Search

The fusarium yellows resistance (YR) gene FocBo1 was previously identified and the DNA markers were developed to assist the breeding of YR cultivars in Brassica oleracea. However, the further analysis revealed discrepancies between the phenotypes and the genotypes predicted by those DNA markers in cabbage commercial cultivars. Since this discrepancy seemed to be due to unknown susceptible alleles of focbo1, we sequenced the gene in 19 accessions to determine the sequence variations between alleles and found that there were two resistant FocBo1 alleles and six susceptible alleles in the investigated population. The newly designed PCR markers detected three mutations in the susceptible alleles that generate premature termination codons. These were shown to accurately distinguish resistant and susceptible alleles in more than 200 accessions of B. oleracea inbred lines and cultivars. The study revealed that the locus is represented by 37.2% resistant and 62.8% susceptible alleles within seventy-eight commercial cultivars. Structural analysis of the gene revealed that a part of the allelic variation comes from intragenic recombination between alleles. Our results enable a more precise prediction of the phenotype by marker assisted selection, promoting the production of YR cultivars in B. oleracea.

Flowering time is an important agronomic trait for Brassica rapa crops, and previous breeding work in Brassica has successfully transmitted other important agronomic traits from donor species. However, there has been no previous attempts to produce hybrids replacing the original Brassica FLC alleles with alien FLC alleles. In this paper, we introduce the creation of a chromosome substitution line (CSSL) containing a homozygous introgression of Flowering Locus C from Brassica oleracea (BoFLC2) into a B. rapa genomic background, and characterize the CSSL line with respect to the parental cultivars. The preferential transmission of alien chromosome inheritance and the pattern of transmission observed during the production of the CSSLs are also discussed.

Flowering time is an important agronomic trait for Brassica rapa crops, and previous breeding work in Brassica has successfully transmitted other important agronomic traits from donor species. However, there has been no previous attempts to produce hybrids replacing the original Brassica FLC alleles with alien FLC alleles. In this paper, we introduce the creation of a chromosome substitution line (CSSL) containing a homozygous introgression of Flowering Locus C from Brassica oleracea (BoFLC2) into a B. rapa genomic background, and characterize the CSSL line with respect to the parental cultivars. The preferential transmission of alien chromosome inheritance and the pattern of transmission observed during the production of the CSSLs are also discussed.

Lilies and tulips (Liliaceae family) are economically very important ornamental bulbous plants. Here, we summarize major breeding goals, the role of an integrated method of cut-style pollination and fertilization followed by embryo rescue and mitotic and meiotic polyploidization involved in new assortment development. Both crops have been subjected to extensive interspecific hybridization followed by selection. Additionally, spontaneous polyploidization has played a role in their evolution. In lilies, there is a tendency to replace diploids with polyploid cultivars, whereas in tulip a majority of the cultivars that exist today are still diploid except for triploid Darwin hybrid tulips. The introduction of molecular cytogenetic techniques such as genomic in situ hybridization (GISH) permitted the detailed studies of genome composition in lily and tulip interspecific hybrids and to follow the chromosome inheritance in interspecific crosses. In addition, this review presents the latest information on phylogenetic relationship in lily and tulip and recent developments in molecular mapping using different DNA molecular techniques.

The genome-wide characterization of single nucleotide polymorphism (SNP) between cultivars or between inbred lines contributes to the creation of genetic markers that are important for plant breeding. Functional markers derived from polymorphisms within genes that affect phenotypic variation are especially valuable in plant breeding. Here, we report on the genome re-sequencing and analysis of the two parental inbred lines of the commercial F1 hybrid Chinese cabbage cultivar "W77". Through the genome-wide identification and classification of the SNPs and indels present in each parental line, we identified about 1,500 putative non-functional genes in each parent. We designed cleaved amplified polymorphic sequence (CAPS) markers using specific mutations found at Eco RI restriction sites in the parental lines and confirmed their Mendelian segregation by constructing a linkage map using 96 F2 plants derived from the F1 hybrid cultivar, "W77". Our results and data will be a useful genomic resource for future studies of gene function and metagenomic studies in Chinese cabbage.

The fusarium yellows resistance (YR) gene FocBo1 was previously identified and the DNA markers were developed to assist the breeding of YR cultivars in Brassica oleracea. However, the further analysis revealed discrepancies between the phenotypes and the genotypes predicted by those DNA markers in cabbage commercial cultivars. Since this discrepancy seemed to be due to unknown susceptible alleles of focbo1, we sequenced the gene in 19 accessions to determine the sequence variations between alleles and found that there were two resistant FocBo1 alleles and six susceptible alleles in the investigated population. The newly designed PCR markers detected three mutations in the susceptible alleles that generate premature termination codons. These were shown to accurately distinguish resistant and susceptible alleles in more than 200 accessions of B. oleracea inbred lines and cultivars. The study revealed that the locus is represented by 37.2% resistant and 62.8% susceptible alleles within seventy-eight commercial cultivars. Structural analysis of the gene revealed that a part of the allelic variation comes from intragenic recombination between alleles. Our results enable a more precise prediction of the phenotype by marker assisted selection, promoting the production of YR cultivars in B. oleracea.

