Mukhlesur Rahman

Inheritance of seed coat color genes in Brassica napus (L.) and tagging the genes using SRAP, SCAR and SNP molecular markers

Seed coat color inheritance in Brassica napus was studied in F1, F2, F3 and backcross progenies from crosses of five black seeded varieties/lines to three pure breeding yellow seeded lines. Maternal inheritance was observed for seed coat color in B. napus, but a pollen effect was also found when yellow seeded lines were used as the female parent. Seed coat color segregated from black to dark brown, light brown, dark yellow, light yellow, and yellow. Seed coat color was found to be controlled by three genes, the first two genes were responsible for black/brown seed coat color and the third gene was responsible for dark/light yellow seed coat color in B. napus. All three seed coat color alleles were dominant over yellow color alleles at all three loci. Sequence related amplified polymorphism (SRAP) was used for the development of molecular markers co-segregating with the seed coat color genes. A SRAP marker (SA12BG18388) tightly linked to one of the black/brown seed coat color genes was identified in the F2 and backcross populations. This marker was found to be anchored on linkage group A9/N9 of the A-genome of B. napus. This SRAP marker was converted into sequence-characterized amplification region (SCAR) markers using chromosome-walking technology. A second SRAP marker (SA7BG29245), very close to another black/brown seed coat color gene, was identified from a high density genetic map developed in our laboratory using primer walking from an anchoring marker. The marker was located on linkage group C3/N13 of the C-genome of B. napus. This marker also co-segregated with the black/brown seed coat color gene in B. rapa. Based on the sequence information of the flanking sequences, 24 single nucleotide polymorphisms (SNPs) were identified between the yellow seeded and black/brown seeded lines. SNP detection and genotyping clearly differentiated the black/brown seeded plants from dark/light/yellow-seeded plants and also differentiated between homozygous (Y2Y2) and heterozygous (Y2y2) black/brown seeded plants. A total of 768 SRAP primer pair combinations were screened in dark/light yellow seed coat color plants and a close marker (DC1GA27197) linked to the dark/light yellow seed coat color gene was developed. These three markers linked to the three different yellow seed coat color genes in B. napus can be used to screen for yellow seeded lines in canola/rapeseed breeding programs.

A review of Brassica seed color

Rahman, M. and McVetty, P. B. E. 2011. A review of Brassica seed color. Can. J. Plant Sci. 91: 437-446. Canola oil has excellent fatty acid composition and low saturated fat levels, and canola meal has protein with excellent amino acid composition. Canola seed quality can be further improved by the development of higher oil, higher protein and lower fiber content germplasm through the development of yellow seeded lines. While there is no naturally occurring yellow seeded B. napus, yellow seeded mutants that have arisen in nature can be readily indentified in Brassica rapa, B. juncea and B. carinata species. Brassica napus is widely cultivated in Asia, Australia, Europe and North America. Yellow seed in Brassica species is associated with seed that has higher oil and protein content and lower fiber content. Because of these seed quality advantages of yellow seeded lines, plant breeders around the world have been attempting to develop yellow seeded B. napus genotypes using crosses involving naturally occurring yellow seeded Brassica species. Seed color in B. rapa is controlled by two genes. Two duplicate genes are responsible for seed color in B. juncea. In B. carinata, one repressor gene represses the seed color gene resulting in yellow seed, while the absence of the repressor gene results in brown seed. Several yellow seeded B. napus genotypes have been developed and in most cases three genes are reported as being are responsible for seed color. Numerous different molecular markers for seed color genes in B. rapa, B. juncea and B. napus have been developed for use in marker-assisted selection in plant-breeding programs. These molecular markers can also be used to clone the Brassica seed color gene(s) and then create transgenic yellow seeded B. napus genotypes. This review summarizes past and current research on Brassica seed color breeding, genetics and genomics/biotechnology.

QTL mapping for root vigor and days to flowering in Brassica napus L.

