High H2b Research Articles

Estimation of variability, heritability, and genetic advance among Ethiopian coriander (Coriandrum sativum L.) accessions

The objective of this study was to assess the extent of variability of yield and yield-related traits, heritability, and genetic advances among Ethiopian coriander accessions. The experiment was conducted at Kulumsa Agricultural Research Center, Southeast Ethiopia, during 2019- 2020 cropping seasons. Twenty-five Ethiopian coriander accessions were tested in a 5 x 5 simple lattice design with two replications; and data were collected on eight yield and yield-related traits. The combined analysis of variance revealed highly significant differences (P<0.01) between coriander accessions for each trait. The results showed a wide range of variability in all studied traits, indicating the potential for simultaneous improvement of yield and yield-related traits. The heritability (H2b) estimates ranged from low for seeds per umbellet and thousand seed weight to very high, for seed yield per hectare and number of umbels per plant in the first and second cropping season, respectively. The highest genetic advances as a percentage of the mean (GAM (%)) were observed for seed yield per plant, seed yield per hectare, and number of umbellets per umbel. These findings suggest that cultivar selection based on these traits with high H2b coupled with GAM (%) could enhance progeny performance and increase the productivity and profitability of coriander. Therefore, the results had practical implications for coriander breeders and farmers in Ethiopia and could contribute to the development and sustainable coriander farming practices. Further investigations are necessary to identify superior accessions with desirable processing qualities, assess the phenotypic and genotypic diversity among Ethiopian coriander accessions.

Analysis of genetic variability and agronomic performance of Indian lettuce (Lactuca indica L.)

Lactuca indica L. is an undomesticated medicinal crop in the Asteraceae family. The study was carried out to identify elite genotypes for lettuce cultivation and breeding improvement. Data was recorded for 19 morphological and developmental traits across 38 accessions (Acc). The genotypic mean square variance was significant for all characters. The higher extent of genotypic and phenotypic coefficient of variation were obtained for basal branch, leaf blade width, and node number. The broad-sense heritability (H2B) ranged from 45.85% (seed length) to 98.59% (node number), whereas genetic advance as a percentage of the mean (GAM%) ranged from 9.33 to 191. Vegetative characters such as node number, plant height, basal branches were conjugated with high H2B and high GAM% indicating additive gene effect and selection of these traits based on phenotypic observation is effective for better gain. Reproductive traits, including bolting duration, flowering duration, and seed weight were linked with high H2B, and moderate GAM% revealing that these traits are amenable to genetic improvement, these traits also showed a significant and high positive correlation. Acc 55 and 8 showed the best performance for the majority of the attributes could be good material for further research and breeding. In the Wards’ phylogenetic tree of morphological traits, accessions were clustered based on their phenotypic characters rather than the geographic origin.

Potential Adoption of the F2 Generation of Some TYLCV-Resistant Tomato Hybrids in Commercial Production under Natural Field Infection

The economic feasibility of using the tomato yellow leaf curl virus (TYLCV) resistant F1 tomato hybrids (Solanum lycopersicum L.) may be improved with the possibility of using their F2 generation in commercial production. Hence, this study was performed to evaluate the F1 and F2 generations of 15 TYLCV resistant/tolerant commercial tomato hybrids during the 2018 and 2019 fall season to identify the best hybrids and F2 populations for commercial production. Both F1 and F2 populations were evaluated separately for TYLCV resistance, yield, and fruit quality traits. Broad sense heritability (H2b) values of TYLCV-resistance were high, being > 60% in hybrids 186, Goldstone, Rabha, SV0922 and SV8320 in both seasons. F1 and F2 populations of ‘186’, ‘Dania’, ‘PS550’, ‘Rozalina’, ‘SV0922’, ‘SV8320’, and ‘Tyrmes’ had the highest total yield (TY)/plant, low TYLCV disease (TYLCVD) mean scores, acceptable fruit quality traits, and average fruit weight > 80 g. Desirable inbreeding depression (ID) values were observed for TYLCVD-mean score in F2 populations of most evaluated hybrids; for TY/plant in F2 populations of ‘SV3773’ in both seasons, and in populations of ‘186’, ‘448’, ‘Goldstone’, ‘Rabha’, ‘SV8320’ and ‘SV0922’ in the second season. Most hybrids had desirable significant ID values for fruit quality traits. Accordingly, it is concluded that the F2 populations of hybrids 186, SV0922 and SV8320 may be used in commercial tomato production under TYLCV-infection in fall season, as these populations recorded high h2b values for TYLCV-resistance trait and desirable ID for TYLCV-resistance, yield, and fruit quality traits.