Brassica napus is a leading oilseed crop throughout many parts of the world. It is well adapted to long day photoperiods, however, it does not adapt well to short day subtropical regions. Short duration B. napus plants were resynthesized through ovary culture from interspecific crosses in which B. rapa cultivars were reciprocally crossed with B. oleracea. From five different combinations, 17 hybrid plants were obtained in both directions. By self-pollinating the F1 hybrids or introgressing them with cultivated B. napus, resynthesized (RS) F3 and semi-resynthesized (SRS) F2 generations were produced, respectively. In field trial in Bangladesh, the RS B. napus plants demonstrated variation in days to first flowering ranging from 29 to 73 days; some of which were similar to cultivated short duration B. napus, but not cultivated short duration B. rapa. The RS and SRS B. napus lines produced 2-4.6 and 1.6-3.7 times higher yields, respectively, as compared to cultivated short duration B. napus. Our developed RS lines may be useful for rapeseed breeding not only for subtropical regions, but also for areas such as Canada and Europe where spring rapeseed production can suffer from late spring frosts. Yield and earliness in RS lines are discussed.

We postulate the phylogenetic relationships of section Archelirion (genus Lilium) based on the nucleotide sequence variations of three spacer regions in chloroplast DNA, trnT-trnL, trnL-trnF and atpB-rbcL. The sequences aligned provided a matrix of 1,627 bp, and were analyzed phylogenetically by the maximum parsimony method. Section Archelirion was divided into two major clades, one consisting of L. auratum var. auratum and L. rubellum, and the other consisting of the rest of taxa in Archelirion. The cytoplasm of the former clade was regarded as the rubellum type (eastern type), and that of the latter clade as the japonicum type (western type). Each taxon was monophyletic, but two varieties of L. auratum were belonged to a different clade. The phylogeny of L. auratum var. auratum is different from that of L. auratum var. platyphyllum, and it has a sister-relationship with L. rubellum. These results provide a more convincing phylogenetic relationship within section Archelirion.

We postulates the phylogenetic relationships of section Sinomartagon using 64 Lilium taxa and two related taxa based on nucleotide sequence variations in the internal transcribed spacer regions of nuclear ribosomal DNA. Excluding the 5.8S unit, a total of 479bp were analyzed by three methods, i.e. maximum likelihood, maximum parsimony and neighbor-joining. Sinomartagon was polyphyletic and divided into five groups: (1) L. henryi, (2) L. henricii, L. macklinae, L. oxypetalum and L. nanum, (3) L. nepalense, (4) L. duchartrei, L. lankongense, L. amoenum, L. wardii and L. taliense, and (5) 10 other taxa of subsections 5a and 5b. This classification did not correspond to the subsections defined by Comber (1949), and all the groups should be recognized as distinct taxa. The second group which included mainly Nomocharis-like Lilium, should be treated as a different taxon such as section Lophophorum. Since the last group with section Dauricum and L. bulbiferum included L. davidii, the type of Sinomartagon, they could be considered to correspond to the true section Sinomartagon. The results provide a more convincing phylogenetic position for Sinomartagon.

Fertile plants undergoing male gametogenesis can be treated with nitrous oxide (N(2)O) gas to obtain 2n male gametes. N(2)O treatment is also expected to restore the fertility of interspecific hybrids through meiotic restitution or mitotic amphidiploidization. However, this technique has few applications to date, and it is un-known how N(2)O treatment restores fertility in sterile hybrids. To establish optimal N(2)O treatment conditions and determine its cytological mechanism of action, we treated various sized floral buds with N(2)O gas at different anther developmental stages from fertile and sterile hybrid lilies. N(2)O treatment using the optimal 1-4 mm floral buds induced mitotic polyploidization of male archesporial cells to produce 2n pollen in fertile hybrid lilies. In sterile hybrid lilies, N(2)O treatment doubled the chromosome number in male archesporial cells followed by homologous chromosome pairing and normal meiosis in pollen mother cells (PMC), resulting in restoration of pollen fertility. Backcrossing the resultant fertile pollen to Lilium × formolongi produced many triploid BC(1) plants. Thus N(2)O treatment at the archesporial cell proliferating stage effectively overcame pollen sterility in hybrid lilies, resulting in fertile, 2n pollen grains that could produce progeny. The procedure presented here will promote interspecific or interploidy hybridization of lilies.