Inheritance of plant height in hexaploid triticales with R/D substitution

Inheritance of plant height has been studied in combinations of R/D-substituted forms of hexaploid triticale and varieties that have a complete chromosome set of rye and carry various genes determining dwarfism. Analysis of F₁-F₃ hybrids has demonstrated an additive effect of the dwarfism genes and the genetic component of chromosome D affecting the plant height. Deviations in the segregation with respect to plant height found in F₂ combinations involving R/D-substituted forms and varieties with a complete chromosomal set of the R genome may be caused by meiotic disturbances resulting from the R/D substitution and an increased frequency of the transmission of the heterologous chromosome in the monosomic substituted form.     

Genetic control of dwarfism in hexaploid triticale (Triticosecale Wittm.)

The genetic control of plant height has been studied in hexaploid forms of triticale (2n = 42) with genomic structure AABBRR. Thirty-four specimens from the world collection of triticale at the Vavilov All-Russian Research Institute of Plant Breeding with plant heights from 70 to 180 cm have been used in the study. The hybrid analysis of the first, second, and third generations, as well as backcross offsprings, has demonstrated that the given trait is characterized by different modes of inheritance: dominance of dwarfism, dominance of tallness, and intermediate inheritance. It has been found that triticale cultivars of middle and large height differ from short ones in alleles of one or two major genes.     

Genetic control of dwarfism in hexaploid triticale (Triticosecale wittm.)

The genetic control of plant height has been studied in hexaploid forms of triticale (2n = 42) with genomic structure AABBRR. Thirty-four specimens from the world collection of triticale at the Vavilov All-Russia Research Institute of Plant Breeding with plant heights from 70 to 180 cm have been used in the study. The hybrid analysis of the first, second, and third generations, as well as backcross offsprings, has demonstrated that the given trait is characterized by different modes of inheritance: dominance of dwarfism, dominance of tallness, and intermediate inheritance. It has been found that triticale cultivars of middle and large height differ from short ones in alleles of one or two major genes.     

太空诱变玉米核不育突变体矮化的遗传及外施赤霉素分析

为了解太空诱变玉米核不育突变体矮化的遗传规律和原因,该研究以不育突变体为母本,自交系178、478为父本,对测交 F1、F2群体进行育性鉴定和株高分析,对 F2可育株进行基因型和株高分析,对姊妹交后代分离群体进行育性鉴定和株高、雄穗长度、节间数、节间长度分析,同时,还对姊妹交后代分离群体进行施赤霉素处理,调查育性和株高的变化。结果表明：178和478背景下的 F1表现出与测交母本一样的极显著差异;在178和478核背景下的 F2中,不育株株高极显著矮于可育株,两核背景下的不育株间株高差异不显著,而可育株间株高差异极显著;F2中纯合和杂合可育株的株高差异不显著;姊妹交后代分离群体中不育株株高、雄穗长度、节间数和节间长度极显著小于可育株;外施赤霉素的不育株在苗期表现出对赤霉素一定的敏感性,但株高最终未恢复正常高度。因此,得出该突变体矮化表现稳定,与不育性状并存,且不受细胞核背景的影响;核不育基因对植株株高的矮化无剂量效应;突变体的矮化与雄穗长度、节间数和节间长度有关;突变体不完全属于赤霉素不敏感型,其矮化并不是单一缺乏赤霉素而引起。该研究结果为认识太空诱变玉米核不育突变体矮化的遗传和生理机制提供了参考。     

Combining ability according to the traits of stem branching and plant height in linseed lines

The combining ability according to the traits of stem branching and plant height has been studied for ten pure lines of oil flax under the conditions of complete and incomplete diallel crosses. The high heritability of traits, such as plant height, the number of lateral stems and shoots, and the essential role of genes with dominant effects of interaction in genetic control of the traits of stem branching and plant height have been shown. The methods of application of certain genotypes and crossed combinations in flax breeding based on combining-ability indexes were identified. Some new complexes of habitus traits and agriculturally valuable plant characteristics were obtained as a result of individual selection from hybrid combinations.     

