting a considerably higher benefit of maize and common bean intercropping. Overall, intercropping maize with common bean rendered higher yields in the SER83/SC672 intercropping system than the sole crop in the study areas. Therefore, intra-row intercropping of the newly released common bean variety SER83 with a maize hybrid variety SC672 is recommended in the study area and other similar agro-ecologies for stable and sustainable production of both crops.

Oxytocin receptor polymorphism influences characterization of harm avoidance by moderating susceptibility to affectionless control parenting.

IntroductionOxytocin receptor (OXTR) gene polymorphism reportedly moderates effects of negative environments during childhood on mental function and behavior such as depressive symptoms and externalizing problems. This study examined OXTR gene polymorphism effects on personality traits in healthy participants, considering interaction effects of polymorphism with affectionless control (AC) parenting which is one of the dysfunctional and pathogenic parenting styles.MethodsFor 496 Japanese volunteers, personality was evaluated using the Temperament and Character Inventory. The Parental Bonding Instrument, which has subscales of care and protection, was used to assess perceived parental rearing. AC parenting was defined as low care and high protection. A/G polymorphism of the OXTR gene (rs53576) was detected using TaqMan SNP Genotyping Assay.ResultsTwo‐way analysis of covariance revealed significant interaction effects between the genotype and the number of AC parents on scores of harm avoidance, with no significant main effect of genotype on any personality. Post‐hoc analysis revealed that the harm avoidance scores were increased in a stepwise manner with respect to the increase of the number of AC parents in the A allele carriers. No similar association was observed in the A allele noncarriers.ConclusionThe results of this study suggest that OXTR polymorphism influences characterization of harm avoidance by moderating susceptibility to AC parenting.

Dissection of genotype × tissue interactions for immunological factors in turbot (Scophthalmus maximus) infected with Vibrio anguillarum

Seven immune factors, lysozyme, hepcidin, heat-shock protein (HSP) 70, HSP90, immunoglobulin M, C-type lectin, and Lily-type lectin, were measured by PCR in the livers, spleens, and head kidneys of turbot infected with Vibrio anguillarum. Additive main effects and multiplicative interaction (AMMI) and genotype main effects and genotype × environment interaction (GGE) biplot analysis were used to analyze genotype × tissue interactions for immunological factors. The AMMI analysis revealed that immune factor expression was significantly affected by genotype, tissue, and genotype × tissue interactions. Genotype (65.85%) was the major contributor to the total variation in immune factor expression in comparison to tissue effects (7.54%) and genotype × tissue interactions (12.52%). GGE biplot analysis revealed differences in the ranking of the seven immune factors in the three tissues; head kidney possessed the strongest ability to distinguish the seven immune factors. The test tissue locations were divided into liver-spleen and head kidneys regions; HSP70 was expressed the highest in the liver-spleen regions, and lysozyme had the highest expression in the head kidney region. Overall, HSP70 and HSP90 had the best expression and stability in the three tissues.

Delineation of genotype\u2009\xd7\u2009environment interaction for identification of stable genotypes for tillering phase drought stress tolerance in sugarcane

Sugarcane is a trans-seasonal long-duration crop and tillering phase (60–150 days) is the most sensitive phase for moisture stress, causing significant reduction in biomass accumulation. The study focussed to assess the Genotype × Environment Interaction (GEI) for tillering phase moisture stress and to identify the stable genotypes in sugarcane. The study dealt with 14 drought tolerant genotypes and two standards (Co 86032 and CoM 0265) which were evaluated in two plant and one ratoon trials at four locations in Maharashtra, India. The moisture stress was imposed for 60 days from 90 to 150 days after planting and corresponded to tillering phase by withholding the irrigation. The AMMI ANOVA showed significant GEI for cane and CCS yield accounting 18.33 and 19.45 percent of variability respectively. Drought and genotype main effects were highly significant accounting 49.08 and 32.59 percent variability for cane yield and, 52.45 and 28.10 percent variability for CCS yield respectively. The first two interactive principal component (IPCA) biplots of AMMI showed diverse nature of all four environments and the Discriminative vs Mean biplots of Genotype + genotype × environment interaction (GGE) model showed that ‘Pune’ as the highly discriminating environment. The genotype ranking biplots of GGE showed that Co 85019 was the most stable genotype followed by Co 98017. Similar results were also observed in Yield vs IPCA1 biplot of AMMI, which revealed Co 85019 and Co 98017 as high yielding stable varieties. Yield related environmental maximum (YREM) showed thirteen and nine percent loss due to crossover interactions in Co 85019 for cane yield and CCS yield respectively. The multi-environment BLUP and genotype stability index (GSI) has reaffirmed that Co 85019 as a drought proof and stable genotype with high yield under tillering phase drought stress. The results suggested using Co 85019 for cultivation in drought prone regions and the usefulness of the methodology for identifying more such sugarcane varieties for the benefit of resource poor famers in drought affected regions.

