A More Complete Story of the Genetic Bases of Resistance to the Rice Hoja Blanca Virus

Rice hoja blanca is one of the most serious diseases in rice growing areas in tropical Americas. Its causal agent is the Rice hoja blanca virus (RHBV), transmitted by the planthopper Tagosodes orizicolus Müir. Genetic resistance is the most effective and environment-friendly way of controlling the disease. So far, only one major quantitative trait locus (QTL) of Oryza sativa ssp. japonica origin, qHBV4.1, that alters incidence of the virus symptoms in two Colombian cultivars has been reported. This resistance has already started to be broken, stressing the urgent need for diversifying the resistance sources. In the present study we performed a search for new QTLs of O. sativa indica origin associated with RHBV resistance. We used four F2:3 segregating populations derived from indica resistant varieties crossed with a highly susceptible japonica pivot parent. Beside the standard method for measuring disease incidence, we developed a new method based on computer-assisted image processing to determine the affected leaf area (ALA) as a measure of symptoms severity. Based on the disease severity and incidence scores in the F3 families under greenhouse conditions, and SNP genotyping of the F2 individuals, we identified four new indica QTLs for RHBV resistance on rice chromosomes 4, 6 and 11, namely qHBV4.2WAS208, qHBV6.1PTB25, qHBV11.1 and qHBV11.2. We also confirmed the wide-range action of qHBV4.1. Among the five QTLs, qHBV4.1 and qHBV11.1 had the largest effects on incidence and severity, respectively. These results provide a more complete understanding of the genetic bases of RHBV resistance in the cultivated rice gene pool, and can be used to develop marker-aided breeding strategies to improve RHBV resistance. The power of joint- and meta- analyses allowed precise mapping and candidate genes identification, providing the basis for positional cloning of the two major QTLs qHBV4.1 and qHBV11.1.

Genomic Prediction of Grain Yield in a Barley MAGIC Population Modeling Genotype per Environment Interaction

Multi-parent Advanced Generation Inter-crosses (MAGIC) lines have mosaic genomes that are generated shuffling the genetic material of the founder parents following pre-defined crossing schemes. In cereal crops, these experimental populations have been extensively used to investigate the genetic bases of several traits and dissect the genetic bases of epistasis. In plants, genomic prediction models are usually fitted using either diverse panels of mostly unrelated accessions or individuals of biparental families and several empirical analyses have been conducted to evaluate the predictive ability of models fitted to these populations using different traits. In this paper, we constructed, genotyped and evaluated a barley MAGIC population of 352 individuals developed with a diverse set of eight founder parents showing contrasting phenotypes for grain yield. We combined phenotypic and genotypic information of this MAGIC population to fit several genomic prediction models which were cross-validated to conduct empirical analyses aimed at examining the predictive ability of these models varying the sizes of training populations. Moreover, several methods to optimize the composition of the training population were also applied to this MAGIC population and cross-validated to estimate the resulting predictive ability. Finally, extensive phenotypic data generated in field trials organized across an ample range of water regimes and climatic conditions in the Mediterranean were used to fit and cross-validate multi-environment genomic prediction models including G×E interaction, using both genomic best linear unbiased prediction and reproducing kernel Hilbert space along with a non-linear Gaussian Kernel. Overall, our empirical analyses showed that genomic prediction models trained with a limited number of MAGIC lines can be used to predict grain yield with values of predictive ability that vary from 0.25 to 0.60 and that beyond QTL mapping and analysis of epistatic effects, MAGIC population might be used to successfully fit genomic prediction models. We concluded that for grain yield, the single-environment genomic prediction models examined in this study are equivalent in terms of predictive ability while, in general, multi-environment models that explicitly split marker effects in main and environmental-specific effects outperform simpler multi-environment models.

Lack of Molecular Mimicry between Nonhuman Primates and Infectious Pathogens: The Possible Genetic Bases

Recently, it was found that proteomes from poliovirus, measles virus, dengue virus, and severe acute respiratory syndrome-related Coronavirus 2 (SARS-CoV-2) have high molecular mimicry at the heptapeptide level with the human proteome, while heptapeptide commonality is minimal or absent with proteomes from nonhuman primates, that is, gorilla, chimpanzee, and rhesus macaque. To acquire more data on the issue, analyses here have been expanded to Ebola virus, Francisella tularensis, human immunodeficiency virus-1 (HIV-1), Toxoplasma gondii, Variola virus, and Yersinia pestis. Results confirm that heptapeptide overlap is high between pathogens and Homo sapiens, but not between pathogens and primates. Data are discussed in light of the possible genetic bases that differently model primate phenomes, thus possibly underlying the zero/low level of molecular mimicry between infectious agents and primates. Notably, this study might help address preclinical vaccine tests that currently utilize primates as animal models, since autoimmune cross-reactions and the consequent adverse events cannot occur in absentia of shared sequences.