Combining ability for the traits of stem branching and plant height in linseed lines

Combining ability for the traits of stem branching and plant height has been studied in ten pure lines of flax under complete and incomplete diallel crosses. High heritability of the traits "plant height", "the number of lateral stems" and "the number of lateral shoots" and essential role of genes with dominant effects of interaction in genetic control of the traits of stem branching and plant height have been shown. On the basis of combining ability indexes the ways for usage of certain genotypes and crossing combinations in flax breeding were defined. As a result of individual selection from hybrid combinations some new complexes of habit traits and agriculturally valuable plant characteristics were obtained.     

Study of androgenetic performance and molecular characterisation of a set of wheat-rye addition lines

Rye chromosomes of wheat-rye addition lines were successfully identified by means of an RFLP analysis with 30 probes. Our results are in agreement with previous cytological data concerning the identity of lines F (+1R), D (+2R), C (+3R), A (+4R), E (+5R) and B (+7R). Two categories of chromosomal rearrangements have been distinguished, namely: (1) deletions: the current line D possesses a chromosome 2R deleted on its short arm and the line G a chromosome 3R deleted on its long arm; we have also noticed a deletion on the long arm of wheat chromosome 1A in line F61; and (2) evolutionary reciprocal translocations in rye relative to wheat which have been previously mentioned in the literature. The anther culture response of the different lines was studied. A significant difference between FEC 28 and the addition lines was observed for embryo production and plant regeneration. It appears that genes located on S 10 chromosome arm 3RL and on FEC 28 chromosome arm 1AL increase embryo frequency whereas gene(s) located on S 10 chromosome 5R reduce(s) it. Plant regeneration results suggest that genes increasing regeneration ability and green-plant frequency are located on S 10 chromosome 4R. The long arm of chromosome 1A seems to be involved positively in green-plant regeneration whereas chromosomes 1R and 3R limit plant regeneration.     

大豆种皮色相关基因研究进展

大豆种皮色在从野生大豆到栽培大豆的演变过程中逐渐从黑色变成黄色,是重要的形态标记,因此,大豆种皮色相关基因研究无论对进化理论还是育种实践都具有重要的意义。种皮颜色是通过各种花色苷的沉积而形成的。虽然很多植物色素沉积的分子调控机制比较明晰,但大豆中控制种皮颜色形成的基因尚未被完全了解。文章综述了控制大豆种皮色基因与位点的相关研究进展,主要有I、T、W1、R、O 5个经典遗传位点,其中I位点被定位在第8号染色体(A2连锁群)一个富含查尔酮合成酶(CHS)的区域,CHS基因在大豆中是多基因家族且同源性较高;定位于第6号染色体(C2连锁群)T位点的基因F3’H已被克隆和转基因验证,由于碱基缺失导致所编码的氨基酸缺少了保守域GGEK,从而不能与血红素结合而丧失功能;R位点定位在第9号染色体(K连锁群)A668-1与K387-1两标记之间,可能是R2R3类MYB转录因子,也可能是UDP类黄酮3-O糖基转移酶;O位点定位在第8号染色体(A2连锁群)Satt207与Satt493两标记之间,其分子特性尚不清楚;W1位点可能由F3’5’H基因控制遗传。     

Single-Stranded DNA and RNA Targeted Triplex-Formation: UV,CD and Molecular Modeling Studies of Foldback Triplexes Containing Different RNA, 2′-OMe-RNA and DNA Strand Combinations