GGE Biplot Analysis of Genotype × Environment Interaction and Yield Stability in Bambara Groundnut

In plant breeding and agricultural research, biplot analysis has become an important statistical technique. The goal of this study was to find the winning genotype(s) for the test settings in a part of the Southwest region of Nigeria, as well as to investigate the nature and extent of genotype × environment interaction (GEI) effects on Bambara groundnut (BGN) production. The experiment was carried out in four environments (two separate sites, Ibadan and Ikenne, for two consecutive years, 2018 and 2019) with ninety-five BGN accessions. According to the combined analysis of variance over environments, genotypes and GEI both had a substantial (p < 0.001) impact on BGN yield. The results revealed that BGN accessions performed differently in different test conditions, indicating that the interaction was crossover in nature. The results revealed that BGN accessions performed differently in different test conditions, indicating that the interaction was crossover in nature. To examine and show the pattern of the interaction components, biplots with the genotype main effect and genotype × environment interaction (GEI) were used. The first two PCs explained 80% of the total variation of the GGE model (i.e., G + GE) (PC1 = 48.59%, PC2 = 31.41%). The accessions that performed best in each environment based on the “which-won-where” polygon were TVSu-2031, TVSu-1724, TVSu-1742, TVSu-2022, TVSu-1943, TVSu-1892, TVSu-1557, TVSu-2060, and TVSu-2017. Among these accessions, TVSu-2017, TVSu-1557, TVSu-2060, TVSu-1892, and TVSu-1943 were among the highest-yielding accessions on the field. The adaptable accessions were TVSu-1763, TVSu-1899, TVSu-2019, TVSu-1898, TVSu-1957, TVSu-2021, and TVSu-1850, and the stable accessions were TVSu-1589, TVSu-1905, and TVSu-2048. In terms of discriminating and representativeness for the environments, Ibadan 2019 is deemed to be a superior environment. The selected accessions are recommended as parental lines in breeding programs for grain yield improvement in Ibadan or Ikenne or similar agro-ecological zones.

Nicotine preference and affective behavior of Cd81 knockout mice.

Cd81 -/- (knockout) mice have previously been reported to have reduced cocaine preference and increased striatal dopamine content and dopamine turnover, but normal learning and memory in the Morris water maze. The effects of Cd81 on other behaviors and drugs of abuse have not been investigated. We measured the effects of Cd81 -/- in a modified two-bottle choice test for nicotine, as well as in somatic signs of nicotine withdrawal, four tests of affective behavior, and tyrosine hydroxylase gene expression assays. We found that Cd81 loss-of-function significantly increased voluntary nicotine consumption and somatic signs of nicotine withdrawal. Nicotine consumption of Cd81 -/- female mice increased for 3weeks and then remained relatively stable for the next 5weeks, suggesting that their nicotine consumption continued to be limited by aversion to higher nicotine doses. Cd81 -/- also produced a dramatic and significant increase in struggling in the forced swim test and a significant increase in the time spent in the light chamber of the light/dark box. The elevated plus maze and the tail suspension test did not show a main effect of genotype. Therefore, we conclude that Cd81 did not have an overall effect on anxiety- or depression-like behavior. Tyrosine hydroxylase mRNA levels were unchanged. Cd81 knockouts have a strongly increased nicotine preference, plus a proactive response to specific stressful situations. Together with reports of increased striatal dopamine content and anecdotal reports of increased aggressiveness, these provide intriguing parallels to some aspects of post-traumatic stress disorder.

