Use Of Genetic Variability Research Articles

Physiological and Enzymatic Evaluation of Selected Genotypes of Stevia rebaudiana Bertoni

The Germplasm Bank of Stevia rebaudiana segregants of the University of Córdoba is a strategy for the use of genetic variability and efficient crop yield. There are genotypes with important characteristics such as: high tolerance to salt stress and climatic change (high CO2 in the Earth surface), late flowering, erect architecture, and high contents of steviol glycosides. However, there is a lack of in-depth studies of morphophysiological and biochemical indicators such as gas exchange, chlorophyll a fluorescence, chloroplast pigments, and antioxidant systems, which allow us to develop early selection tools for elite genotypes. The genotypes (L020, Morita II, and L102) were found to have elite characteristics such as high efficiency in water use, excellent biomass production, and a more robust antioxidant system than the genotypes (L057 and L082). The L020 genotype presented the highest content of stevioside and rebaudioside A, followed by the Morita II genotype. We found a close correlation between the electron transport rate and the mechanisms that increase photosystem complexes. In this sense, non-photochemical cooling modulated by the release of heat by the leaves is a fact that is confirmed by the greater activity of the xanthine pool to protect the photochemical complexes in S. rebaudiana.

Maize yields over Europe may increase in spite of climate change, with an appropriate use of the genetic variability of flowering time

Projections based on invariant genotypes and agronomic practices indicate that climate change will largely decrease crop yields. The comparatively few studies considering farmers' adaptation result in a diversity of impacts depending on their assumptions. We combined experiments and process-based modeling for analyzing the consequences of climate change on European maize yields if farmers made the best use of the current genetic variability of cycle duration, based on practices they currently use. We first showed that the genetic variability of maize flowering time is sufficient for identifying a cycle duration that maximizes yield in a range of European climatic conditions. This was observed in six field experiments with a panel of 121 accessions and extended to 59 European sites over 36 years with a crop model. The assumption that farmers use optimal cycle duration and sowing date was supported by comparison with historical data. Simulations were then carried out for 2050 with 3 million combinations of crop cycle durations, climate scenarios, management practices, and modeling hypotheses. Simulated grain production over Europe in 2050 was stable (-1 to +1%) compared with the 1975-2010 baseline period under the hypotheses of unchanged cycle duration, whereas it was increased (+4-7%) when crop cycle duration and sowing dates were optimized in each local environment. The combined effects of climate change and farmer adaptation reduced the yield gradient between south and north of Europe and increased European maize production if farmers continued to make the best use of the genetic variability of crop cycle duration.

EX SITU MORPHOLOGICAL ASSESSMENT OF WILD LAVANDULA POPULATIONS IN PORTUGAL

The genus Lavandula L. (Lamiaceae family) belongs to the subfamily Nepetoideae. The tribe Lavanduleae (Endl.) Boiss contain just the single genus Lavandula . The Lavandula species occur in Portugal, either spontaneously or grown for their ornamental and aromatic value. These species are also used in traditional medicine in the form of infusions, for internal and external uses. The wild populations of this genus are represented by five species and several subspecies in the Portuguese flora. This genus has revealed a complex taxonomy with some taxa known under different scientific names, although under the same common name. In Portugal has been significant research on these species, with significant results, in ethnobotany, essential oils, biological activities and in vitro research. The present assessment aimed to present the Banco Portugues de Germoplasma Vegetal contribution to the ex situ conservation of Lavandula species genetic resources: ex situ evaluation of Lavandula stoechas and L. pedunculata wild genetic resources, the need to plan new collecting missions and, the prospects for the use of genetic variability preserved in this collection. The main results of the morphological assessment showed that L. stoechas presents greater morphological diversity.

Genetic Variability and Association Among Agronomic Characters in Selected Field Pea (<i>Pisumsativum L.</i>) Genotypes at Bale Zone, Sinana Research Center, Oromia Region, Ethiopia

Field pea (Pisumsativum L.) is an annual herbaceous legume belonging to the family Fabaceae that adapted to cool moist climate with moderate temperature. The species P. sativumis dominant in Ethiopia even though wild and primitive forms are also known to exist in the high elevation of the country. No sufficient work has been done for understanding and describing the nature and extent of genetic variability on Field Pea. Thus use of genetic variability is suggested to alleviate the shortage of released varieties in Field pea. The studies of association characters solve the low yield of field pea in Ethiopia. Therefore, the present study was conducted to study genetic variability and association among agronomic characters of field pea (Pisumsativum L.) genotypes. The field experiment was conducted using 29 varieties and 7 accessions at Sinana Agricultural Research Centre during 2013/14 main growing season. Treatments were arranged in Simple Lattice design with two replications. The results obtained revealed that the mean squares of the genotypes were highly significant for most of the characters (p < 0.05) except for days to emergence, days to flowering, pods per plant, above ground biomass and harvest index implying that wide range of variability has been obtained for the traits studied. The genotypic coefficient of variation ranged from 2.91% for plant height to 37.9% for above ground biomass, while phenotypic coefficient of variation ranged from 6.28% for days to maturity to 62.6% for above ground biomass. The estimated broad sense heritability ranged from 6.9% for yield per plant to 93.0.0% for pod length. Correlation between different traits and seed yield indicated that there was marked positive and highly significant association of seed yield with days to emergence (rg=0.296**), days to maturity (rg=0.184**), seeds per pod (rg=0.325**) and harvest index (rg=0.341**) indicating the yield improvement perhaps be contributed to changes in these traits. The path analysis at phenotypic level revealed that maximum positive direct effect was exerted by 100 seed weight (1.754) followed by pod length (2.211) and days to emergence (2.056). These traits best contributing to yield variation that emphasis by breeders for future yield improvement of the crop. It can be conclude that Field pea yield can be successfully improved by studying genetic variability and its agronomic characters.

