Production of n + 1 plants and tetrasomics by means of anther culture of trisomic plants in rice (Oryza sativa L.)

Summary Eleven primary trisomics of rice, variety Nipponbare, were subjected to anther culture. The 12th trisomic did not produce normal anthers. A total of 3,734 plants were obtained, which were examined morphologically at the seedling stage in the greenhouse. A number of plants appeared in the progenies of ten trisomics which had unique morphological features. The frequency of these variant types differed among different progenies. Cytological observations revealed that 43 variant plants in the progenies of nine trisomics had 13 chromosomes (n + 1), and 56 were tetrasomics (2n = 26). The tetrasomic plants in the progeny of a trisomic were morphologically identical. Similarly, n + 1 plants in the progeny of a trisomic were also identical. Plants with 23, 25, 36, 39, and 73 chromosomes were also obtained. Results show that valuable aneuploids such as n + 1 and 2n + 2 can be obtained in the anther-culture-derived progenies of trisomics.     

TRISOMIC TRANSMISSION IN CLARKIA UNGUICULATA

Vasek , F. C. (U. California, Riverside.) Trisomic transmission in Clarkia unguiculata. Amer. Jour. Bot. 48(9): 829–833. 1961.—Seven primary trisomic plants derived from a triploid-diploid cross were self-pollinated. The 7 progenies included diploids and trisomics, the latter varying in frequency from 16 to 30%. In addition, 2 of the progenies included tetrasomic plants. Crosses were made between diploids and either trisomics or tetrasomics. The extra chromosome of 1 progeny was readily transmitted through the pollen of trisomic and tetrasomic plants. When a trisomic of the same progeny was used as a seed parent, only diploids and tetrasomics were found among the offspring, indicating a duplication of the extra chromosome. The extra chromosomes of other progenies were not transmitted through either pollen or eggs in controlled diploid-trisomic crosses but trisomics of these progenies were recovered after self-pollination. It is suggested that differential pollen-tube growth precluded transmission to diploid-trisomic hybrids and that under conditions of reduced pollen competition the extra chromosome normally would be transmitted through pollen. The extra chromosomes generally occur as univalents at metaphase and are ordinarily included in telophase nuclei.     

Aneuploidy in guava

Aneuploids have been identified cytomorphologically in progenies from triploid and diploid-triploid crosses. 30 trisomics, 2 double trisomics, 1 tetrasomic, and 2 higher aneuploids were obtained. Some of the aneuploids were found to be different from those reported earlier and higher aneuploids carried eight extra chromosomes. The plants with one extra chromosome occurred more frequently (67%) than the other aneuploid types. The changes in morphological traits such as a reduction in the amount of growth and the size of leaf etc. distinguished aneuploids from diploids. In the higher aneuploids the plant parts were highly exaggerated and pollen sterility was very high. The chromosomal counts in acetocarmine squashes confirmed the presence of extra chromosome(s). Aneuploids particularly trisomics were found to be promising and may lead to the production of commercially viable plants.     

Trisomics and aneuploids of ryegrass

Summary Primary trisomics (2 n + 1 = 15), double trisomics (2 n + 1 + 1 = 16) and aneuploids with 24 to 30 chromosomes, as well as a diploid and tetraploids, were found in the progeny of a hypertriploid (2 n = 22) plant of perennial ryegrass, Lolium perenne L. Trisomics and double trisomics differed in their mean chromosome association, chiasma number and spike morphology. A few aneuploids and tetraploids had reciprocal translocations. The diploid, primary trisomics and tetraploids were more fertile than the double trisomics and aneuploids. Most trisomics and aneuploids were probably produced through female transmission. One double trisomic had a high univalent number, a low chiasma number and loose chromosome coiling. Both the extra chromosomes carried secondary constrictions. The gene for desynapsis might be located on one of these chromosomes.     