Lactose tolerance test as an alternative to hydrogen breath test in the study of lactose malabsorption.

Lactose malabsorption is generally assessed by hydrogen breath testing (HBT). However, this test is not recommended in patients with high baseline hydrogen concentrations (H2B). In addition, breath testing is not recommended in the current situation created by the COVID-19 pandemic, due to the potential infectiveness of the samples. The objective is to assess concordance between HBT and lactose tolerance test (LTT) depending on H2B concentrations. A total of 430 patients (40years, Q1-Q3=28-54years; 66.7% women) suspected of lactose malabsorption were included in the study. Breath and heparinized blood samples were collected at baseline and sequentially after the intake of 50g of lactose, to measure hydrogen in breath and glycemia in blood, respectively. H2B was <10ppm in 69.5% of subjects; 10-20ppm in 14.7%; and >20ppm in 15.8% of subjects. In patients with H2B <20ppm, concordance between HBT and LTT was moderate and consistently improved when the cut-off in LTT was set at 15mg/dL. The increase in hydrogen and glucose correlated negatively (r=-0.389; p<0.05). The increase in glycemia during LTT was not influenced by H2B levels obtained in HBT. LTT emerges as an alternative to HBT to assess lactose malabsorption in the presence of high H2B levels or when breath testing is not recommended by the circumstances. The best concordance was obtained when the cut-off for LTT was set at 15mg/dL.

Poly(ADP-ribose) glycohydrolase silencing-mediated H2B expression inhibits benzo(a)pyrene-induced carcinogenesis.

Poly(ADP‐ribose) glycohydrolase (PARG) as a main enzyme hydrolyzing poly(ADP‐ribose) in eukaryotes, and its silencing can inhibit benzo(a)pyrene (BaP)‐induced carcinogenesis. A thorough understanding of the mechanism of PARG silenced inhibition of BaP‐induced carcinogenesis provides a new therapeutic target for the prevention and treatment of environmental hazard induced lung cancer. We found that the expression of several subtypes of the histone H2B was downregulated in BaP‐induced carcinogenesis via PARG silencing as determined by label‐free proteomics and confirmed by previous cell line‐ and mouse model‐based studies. Analysis using the GEPIA2 online tool indicated that the transcription levels of H2BFS, HIST1H2BD, and HIST1H2BK in lung adenocarcinoma (LUAD) tissues and squamous cell lung carcinoma (LUSC) tissues were higher than those in normal lung tissues, while the transcription levels of HIST1H2BH in LUSC tissues were higher than those in normal lung tissues. The expression levels of HIST1H2BB, HIST1H2BH, and HIST1H2BL were significantly different in different lung cancer (LC) stages. Moreover, the expression of H2BFS, HIST1H2BD, HIST1H2BJ, HIST1H2BK, HIST1H2BL, HIST1H2BO, HIST2H2BE, and HIST2H2BF was positively correlated with that of PARG in LC tissues. Analysis of the Kaplan‐Meier plotter database indicated that high H2B levels predicted low survival in all LC patients suggesting that H2B could be a new biomarker for determining the prognosis of the LC, and that its expression can be inhibited by PARG silencing in BaP‐induced carcinogenesis.

