Mapping of Re,a gene conferring the red leaf trait in ornamental kale (Brassica oleracea L. var. acephala)

Variegated leaf colour is an important agronomic trait that affects the market value of ornamental kale (Brassica oleracea L. var. acephala). The red leaf phenotype in kale is due to anthocyanin accumulation. To investigate the pattern of inheritance of this trait, we constructed an F₂ population by crossing ‘Y005‐15’, a double haploid with red leaves, with a white‐leaved double haploid, ‘Y011‐13‐38’, followed by self‐pollination. An F₂ population consisting of 4284 individuals was used to study the inheritance of this trait, which showed that the character was controlled by a dominate gene. All of the 1050 white leaf trait plants in the F₂ were used for mapping and developing markers linked to Re gene. Results showed that Re was mapped to a locus on linkage group C09 of Brassica oleracea, and the locus was mapped between six SSR markers (C9Z1, C9Z16‐1, C9Z90, C9Z94, C9Z96 and C9Z99), with a genetic distance of 6.7, 1.0, 0.3, 2.0, 2.1 and 0.4 cM from Re gene, respectively. These results may facilitate marker‐assisted selection of the red leaf trait in kale breeding as well as map‐based cloning of the red leaf trait gene.     

Identification of the fourth allele of the ANS (anthocyanidin synthase) gene and its effect on red color intensity in onions (Allium cepa)

Bulb color in onions (Allium cepa) is an important trait, and homogenous red coloration is desirable in red onion cultivars. The gene encoding anthocyanin synthase (ANS) is required for anthocyanin biosynthesis in onions. We have previously described three different alleles of the ANS gene. Here we report identification of the fourth allele of ANS, ANS-h1, found in a dark red doubled haploid line. ANS-h1 is similar to a non-functional allele found in Brazilian yellow cultivars except that it has several point mutations and indels throughout the promoter and coding regions, none of which are predicted to inactivate enzymatic activity. F₂ and backcross populations originating from the crosses between wild-type (ANS-L) allele-containing red and pink (ANS-p) allele-containing white or yellow parents show a discrete segregation ratio of 3 red to 1 light pink, indicating that the wild-type allele is completely dominant over the pink allele. In contrast, segregating populations derived from the crosses between ANS-h1 allele-containing red and the same white or yellow parents show a gradient of red intensity from light pink to dark red, suggesting that other genetic factors may affect expression of ANS-h1. A newly developed PCR-based marker and two previously developed markers for allelic selection of the ANS gene were used to examine allele composition in fifty-six breeding lines and commercial cultivars. Most lines are heterogeneous for the ANS gene with two or three alleles detected. The frequency of the pink allele is low in red breeding lines, but it is predominant in white and yellow lines.     

Quantitative trait loci mapping of seed colour,hairy leaf,seedling anthocyanin,leaf chlorosis and days to flowering in F2 population of Brassica rapa L.

A diversity arrays technology (DArT) map was constructed to identify quantitative trait loci (QTL) affecting seed colour, hairy leaf, seedling anthocyanin, leaf chlorosis and days to flowering in Brassica rapa using a F₂ population from a cross between two parents with contrasting traits. Two genes with dominant epistatic interaction were responsible for seed colour. One major dominant gene controls the hairy leaf trait. Seedling anthocyanin was controlled by a major single dominant gene. The parents did not exhibit leaf chlorosis; however, 32% F₂ plants showed leaf chlorosis in the population. A distorted segregation was observed for days to flowering in the F₂ population. A linkage map was constructed with 376 DArT markers distributed over 12 linkage groups covering 579.7 cM. The DArT markers were assigned on different chromosomes of B. rapa using B. rapa genome sequences and DArT consensus map of B. napus. Two QTL (RSC1‐2 and RSC12‐56) located on chromosome A8 and chromosome A9 were identified for seed colour, which explained 19.4% and 18.2% of the phenotypic variation, respectively. The seed colour marker located in the ortholog to Arabidopsis thaliana Transparent Testa2 (AtTT2). Two QTL RLH6‐0 and RLH9‐16 were identified for hairy leaf, which explained 31.6% and 20.7% phenotypic variation, respectively. A single QTL (RSAn‐12‐157) on chromosome A7, which explained 12.8% of phenotypic variation was detected for seedling anthocyanin. The seedling anthocyanin marker is found within the A. thaliana Transparent Testa12 (AtTT12) ortholog. A QTL (RLC6‐04) for leaf chlorosis was identified, which explained 55.3% of phenotypic variation. QTL for hairy leaf and leaf chlorosis were located 0–4 cM apart on the same chromosome A1. A single QTL (RDF‐10‐0) for days to flowering was identified, which explained 21.4% phenotypic variation.     

