Molecular breeding

About: Molecular breeding is a research topic. Over the lifetime, 2120 publications have been published within this topic receiving 56908 citations.

Recent Insights in Rice Blast Disease Resistance

Abstract: Magnaporthe oryzae that causes blast disease in rice is one of the most notorious phytopathogenic fungi responsible for severe economic loss in rice production. The fungus is one among the top ten devastating biotic threats to food security worldwide. To counter the pathogen and minimize the losses, various biological, conventional, and advanced molecular approaches have been utilized. Conventional and marker-assisted selection (MAS) breeding methods were deployed and varieties having tolerance or resistance have been developed. Durable and broad-spectrum resistance is the demand of the hour to protect the crop against blast disease, and several studies have made significant progress in this direction. Identification and molecular characterization of different blast resistance genes (R) and defense regulators (DR), and their deployment in various cultivars, is the most preferred approach to breed the disease-resistant varieties. The inclusive approaches including quantitative trait locus (QTL), association mapping, allele mining, bioinformatics tools and genetic engineering, miRNA, genome editing, CRISPR/Cas9 etc. have contributed to the strengthening of molecular breeding and providing of new opportunities for the development of rice varieties resistant to blast. Recent advances show that R-genes Pikh, Pi-1, Pi9, Pi20, Pi27, Pi39, Pi40, and Pita impart broad-spectrum resistance against blast disease. The bsr-d1, bsr-k1, spl11, spl33, and OsBBI1 transcription factors have also been reported for broad-spectrum resistance. The R-genes are broadly classified into eight groups, and in plants, the NBS-LRR genes correspond to the major group. These R-genes are the master keys of the entire defense system of plants, act in multilayered surveillance, and are governed by various extra- and intracellular receptor molecules to ward off pathogen invasion. The updated information on rice blast pathogen provided here will help to understand the different mechanism, advancement in resistance gene research, and focus on the breeding program in rice against blast disease.

Development and validation of InDel markers for identification of QTL underlying flowering time in soybean

Abstract: Soybean [ Glycine max (L.) Merrill] is a major plant source of protein and oil. An accurate and well-saturated molecular linkage map is a prerequisite for forward genetic studies of gene function and for modern breeding for many useful agronomic traits. Next-generation sequence data available in public databases provides valuable information and offers new insights for rapid and efficient development of molecular markers. In this study, we attempted to show the feasibility and facility of using genomic resequencing data as raw material for identifying putative InDel markers. First, we identified 17,613 InDel sites among 56 soybean accessions and obtained 12,619 primer pairs. Second, we constructed a genetic map with a random subset of 2841 primer pairs and aligned 300 polymorphic markers with the 20 consensus linkage groups (LG). The total genetic distance was 2347.3 cM and the number of mapped markers per LG ranged from 10 to 23 with an average of 15 markers. The largest and smallest genetic distances between adjacent markers were 52.3 cM and 0.1 cM, respectively. Finally, we validated the genetic map constructed by newly developed InDel markers by QTL analysis of days to flowering (DTF) under different environments. One major QTL ( qDTF4 ) and four minor QTL ( qDTF20 , qDTF13 , qDTF12 , and qDTF11 ) on 5 LGs were detected. These results demonstrate the utility of the InDel markers developed in this work for map-based cloning and molecular breeding in soybean.

Molecular marker-assisted selection: a novel approach for host plant resistance to insects in grain legumes

Abstract: Grain such as chickpea, pigeonpea, cowpea, fieldpea, lentil, grams, beans, soybean, and groundnut play an important role in "the daily diets the people worldwide. Being a rich source of protein, they are damaged by. a large number of insect pests such as legume pod borer, corn earworm, pod borer, aphids, white fly, tobacco caterpillar, leafhoppers, thrips and bruchids. of resistance to insects in grain legumes have been identified long ago, but these have not been used. effectively in crop improvement because of the difficulties involved in screening and selection of the test material under conditions. Molecular markers can play an important role in accelerating the introgresslOn of genes conferring to target insects into high-yielding cultivars, understanding the nature of gene action, and reducing the deleterious effects introgressing unwanted genes from wild species through linkage drag. Molecular breeding also offers the opportunity to pyramid different sources of resistance that could not be effectively selected through conventional breeding due to identical phenotypes and thereby accumulate levels of resistance and/or create potentially more durable resistant cultivars. Considerable has been made in developing genetic linkage maps of chickpea, cowpea, and soybean, while much remains to be done in pigeonpea, beans, lentil, and fieldpea. Preliminary identification of molecular markers resistance to insects in soybean, chickpea, mungbean, fieldpea, and cowpea has been reported. However, no distinct advantage has been observed by using assisted selection resistance to insect pests over the conventional approach, and in most cases, the epistatic are also quite high. Thus, a new paradigm approach may be required to combine conventional approaches and marker-assisted selection in such way as to create systems better than either approach. This paper reviews current state-of-the-art concerning conventional and molecular breeding for pest resistance, and highlight the opportunities and con~traints for use of molecular markers for accelerating the pace of development of insectresistant culrivars in grain legumes.

Development of microsatellite markers in the oil-producing species Vernicia fordii (Euphorbiaceae), a potential biodiesel feedstock.

Abstract: Premise of the study: Tung tree, Vernicia fordii, is native to China. Little has been done on genetics and breeding at the molecular level in this species, let alone utilizing microsatellite (simple sequence repeat [SSR]) markers. Therefore, a set of SSR molecular markers was developed for studies on molecular genetics and breeding in tung tree. Methods and Results: We designed 78 SSR markers using a protocol based on the Fast Isolation by AFLP of Sequences Containing repeats (FIASCO) protocol. Assessed in 81 V.fordii accessions, 40 of these markers were polymorphic and 12 of them showed monomorphism. When tested using six V. montana accessions, 52 of the markers were capable of PCR amplification and 25 were polymorphic. Conclusions: The newly developed SSR markers are effective and helpful in the evaluation of genetic germplasm and molecular breeding in tung tree.

Molecular Breeding of Rice for Problem Soils

Abstract: Soil problems resulting from either excess or shortage of certain elements as a consequence of specific soil properties are widespread globally and significantly constrain agriculture production. Reclaiming these soils is too costly for rice farmers who are predominately resource-poor with small land holdings. However, breeding cultivars with improved tolerances of prevailing stresses is more feasible and sustainable, particularly when combined with best agronomic and mitigation practices. The recent developments in unraveling molecular and physiological bases of tolerance of various abiotic stresses, the discoveries made in identifying major quantitative trait loci (QTLs) and genes associated with tolerance, and the advances in molecular marker technologies have made it possible to achieve faster progress in developing more resilient, high-yielding varieties for these unfavorable soil conditions. Precise marker-assisted backcrossing (MABC) systems are being developed and used for introgressing major QTLs associated with tolerance of various soil problems into popular varieties and elite breeding lines lacking these traits, and this has enabled the swift development and deployment of such varieties. We have summarized the progress made so far in major stresses encountered in rice problem soils including salt stress and nutritional toxicities and deficiencies. We have also provided a brief account of the progress toward developing and using MABC for cultivar improvement.