Genetic Variation of Quantitative and Quality Traits in Rice Varieties

An investigation was carried out to study the genetic parameters and character association for yield, yield attributing, quality and nutritional traits of twelve rice varieties. Analysis of variance revealed significant differences for all the traits under study indicated the presence of wide genetic variability among the genotypes. Small differences between genotypic coefficient of variation and phenotypic coefficient of variation were recorded for all the characters studied which indicated less influence of environment on these characters. High heritability coupled with high genetic advance was observed for zinc content (brown) and number of chaffy grain per panicle exhibited, indicating that simple selection could be effective for improving these characters. Yield per hill had the highest positive direct effect. This study revealed that yield per hill, days to 50% flowering, days to maturity, panicle length and thousand grain weight are the most important yield contributing characters and an attempt should, therefore, be made for effective selection on these traits. Yield per hill might be considered as the most important trait due to low difference of GCV and PCV, high heritability in broad sense (h2b) with high genetic advance (GA) in percent of mean, significant positive correlation and high positive indirect effects. Another important trait such as days to 50% plants to flowering and thousand grain weight might also be considered due to their minimum difference of GCV and PCV values, high h2b with high GA in percent of mean, significant positive correlation and higher positive direct effects.&#x0D; Ann. Bangladesh Agric. (2019) 23(1) : 69-77

Selection Criteria and Selection Environment for Drought Tolerance of Egyptian Wheat (Triticum aestivum L.) Landraces

Strong correlations between wheat traits and drought tolerance (DT) associated with high heritability and high genetic advance from selection would allow plant breeder to use such traits as selection criteria. The objective of the present investigation was to determine the optimum selection criteria and selection environment for drought tolerance via estimation of correlation coefficients (r) among 13 agronomic, grain yield and quality traits and DT of 20 wheat landraces, broad-sense heritability (h2b) and genetic advance (GA) from selection for such traits under well-watered (WW) and water stressed (WS) environments. A two-year experiment was carried out using a split-plot design with four replications. Results concluded that the best selection criterion for drought tolerance in our study was grain yield/plant (GYPP), followed by a number of grains/spike (GPS), grain filling period (GFP), grain starch (GSC) and protein (GPC) content, plant height (PH) and days to maturity (DTM), since they showed high (r), high h2b and high GA estimates. The best selection environment was WW for days to anthesis, PH, spikes/plant, GPS, spikelets/spike, GYPP, GPC and WS for DTM, GFP, GSC and thousand-grain weight traits. This information could help future breeding programs in selection for improving drought tolerance of wheat.

Phenotypic Parent Selection Within a Khorasan Wheat Collection and Genetic Variation in Advanced Breeding Lines Derived by Hybridization With Durum Wheat.

Tetraploid relatives of durum wheat (Triticum turgidum L. subsp. durum (Desf.) Husnot) represent an important reservoir of economically useful genes for development of new wheat cultivars. Two field experiments were conducted at Foggia (Italy), in the 2004 to 2006 and 2012 to 2015 growing seasons. In the first, 77 Khorasan wheat [T. turgidum subsp. turanicum (Jakubz.) Á. Löve & D. Löve] accessions from 23 countries of four geographic regions (Africa, Asia, Europe, and others) were evaluated to explore breeding opportunities. Seven agronomic traits were used to describe the diversity among the accessions: days to heading (HT), plant height (PH), grain yield (GY), specific weight (SW) as an indication of the density of the grain, 1000-grain weight (TGW), protein content, and gluten content. The total Shannon–Weaver diversity index was used to estimate phenotypic diversity, which ranged from monomorphic for PC (0.39) to highly polymorphic for TGW (0.67). A high level of total variation (87%) was attributed to the within-region diversity. The accessions grouped into six clusters, and seven elite accessions were selected as parents for crosses with durum wheat. In the second experiment, ten parents (seven Khorasan accessions and three durum wheat cultivars) and 790 F6 recombinant inbred lines (RILs) from the different T. durum × T. turgidum subsp. turanicum crosses were included to study genotypic and phenotypic variability of the same agronomic traits, plus the susceptibility index (SI) for disease. The genotypic coefficients of variation were lower than the phenotypic ones for all of the traits, which showed an environment effect on expression of these traits. High broad-sense heritability (h2 b > 86%) was recorded for all traits, and high h2 b coupled with high genetic gain as percentage of the mean (ΔG) was observed for HT, PH, GY, and SW, and for SI. This suggests that selection for these traits will provide good responses. Four principal components explained 70% of the total variation, and the genotypes were clustered into 20 groups. According to the results, some lines could be tested in varietal registration trials, and/or could be used as a significant breeding pool for durum wheat cultivar development in Mediterranean area.

