Genetics and genomics studies of rice disease resistance and development of alternative disease management methods for bacterial panicle blight and sheath blight

Bacterial panicle blight (BPB) and sheath blight (SB), caused by the bacteria Burkholderia glumae and B. gladioli, and the fungus Rhizoctonia solani, respectively, are two major rice diseases in southern rice growing regions of US. No completely resistant rice cultivars have been identified for these diseases. However, a medium-grain cultivar, Jupiter, showed partial resistance to BPB. In order to understand the mechanisms of rice resistance against BPB and SB, rice genetics and genomics studies have been conducted. Alternative methods to suppress BPB and SB were also studied. Broad-sense heritability and correlations were calculated for the traits, BPB and SB disease ratings, days to heading, and plant height, with recombinant inbred lines generated from a cross between Trenasse and Jupiter in replicated trials for two years. Days to heading and plant height had high heritability, and were negatively correlated with BPB and SB disease ratings. The traits with high heritability will not have environmental influence, and can be used as indirect selection tools. Study on genomic characteristics of five rice genotypes grown in Louisiana using their whole genome sequence data provides genome-wide DNA polymorphisms among them. These information will enable us to understand genetic elements for phenotypic variations among these genotypes, which will help to enhance the genetic studies of US rice cultivars. The sequence data were also used to develop microsatellites and single nucleotide polymorphism markers, which can be used for genetic mapping studies. Previous microarray studies showed that the gene encoding a NAC4-like transcription factor, named bacterial panicle blight response gene 1 (BPR1), was highly up-regulated in Jupiter upon B. glumae inoculation. Expression of BPR1 in response to B. glumae was not detected in both Jupiter and Trenasse at seedling and tillering stages. However, rapid induction of BPR1 expression was observed in Jupiter, but not in Trenasse, when it was treated with B. glumae or chemicals, such as ascorbic acid and jasmonic acid, at its heading stage, suggesting that BPR1 expression is tissue-specific, and might be involved in rice defense response against B. gluame. Several rice-associated bacteria (RAB) isolated from healthy rice leaves were tested for their ability to suppress BPB and SB in rice. Those RAB were able to suppress bacterial cell growth and sclerotia germination in vitro, and were able to reduce the BPB and SB symptoms in rice in the field. Based on the 16S rDNA sequencing analysis, those RABs were identified as Bacillus and Lysinibacillus spp., and are potential candidates for biological control agents

Characterization and Utilization of Rice Defense Associated with Partial Resistance to Bacterial Panicle Blight: An Emerging Rice Disease Problem in the Southeastern United States

Rice is a staple food for much of the world’s growing population. Rice production is limited by a number of abiotic and biotic factors. These factors have direct effects on food security because less food is available to growing population. Bacterial panicle blight (BPB), caused by the bacterium Burkholderia glumae, is an emerging disease that causes grain rot, panicle discoloration, and unfilled grains in rice. Up to 70% of yield reduction has been reported in severely infected rice fields. No completely resistant rice cultivars have been identified, however, a medium-grain cultivar, Jupiter, showed a high level of partial resistance to this disease. A research was conducted to characterize and utilize the rice defense system associated with partial resistance to BPB. Various chemical compounds and biological agents were used to enhance the rice defense system and in vitro control of B. glumae, respectively. Microarray studies done by Dr. Nandakuar and Dr. Rush, showed that several defense related genes and transcriptional regulators were highly up-regulated in Jupiter and slightly up-regulated in Trenasse, a susceptible long-grained cultivar, when challenged with B. glumae. Induction of the expression of those genes in Jupiter and Trenasse were verified by reverse-transcription PCR. Genes encoding an NAC-like transcription factor (NTF) and a grain filling protein, prolamin, was highly induced in Jupiter but not in Trenasse under different treatments of B. glumae and its mutant derivatives. These genes may be involved in the partial resistance to BPB, and could be used as a genetic marker and breeding tools to develop BPB resistant rice cultivars. In an attempt to develop control measures for BPB in rice, several chemicals, including jasmonic acid, salicylic acid, ascorbic acid, 2, 6-dichloroisonicotinic acid, and ethylene, known to induce plant defense systems against various plant pathogens were tested for their ability to enhance rice defense systems and reduce BPB development. Results showed that pretreatment of rice with ascorbic acid significantly suppressed BPB development while only minimally reducing yield. In the meantime, several biological agents isolated from rice leaves showed antagonistic effect on B. glumae, and Rhizoctonia solani, the causal agent of sheath blight in rice

