Kishor U. TribhuvanSandhyaKuldeep KumarAmitha Mithra Sevanthi...
10页
查看更多>>摘要：With the advancement of sequencing technologies and improvement in data analysis tools, draft genomes of many organisms are readily available. Accessibility to such draft genome sequences assists researchers, especially, plant breeders, to rapidly identify genomic regions contributing to the observed phenotypic variation leading to identification of candidate genes for a particular trait. Traditionally gene mapping is a complex, time-consuming and costly affair requiring large mapping populations and abundant molecular markers spread across the entire linkage groups. With the emergence of re-sequencing techniques, quick mapping of genes has become possible with reduced time and cost by using approaches like SHOREmap, NGM and MutMap methodologies. Among these, MutMap is widely used because it is more focused on causal SNPs. This is made possible by generating a backcross population of the mutant genotype with the parent (wild type), thereby removing the false SNPs and retaining only the SNPs linked to the mutant phenotype. Improved and specialized methods of MutMap like MutMap+, MutMap-Gap, and QTL-Seq have also emerged to expand the horizon of application of MutMap approach. The Mutmap+ methodology is specially designed for capturing those traits where the homozygous mutant leads to either lethality or sterility. MutMap-Gap methodology identifies the mutation site present in the gap regions of the reference genome, whereas QTL-Seq is an improved version of MutMap, specially designed for mapping of quantitative trait loci (QTLs). All these methods are akin to bulked segregant analysis popularly employed for mapping simply inherited traits. These methods escape the requirement of genotyping all the individuals of the mapping population and generation of high-density linkage maps for mapping of the gene for the trait of interest. This article reviews various Next Generation Sequencing-based gene mapping technologies with more emphasis on MutMap and its modifications, and discusses their advantages and proven applications for gene mapping for subsequent crop improvement.
查看更多>>摘要：Identification of the QTL/genes associated with traits of interest determines the successful application of those genes for crop improvement. After identification of QTL, fine mapping and cloning of important QTL can also enhance our understanding of the genetic structure of the underlying genes responsible for the phenotypic variation. Genetic or recombination mapping is the most common approach used to identify, map and clone QTL or genes in plants. However, genetic mapping approach for fine mapping or map-based cloning is associated with many drawbacks including the need of developing a homogenous and large population, the availability of polymorphic markers, and the poor recombination in certain chromosomal regions. In this article, we describe an alternative approach, called radiation hybrid (RH) mapping, for forward genetic studies in plants. This approach has been extensively used in animal system and offer greater prospects for forward genetic studies in plants as well. The RH mapping uses radiation induced chromosomal breaks to map markers, and thus offers many advantages compared to traditionally used genetic mapping approach, particularly for loci located in recombination cold spots and for the traits which lack genetic diversity. Here, we reviewed the progress made in application of RH approach for forward genetics in plants.
Lan TaoMirza IslamFatma SarsuSneh L. Singla-Pareek...
17页
查看更多>>摘要：Climate change impact on global agricultural food production has been evident in the past few decades. Abiotic factors such as heat, drought, and salinity share a major proportion of crop yield losses and posing a serious threat to global food security. Developing climate resilient crops has become a frontier area of basic plant science and agricultural research. Persistent efforts by scientists to understand crop responses under natural environment and progress in the field of genomics and phenomics has provided unprecedented pace to crop development programs. Rice is the most important cereal crop and staple food for more than 3 billion people worldwide. Heat, drought and salinity stress are the major constraints for global rice production. Hence, efforts are warranted to develop climate-resilient rice cultivars that can produce substantially under different abiotic stresses. Crop plants seldom face single stress in the natural environment. Indeed, heat and drought or drought and salinity are documented as very obvious combinations suggesting multiple stress tolerance as an important breeding target. Forward and reverse genetic tools could effectively contribute towards achieving the target food production to feed the future population despite limiting resources and unfavorable climatic conditions. Genetic approaches adopted for crop improvement programs categorized as forward and reverse genetics are discussed highlighting their potential benefits for tailoring stress tolerant cultivars.
P. B. Kavi KishorK. VenkateshP. AmareshwariP. Hima Kumari...
6页
查看更多>>摘要：Peanut ( Arachis hypogaea L.) is an important oil-yielding cash crop as well as an exportable agricultural commodity. It is a rich source of proteins, fats, and plays a crucial role in oilseed economy of India and many other countries. Peanut frequently encounters water-deficit and soil salinity conditions that affect its growth and productivity. Traditional breeding methods were not successful in generating lines tolerant to abiotic stress conditions. On the other hand, introduction of genes through genetic engineering methods conferred tolerance against both biotic and abiotic stresses. In all, the transgenics that were developed so far, stable inheritance of transgenes was noticed. Transgenics displayed higher biomass, yield and better resistance to abiotic stresses when compared with wild-type plants inferring that this method has potential for improving the crop with desired traits. Genetically engineered stress tolerant peanut plants could provide an avenue to the restoration of farmlands lost due to severe drought or salinity conditions and highlight the potential of this technology for developing climate resilient crop.