Heritability and Correlations for Agronomic and Physiologic Traits of Maize under Deficit Irrigation at Two Growth Stages

Strong associations between agronomic and physiologic traits and drought tolerance, high heritability and high genetic advance for such traits would allow plant breeder to use such traits as selection criteria for selecting drought tolerant genotypes. The objectives of the present investigation were: (i) to explain the relationships between the drought tolerance index (DTI) and 14 agronomic and physiologic traits of 22 maize genotypes and (ii) to estimate the broad-sense heritability (h2b) and genetic advance (GA) from selection for such traits, in order to determine the selection criteria for DTI. A two-year experiment was carried out using a split plot experiment with three replications. The main plots were devoted to irrigation regimes, i.e. well watering (WW), water stress at flowering (WSF) and at grain filling (WSG), and sub plots to maize genotypes. It is evident from results that the best selection criteria for drought tolerance in our study were: 100-kernel weight (100KW) and chlorophyll concentration index (CCI) under WSF and WSG, anthesis-silking interval (ASI), upper stem diameter (SDU) and lower stem diameter (SDL) under WSF and kernels/row (KPR) and ear leaf area (ELA) under WSG, since they show high correlation (r) values with grain yield/plant (GYPP), high h2b and high GA estimates under the respective environments. Under well watering conditions, KPR, 100KW, CCI, and SDL traits showed high (r) values, high h2b and high GA estimates and therefore could be considered selection criteria for GYPP under non-stressed environment. The results concluded that predicted selection gain would be higher if selection was practiced under WW for lower values of days to silking and higher values of ears/plant, rows/ear, KPR, 100KW, SDU and SDL, under WSF for lower values of ASI and higher values of GYPP and under WSG for lower values of plant height, ear height, and barren stalks, and higher values of CCI and ELA.

Agro-morphological variation in “Jhinuwa” rice landraces (Oryza sativa L.) of Nepal

Jhinuwa is an aromatic rice (Oryza sativa L.) landrace from the Pokhara Valley of Nepal. A total of 210 accessions comprising seven types of Jhinuwa rice landraces were randomly collected from the rice fields to evaluate inter- and intra-population variability based on agro-morphological traits. The experiment was conducted in factorial randomized complete block design with three replicates in 2005. The first six principal components (PCs) accounted for 76.6 % variation for agro-morphological traits. Major traits that accounted for the variation by six PCs includes days to heading, days to maturity, total grain panicle−1, fertile grain panicle−1, culm length, panicle length, milling recovery, head rice recovery, aroma, 1,000 grain weight, sterile grain panicle−1, grain sterility %, and leaf characteristics. Both principal coordinate analysis and cluster analyses revealed four phenotypic groups, two of which represent Bayarni, Jhinuwa, and Biramphul while the other two account for Tunde and Pakho Tunde. Tunde, Pakho Tunde, Kalo Bayarni, and Seto Bayarni showed higher intra- as well as inter-population variation compared to other populations. The phenotypic and genotypic coefficients of variation, broad sense heritability (h 2B) and genetic advance (GA) as a percent of the mean assessed for 210 accessions revealed high h 2B and GA estimates for leaf width, leaf length breadth ratio, ligule length, sterile grain panicle−1, grain sterility % and 1,000 grain weight. The current study demonstrates that improvement in Jhinuwa rice landrace is possible by selecting superior accessions from existing natural populations while selection should be focussed to market traits with higher h 2B and GA estimates.