Использование генетического разнообразия форм черной смородины в селекции на комплексную устойчивость к почковому смородинному клещу (Cecidophyоpsis ribis Westw.) и американской мучнистой росе (Sphaerotheca mors uvae (Schw. Berk)) в Кировской области

Использование генетического разнообразия форм черной смородины в селекции на комплексную устойчивость к почковому смородинному клещу (Cecidophyоpsis ribis Westw.) и американской мучнистой росе (Sphaerotheca mors uvae (Schw. Berk)) в Кировской области

Assessment of genetic diversity of non-basmati rice of Jammu and Kashmir using microsatellite markers

Rice (Oryza sativa L.) is one of the oldest domesticated crop species in the world and is widely recognized as an ideal model plant for the study of grass genetics and genome organization. Rice improvement depends on the conserved use of genetic variability and diversity in plant breeding programmes. Phenotypic variability and genetic diversity was studied in 13 non basmati rice samples collected from Jammu and Kashmir. The length of the seeds varied from 0.5 to 0.8 cm and the seed width varied from 0.1 to 0.3 cm. The weight of the seed varied from 0.36 to 0.77 g. A total of 94 alleles were amplified in 13 rice samples using six simple sequence repeat (SSR) markers. The analysis and dendrogram construction was performed using the DARWin 5.0 software. The genetic dissimilarity index calculated between samples ranged from 0.00 to 0.63. The generated dendrogram based on the dissimilarity matrix using the neighbor-joining approach of the unweighted pair group with arithmetic mean (UPGMA) method showed three distinct clusters. Key words: Oryza sativa, diversity, characterization, molecular markers

Assessment of genetic diversity of non-basmati rice of Jammu and Kashmir using microsatellite markers

Rice (Oryza sativa L.) is one of the oldest domesticated crop species in the world and is widely recognized as an ideal model plant for the study of grass genetics and genome organization. Rice improvement depends on the conserved use of genetic variability and diversity in plant breeding programmes. Phenotypic variability and genetic diversity was studied in 13 non basmati rice samples collected from Jammu and Kashmir. The length of the seeds varied from 0.5 to 0.8 cm and the seed width varied from 0.1 to 0.3 cm. The weight of the seed varied from 0.36 to 0.77 g. A total of 94 alleles were amplified in 13 rice samples using six simple sequence repeat (SSR) markers. The analysis and dendrogram construction was performed using the DARWin 5.0 software. The genetic dissimilarity index calculated between samples ranged from 0.00 to 0.63. The generated dendrogram based on the dissimilarity matrix using the neighbor-joining approach of the unweighted pair group with arithmetic mean (UPGMA) method showed three distinct clusters. Key words: Oryza sativa, diversity, characterization, molecular markers

Biofortification of Trace Elements in Food Crops for Human Health

Micronutrient deficiencies have been reported in food crops worldwide. Several macro- and micronutrients are essential for human health. However, among these elements, the trace elements zinc (Zn), iron (Fe), iodine (I), selenium (Se), and cobalt (Co) are limiting in the diets of much of the world's population. According to United Nations estimates, about 1 billion people, especially woman and children, are suffering from malnutrition of trace elements, especially in Africa, Asia, and South America. Improving bioavailability of these elements in food crops is an important strategy to overcome trace-element deficiencies in food crops and improving human health. Genetic variability in micronutrient contents in the grain of crops such as rice, corn, wheat, barley, soybean, and dry bean is widely reported in the literature. Hence, use of genetic variability among crop species and genotypes within species is an important strategy to achieve biofortification of grain of staple food crops. Other practices that can be adopted to improve bioavailability of essential elements in food crops are adopting appropriate agronomic practices, such as adequate rate, effective sources, and effective methods of fertilizer application. Use of biotechnology is also feasible to biofortification of staple food crops. Planting indigenous and traditional food crop species with high nutritive value is another important strategy to improve trace elements in human food.