GENETIC VARIABILITY, HERITABILITY AND GENETIC ADVANCE ESTIMATES IN MAIZE (ZEA MAYS L.) GENOTYPES IN NEPAL

Eleven early maize and ten winter maize  genotypes were evaluated in randomized complete block design (RCBD) with three replications at the research field  of Regional Agricultural Research Station (RARS), Lumle, Kaski and National Maize Research Program (NMRP), Rampur, Chitwan, Nepal respectively  to assess the magnitude of genetic variability, heritability and genetic advance for yield and yield contributing traits during summer (Kharif) and winter (rabi) seasons of 2016-2017. Analysis of variance revealed significant differences for 10 characters studied among the genotypes. The phenotypic coefficient of variation (PCV) is higher than genotypic coefficient of variation (GCV) recorded for all traits. High GCV and PCV was recorded for grain yield, thousand kernel weight and ear height. Heritability was  moderate to high  except thousand kernel weight in Kharif whereas number of kernel per ear showed lowest heritability in winter season. Genetic gain as percentage of mean (GAM) was greater for grain yield, thousand kernel weight, plant height and ear height.  As grain yield had higher genetic advance along with high heritability in both the seasons that indicated the presence of large proportion of additive gene action for deciding this trait

Aneurysmal Bone Cyst of Talus

Aneurysmal bone cyst (ABC) of talus is rare benign, expansile and osteolytic bone growth. Cyst contains bloody fluid lined with variable amount of osteolytic giant cells. This is common in epiphyseal ends of long bone and rare in small bones like talus. Here a 20 years’ male with aneurysmal bone cyst of talus managed with wide intralesional curettage with autologous bone graft mixed with synthetic bone graft been presented

Nutritive values of fodders at different seasons and altitudes in Gandaki River Basin of Nepal

This study aimed to assess the seasonal and ecological variation of chemical and nutritional values of locally preferred fodders in Gandaki River Basin (GRB) areas. The study was conducted in four altitudinal gradients viz. <400m, 400-800m, 800-1200m and 1200–1600m altitude above sea level in different looping seasons: rainy, spring and winter seasons. The most important five species of fodder trees Artocarpus lakoocha, Ficus roxburghii, Thysanolaena maxima, Ficus semicordata and Bauhinia purpurea were selected based on farmers’ preferences in nutritional values. Fodder samples comprised young leaves, old leaves and young twigs that were taken in July, September and December. It was revealed that nutritive value is not very much influenced by altitude but it is strongly influenced by lopping seasons. Among Thysanolaena maxima, Artocarpus lakoocha, Ficus roxburghii and Bauhinia purpurea the cellulose contents were significantly different (p<0.001) with seasons but there was no significant variation with altitudes. Similarly, Acid Detergent Fibre (ADF) contents in Thysanolaena maxima, Ficus roxburghii and Bauhinia purpurea were found significantly different with seasons. Ficus roxburghii fodder tree was found significantly different in Neutral Detergent Fibre (NDF), ADF, Cellulose and Potassium content with seasons. Similarly, fodder tree Bauhinia purpurea was found significant on Dry matter (DM), Crude fibre (CF), NDF, ADF, cellulose, tannin and potassium with seasons. The study hinted how careful planning of species selection and prudent decision in scheduling looping and feeding fodder trees can help improve animal metabolism, health, growth and productivity