Abstract: A segregating F2 population was developed from a winter and spring type cross to identify quantitative trait loci (QTL) controlling root vigor and days to flowering in canola (Brassica napus). About 3090 polymorphic SNPs derived from genotyping by sequencing were used to develop a linkage map. A final linkage map was constructed with 658 SNPs at LOD 4. One QTL, NRV (Napus Root Vigor) was identified on chromosome A01 (24.7 Mbp) for root vigor explaining 16.3% of the phenotypic variation. GBF Interacting Protein 1 (GIP1) and SAUR-like family proteins are the two candidate genes related to root growth and development identified within this QTL region. Two QTL, DTF1 and DTF2, were identified for days to flowering, accounting for 21.7% and 15% of the phenotypic variation, respectively. DTF1 was assigned on chromosome C08 (9.43 Mbp) and two putative candidate genes, Light Regulated WD1 (LWD1) and FLOWERING BHLH 1 (FBH1) were identified within this QTL region. For DTF2, three putative candidate genes A. thaliana CENTRORDIALIS (ATC), Tetracopeptide Repeat (TPR), and Poly A Binding protein 3 (PAB3) were identified on the chromosome C04 (14.56 Mbp).

Behind the scenes of microspore-based double haploid development in Brassica napus: A review

Double haploids are extremely valuable for generating completely homozygous genotypes and have been used in plant breeding program of a number of crop species. This method is a much faster way of developing genetically pure breeding lines in one single generation. The main objective of this review is to describe in a clear and simple manner how microspore-based double haploids of rapeseed are produced and helps a reader to understand the amazing process of microspore embryogenesis, also referred to as androgenesis or pollen embryogenesis. This review will explain what double haploids are as well as their importance in both Brassica breeding and molecular studies. Additionally, a brief discussion of different factors affecting the double haploid production and a comprehensive explanation of the steps involved in the development of the double haploids will be covered.

Chapter 15 – Designer Oil Crops

Oilseed crops are predominantly grown for the oil contained in their seeds. The vegetable oil is primarily utilized as edible oil; however, oilseeds are also used as protein meals for livestock, pharmaceuticals, biofuels, as well as other oleochemical industrial uses. Oilseeds have attracted more attention in the last two decades due to their application in biofuel production. The increased interest resulted in an expansion of oilseed crop cultivation area and production. Triglycerides, composed of various fatty acids, are the main component of vegetable oil. Many genes in the triglyceride biosynthesis pathway have been identified and are well studied. Genetic engineering allows insertion or modification of genes involved in the synthesis of a desired fatty acid to accumulate its higher level or even to produce a desired fatty acid. Novel technologies have opened up new pathways making sustainable production of these designer crops a reality.

Inheritance of seed coat color of Ethiopian mustard (Brassica carinata A. Braun).

The inheritance of seed coat color was investigated in Brassica carinata in F1, F2, F3 and backcross progenies of crosses between brown- and yellow-seeded pure lines. Seed coat color in B. carinata was not influenced by xenia effect. Segregation pattern followed a mono-genic incomplete dominance inheritance model The occurrence of yellow/light yellow-brown seed trait in B. carinata may be due to an interaction between brown seed coat color gene and dominant repressor (Rp) genes. Key words: Brassica carinata, inheritance, seed coat color, dominant repressor

Independent assortment of seed color and hairy leaf genes in Brassica rapa L.

Rahman, M. 2014. Independent assortment of seed color and hairy leaf genes in Brassica rapa L. Can. J. Plant Sci. 94: 615-620. A genetic study of seed color and hairy leaf in Brassica rapa was conducted in progeny originating from the brown-seeded, hairy leaf B. rapa subsp. chinensis line and the Bangladeshi B. rapa var. trilocularis line. A joint segregation of both traits was also examined in the F2 and backcross populations. Seed color segregated into brown, yellow-brown, and yellow, which suggests that digenic control of brown or yellow-brown color was dominant over yellow seed color. Hairy leaves were found to be under monogenic control, and hairy leaf was dominant over non-hairy leaf. The data show that genes controlling seed color and hairy leaf are inherited independently.