Salt and genotype impact on plant physiology and root proteome variations in tomato

To evaluate the genotypic variation of salt stress response in tomato, physiological analyses and a proteomic approach have been conducted in parallel on four contrasting tomato genotypes. After a 14 d period of salt stress in hydroponic conditions, the genotypes exhibited different responses in terms of plant growth, particularly root growth, foliar accumulation of Na(+), and foliar K/Na ratio. As a whole, Levovil appeared to be the most tolerant genotype while Cervil was the most sensitive one. Roma and Supermarmande exhibited intermediary behaviours. Among the 1300 protein spots reproducibly detected by two-dimensional electrophoresis, 90 exhibited significant abundance variations between samples and were submitted to mass spectrometry for identification. A common set of proteins (nine spots), up- or down-regulated by salt-stress whatever the genotype, was detected. But the impact of the tomato genotype on the proteome variations was much higher than the salt effect: 33 spots that were not variable with salt stress varied with the genotype. The remaining number of variable spots (48) exhibited combined effects of the genotype and the salt factors, putatively linked to the degrees of genotype tolerance. The carbon metabolism and energy-related proteins were mainly up-regulated by salt stress and exhibited most-tolerant versus most-sensitive abundance variations. Unexpectedly, some antioxidant and defence proteins were also down-regulated, while some proteins putatively involved in osmoprotectant synthesis and cell wall reinforcement were up-regulated by salt stress mainly in tolerant genotypes. The results showed the effect of 14 d stress on the tomato root proteome and underlined significant genotype differences, suggesting the importance of making use of genetic variability.

Unlocking wheat genetic resources for the molecular identification of previously undescribed functional alleles at the Pm3 resistance locus.

The continuous improvement of crop plants is essential for agriculture in the coming decades and relies on the use of genetic variability through breeding. However, domestication and modern breeding have reduced diversity in the crop germplasm. Global gene banks conserve diversity, but these resources remain underexplored owing to a lack of efficient strategies to isolate important alleles. Here we describe a large-scale allele-mining project at the molecular level. We first selected a set of 1,320 bread wheat landraces from a database of 16,089 accessions, using the focused identification of germplasm strategy. On the basis of a hierarchical selection procedure on this set, we then isolated 7 resistance alleles of the powdery mildew resistance gene Pm3, doubling the known functional allelic diversity at this locus. This targeted approach for molecular utilization of gene bank accessions reveals landraces as a rich resource of new functional alleles. This strategy can be implemented for other studies on the molecular diversity of agriculturally important genes, as well as for molecular breeding.

Intellectual Property Rights on varieties and access to plant genetic resources: towards a coherent and an ethically based approach

AbstractThe concept of Intellectual Property Rights (IPRs) is a very old one, dating as far back as Ancient Greek times. A specific system of IPRs for living organisms was adopted internationally for the first time, for plant varieties, in 1961, through the UPOV Convention. Progress in the field of biotechnology in the 1970s was the starting point for extensive debate on the patenting of living material among both the scientific community and in public fora, resulting in several independent international agreements which, in turn, contributed to the evolution of the Patent System for gene protection and of the statute of plant genetic resources. But, in their current state, the provisions of these various agreements are not globally coherent and, more particularly, conflict specifically with plant varieties and genetic resources. The questions could be solved by generalizing the cornerstone principle of the UPOV Convention, i.e. the free use of genetic variability, which seems to meet the demand of the scientific community.

Effects of metal contamination from mine tailings on allozyme distributions of populations of great plains fishes

This study was conducted to assess the effects of zinc and lead on genetic variability of minnow populations (Gambusia affinis, Pimephales notatus, and Fundulus notatus) sampled from two creeks, one receiving mine drainage (Willow Creek) and one reference (Brush Creek), in the Tri-State Mining district in Kansas. Zinc and lead concentrations were greater in water samples taken from sites in Willow Creek compared to sites sampled in Brush Creek. While total numbers of fish captured from Willow Creek were smaller than numbers taken from Brush Creek, there were no differences in these fish communities for estimates of species diversity, richness and evenness. Genetic differentiation within creeks was rare. However, there was significant differentiation between creeks for allozymes of the enzymes glucose phosphate isomerase (GPI) in F. notatus and P. notatus, malate dehydrogenase (MDH) in G. affinis, and phosphogluconate dehydrogenase (PGDH) in F. notatus. Proportions of heterozygous genotypes of P. notatus and G. affinis were higher in Willow Creek compared to Brush Creek. In vitro experiments were conducted to assess the effects of zinc and lead on sensitivity of enzyme staining during electrophoresis. Results indicated allozyme sensitivity to zinc for GPI and PGDH loci. Other studies suggest that zinc competitively competesmore » with magnesium as a cofactor for these enzymes. Allozymes did not exhibit differential sensitivity to lead. The significant differentiation between creek populations and the results of the in vitro tests indicate a selective effect of zinc on allozymic distributions of these fishes. These results demonstrate the potential use of genetic variability as a bioindicator of heavy metal contamination.« less