Varietal evaluation of promising maize genotypes

The selection efficiency can be broadened for certain traits using estimates of genetic parameters, which are fundamental for plant breeding. The present study was carried out with ten maize genotypes grown in October, 2016 to April, 2017 using randomized complete block design with three replications at research field of National Maize Research Program, Rampur, Chitwan, Nepal. The objective of this study was to estimate the variability and correlation of agro-morphological traits in maize genotypes. Variation was observed for all the growth, phenology, yield and yield attributing traits among the genotypes. The genotypes, ZM-627 (4984 kg ha-1) and Across9942/Across9944 (4523 kg ha-1) were identified as promising genotypes. Grain yield had significant positive correlation for ear length, number of grains per row, number of ears per plot and thousand grains weight. Path analysis showed that ear height, days to 50% tasseling, anthesis-silking interval, ear length, ear diameter, number of grain rows per ear, number of grains per ear, number of ears per plot and 1000 grains weight had direct and positive effects on grain yield. Moderate to high estimates of GCV, PCV, heritability and genetic advance were found for plant height, ear height, thousand kernels weight, tasseling days, anthesis- silking interval and grain yield. Therefore, these traits can be used as selection indices for indirect selection for the improvement of maize productivity

Variation in grain zinc and iron concentrations, grain yield and associated traits of biofortified bread wheat genotypes in Nepal

Wheat (Triticum aestivum L.) is one of the major staples in Nepal providing the bulk of food calories and at least 30% of Fe and Zn intake and 20% of dietary energy and protein consumption; thus, it is essential to improve its nutritional quality. To select high-yielding genotypes with elevated grain zinc and iron concentration, the sixth, seventh, eighth, and ninth HarvestPlus Yield Trials (HPYTs) were conducted across diverse locations in Nepal for four consecutive years: 2015–16, 2016–17, 2017–18, and 2018–19, using 47 biofortified and 3 non-biofortified CIMMYT-bred, bread wheat genotypes: Baj#1, Kachu#1, and WK1204 (local check). Genotypic and spatial variations were found in agro-morphological traits; grain yield and its components; and the grain zinc and iron concentration of tested genotypes. Grain zinc concentration was highest in Khumaltar and lowest in Kabre. Likewise, grain iron concentration was highest in Doti and lowest in Surkhet. Most of the biofortified genotypes were superior for grain yield and for grain zinc and iron concentration to the non-biofortified checks. Combined analyses across environments showed moderate to high heritability for both Zn (0.48–0.81) and Fe (0.46–0.79) except a low heritability for Fe observed for 7th HPYT (0.15). Grain yield was positively correlated with the number of tillers per m2, while negatively correlated with days to heading and maturity, grain iron, grain weight per spike, and thousand grain weight. The grain zinc and iron concentration were positively correlated, suggesting that the simultaneous improvement of both micronutrients is possible through wheat breeding. Extensive testing of CIMMYT derived high Zn wheat lines in Nepal led to the release of five biofortified wheat varieties in 2020 with superior yield, better disease resistance, and 30–40% increased grain Zn and adaptable to a range of wheat growing regions in the country – from the hotter lowland, or Terai, regions to the dry mid- and high-elevation areas

Global age-sex-specific mortality, life expectancy, and population estimates in 204 countries and territories and 811 subnational locations, 1950–2021, and the impact of the COVID-19 pandemic: a comprehensive demographic analysis for the Global Burden of Disease Study 2021