EXPLORING THE GENETIC DETERMINISMS OF ARCHITECTURAL AND FUNCTIONAL TRAITS IN AN APPLE PROGENY

Traits related to tree architecture and tolerance to abiotic stress represent innovative targets for the selection of new cultivars in the contexts of integrated fruit production (IFP) and global climatic changes. Controlling tree form and leaf functioning is thus a desirable breeding objective, but efforts have been hampered by a poor knowledge of their determinisms in apple. In the last four years, the genetic basis of architectural and ecophysiological traits was investigated in a F1 apple progeny (‘Starkrimson’ × ‘Granny Smith’ cross) of 123 genotypes. A fine phenotyping was performed over the first 3 years of growth in the open field, collecting both topological and geometrical traits along the scaffold axes and at the whole tree level. After replication of the progeny, the leaf gas exchange responses to different air droughts were studied on 1-year-old plants in a controlled environment chamber, through five increasing leaf-to-air vapour pressure deficits (VPD, from 0.5 to 3 kPa). Stomatal conductance (gsw), net CO2 assimilation (An) and transpiration (E) rates were measured, and instantaneous water use efficiency (WUE, An / E) computed. All traits were analyzed through linear models and broad sense heritability values (h²b) were estimated. A quantitative trait loci (QTL) analysis was carried out using a consensus genetic map. For each trait, QTL detection was performed on the best linear unbiased predictor (BLUP) of genotypic values, computed from the linear model. For architectural traits, high h²b values were estimated and QTLs detected for many topological and geometric traits: (i) at tree scale, surface and volume; (ii) on the trunk, mean internode length and number of sylleptic and proleptic axillary shoots; (iii) on lateral shoots, orientation, mean internode length, and number of proleptic axillary shoots. Regarding ecophysiological traits h²b values were also high, indicating a good repeatability of ecophysiological measurements in controlled conditions. QTLs were detected for gsw and E suggesting a strong genetic control of these two traits. The putative agronomic interests and potential values for selection of the architectural and ecophysiological traits are discussed.

Quantitative proliferation dynamics and random chromosome segregation of hair follicle stem cells

Regulation of stem cell (SC) proliferation is central to tissue homoeostasis, injury repair, and cancer development. Accumulation of replication errors in SCs is limited by either infrequent division and/or by chromosome sorting to retain preferentially the oldest 'immortal' DNA strand. The frequency of SC divisions and the chromosome-sorting phenomenon are difficult to examine accurately with existing methods. To address this question, we developed a strategy to count divisions of hair follicle (HF) SCs over time, and provide the first quantitative proliferation history of a tissue SC during its normal homoeostasis. We uncovered an unexpectedly high cellular turnover in the SC compartment in one round of activation. Our study provides quantitative data in support of the long-standing infrequent SC division model, and shows that HF SCs do not retain the older DNA strands or sort their chromosome. This new ability to count divisions in vivo has relevance for obtaining basic knowledge of tissue kinetics.