Fine mapping the QTL qFS‐chr.23, using a CSIL

In an earlier advanced‐backcross quantitative trait locus (QTL) analysis of an interspecific cross of Gossypium hirsutum cv. ‘Xinluzhong 36’(‘XLZH36’) and G. barbadense cv. ‘Xinhai 21’(‘XH21’), a QTL for fibre strength in the chromosome segment introgression line IL23‐09 was analysed. Single marker analysis revealed that the markers on chro.23 were associated with fibre strength. Using composite interval mapping with the F₂ population (1296 plants), a QTL for fibre strength was detected on chro. 23. The QTL explained 8.9% and 15.9% of phenotypic variances in the F₂ and F_2 : 3 generations, respectively. Substitution mapping suggested that the QTL was located at a physical distance of 23.4 kb between the markers BNL1414 and the single nucleotide polymorphism (SNP) locus D09_43776813 C‐G. We designated this QTL as qFS‐chr.23 (quantitative trait locus for fibre strength on chro.23). This work provides a valuable genetic resource for the breeding of high fibre quality in cotton and will facilitate future efforts for map‐based cloning.     

水稻花色苷含量及合成结构基因的差异表达研究

水稻花色苷的生物合成受许多因素影响,而控制关键酶的结构基因是最主要的因素。针对2个红米材料和2个白米材料,采用实时荧光定量的方法,对合成水稻花色苷的结构基因( OsPAL 、 OsCHS 、 OsCHI 、 OsF3H 、 OsF3′H 、 OsDFR 、 OsANS 、 OsF3′5′H 、 OsUFGT )在茎、叶及种子发育过程中的相对表达水平进行了测定。结果表明:1) OsPAL 、 OsCHS 在水稻的茎、叶和种子中表达, OsCHI 在白米恢复系蜀恢498和白米株系的组织中均有表达,是花色苷合成的组成型基因;其它基因在参试材料的茎、叶和种子中的表达量不同,具有组织特异性。2)在红米品种贵红1号和红米株系开花后7~28 d的花色苷含量逐渐增加,而白米恢复系蜀恢498和白米株系的花色苷含量逐渐下降;这些基因在红米品种贵红1号和红米株系的前中后期均有表达且表达量较高, OsCHS 在红米品种贵红1号种子发育过程中的表达量逐渐增加;这些基因在白米恢复系蜀恢498和白米株系开花后7~28 d的前中期表达量较低,后期急剧降低。表明这些基因的表达量与其花色苷的含量动态变化相同,对花色苷的积累有一定的作用。3) OsPAL 、 OsCHS 表达量与红米品种贵红1号花色苷含量呈显著正相关, OsF3H 表达量与白米株系花色苷含量呈显著正相关, OsPAL 表达量与红米株系花色苷含量呈显著正相关, OsCHI 、 OsF3′5′H 、 OsUFGT 表达量与红米株系花色苷含量呈极显著正相关。研究表明,这些基因在参试材料的茎、叶和种子开花后7~28 d前中后期的差异表达,可能是造成它们着色差异的主要原因。 OsPAL 、 OsCHS 是红米品种贵红1号籽粒花色苷合成的关键基因, OsF3H 在白米株系籽粒发育过程中扮演重要的角色, OsPAL 、 OsCHI 、 OsF3′5′H 、 OsUFGT 在红米株系籽粒花色苷积累中起重要作用。     