Development and applications of a complete set of rice telotrisomics

We previously isolated a complete set of primary trisomics along with many other aneuploids from triploid plants derived from an indica rice variety "Zhongxian 3037." About 30,000 progeny from these trisomic and aneuploid plants were grown each year from 1994 to 1999. The variants that differed morphologically from both the diploids and the original primary trisomics were collected for cytological identification. From these variants, a complete set of telotrisomics covering all 24 rice chromosome arms was obtained. The identities of the extra chromosomes were further confirmed by dosage analysis of the RFLP markers on extra chromosome arms. The telocentric nature of the extra chromosomes in these stocks was verified by fluorescence in situ hybridization (FISH) using a rice centromeric BAC clone as a marker probe. In general, the shorter the extra chromosome arm of a telotrisomic, the stronger the resemblance it bears to the diploid; the longer the extra chromosome arm, the stronger the resemblance to the corresponding primary trisomic. We demonstrated that DNA clones can be rapidly assigned to specific chromosome arms by dosage analysis with the telotrisomics. We also showed that telotrisomics are valuable tools for chromosome microdissection and for developing chromosome-specific DNA markers.     

Cytogenetical analysis on aneuploids obtained from pollenclones of rice (Oryza sativa L.)

Summary Rice aneuploids were obtained from 1,715 pollenclones with a mean frequency of 10.2% in anther culture (1983 to 1985). Among the aneuploids obtained, the frequency of primary trisomics ranged from 5.4% to 6,7%, tetrasomics from 1.1% to 1.7% monosomics from 0.9% to 1.3%, nullisomics from 0.5% to 1% and double trisomics from 0.5% to 0.7%. The chromosome complements of those aneuploids were identified by pachytene analysis on the absolute length of the extra chromosomes. Pollen clonal aneuploids showed a different range of variation in agronomic characters from dihaploids of the same origin but the phenotypic variations ressembled those found in aneuploids created by conventional breeding methods. The meiotic chromosome behavior of PMC revealed various chromosomal aberrations of aneuploids: loose pairing, trivalents, univalents, straggling chromosomes, bridges and laggards.     

谷子雄性不育系1066A不育基因和黄苗基因的染色体定位

以谷子(Setaria italica (L.) Beauv.)雄性不育系1066A为母本,豫谷1号三体(1～7)及四体8和四体9作父本进行杂交,应用初级三体分析法,进行了谷子雄性不育基因和黄苗基因的染色体定位研究.通过配置大量杂交组合和反复授粉,利用豫谷1号三体的极少量花粉,获得了三体2～9的F1代杂种,各杂种三体的形态与豫谷1号三体基本相似,略有差异,苗色呈绿色且可育.杂种F2植株的苗色和育性都产生分离.结果是三体3、5、7、8、9的F2代分离出的可育株与不育株之比为3∶1,三体6的可育株与不育株之比为14∶1 (χ2=0.012,P=0.01).杂种F2分离出的绿苗与黄苗之比只有三体7为12∶1 (χ2=0.36, P=0.01),其他均为3∶1.因此,可以确定1066A的不育基因为隐性单基因,位于第6号染色体上,该品系的黄苗基因也是隐性单基因,位于第7号染色体上.     

Comparison of the transmission of three trisomies by males and females in the newt Pleurodeles waltlii (author's transl)]

In the newt Pleurodelles waltlii, males and females trisomic for chromosomes 8, 10 and 11 are fertile. Crosses between such trisomics and diploids were carried out. Progeny analysis showed that an extra chromosome is transmitted to half of the gametes of both males and females trisomics. The extra chromosome apparently causes interference in the regular mechanics of meiotic division, so that trisomics throw nonparental aneuploids and polyploids in their progenies. Moreover, some descendants develop chromosome anomalies during embryonic life ; thus, the progeny of trisomics include diploids, parentaltype trisomics, and embryos with new chromosome anomalies. Morphology and chromosome anomalies of the embryos are compared. A possible explanation for the secondarily acquired anomalies are discussed.     