Abstract

We studied the influence of different 2′-OMe-RNA and DNA strand combinations on single strand targeted foldback triplex formation in the Py.Pu:Py motif using ultraviolet (UV) and circular dichroism (CD) spectroscopy, and molecular modeling. The study of eight combinations of triplexes (D D:D, R* D:D, D D:R*, R* D:R*, D R:D, R* R:D, DR:R*, and R*-R:R*; where the first, middle, and last letters stand for the Hoogsteen Pyrimidine, Watson-Crick [WC] purine and WC pyrimidine strands, respectively, and D, R and R* stand for DNA, RNA and 2′-OMe-RNA strands, respectively) indicate more stable foldback triplex formation with a DNA purine strand than with an RNA purine strand. Of the four possible WC duplexes with RNA/DNA combinations, the duplex with a DNA purine strand and a 2′-O-Me-RNA pyrimidine strand forms the most thermally stable triplex, although its thermal stability is the lowest of all four duplexes. Irrespective of the duplex combination, a 2′-OMe-RNA Hoogsteen pyrimidine strand forms a stable foldback triplex over a DNA Hoogsteen pyrimidine strand confirming the earlier reports with conventional and circular triplexes. The CD studies suggest a B-type conformation for an all DNA homo-foldback triplex (D.D.D), while hetero-foldback triplex spectra suggest intermediate conformation to both Atype and B-type structures. A novel molecular modeling study has been carried out to understand the stereochemical feasibility of all the combinations of foldback triplexes using a geometric approach. The new approach allows use of different combinations of chain geometries depending on the nature of the chain (RNA vs. DNA).     

Whole Genome Association Mapping of Plant Height in Winter Wheat (Triticum aestivum L.)

The genetic architecture of plant height was investigated in a set of 358 recent European winter wheat varieties plus 14 spring wheat varieties based on field data in eight environments. Genotyping of diagnostic markers revealed the Rht-D1b mutant allele in 58% of the investigated varieties, while the Rht-B1b mutant was only present in 7% of the varieties. Rht-D1 was significantly associated with plant height by using a mixed linear model and employing a kinship matrix to correct for population stratification. Further genotyping data included 732 microsatellite markers, resulting in 770 loci, of which 635 markers were placed on the ITMI map plus a set of 7769 mapped SNP markers genotyped with the 90 k iSELECT chip. When Bonferroni correction was applied, a total of 153 significant marker-trait associations (MTAs) were observed for plant height and the SSR markers (−log₁₀ (P-value) ≥4.82) and 280 (−log₁₀ (P-value) ≥5.89) for the SNPs. Linear regression between the most effective markers and the BLUEs for plant height indicated additive effects for the MTAs of different chromosomal regions. Analysis of syntenic regions in the rice genome revealed closely linked rice genes related to gibberellin acid (GA) metabolism and perception, i.e. GA20 and GA2 oxidases orthologous to wheat chromosomes 1A, 2A, 3A, 3B, 5B, 5D and 7B, ent-kaurenoic acid oxidase orthologous to wheat chromosome 7A, ent-kaurene synthase on wheat chromosome 2B, as well as GA-receptors like DELLA genes orthologous to wheat chromosomes 4B, 4D and 7A and genes of the GID family orthologous to chromosomes 2B and 5B. The data indicated that besides the widely used GA-insensitive dwarfing genes Rht-B1 and Rht-D1 there is a wide spectrum of loci available that could be used for modulating plant height in variety development.     

Cytological evidence for a complex of species within the taxon Bactrocera tau (Diptera: Tephritidae) in Thailand

Analysis of mitotic karyotypes of wild specimens of larvae of the Bactrocera tea-like fruit flies (Diptera: Tephritidae) in Thailand has revealed seven distinct chromosome forms, based on the amount and distribution of heterochromatin in sex chromosomes and autosomes. Such cytological differences are perfecdy correlated with morphological observations and molecular genetics data. These findings clearly suggest that B. tau is a cluster of at least seven closely related species temporarily designated as species A (= B. tau) , B, C, D, E, F and G. On die basis of the gross quantity of heterochromatin accumulation in the genome, three groups of mitotic karyotypes can be recognized. Group 1 comprises species A and E. Species E specifically occurs only in fruits of Strychnos thorelii while species A attacks many kinds of host plants. Group 2 contains species B, F and G. Species B has been found only in Siphonodon celastrineus fruit, whereas species F and G attack die same host species, the medically important plant, Hydnocarpus anthelminthicus , albeit in different localities. Group 3 includes species C and D, each of which comprises larger amounts of pericentric heterochromatin in all chromosomes than die other two groups. Hence, diese two species are cytologically remote from those of groups 1 and 2. Species C and D occur allopatrically but they attack the same host plant species, Momordica cochinchinensis. Thus, genetic differentiation at the chromosomal level to specific host plant species and geographic isolation seem to play an important role in speciation of members of the B. tau complex.     