Development of dominant nuclear male-sterile lines with a blue seed marker in durum and common wheat

In order to develop genie male‐sterile lines with a blue seed marker, male‐sterile plants, controlled by a dominant nuclear gene Ms2, were used as female parents against a 4E disomic addition line ‘Xiaoyan Lanli’(2n= 44, AABBDD+4EII) as the male parent to produce monosomic addition lines with blue seed. Male‐sterile plants from the monosomic addition lines were pollinated with durum wheat for several generations and in 1989 a male‐sterile line with the blue grain gene and the male‐sterile gene Ms2 on the same additional chromosome was detected and named line 89‐2343. Using this line, the blue seed marker was successfully added to a short male‐sterile line containing Ms2 and Rht10. The segregation ratios of male sterility and seed colour as well as the chromosome figurations of different plants indicated that the blue grain genes, Ms2 and Rht10 were located on the same additional chromosome. Cytological analysis showed that the blue marker male‐sterile lines in durum wheat and common wheat were monosomic with an additional chromosome 4E. The inheritance ratio for blue seed male‐sterile plants and white seed male‐fertile plants was 19.7% and 80.3%, respectively, in common wheat. The potential for using blue marker sterile lines in population improvement and hybrid production is discussed.     

Genetic characterization of the red coloured corolla phenotype for Gossypium arboreum accession PI 529731

Flower corolla colour is an important trait for the attraction of pollinators and for the horticultural industry. Gossypium arboreum (L.) accessions from the United States Department of Agriculture germplasm collection frequently show flowers with a yellow coloured corolla. Accession PI 529731 is unique in that the flowers have a red coloured corolla. Genetic characterization of corolla pigmentation was conducted by crossing PI 529731 with two white flower accessions. Flowers with a red corolla were observed in the F₁ generations suggesting a dominant trait. Variation in corolla colour was observed for plants in the F₂ populations including dark red, red, light red, white, yellow and white with petals having red coloured margins. These data support a single dominant gene conferring the four red corolla phenotypes. The yellow corolla phenotype also supported a single dominant gene model. Dominant alleles at both loci are required for expression of the PI 529731 phenotype and data support a two gene model with a 9:3:3:1 segregation ratio. These data are useful for the characterization of genetic mechanisms controlling tissue‐specific pigmentation.     

Mapping genes controlling anthocyanin pigmentation on the glume and pericarp in tetraploid wheat (<Emphasis Type="Italic">Triticum durum</Emphasis> L.)

A novel gene, designated Pg (purple glume), controlling anthocyanin pigmentation of the glume was identified and mapped in an F₂ population from the durum wheat (Triticum durum) cross TRI 15744/TRI 2719. This gene was close to one of the two complementary dominant genes, controlling anthocyanin pigmentation of the pericarp (gene Pp3) in the centromere region of chromosome 2A; the other Pp gene (Pp1) was mapped on the short arm of chromosome 7B, near gene Pc controlling anthocyanin pigmentation of the culm and co-segregating with Pls (purple leaf sheath) and Plb (purple leaf blade). On the basis of the mapping results, the Pp3, Pc, Pls and Plb genes of T. durum were regarded as allelic to the T. aestivum Pp3, Pc-B1, Pls-B1 and Plb-B1 loci. The likely allelism of Pp1 in T. durum and T. aestivum remains in dispute, the present durum Pp gene mapped to the short arm of chromosome 7B, whereas in common wheat it was reportedly located on the long arm.     

