Fine-Mapping And Identification of A Candidate Gene Controlling Seed Coat Color In Melon (Cucumis Melo L. Var. Chinensis Pangalo)

Seed coat color is related to flavonoid content which is closely related to seed dormancy. According to the genetic analysis of a six-generation population derived from two parents (IC2508 with a yellow seed coat and IC2518 with a brown seed coat), we discovered that the yellow seed coat trait in melon was controlled by a single dominant gene, named CmBS-1. Bulked segregant analysis sequencing (BSA-Seq) revealed that the gene was located at 11,860,000–15,890,000 bp (4.03 Mb) on Chr 6. The F2 population was genotyped using insertion-deletions (InDels), from which cleaved amplified polymorphic sequence (dCAPS) markers were derived to construct a genetic map. The gene was then fine-mapped to a 233.98 kb region containing 12 genes. Based on gene sequence analysis with two parents, we found that the MELO3C019554 gene encoding a homeobox protein (PHD transcription factor) had a nonsynonymous single nucleotide polymorphism (SNP) mutation in the coding sequence (CDS), and the SNP mutation resulted in the conversion of an amino acid (A→T) at residue 534. In addition, MELO3C019554 exhibited lower relative expression levels in the yellow seed coat than in the brown seed coat. Furthermore, we found that MELO3C019554 was related to 12 flavonoid metabolites. Thus, we predicted that MELO3C019554 is a candidate gene controlling seed coat color in melon. The study lays a foundation for further cloning projects and functional analysis of this gene, as well as marker-assisted selection breeding.

Resistance to Charcoal Rot Identified Within Soybean Cyst Nematode Resistant Accessions

Two infectious root diseases that cause significant yield losses worldwide in soybean [Glycine max (L.) Merr.] are charcoal rot caused by Macrophomina phaseolina (Tassi) Goid. and the soybean cyst nematode, caused by Heterodera glycines Ichinohe. The objective of this research was to evaluate resistance to charcoal rot in a set of 120 soybean accessions reported to have resistance to one or more races of soybean cyst nematode so that lines with combined resistance could be identified. These accessions were screened in infested field in 2006 and 2007. Charcoal rot severity ranged from 1 to 5, where 1 is resistant and 5 susceptible. The result showed that out of the 120 soybean accessions tested for charcoal rot resistance 12 were identified to have moderate levels of resistance, 51 had moderate susceptibility, and 60 were susceptible. Furthermore, the accessions with moderate resistance to charcoal rot had resistance for one to two races of soybean cyst nematode. Within the lines identified with moderate resistance to charcoal rot, nine had a yellow seed coat, a desirable agronomic trait. These lines can be used as parents in soybean breeding programs for developing soybean cultivars with combined resistance to both charcoal rot and soybean cyst nematode.

Comparative transcriptome and flavonoids components analysis reveal the structural genes responsible for the yellow seed coat color of Brassica rapa L.

Background Seed coat color is an important horticultural trait in Brassica crops, which is divided into two categories: brown/black and yellow. Seeds with yellow seed coat color have higher oil quality, higher protein content and lower fiber content. Yellow seed coat color is therefore considered a desirable trait in hybrid breeding of Brassica rapa, Brassica juncea and Brassica napus. Methods Comprehensive analysis of the abundance transcripts for seed coat color at three development stages by RNA-sequencing (RNA-seq) and corresponding flavonoids compounds by liquid chromatography-tandem mass spectrometry (LC-MS/MS) were carried out in B. rapa. Results We identified 41,286 unigenes with 4,989 differentially expressed genes between brown seeds (B147) and yellow seeds (B80) at the same development stage. Kyoto Encyclopedia of Genes and Genomes enrichment analysis identified 19 unigenes associated with the phenylpropanoid, flavonoid, flavone and flavonol biosynthetic pathways as involved in seed coat color formation. Interestingly, expression levels of early biosynthetic genes (BrCHS, BrCHI, BrF3H, BrF3’H and BrFLS) in the flavonoid biosynthetic pathway were down-regulated while late biosynthetic genes (BrDFR, BrLDOX and BrBAN) were hardly or not expressed in seeds of B80. At the same time, BrTT8 and BrMYB5 were down-regulated in B80. Results of LC-MS also showed that epicatechin was not detected in seeds of B80. We validated the accuracy of our RNA-seq data by RT-qPCR of nine critical genes. Epicatechin was not detected in seeds of B80 by LC-MS/MS. Conclusions The expression levels of flavonoid biosynthetic pathway genes and the relative content of flavonoid biosynthetic pathway metabolites clearly explained yellow seed color formation in B. rapa. This study provides a foundation for further research on the molecular mechanism of seed coat color formation.

Screening and genetic studies on resistance to Soil-born Cereal Mosaic Virus (SBWMV) in rye

Due to several reasons soil-borne viruses such as the furoviruses, i. e., cereal mosaic virus (SBCMV) and wheat mosaic virus (SBWMV) as well as the bymovirus wheat spindle streak mosaic virus (WSSMV) gained importance in cereal breeding including rye. High yield losses are recorded, today. Since there is no or little resistance to these viruses in modern rye cultivars, an extended screening for resistance was initiated. In addition to earlier screenings, 37 rye genotypes were tested for resistance. Among them, three genotypes were found with persistent resistance to SBCMV. They belong to Secale montanum and S. vavilovii species, i. e., wild types of rye. One accession, PC2243 (S. montanum), was used as a resistance donor for the present genetic study. In F2 generation, it was observed that resistance to SBCMV is independently inherited from WSSMV. The evaluation of the ELISA values pointed to a 3:1 distribution assuming duplicate dominant epistasis. Molecular marker analysis supports this segregation pattern. By composite interval mapping a QTL on chromosome 2R could be detected. It can be assumed that there is a DNA region of about 13 cM on the long arm of chromosome 2R (2RL) harboring SBCMV resistance with the closest markers “C9654_1947” and “isotig11640”. Moreover, genotypes with a yellow seed coat showed practically no infection with SBCMV. Thus, the resistance gene could be linked to the allele an1 determining non expression of anthocyanins. This locus was also mapped earlier on chromosome 2R.