Background: Estimates of demographic metrics are crucial to assess levels and trends of population health outcomes. The profound impact of the COVID-19 pandemic on populations worldwide has underscored the need for timely estimates to understand this unprecedented event within the context of long-term population health trends. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 provides new demographic estimates for 204 countries and territories and 811 additional subnational locations from 1950 to 2021, with a particular emphasis on changes in mortality and life expectancy that occurred during the 2020–21 COVID-19 pandemic period. Methods: 22 223 data sources from vital registration, sample registration, surveys, censuses, and other sources were used to estimate mortality, with a subset of these sources used exclusively to estimate excess mortality due to the COVID-19 pandemic. 2026 data sources were used for population estimation. Additional sources were used to estimate migration; the effects of the HIV epidemic; and demographic discontinuities due to conflicts, famines, natural disasters, and pandemics, which are used as inputs for estimating mortality and population. Spatiotemporal Gaussian process regression (ST-GPR) was used to generate under-5 mortality rates, which synthesised 30 763 location-years of vital registration and sample registration data, 1365 surveys and censuses, and 80 other sources. ST-GPR was also used to estimate adult mortality (between ages 15 and 59 years) based on information from 31 642 location-years of vital registration and sample registration data, 355 surveys and censuses, and 24 other sources. Estimates of child and adult mortality rates were then used to generate life tables with a relational model life table system. For countries with large HIV epidemics, life tables were adjusted using independent estimates of HIV-specific mortality generated via an epidemiological analysis of HIV prevalence surveys, antenatal clinic serosurveillance, and other data sources. Excess mortality due to the COVID-19 pandemic in 2020 and 2021 was determined by subtracting observed all-cause mortality (adjusted for late registration and mortality anomalies) from the mortality expected in the absence of the pandemic. Expected mortality was calculated based on historical trends using an ensemble of models. In location-years where all-cause mortality data were unavailable, we estimated excess mortality rates using a regression model with covariates pertaining to the pandemic. Population size was computed using a Bayesian hierarchical cohort component model. Life expectancy was calculated using age-specific mortality rates and standard demographic methods. Uncertainty intervals (UIs) were calculated for every metric using the 25th and 975th ordered values from a 1000-draw posterior distribution. Findings: Global all-cause mortality followed two distinct patterns over the study period: age-standardised mortality rates declined between 1950 and 2019 (a 62·8% [95% UI 60·5–65·1] decline), and increased during the COVID-19 pandemic period (2020–21; 5·1% [0·9–9·6] increase). In contrast with the overall reverse in mortality trends during the pandemic period, child mortality continued to decline, with 4·66 million (3·98–5·50) global deaths in children younger than 5 years in 2021 compared with 5·21 million (4·50–6·01) in 2019. An estimated 131 million (126–137) people died globally from all causes in 2020 and 2021 combined, of which 15·9 million (14·7–17·2) were due to the COVID-19 pandemic (measured by excess mortality, which includes deaths directly due to SARS-CoV-2 infection and those indirectly due to other social, economic, or behavioural changes associated with the pandemic). Excess mortality rates exceeded 150 deaths per 100 000 population during at least one year of the pandemic in 80 countries and territories, whereas 20 nations had a negative excess mortality rate in 2020 or 2021, indicating that all-cause mortality in these countries was lower during the pandemic than expected based on historical trends. Between 1950 and 2021, global life expectancy at birth increased by 22·7 years (20·8–24·8), from 49·0 years (46·7–51·3) to 71·7 years (70·9–72·5). Global life expectancy at birth declined by 1·6 years (1·0–2·2) between 2019 and 2021, reversing historical trends. An increase in life expectancy was only observed in 32 (15·7%) of 204 countries and territories between 2019 and 2021. The global population reached 7·89 billion (7·67–8·13) people in 2021, by which time 56 of 204 countries and territories had peaked and subsequently populations have declined. The largest proportion of population growth between 2020 and 2021 was in sub-Saharan Africa (39·5% [28·4–52·7]) and south Asia (26·3% [9·0–44·7]). From 2000 to 2021, the ratio of the population aged 65 years and older to the population aged younger than 15 years increased in 188 (92·2%) of 204 nations. Interpretation: Global adult mortality rates markedly increased during the COVID-19 pandemic in 2020 and 2021, reversing past decreasing trends, while child mortality rates continued to decline, albeit more slowly than in earlier years. Although COVID-19 had a substantial impact on many demographic indicators during the first 2 years of the pandemic, overall global health progress over the 72 years evaluated has been profound, with considerable improvements in mortality and life expectancy. Additionally, we observed a deceleration of global population growth since 2017, despite steady or increasing growth in lower-income countries, combined with a continued global shift of population age structures towards older ages. These demographic changes will likely present future challenges to health systems, economies, and societies. The comprehensive demographic estimates reported here will enable researchers, policy makers, health practitioners, and other key stakeholders to better understand and address the profound changes that have occurred in the global health landscape following the first 2 years of the COVID-19 pandemic, and longer-term trends beyond the pandemic