Identification of novel QTL for leaf traits in soybean

Several leaf traits of soybean (Glycine max L. Merr.), including leaf area (LA), leaf shape (LS) and specific leaf weight (SLW) may be related to soybean yield. The objective of this study was to identify novel quantitative trait loci (QTL) for LA, LS and SLW in a recombinant inbred line (RIL) population. The phenotype data were collected in 2011 and 2012 for 93 F_7:10 RILs using a randomized complete block design with 2 replicates each year. Five hundred and sixteen single‐nucleotide polymorphism (SNP) markers and the phenotype data were used to detect QTL using single marker analysis (SMA) and composite interval mapping (CIM). Single markers analysis identified 26 QTL for the three traits, of which 17 were novel and the rests were previously reported QTL. Most of these QTL were also identified by CIM. Most QTL reported in this study were in close proximity (<1 cM) of one or more SNP markers. These publicly available SNP markers with close linkage to LA, LS and SLW should be useful for marker‐assisted breeding for these traits.     

Mapping the BrPur gene for purple leaf color on linkage group A03 of Brassica rapa

The purple-leaf phenotype in Chinese cabbage is due to the accumulation of anthocyanin. To investigate the pattern of inheritance of this trait in Brassica rapa, F₁, F₂ and backcross (BC) populations were constructed by crossing 09N-742, a pak-choi inbred line that has purple leaves, with a green-leaved Chinese cabbage inbred line, 09-680. Using a segregating F₂ population, we identified a single dominant gene, BrPur, for purple leaf, and mapped the gene to a locus on linkage group A03 of B. rapa. Furthermore, sequences from BAC clones and other sources were used to develop molecular marker loci that are tightly linked to BrPur by using a BC₁ population of 1,152 individuals. BrPur was assigned to a locus between Indel markers BVRCPI613 and BVRCPI431, which defined a genetic interval of 0.6 cM and a genomic region of 54.87 kb. Sequence analysis of this chromosomal region revealed seven open reading frames. These results provide a foundation for map-based cloning, identification, and functional analysis of the BrPur gene in B. rapa.     

Molecular mapping of a new gene for resistance to frogeye leaf spot of soya bean in 'Peking'

Amplified fragment length polymorphism (AFLP) and microsatellite (simple sequence repeat, SSR) techniques were used to map the _RGSp_eking gene, which is resistant to most isolates of Cercospora sojina in the soya bean cultivar ‘Peking’. The mapping was conducted using a defined F₂ population derived from the cross of ‘Peking’(resistant) בLee’(susceptible). Of 64 EcoRI and MseI primer combinations, 30 produced polymorphisms between the two parents. The F₂ population, consisting of 116 individuals, was screened with the 30 AFLP primer pairs and three mapped SSR markers to detect markers possibly linked to Rcs_Peking. One AFLP marker amplified by primer pair E‐AAC/M‐CTA and one SSR marker Satt244 were identified to be linked to Res_Peking. The gene was located within a 2.1‐cM interval between markers AACCTA178 and Satt244, 1.1 cM from Satt244 and 1.0 cM from AACCTA178. Since the SSR markers Satt244 and Satt431 have been mapped to molecular linkage group (LG) J of soya bean, the Res_Peking resistance gene was putatively located on the LG J. This will provide soya bean breeders an opportunity to use these markers for marker‐assisted selection for frogeye leaf spot resistance in soya bean.     

SSR and SCAR markers linked to the fertility-restoring gene for a D2-type cytoplasmic male-sterile line in wheat

‘Yi 4060’ is an elite restorer line of a non‐photoperiod‐sensitive D²‐type cytoplasmic male‐sterile (CMS) line of wheat. Random amplified polymorphic DNA (RAPD) and simple sequence repeat (SSR) markers were employed to map one major fertility‐restoring gene (D²Rf₁) in ‘Yi 4060′. The sterile and fertile DNA pools were established from individuals in BC₆, based on bulked segregant analysis. One RAPD marker E09, linked to D²Rf₁, was converted to a SCAR marker and designated as E09‐SCAR₈₆₅. The genetic distance between E09‐SCAR₈₆₅ and D²Rf₁ is 9.5 cM. Two SSR markers, Xgwm11 and Xgwm18, were also linked to a D²Rf₁ and co‐segregated with E09‐SCAR₈₆₅. The three molecular markers are useful in marker‐assisted breeding of the elite restorer lines for D² ‐type CMS lines in wheat.     