查看更多>>摘要：The emergence of nuclease guided genome editing tools like FokI-I, TALENS, meganucleases, and CRISPR associated Cas9 could be a revolutionary step for the improvement of different organisms. These tools have helped in performing site-specific editing in an efficient and reliable manner to obtain the desired results. Of all the nucleases, CRISPR/Cas9 is emerging a most favourite arsenal owing to its easy adaptability, versatility, and cost-effectiveness. It has been successfully employed in all the model systems ranging from multicellular organisms to single-celled ones including algae, which are a diverse group of photosynthetic organisms and promising sources for the sustainable biofuel. The CRISPR/Cas9 technology has been used efficiently to generate stable targeted gene mutations in some algal species and has great potential to be explored further for the commercially important algal species to produce sustainable algae biofuel, pharmaceuticals and value-added products.
Ashok BadigannavarNiaba TemeFatma SarsuAntonio Costa de Oliveira...
19页
查看更多>>摘要：Developing drought resistant cereal crops continues to be a major challenge in the climate change scenario. Sorghum is a C~(4)crop and its yield levels are highly affected by terminal drought stress under rainfed conditions. Efficient screening methods coupled with high throughput phenotyping techniques are required for breeding climate resilient crops. Plant adaptation to drought stress is manifested by several modifications at morphological, anatomical, physiological levels. Several mechanisms including?osmotic adjustments, stay green, leaf rolling, waxyness on stem, root morphology and its?architecture, transpiration efficiency, secretion of soluble solutes are known to play?important role in bringing?drought tolerance. Several breeding methods have been proposed and a single method may not hold good for all the crop species. Recombination, mutation and molecular breeding methods are mainly used for breeding drought resistant plants. At molecular level, several QTL’s governing pre- and post flowering drought tolerance have been identified in cereals and specifically in sorghum. At genome level, genes involved in proline metabolism, transmembrane ion?transporter, abscisic acid metabolism, etc., are known to be?upregulated under water deficit conditions. Recent studies on transcriptome analysis showed that genes which are expressed in sensitive plants are related to stress responses and oxy reduction reactions. Recently high throughput phenotyping tools have been developed to associate drought responsive traits to genomic regions governing quantitative traits. In this review, detailed mechanisms and breeding approaches related to drought stress in cereals and specifically in sorghum are discussed.
Yinglong ChenZed RengelJairo PaltaKadambot H. M. Siddique...
8页
查看更多>>摘要：Development of future crop varieties with efficient root systems for enhanced water and phosphorus uptake is essential for improving crop adaptation and hence food security. Root system architecture (RSA) traits that overcome low-water and low-phosphorus stresses are critical to maintaining structural and functional properties, and are considered the first-order targets in breeding programmes for rainfed environments. Modification of root system architecture could contribute to improvements of desirable agronomic and physiological traits such as biomass, yield, drought resistance, and tolerance to nutrient deficiencies. Advanced phenotyping, imaging, modelling and molecular biotechnologies offer promise in identifying RSA traits for efficient resource acquisition and adaptation to abiotic stresses. This review highlights the complexity and regulation of RSA in response to water and P stresses.
K. H. M. SiddiqueO. P. DhankharP. V. Vara PrasadBindumadhava Hanumantha Rao...
24页
查看更多>>摘要：Heat stress is a significant threat that limits crop yield and fecundity all over the world. Prevalent strategies for heat adaptation that alter technical and management systems are inadequate to sustain yield. As such, the identification of heat-tolerant genotypes with improved yield potential is crucial. Raising tolerant and stable cultivars can be tedious as heat-stress responses are highly variable across different developmental stages. While molecular breeding has progressed in engineering heat-tolerant lines, the complexity of genetic networks and divergence of heat tolerance mechanisms is the main hindrance for plant breeders. Hence, insight into the physiological and reproductive traits associated with heat tolerance could assist in the development of strategies to screen germplasm for heat tolerance. Exploitation and use of landraces and wild relatives in breeding may enhance favorable genetic diversity in crop plants. A holistic approach to delineate molecular markers, where quantitative trait loci (QTLs) for different traits linked to heat tolerance involving physiological and reproductive traits are characterized in well-controlled field environments, may be an option for optimizing germplasm under heat stress. Here, we present an outline of the effects of heat stress and its associated tolerance mechanisms in food crops, along with some physiological, molecular and reproductive characteristics such as ‘stay-green,’ membrane thermostability, canopy temperature depression, metabolites, genes, QTLs, and pollen fertility. Further, we provide information on conventional and molecular breeding approaches as well as different selection strategies for heat stress tolerance.
Kundan KumarKareem A. MosaAhmed G. MeselhyOm Parkash Dhankher...
10页
查看更多>>摘要：Aquaporins are channel proteins reported to play multiple functions in plants ranging from water, solutes, metalloids (arsenic, boron, silicon) transport, and tolerance to abiotic stresses including drought, salinity and cold. Based on their localization and sequence similarities, aquaporins have been classified into seven major subfamilies: plasma membrane intrinsic proteins (PIPs), nodulin 26-like intrinsic proteins, tonoplast intrinsic proteins, small basic intrinsic proteins, GlpF-like intrinsic protein, hybrid intrinsic proteins and the uncategorized (X) intrinsic proteins. PIP subfamily is one of the biggest subfamilies of aquaporin superfamily and they are localized to plasma membrane. Members of PIPs are involved in water and small neutral solute transport and play an important role in maintaining water homeostasis under environmental stress and are known to provide tolerance to various abiotic stresses. Recently, members of PIP subfamily have been shown to be involved in the bidirectional transport of metalloids, arsenic and boron in plants. This review highlights the involvement of various PIP homologs in plant stress responses against a variety of environmental stresses and metalloid transport and tolerance. Molecular insights and biotechnological approaches for developing climate resilient crops by modulating PIPs will be discussed.
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