Tertiary trisomics in the garden pea as a model of B chromosome evolution in plants

It is hypothesized that, in plants, genetically empty B chromosomes may originate from the extra chromosome (E) of tertiary trisomics if (i) the region of basic chromosomes homologous to the E (H-region) harbors a sporophytic lethal covered by the wild-type allele in E, and (ii) crossing-over between E and the H-region is suppressed. Under these conditions, most loss-of-function mutations occurring in the H-region are deleterious for haploid gametophytes, whereas those occurring in E are neutral or advantageous for hyperploid (n+1) gametophytes. As a result, natural selection at the gametophyte level can lead to the degeneration of E, leaving the H-region intact. Using Hammarlund translocation T(3-6)a, we synthesized two trisomic lines of the garden pea (Pisum sativum L.), where E was composed of the short arms of chromosomes 3 and 6 and the H-region carried recessive markers. In the trisomic line TRIS, we found few crossovers between E and the H-region. In the trisomic line TRUST, obtained after a change of basic chromosome constitution, recombination in this region was completely suppressed. After induction in the H-region of TRUST of a recessive sporophytic mutation rmv, two 15-chromosome lines of stable trisomics were established. One of them passed 11 generations, having produced more than 6000 individuals, all of them trisomic, and E remained present as a single element with no pairing partners. No tetrasomics were detected in these lines. If such trisomics occurred in nature, their extra chromosomes are likely to become a B chromosome.     

Selection of Primary Trisomics from Anther Culture of Autotetraploid Rice (Oryza sativa L.)

The hybrids from different generations of autotetraploid rice (Oryza sativa L. ) and the original autotetraploid rice (indica and japonica) were used for anther culture, and the pollen-plantlets from them were induced. Due to the significant difference on phenotype among the trisomics and between trisomics and diploid, 15 lines of 4390 H1 induced plants were selected for chromosome study. Their PMC meiosis were observed. The results showed that the chromosomes from these plants consisted of 2n, 4n and aneuploids, and their ratios were 88.00%, 5.53% and 6.47% respectively. 272 trisomics from 284 aneuploids were identified, which acounted for 6.20% of all the pollen-plants. According to the special characters from the whole set of trisomics, they were classified as 9 types. The 9124- 7 trisomics were designated as triplo-8 by the pachytene analysis. Sowing the seeds of triplo8, the transmission rate of extra chromosome was calculated at the seedling stage of H2. The rate of trisomic was 34.11% of all plants, the agronomic characters were similar to the H1 parent plants.     

Maize tertiary trisomic stocks derived from B-A translocations

Reciprocal translocations between supernumerary B chromosomes and the basic complement of A chromosomes in maize have resulted in a powerful set of tools to manipulate the dosage of chromosomal segments. From 15 B-A reciprocal translocation stocks that have the B-A chromosome genetically marked we have developed tertiary trisomic stocks. Tertiary trisomics are 2n + 1 aneuploids where the extra chromosome is a translocation element, in this case a B-A chromosome. Whereas B-A translocations produce aneuploidy in the sperm, the tertiary trisomic plant efficiently transmits hyperploid gametes maternally. Because the B-A tertiary trisomic stocks and the B-A translocation stocks from which they were derived are introgressed into the W22 inbred line, the effects of maternally and paternally transmitted trisomic B-A chromosomes can be compared. Data are presented on both the male and female transmission rates of the B-A chromosomes in the tertiary trisomic stocks.     

The origin, identification, and plant morphology of five rice monosomics.