Detection of linkage disequilibrium QTLs controlling low-temperature growth and metabolite accumulations in an admixed breeding population of <Emphasis Type="BoldItalic">Leymus</Emphasis> wildryes

Low-temperature soluble carbohydrate accumulations are commonly associated with anthocyanin coloration, attenuated growth, and cold adaptation of cool-season grasses. A total of 647 AFLP markers were tested for associations with anthocyanin coloration, tiller formation, leaf formation, cumulative leaf length, percent soluble carbohydrate, and dry matter regrowth among replicated clones of an admixed Leymus wildrye breeding population evaluated in low-temperature growth chambers. The admixed breeding population was derived from a heterogeneous population of L. cinereus × L. triticoides F₁ hybrids, with two additional generations of open pollination. Two AFLP linkage maps, constructed from two full-sib mapping populations derived from the same F₁ hybrid population, were integrated to produce a framework consensus map used to examine the distribution of marker-trait associations in the admixed F₁OP₂ population. Thirty-seven linkage blocks, spanning 258 cM (13.6%) of the 1895 cM consensus map, contained 119 (50%) of the 237 markers showing at least one possible trait association (P < 0.05). Moreover, 28 (68%) of the 41 most significant marker-trait associations (P < 0.005) were located in 15 QTL linkage blocks spanning 112.9 cM (6%) of the linkage map. The coincidence of these 28 significant marker-trait associations, and many less significant associations, in 15 relatively small linkage blocks (0.6 cM to 21.3 cM) provides evidence of admixture linkage disequilibrium QTLs (ALD QTLs) in this heterogeneous breeding population. At least four of the remaining 13 putative marker-trait associations (P < 0.005) were located in genetic map regions lacking other informative markers. The complexity of marker-trait associations results from heterogeneity within and substantial divergence among the parental accessions.     

Significance of host complexity and diversity for race-specific leaf-rust resistance in self-fertile synthetic rye populations

Leaf rust (Puccinia recondita Rob. ex. Des.) is the most frequently occurring leaf disease in German winter rye (Secale cereale L.). To test the usefulness of race‐specific resistance genes, the effects of increased host diversity and complexity by producing two‐ and four‐line synthetics from inbred lines carrying different resistance genes were analysed. Thirty‐three synthetics along with two full‐sib families and one hybrid variety were tested in 17 environments in Germany under natural infections. For comparison, the parent lines of the synthetics were evaluated in 11 environments. Only two synthetics and the full‐sib families were resistant across all environments. Observed resistance levels of the synthetics were highly correlated (r = 0.83, P = 0.01) with those predicted from the parental values. Host complexity had a minor effect in two‐line synthetics only. In conclusion, the effectiveness of race‐specific leaf‐rust resistances among environments, and increasing the host complexity and diversity does not lead to a higher resistance level than that expected from the resistances of the parents.     

Mapping of the Vrn-B1 gene in Triticum aestivum using microsatellite markers

An F₂ population segregating for the dominant gene Vrn‐B1 was developed from the cross of the substitution line ‘Diamant/'Miro‐novskaya 808 5A’ and the winter wheat cultivar ‘Bezostaya 1′. Microsatellite markers (Xgwm and Xbarc) with known map locations on chromosome 5B of common wheat were used for mapping the gene Vrn‐B1. Polymorphism between parental varieties was observed for 28 out of 34 microsatellite markers (82%). Applying the quantitative trait loci mapping approach, the target gene was mapped on the long arm of chromosome 5B, closely linked to Xgwm408. The map position of Vrn‐B1 suggests that the gene is homoeologous to other vernalization response genes located on the homoeologous group 5 chromosomes of wheat, rye and barley.