Genetics of dominant gibberellin-insensitive dwarfism in maize

D8 and Mpl1 are two dominant dwarfing mutations of maize. Although they differ in severity of dwarfism, both D8 and Mpl1 mutants are unresponsive to gibberellin (GA). Because of their close phenotypic resemblance to the recessive GA-sensitive dwarf mutants these dominant mutations may identify a gene whose product is involved in the reception of GA. With this possibility in mind we have studied the genetic properties of D8 and Mpl1. Both mutations map close to Adh1 on chromosome 1L. By marking normal and translocated 1L arms with different Adh1 electrophoretic mobility alleles, we investigated the effect of gene dosage on dominant dwarf phenotype. The results suggest that D8 and Mpl1 encode novel product functions and that these functions are relatively insensitive to the presence of the (presumed) wild-type product. Using X-ray induced chromosome breakage we created sectors of wild-type cells within D8 or Mpl1 tissue; these sectors were marked by the linked recessive lw mutation. The phenotypes of these sectors demonstrated that, at least in certain plant organs and tissues, dominant dwarfism can be an autonomous phenotype. These results are consistent with the hypothesis that the wild-type gene product acts as a GA receptor. The potential utility of dominant dwarf phenotype in plant developmental analysis is discussed, and possible mechanisms for the action of the D8 and Mpl1 mutations are considered.     

Intra-and interchromosomal effects of heterozygous inversions on recombination in the third chromosome of Drosophila ananassae

In order to study intra-and interchromosomal effects of heterozygous inversions on recombination in the third chromosome of D.ananassae, experiments were conducted using Stw-pr marker stock and five wild stocks with known karyotypes. The stocks used were homozygous for standard or inverted gene sequence in 2L, 3L, and 3R. Recombination was investigated in both sexes. There was complete absence of crossing-over in males in all the experiments which appeared to be the characteristic of marker stock as spontaneous male crossing-over was reported earlier with the same wild stocks when the second chromosome markers were used. Based on the data of karyotypically homozygous F1 females, the map distance between stw-pr was 36.55 map units. The heterozygosity due to a lengthy inversion in 2L increased the level of crossing-over between stw-pr genes of the third chromosome indicating interchromosomal effect. There was a considerable reduction in the rate of recombination between the same markers due to inversion heterozygosity in 3R indicating intrachromosomal effect. However, 3L inversion heterozygosity had no effect on crossover rate. These results provide evidence for intra-and interchromosomal effects of inversions on crossing-over in the third chromosome of D. ananassae.     

Lack of Degeneration of Loci on the Neo-Y Chromosome of Drosophila Americana Americana

The extent of genetic degeneration of the neo-Y chromosome of Drosophila americana americana has been investigated. Three loci, coding for the enzymes enolase, phosphoglycerate kinase and alcohol dehydrogenase, have been localized to chromosome 4 of D. a. americana, which forms the neo-Y and neo-X chromosomes. Crosses between D. a. americana and D. virilis or D. montana showed that the loci coding for these enzymes carry active alleles on the neo-Y chromosome in all wild-derived strains of americana that were tested. Intercrosses between a genetically marked stock of virilis and strains of americana were carried out, creating F(3) males that were homozygous for sections of the neo-Y chromosome. The sex ratios in the F(3) generation of the intercrosses showed that no lethal alleles have accumulated on any of the neo-Y chromosomes tested. There was evidence for more minor reductions in fitness, but this seems to be mainly caused by deleterious alleles that are specific to each strain. A similar picture was provided by examination of the segregation ratios of two marker genes among the F(3) progeny. Overall, the data suggest that the neo-Y chromosome has undergone very little degeneration, certainly not to the extent of having lost the functions of vital genes. This is consistent with the recent origin of the neo-Y and neo-X chromosomes, and the slow rates at which the forces that cause Y chromosome degeneration are likely to work.     