TECHNOLOGIES OF GENETIC MATERIAL USE RESTRICTION: TYPES, MOLECULAR-GENETIC BASE AND ETHICAL ANALYSIS OF THEIR APPLICATION

In order to save money, some farms use the seed obtained in the process of cultivation not only for sale, but also for sowing, which has not found supporters among companies engaged in the production of genetically modified seed. To protect their rights, the latter have created technologies to limit the use of genetic material, which are intended to be used for protection the intellectual rights to reproduce plants with a changed genotype. However, these technologies contain also a commercial component and violate a number of moral principles and international acts. Aim. To describe the types of terminator technologies, their genetic and molecular basis and purpose. To assess a correspondence of their compliance with the international documents and norms. Method. Terminator technologies types, genetic bases and application and their analysis from the standpoint of international norms were studied. To achieve the goal, the methods of fact analysis, comparison and generalization were used. Results. There are two types of terminator technologies (variety- and trait-specific), which are based on the interaction of three genes, which leads to the implementation of certain phenotypic manifestations. It was found that the technologies for limiting the use of genetic material are both contradictory and consistent with a number of international legal acts, which did not make it possible to determine clearly the appropriateness of their use in agriculture. Conclusions. Terminator technologies application is still a controversial fact since they are based on the duality principle: to carry simultaneously a positive and a negative manifestation for people.

Molecular breeding in wheat, maize and sorghum: strategies for improving abiotic stress tolerance and yield

This book contains 29 chapters focusing on wheat, maize and sorghum molecular breeding. It aims to contribute the latest understandings of the molecular and genetic bases of abiotic stress tolerance, yield and quality improvement of wheat, maize and sorghum to develop strategies for improving abiotic stress tolerance that will lead to enhance productivity and better utilization of natural resources to ensure food security through modern breeding.

Molecular-genetic bases of development of acute pancreatitis

Acute pancreatitis is included into the three most common diseases of organs of the abdominal cavity following acute appendicitis and cholecystitis, with the middle share in this group of 10-16%. As before, acute pancreatitis is characterized by high morbidity and mortality. Many researchers confirm growth of severe forms of the disease with destructive changes in the pancreas. Aim. A review of literature sources devoted to study of etiology, pathogenesis, classification, diagnosis and molecular-genetic bases of acute pancreatitis. Factors that play a role in development of the disease (episodes of infringement of the diet, cholelithiasis, vascular diseases, abuse of alcohol) are elucidated. Mechanisms of development of acute pancreatitis depending on the etiology, are described in detail, modern classification of acute pancreatitis is given. The main methods of diagnosis of the disease including both laboratory and instrumental ones, are described. Data of the methods of determination of severity of patients state based on evaluation of all the most important physiological systems, are presented. In terms of modern understanding of mechanisms of development of acute pancreatitis, the results of investigation of the probability for genetic predisposition to the studied disease are given that opens the ways for optimization of therapy and diagnosis. The results of both individual and large-scale genetic studies of acute pancreatitis are described. Research works with isolation of certain candidate genes whose protein products participate in the pathogenesis of acute pancreatitis, are presented. Conclusion. A complex approach to diagnosis of acute pancreatitis with identification of different mutations in the studied genes, and also determination of the influence of epigenetic phenomena in the individuals of risk groups will permit to improve the results of the prophylactic, diagnostic and therapeutic activity in acute pancreatitis.

Genetic bases of corn inoculated with Azospirillum brasilense via seed and foliar application

Nitrogen is available in insufficient quantities in Brazilian soils, and is the nutrient that raises the most cost of production of maize. Nowadays there is a more interest in the use of alternative nitrogen sources, such as biological nitrogen fixation, to supply plant demand. Among the most used bacteria in association with grasses is Azospirillum brasilense. In this way this study aimed to establish a relationship between the genetic bases of corn and the forms of A. brasilense application and the effects on the plant morphological components, grain yield, and relative nitrogen contribution. Experiments were conducted during the 2013/14 and 2014/15 crop seasons. The experiments included two single hybrids, two double hybrids, and two triple hybrids inoculated with A. brasilense via seed treatment; foliar application during phenological stages V2, V2 + V4, and V4; and a control treatment without bacteria. The response varied with the hybrid and the year. In the 2013/14 crop, a significant difference was observed in the grain yield for the single hybrid AG9045 inoculated with A. brasilense via seed and foliar application in V2. In the 2014/15 crop, inoculation with A. brasilense via seed application resulted in significant increases in the grain yield for the triple hybrid BG7051. Foliar application of A. brasilense is an efficient alternative for the improvement of plant morphological traits, and inoculation via seed and with foliar application in V2 increases the relative contribution of N.