Five different monosomics of rice (Oryza sativa L.) were obtained by treatment of pollen with gamma irradiation, as a by-product of attempts to determine the cytological loci of certain marker genes, i.e., mature pollen carrying normal alleles at all loci was given gamma rays and used for pollinating strains that were homozygous for recessive marker genes. The monosomics showed distinguishable morphological features and had complete seed sterility. Cytological studies revealed that one monosomic was tertiary, the others primary. The tertiary monosomic was related to chromosome 10. Two primary monosomics for chromosomes 10 and 11 were identified. At metaphase I, the tertiary monosomic showed the chromosome configurations 1 III + 10 II, 11 II + 1 I, and 10 II + 3 I, and all primary ones showed the configuration 11 II + 1 I. All five monosomics showed very poor crossing ability and were not transmitted to the few progenies observed. A few trisomic plants were found in the progenies of a cross between monosomic and normal pollen in one monosomic. This is the first time that many monosomics in rice have been characterized. This information will be useful in studies of rice aneuploidy and cytogenetics. Key words : rice, monosomics, morphology, cytology, transmission, trisomics.     

MHC-chromosome dosage effects: evidence for increased expression of Ia glycoprotein and alteration of B cell subpopulations in neonatal aneuploid chickens

Quantitative variation in the expression of MHC-encoded class II (Ia) glycoproteins has been associated with stages of lymphocyte development and a number of disease conditions. We have used an avian MHC dosage model to study the regulation of Ia expression and the effects of quantitative variation in membrane Ia on B-cell development. Lymphocyte membrane expression of Ia glycoprotein molecules and the frequency of small-versus-large lymphocytes were examined in trisomic line chickens containing either two (disomic), three (trisomic), or four (tetrasomic) copies of the microchromosome encoding the MHC. This was accomplished by quantitative laser flow cytometry analysis of bursa-resident B lymphocytes from neonatal trisomic line chickens. The aneuploids (trisomics and tetrasomics) expressed more cell surface Ia than did normal disomic birds. Furthermore, the aneuploids exhibited a greater frequency of small B lymphocytes as compared to disomic chickens. Dual parameter analysis of Ia. quantity and cell size was undertaken to study B lymphocyte subpopulations in these birds. It was observed that the aneuploids had altered frequencies of two distinct subpopulations of cells: (1) an increased percentage of small cells which express high levels of Ia antigen and (2) a decreased percentage of large cells which express medium levels of Ia antigen. These findings support the view that MHC class II genes are regulated and expressed in a dosage-dependent manner. Therefore, increases in the number of MHC copies per cell result in the increased expression of Ia glycoprotein on bursa-resident B cells. The stepwise increase in membrane Ia on trisomic and tetrasomic B cells is correlated, and perhaps casually linked, with progressive degrees of alteration of developing B cell subpopulations in the bursa of aneuploid chicks. These events may ultimately alter the humoral immunity of the aneuploid animals.     

四倍体水稻花药培养筛选初级三体的研究

以同源四倍体水稻 ( Oryza sativa L.)各世代杂种和四倍体籼、粳原种为材料进行花药培养 ,诱导花粉植株再生。根据三体植株表型上相互区别的特性 ,且又显著区别于二倍体 ,对其中所诱导的 1 5个花药培养品系 4 390株 H1花粉植株进行了重点固定和染色体镜检。结果表明 ,花粉 H1植株染色体组成包括二倍体、四倍体和非整倍体 ,其频率分别为 88.0 %、5 .5 3%和 6.67%。鉴定出 2 72株三体 ,占全部花粉植株的 6.2 0 %。对照已配套三体系的形态 ,将鉴定的三体株划分为 9种类型 ,并对其中的 91 2 4 - 7窄叶三体进行粗线期核型分析 ,鉴定为三体 8。将三体 8的种子播种 ,在 H2 代苗期统计额外染色体的传递率 ,三体株占 34 .1 1 % ,其农艺性状也同于 H1亲代     

Five primary trisomics from translocation heterozygote progenies in common bean,Phaseolus vulgaris L.