Dissecting seed pigmentation-associated genomic loci and genes by employing dual approaches of reference-based and k-mer-based GWAS with 438 Glycine accessions

The soybean is agro-economically the most important among all cultivated legume crops, and its seed color is considered one of the most attractive factors in the selection-by-breeders. Thus, genome-wide identification of genes and loci associated with seed colors is critical for the precision breeding of crop soybeans. To dissect seed pigmentation-associated genomic loci and genes, we employed dual approaches by combining reference-based genome-wide association study (rbGWAS) and k-mer-based reference-free GWAS (rfGWAS) with 438 Glycine accessions. The dual analytical strategy allowed us to identify four major genomic loci (designated as SP1-SP4 in this study) associated with the seed colors of soybeans. The k-mer analysis enabled us to find an important recombination event that occurred between subtilisin and I-cluster B in the soybean genome, which could describe a special structural feature of ii allele within the I locus (SP3). Importantly, mapping analyses of both mRNAs and small RNAs allowed us to reveal that the subtilisin-CHS1/CHS3 chimeric transcripts generate and act as an initiator towards ‘mirtron (i.e., intron-harboring miRNA precursor)’-triggered silencing of chalcone synthase (CHS) genes. Consequently, the results led us to propose a working model of ‘mirtron-triggered gene silencing (MTGS)’ to elucidate a long-standing puzzle in the genome-wide CHS gene silencing mechanism. In summary, our study reports four major genomic loci, lists of key genes and genome-wide variations that are associated with seed pigmentation in soybeans. In addition, we propose that the MTGS mechanism plays a crucial role in the genome-wide silencing of CHS genes, thereby suggesting a clue to currently predominant soybean cultivars with the yellow seed coat. Finally, this study will provide a broad insight into the interactions and correlations among seed color-associated genes and loci within the context of anthocyanin biosynthetic pathways.

CDC Dorado yellow seed coat oilseed flax

CDC Dorado is a yellow seed coat oilseed flax (Linum usitatissimum L.), registered in 2017 by the Crop Development Centre, University of Saskatchewan, Saskatoon, Saskatchewan. This cultivar has 7% higher yield than AC Nugget in the Black soil zone of the Prairies coupled with a maturity earlier than Flanders across ten site years in Western Canada. It has a medium (45.2%) oil content, high iodine value (IV 204.2) and alpha-linolenic acid (ALA) content (64%), and a thousand seed weight (TSW) of 6.0 g. It has disease ratings of immune to flax rust caused by Melampsora lini and is moderately resistant to wilt and powdery mildew caused by Fusarium oxysporum f. sp. lini and Oidium lini, respectively.

CDC Melyn yellow seed coat oilseed flax

CDC Melyn is a yellow seed coat oilseed flax (Linum usitatissimum L.), registered in 2016 by the Crop Development Centre, University of Saskatchewan, Saskatoon, Saskatchewan. This cultivar has yield (106%) comparable to cultivar AC Nugget (the yield standard for yellow seed coat oilseed flax) and maturity rating equal to Flanders. It has a medium (46.6%) oil content, iodine value (199.4), alpha-linolenic acid content (61%) and a thousand seed weight of 5.0 g. It is immune to flax rust caused by Melampsora lini and moderately resistant to wilt and powdery mildew caused by Fusarium oxysporum f. sp. lini and Oidium lini, respectively.

Verification of Soybean Seed Coat Colour Specific Markers Reveals I Loci Specific Markers Capable for Distinguishing Genotypes Differing in Seed Coated Colour

Background: In soybean yellow seed coat is preferred in the market, however, colored ones are currently gaining attention because of their medicinal and nutritive values; besides. Hence it is essential to breed varieties with desired seed coat colour. Methods: Twelve genotypes with six each having yellow and black seed coats were screened with fourteen primers linked to seed coat colour governing loci. Result: Out of them twelve primers showed polymorphism. Monomorphism was observed with both T loci specific and two of the three R loci specific primers. However I locus specific primers i.e. SM303, SM305 and TR showed polymorphism shared by their seed coat color. SM303 amplified a 180 bp sized band in yellow seed coated genotypes and a 130 bp band in black seed coated genotypes. SM305 amplified dual bands with a 200bp band being monomorphic and an additional band (192-216 bp range) present in only yellow seed coated genotypes, of which a 208 bp band was shared by four yellow seed coated genotypes. Cold induced seed coat discoloration specific TR primer generated bands of different size ranges in yellow seed coated (336-344 bp) and black seed coated genotypes (300-320), of which a 340 bp band was shared by four yellow seed coated genotypes.

AAC Y073 yellow dry bean

AAC Y073 is a high-yielding, yellow dry bean (Phaseolus vulgaris L.) cultivar with a partially upright, determinate bush (type I) growth habit, early maturity, and large seeds with a bright yellow seed coat. Large, bright yellow seeds of AAC Y073 is an improvement over the current check cultivar CDC Sol. AAC Y073 was developed at the Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, AB, and is well suited for commercial production under irrigation in Alberta and Saskatchewan.