Shrinkage in the Bayesian analysis of the GGE model: A case study with simulation.

The genotype main effects plus the genotype × environment interaction effects model has been widely used to analyze multi-environmental trials data, especially using a graphical biplot considering the first two principal components of the singular value decomposition of the interaction matrix. Many authors have noted the advantages of applying Bayesian inference in these classes of models to replace the frequentist approach. This results in parsimonious models, and eliminates parameters that would be present in a traditional analysis of bilinear components (frequentist form). This work aims to extend shrinkage methods to estimators of those parameters that composes the multiplicative part of the model, using the maximum entropy principle for prior justification. A Bayesian version (non-shrinkage prior, using conjugacy and large variance) was also used for comparison. The simulated data set had 20 genotypes evaluated across seven environments, in a complete randomized block design with three replications. Cross-validation procedures were conducted to assess the predictive ability of the model and information criteria were used for model selection. A better predictive capacity was found for the model with a shrinkage effect, especially for unorthogonal scenarios in which more genotypes were removed at random. In these cases, however, the best fitted models, as measured by information criteria, were the conjugate flat prior. In addition, the flexibility of the Bayesian method was found, in general, to attribute inference to the parameters of the models which related to the biplot representation. Maximum entropy prior was the more parsimonious, and estimates singular values with a greater contribution to the sum of squares of the genotype + genotype × environmental interaction. Hence, this method enabled the best discrimination of parameters responsible for the existing patterns and the best discarding of the noise than the model assuming non-informative priors for multiplicative parameters.

Morphological and mechanical characterization of bone phenotypes in the Amish G610C murine model of osteogenesis imperfecta.

Osteogenesis imperfecta (OI) is a hereditary bone disease where gene mutations affect Type I collagen formation resulting in osteopenia and increased fracture risk. There are several established mouse models of OI, but some are severe and result in spontaneous fractures or early animal death. The Amish Col1a2G610C/+ (G610C) mouse model is a newer, moderate OI model that is currently being used in a variety of intervention studies, with differing background strains, sexes, ages, and bone endpoints. This study is a comprehensive mechanical and architectural characterization of bone in G610C mice bred on a C57BL/6 inbred strain and will provide a baseline for future treatment studies. Male and female wild-type (WT) and G610C mice were euthanized at 10 and 16 weeks (n = 13-16). Harvested tibiae, femora, and L4 vertebrae were scanned via micro-computed tomography and analyzed for cortical and trabecular architectural properties. Femora and tibiae were then mechanically tested to failure. G610C mice had less bone but more highly mineralized cortical and trabecular tissue than their sex- and age-matched WT counterparts, with cortical cross-sectional area, thickness, and mineral density, and trabecular bone volume, mineral density, spacing, and number all differing significantly as a function of genotype (2 Way ANOVA with main effects of sex and genotype at each age). In addition, mechanical yield force, ultimate force, displacement, strain, and toughness were all significantly lower in G610C vs. WT, highlighting a brittle phenotype. This characterization demonstrates that despite being a moderate OI model, the Amish G610C mouse model maintains a distinctly brittle phenotype and is well-suited for use in future intervention studies.