Identification and development of diagnostic markers for a powdery mildew resistance gene on chromosome 2R of Chinese rye cultivar Jingzhouheimai

Chinese rye cultivar Jingzhouheimai (Secale cereale L.) shows a high level of resistance to powdery mildew. Identification, location, and mapping of the resistance gene would be helpful for developing a highly resistant germplasm or cultivar in wheat. Using sequential C-banding, GISH, and marker analysis, an addition chromosome with powdery mildew resistance was identified in a line derived from a cross between Chinese wheat landrace Huixianhong and rye cultivar Jingzhouheimai. The line, designated H-J DA2RDS1R(1D), had 44 chromosomes including two pairs of rye chromosomes, 1R and 2R, and lacked a pair of wheat chromosomes 1D, that is, it is a double disomic addition disomic substitution line. According to its reaction to different isolates of the powdery mildew pathogen, the resistance gene in H-J DA2RDS1R(1D) differed from the Pm8 and Pm7 genes located earlier on rye chromosomes 1R and 2R, respectively. In order to determine the location of the resistance gene, line H-J DA2RDS1R(1D) was crossed with wheat landrace Huixianhong and the F2 population and corresponding F2:3 families were tested for disease reaction and assessed with molecular markers. The results showed that a resistance gene, designated PmJZHM2RL, is located in rye chromosome arm 2RL.     

Cytogenetic analysis of forms produced by crossing hexaploid triticale with common wheat

Summary Hexaploid triticales were crossed with common wheats, and the resultant froms were selected for either triticale (AD 213/5-80) or common wheat (lines 381/80, 391/80, 393/80). The cytogenetic analysis showed that all forms differ in their chromosome composition. Triticale AD 213/5-80 and wheat line 381/80 were stable forms with 2n = 6x = 42. Lines 391/80 and 393/80 were cytologically unstable. In triticale AD 213/5-80, a 2R (2D) chromosome substitution was found. Each of the three wheat lines had a chromosome formed by the translocation of the short arm of IR into the long arm of the IB chromosome. In line 381/80, this chromosome seems to be inherited from the Kavkaz wheat variety. In lines 391/80 and 393/80, this chromosome apparently formed de novo since the parent forms did not have it. The karyotype of line 381/80 was found to contain rye chromosomes 4R/7R, 5R and 7R/4R. About 15% of the cells in line 391/80 contained an isochromosome for the 5R short arm and also a chromosome which arose from the translocation of the long arms of the 5D and 5R chromosomes. About one-third of the cells in the common wheat line 393/80 contained the 5R chromosome. This chromosome was normal or rearranged. Practical applications of the C-banding technique in the breeding of triticale is discussed.     

Association and interaction of the IL4R,IL4, and IL13 loci with type 1 diabetes among Filipinos

In the search for genes involved in type 1 diabetes (T1D), other than the well-established risk alleles at the human leukocyte antigen loci, we have investigated the association and interaction of polymorphisms in genes involved in the IL4/IL13 pathway in a sample of 90 Filipino patients with T1D and 94 controls. Ten single-nucleotide polymorphisms (SNPs), including two promoter SNPs in the IL4R locus on chromosome 16p11, one promoter SNP in the IL4 locus on chromosome 5q31, and four SNPs--including two promoter SNPs--in the IL13 locus on chromosome 5q31 were examined for association, linkage disequilibrium, and interaction. We found that both individual SNPs (IL4R L389L; odds ratio [OR] 0.34; 95% confidence interval [CI] 0.17-0.67; P=.001) and specific haplotypes both in IL4R (OR 0.10; 95% CI 0-0.5; P=.001) and for the five linked IL4 and IL13 SNPs (OR 3.47; P=.004) were strongly associated with susceptibility to T1D. Since IL4 and IL13 both serve as ligands for a receptor composed, in part, of the IL4R alpha chain, we looked for potential epistasis between polymorphisms in the IL4R locus on chromosome 16p11 and the five SNPs in the IL4 and IL13 loci on chromosome 5q31 and found, through use of a logistic-regression model, significant gene-gene interactions (P=.045, corrected for multiple comparisons by permutation analysis). Our data suggest that the risk for T1D is determined, in part, by polymorphisms within the IL4R locus, including promoter and coding-sequence variants, and by specific combinations of genotypes at the IL4R and the IL4 and IL13 loci.