Inheritance of Seed Dormancy in Weedy Rice

Seed dormancy contributes to the adaptability of plants in nature and is of considerable importance in agriculture. The weedy rice (Oryza sativa L.) strains LD, SS18‐2, and TKN12‐2 and cultivar ‘N22’ were selected to investigate the inheritance of dormancy in controlled conditions. Initial investigations using intact seeds, caryopses, caryopses with pericarp/testa removed, and excised embryos demonstrated that seed dormancy was imposed by the hull in SS18‐2 and TKN12‐2, and by the hull and pericarp/testa in LD and N22. Seed dormancy at 0 d after harvest (DAH) was dominant with average degree of dominance (ADD) &gt; 0.8 in the crosses with weedy strains. Dominance for duration of seed dormancy was incomplete when judged by days to 50% germination. Broad‐sense heritability (h2b) for seed germination was lower at 0 DAH and highest at 20 DAH in all the crosses. The weedy strain‐derived F2 populations maintained a higher h2b during afterripening. The effects of three and two major genes on seed germination at 20 DAH were detected in the SS18‐2‐ and N22‐derived F2 populations, respectively. A positive ADD, a high h2b, and major gene effect for caryopsis germination at 0 DAH were detected only in the cross with LD. Seed or caryopsis dormancy was correlated with the characteristics awn and black hull or red pericarp colors in the SS18‐2‐ or LD‐derived F2 populations. This research demonstrates that weedy rice provides ideal gene resources to elucidate mechanisms of dormancy and to improve resistance to preharvest sprouting.

Inheritance of Seed Dormancy in Weedy Rice

Seed dormancy contributes to the adaptability of plants in nature and is of considerable importance in agriculture. The weedy rice (Oryza sativa L.) strains LD, SS18-2, and TKN12-2 and cultivar ‘N22’ were selected to investigate the inheritance of dormancy in controlled conditions. Initial investigations using intact seeds, caryopses, caryopses with pericarp/testa removed, and excised embryos demonstrated that seed dormancy was imposed by the hull in SS18-2 and TKN12-2, and by the hull and pericarp/testa in LD and N22. Seed dormancy at 0 d after harvest (DAH) was dominant with average degree of dominance (ADD) > 0.8 in the crosses with weedy strains. Dominance for duration of seed dormancy was incomplete when judged by days to 50% germination. Broad-sense heritability (h2b) for seed germination was lower at 0 DAH and highest at 20 DAH in all the crosses. The weedy strain-derived F2 populations maintained a higher h2b during afterripening. The effects of three and two major genes on seed germination at 20 DAH were detected in the SS18-2- and N22-derived F2 populations, respectively. A positive ADD, a high h2b, and major gene effect for caryopsis germination at 0 DAH were detected only in the cross with LD. Seed or caryopsis dormancy was correlated with the characteristics awn and black hull or red pericarp colors in the SS18-2- or LD-derived F2 populations. This research demonstrates that weedy rice provides ideal gene resources to elucidate mechanisms of dormancy and to improve resistance to preharvest sprouting.

Diabetes-Associated Impairment of Hepatic Insulin Receptor Tyrosine Kinase Activity: A Study of Mechanisms*

Insulin receptor tyrosine kinase activity solubilized from liver of control and streptozotocin diabetic rats was studied using histone H2b and poly-Glu-Tyr (4:1) as phosphoacceptors. Both substrates inhibited autophosphorylation and exogenous kinase activity when added before, but not after, receptor activation with ATP. When H2b was added before ATP, insulin stimulated exogenous kinase activity of diabetic-derived receptors was significantly higher (approximately 50%) than control values at low H2b concentrations, but significantly lower (approximately 50%) than control values at high H2b concentrations, suggesting a decrease in the apparent Km and maximal velocity of the diabetic receptor tyrosine kinase toward H2b. When receptors were allowed to maximally autophosphorylate before the addition of H2b, the maximal H2b kinase activity of diabetic-derived receptors was only approximately 25% lower than that of controls. These effects were not attributable to altered ATP kinetics. Insulin receptor kinase activity toward the substrate poly-Glu-Tyr (4:1) was unaltered by insulinopenic diabetes. Insulin receptor alpha-beta dimers were not detectable in either control or diabetic-derived preparations. We conclude that the impairment of hepatic insulin receptor kinase activity associated with insulinopenic diabetes reflects a decreased ability to maximally activate, which is enhanced when the receptor is activated in the presence of some substrates, e.g. H2b. Impaired signalling by the diabetic-derived receptor appears to be dependent on the type of substrate and its concentration.