Genotypes by environment effect on flowering and seed set in cassava, Manihot esculenta Crantz in Uganda

Cassava (Manihot esculenta Crantz) production has been constrained by biotic and abiotic factors, which could be solved by conventional breeding. However, cassava hybridization is difficult because many genotypes do not flower or set seeds and yet cassava sexual reproduction is essential for breeding programs. Consequently, this study was undertaken to identify agro ecologies in Uganda that best promote cassava flowering and seed set in order to facilitate breeding. Field evaluation of eight genotypes in randomized complete block design with three replications at three agro-ecologies of Uganda for two cropping seasons was conducted. Weather data were monitored and cassava flowering/seed set-related traits were collected at one-month interval commencing from 1.5 Months after planting. Results indicated that varieties previously categorized as high flowering and seed set performed differently than those identified as poor flowering and seed set, although with varying genotypic differences in each environment. Genotypes mean performances, additive main effect and multiplicative interaction and genotype main effect and genotype by environment interaction bi-plots model’ results indicated Rwebitaba in Western savannah grassland agro-ecology and Namulonge-NaCRRI in Lake Victoria Crescent agro-ecology as the most favorable environments for the performance of all the evaluated traits, and season one as the most favorable season. However, the most stable environment for all the evaluated traits was Abi-ZARDI. Conclusively, the high proportion of variation which occurred between genotypes and environments was explained by the genotypic variances. Dry months had poorer cassava flower initiation and development than wet months of the cropping season. Therefore, Abi-ZARDI in North-western savannah grassland agro-ecology and season one could be recommended for the establishment and timing of cassava breeding nursery.

Genotype x Environment Interaction and Its Stability Measures; Major emphasis in Arabica Coffee: A Review

Understanding the implication of genotype x environment interaction (GEI) structure is an important consideration in plant breeding programs. The phenotype of an individual is determined by both the genotype and the environment, these two effects are not always additive which indicates that genotype x environment interactions (GEI) are present. The presence of genotype x environment interaction contributes to the unreliability 'of crop yield over a wide range of environments. The occurrence of large genotype x environment interaction makes the selection of superior genotypes difficult and inhibits progress from selection. It prevents the full understanding of genetic control of variability. In the absence of GEI, the superior genotype in one environment may be regarded as the superior genotype in all, whereas the presence of the GEI confirms particular genotypes being superior in particular environments. Therefore, it is important to understand the nature of genotype x environment interaction to make testing and selection of genotypes more efficient. A variety of statistical procedures are available to analyze the results of multi-environment trials. Additive Main Effects and Multiplicative Interaction (AMMI) model which combines the conventional analyses of variance for additive main effects with the principal components analysis (PCA) for the non-additive residuals and Genotypic Main effect plus genotype by environment interaction (GGE) biplot are two popular graphical analysis systems for multi-environment trials. Other method like the regression of genotype means on the environment means is also worthwhile. Keywords: Additive Main Effects and Multiplicative Interaction, genotype x environment interactions, Stability DOI: 10.7176/ALST/89-01 Publication date: August 31 st 2021

HIV Transgenic Rats Demonstrate Superior Task Acquisition and Intact Reversal Learning in the Within-Session Probabilistic Reversal Learning Task.

The HIV transgenic (HIVtg) rat is a commonly used animal model of chronic HIV infection that exhibits a wide range of cognitive deficits. To date, relatively little work has been conducted on these rats' capacity for reversal learning, an assay of executive function and cognitive flexibility used in humans. The present study sought todetermine the impact of HIV genotype on probabilistic reversal learning, effortful motivation, and spontaneous locomotion/exploration in rats. Male (n = 8) and female (n = 8) HIVtg rats and wildtype (WT) controlswere utilized. Cognitive flexibility was assessed via the Probabilistic Reversal Learning Task (PRLT), which reinforced responses to two stimuli on differential probabilistic schedules that periodically reversed. Effortful motivation and locomotor/exploratory behavior were assessed via the Progressive Ratio Breakpoint Task (PRBT) and the Behavioral Pattern Monitor (BPM), respectively. Regardless of sex, HIVtg rats required fewer trials to ascertain initial PRLT reward schedules than WT rats, and completed the same number of reversals. Secondary behaviors suggested that HIVtg PRLT performance was facilitated by a speed-accuracy tradeoff strategy. No main or interactive effects of genotype were observed in the PRBT or BPM. Relative to WT controls, HIVtg rats exhibited superior probabilistic reinforcement learning. Reversal learning was unaffected by HIV genotype, as was effortful motivation and exploratory behavior. These findings contrast with previous characterizations of the HIVtg rat, thus indicating a nuanced cognitive profile that is dependent upon suchtask specifications as within- versus between-session assessment and probabilistic versus deterministic reward schedules.

