Molecular breeding

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

Genome-Wide Association Study Reveals Novel Loci for SC7 Resistance in a Soybean Mutant Panel.

Abstract: Soybean mosaic virus (SMV) is a member of Potyvirus genus that causes severe yield loss and destroys seed quality in soybean [Glycine max (L.) Merr.]. It is important to explore new resistance sources and discover new resistance loci to SMV, which will provide insights to improve breeding strategies for SMV resistance. Here, a genome-wide association study was conducted to accelerate molecular breeding for the improvement of resistance to SMV in soybean. A population of 165 soybean mutants derived from two soybean parents was used in this study. There were 104 SNPs identified significantly associated with resistance to SC7, some of which were located within previous reported quantitative trait loci. Three putative genes on chromosome 1, 9, and 12 were homologous to WRKY72, eEF1Bβ, and RLP9, which were involved in defense response to insect and disease in Arabidopsis. Moreover, the expression levels of these three genes changed in resistance and susceptible soybean accessions after SMV infection. These three putative genes may involve in the resistance to SC7 and be worthy to further research. Collectively, markers significantly associated with resistance to SC7 will be helpful in molecular marker-assisted selection for breeding resistant soybean accessions to SMV, and the candidate genes identified would advance the functional study of resistance to SMV in soybean.

Miniature inverted-repeat transposable elements (MITEs), derived insertional polymorphism as a tool of marker systems for molecular plant breeding

Abstract: Plant molecular breeding is expected to give significant gains in cultivar development through development and utilization of suitable molecular marker systems for genetic diversity analysis, rapid DNA fingerprinting, identification of true hybrids, trait mapping and marker-assisted selection. Transposable elements (TEs) are the most abundant component in a genome and being used as genetic markers in the plant molecular breeding. Here, we review on the high copious transposable element belonging to class-II DNA TEs called "miniature inverted-repeat transposable elements" (MITEs). MITEs are ubiquitous, short and non-autonomous DNA transposable elements which have a tendency to insert into genes and genic regions have paved a way for the development of functional DNA marker systems in plant genomes. This review summarises the characteristics of MITEs, principles and methodologies for development of MITEs based DNA markers, bioinformatics tools and resources for plant MITE discovery and their utilization in crop improvement.

Discovery of miRNAs and Development of Heat-Responsive miRNA-SSR Markers for Characterization of Wheat Germplasm for Terminal Heat Tolerance Breeding.

Abstract: A large proportion of the Asian population fulfills their energy requirements from wheat (Triticum aestivum L.). Wheat quality and yield are critically affected by the terminal heat stress across the globe. It affects approximately 40% of the wheat-cultivating regions of the world. Therefore, there is a critical need to develop improved terminal heat-tolerant wheat varieties. Marker-assisted breeding with genic simple sequence repeats (SSR) markers have been used for developing terminal heat-tolerant wheat varieties; however, only few studies involved the use of microRNA (miRNA)-based SSR markers (miRNA-SSRs) in wheat, which were found as key players in various abiotic stresses. In the present study, we identified 104 heat-stress-responsive miRNAs reported in various crops. Out of these, 70 miRNA-SSR markers have been validated on a set of 20 terminal heat-tolerant and heat-susceptible wheat genotypes. Among these, only 19 miRNA-SSR markers were found to be polymorphic, which were further used to study the genetic diversity and population structure. The polymorphic miRNA-SSRs amplified 61 SSR loci with an average of 2.9 alleles per locus. The polymorphic information content (PIC) value of polymorphic miRNA-SSRs ranged from 0.10 to 0.87 with a mean value of 0.48. The dendrogram constructed using unweighted neighbor-joining method and population structure analysis clustered these 20 wheat genotypes into 3 clusters. The target genes of these miRNAs are involved either directly or indirectly in providing tolerance to heat stress. Furthermore, two polymorphic markers miR159c and miR165b were declared as very promising diagnostic markers, since these markers showed specific alleles and discriminated terminal heat-tolerant genotypes from the susceptible genotypes. Thus, these identified miRNA-SSR markers will prove useful in the characterization of wheat germplasm through the study of genetic diversity and population structural analysis and in wheat molecular breeding programs aimed at terminal heat tolerance of wheat varieties.

Development of Genome-Wide SSR Markers from Angelica gigas Nakai Using Next Generation Sequencing

Abstract: Angelica gigas Nakai is an important medicinal herb, widely utilized in Asian countries especially in Korea, Japan, and China Although it is a vital medicinal herb, the lack of sequencing data and efficient molecular markers has limited the application of a genetic approach for horticultural improvements Simple sequence repeats (SSRs) are universally accepted molecular markers for population structure study In this study, we found over 130,000 SSRs, ranging from di- to deca-nucleotide motifs, using the genome sequence of Manchu variety (MV) of A gigas, derived from next generation sequencing (NGS) From the putative SSR regions identified, a total of 16,496 primer sets were successfully designed Among them, we selected 848 SSR markers that showed polymorphism from in silico analysis and contained tri- to hexa-nucleotide motifs We tested 36 SSR primer sets for polymorphism in 16 A gigas accessions The average polymorphism information content (PIC) was 069; the average observed heterozygosity (HO) values, and the expected heterozygosity (HE) values were 053 and 073, respectively These newly developed SSR markers would be useful tools for molecular genetics, genotype identification, genetic mapping, molecular breeding, and studying species relationships of the Angelica genus

Characterization of Haplotype Diversity in the BADH2 Aroma Gene and Development of a KASP SNP Assay for Predicting Aroma in U.S. Rice

Abstract: Aroma is an important grain quality trait in rice, controlled by mutations within the BADH2 gene. The trait is simply inherited, and its importance in variety development makes it a practical target for marker-assisted selection in applied breeding programs. The predominant functional mutation within BADH2, an 8-bp indel, can be reliably detected using a PCR-based assay, but the available assays and associated genotyping platforms are insufficient for large-scale applied molecular breeding applications and are not compatible with outsourcing genotyping services. We first characterized SNP diversity across the BADH2 gene in a collection of 2932 rice varieties to determine the number of gene haplotypes in O. sativa. Using 297 gene-based SNPs, 11 haplotype groups were detected, and subsequently identified a minimal set of nine informative SNPs that uniquely identified the BADH2 haplotypes. These nine SNPs were developed into KASP assays and used to examine a panel of 369 U.S. rice accessions. The panel represented modern breeding germplasm and included all known aroma pedigree sources in U.S. rice. Six haplotypes were detected within the U.S. panel, of which two were found in majority (85%) of varieties. A representative set of 39 varieties from all haplotype groups was evaluated phenotypically to distinguish aromatic from non-aromatic lines. One haplotype (Hap 6) was found to be perfectly associated with the aromatic phenotype. A single KASP SNP unique to Hap 6 was demonstrated to reliably differentiate aromatic from non-aromatic rice varieties across U.S. germplasm.