Germplasm Bred for Resistance to Striga hermonthica Exhibited High Resistance Levels to Striga asiatica Compared to Commercial Checks

Parasitic weeds belonging to the Orobanchaceae family are a menace in Sub-Saharan African (SSA). Specifically, the two witchweeds from the genus Striga, S. hermonthica and S. asiatica, are jointly responsible for land abandonments and cereal yield reductions in the SSA. Factorial experiments involving fourteen maize genotypes and two levels of Striga asiatica infestation (infested and noninfested) were conducted under pot and laboratory experiments at the Department of Plant Production Sciences and Technologies, University of Zimbabwe, during the 2014/2015 season. A 14 × 2 factorial pot experiment was arranged in a 7 × 4 α-lattice design replicated four times, whereas the laboratory agar gel was arranged in a complete randomized design with four replications. Results revealed significant differences ( p < 0.05) for S. asiatica and genotype main effects for the recorded traits. S. asiatica-infested genotypes had lower biomasses than noninfested ones. However, the University of Zimbabwe bred hybrids such as Ax31, Ax28, Ax7, and Ax32 had similar plant heights and stem, leaf, and cob biomass across the two Striga levels unlike the local checks, particularly SC513, SC537, and SC637, under Striga infestation. Moreover, these genotypes also had the least Striga germination percentage and furthest germination distance indicating that they are resistant/tolerant to Striga asiatica. The University of Zimbabwe bred hybrids, using Striga hermonthica resistance from the International Institute of Tropical Agriculture, exhibited resistance/tolerance to Striga asiatica compared to local checks. Therefore, these varieties could offer a better and viable Striga spp. control option to farmers in both S. hermonthica and S. asiatica endemic areas.

Detection of QTLs in a Mediterranean climate associated with fire blight necrosis length in Pyrus communis using a high‐resolution genetic linkage map

AbstractFire blight caused by the bacterium Erwinia amylovora, is the most critical disease of European pear. Breeding of resistant cultivars is a possible solution for a growing demand for healthier alternative practices for disease control. In this study, we present a pear fire blight genetic study using a large F1 population. Quantitative trait loci (QTLs) were detected using a high‐resolution genetic map, allowing detection of QTLs with small intervals. A total of 162 offspring crossbred between ‘Harrow Sweet’ (HS, low susceptibility cultivar) and ‘Spadona’ (SPD, high susceptibility cultivar) were studied. We detected a significant genotype effect (p < .0001), which explained 46.4% of the variance of the necrosis length. A major QTL of the main genotype effect (AVG) was detected at 8.8 cM in linkage group (LG) 2 (LOD = 7.7). Additional QTLs were detected in LGs 7, 13 and 15. These markers can greatly contribute to pear breeding programs in a Mediterranean climate and can shed light on potential candidate genes that control fire blight resistance.

Estabilidad fenotípica de nuevos cultivares de Saccharum spp. híbrido en ensayos multiambientales en Holguín

For the realization of this work three experiments were established in the Base Bussines Units Loynaz Hechavarria, Fernando de Dios and Lopez-Pena, where 12 cultivars and two controls were evaluated under rainfed conditions, during October 2010–March 2014 period, they were evaluated the harvest variables (percentage of pol in cane, tons of cane per hectare and tons of pol per hectare), in order to identify cultivars that present general phenotypic stability in different environments in study. Multivariate analysis methods were used to evaluate genotypes, environments and genotype - environment interaction. Use of multivariate model of main effects of genotypes, plus effects of genotype-environment interaction (GEI biplot), from Site Regression Model (SREG) allowed to identify the cultivars the best yield and with general stability in all environments, which were C92-524, C97-445 and C95-416, which also presented a satisfactory phytosanitary behavior under natural conditions. Recommendation the incorporation of same to the varieties projects of Base Business Units of Holguin Sugar Company where they were evaluated.