Summary Twelve distinct phenotypic groups of plants were isolated from nondisjunction progenies of 11 translocation heterozygote stocks. All the plants in these phenotypic groups originated in the light weight seed class. Five of the 12 phenotypic groups of plants have been verified as primary trisomics. They are all phenotypically distinguishable from each other and from disomics. One of the five primary trisomic groups, puckered leaf, was directly recovered as a primary trisomic from the original translocation heterozygote progenies. Three of the five trisomics — weak stem, dark green leaf, and convex leaf — originated first as tertiary trisomics. The related primary trisomics were isolated later from progenies of selfed tertiary trisomics. The fifth group, chlorotic leaf, originated at a low frequency among the progenies of three other trisomics: puckered leaf, convex leaf, and dark green leaf. The chlorotic leaf did not set seed under field conditions. The remaining four groups — puckered leaf, dark green leaf, convex leaf, and weak stem — are fertile, though sensitive to high temperature conditions. The transmission rate of the extra chromosome on selfing ranges from 28% to 41%. Physical identification of the extra chromosome has not been achieved for any of the five trisomic groups. Two trisomic groups, dark green leaf and convex leaf, have produced tetrasomics at low frequency. The phenotypes of these two tetrasomics are similar to the corresponding trisomics but more exaggerated.Fla. Agr. Expt. Stn. Journal Series No. 7137     

Primary trisomics of rice: origin, morphology, cytology and use in linkage mapping

Twelve primary trisomics of Oryza sativa L. were isolated from the progenies of spontaneous triploids and were transferred by backcrossing to the genetic background of IR36, a widely grown high yielding rice variety. Eleven trisomics can be identified morphologically from one another and from diploids. However, triplo 11 is difficult to distinguish from diploid sibs.—The extra chromosome of each trisomic was identified cytologically at pachytene stage of meiosis, and the chromosomes were numbered according to their length at this stage. The major distinguishing features of each pachytene chromosome were redescribed.—The female transmission rates varied from 15.5% for triplo 1, the longest chromosome, to 43.9% for triplo 12, the shortest chromosome. Seven of the 12 primary trisomics transmitted the extra chromosome through the male. The low level of chromosomal imbalance tolerated by rice and other evidence are interpreted to indicate that this species is a basic diploid.—Genetic segregation for 22 marker genes in the trisomic progenies was studied. Of a possible 264 combinations, involving 22 genes and 12 trisomics, 120 were examined. Marker genes for each of the 12 chromosomes were identified. The results helped establish associations between linkage groups and cytologically identifiable chromosomes of rice for the first time. Relationships between various systems of numbering chromosomes, trisomics, linkage groups and marker genes are described, and a revised linkage map of rice is presented.     

Trisomics from triploid-diploid crosses in self-incompatible Lycopersicum peruvianum

Summary An attempt was carried out to produce trisomics of the wild tomato L. peruvianum, to define their essential features, and to detect relationships between trisomy and the expression of self-compatibility.Triploid-diploid crosses in L. peruvianum yielded nearly 40% aneuploids. Of these, 18% were single trisomics, and the rest had 2, 3 and 4 extra chromosomes. Almost all the trisomics occurred in crosses where the triploid was used as female parent. Vigour and fertility of trisomics were not much different from those of disomics, and morphologically they were very similar.The extra chromosome was identified in three self-compatible trisomic plants through somatic and pachytene chromosome morphology. One of these plants was trisomic for chromosome 1, while the other two were trisomic for chromosome 3. In these trisomics a positive correlation was found between chromosome length and trivalent formation, but no relationship between chromosome length and frequency of laggards was observed.A series of test-crosses revealed that the capacity of the trisomics to produce seed upon selfing always resulted from alterations of the incompatibility phenotype of the style and not from competitive interaction in the pollen. Progeny analyses showed that the self-compatibility features of the trisomics were not transmitted from one generation to the next. The implications of these findings are discussed.This work has been supported by a contract between the European Communities and the CNEN. This publication is contribution no. 1458 from the Biology Division of the European Communities and contribution no. 472 from the Divisione Applicazioni delle Radiazioni del CNEN.     

Increasing the transmission rate of the extra chromosome in a trisomic Nicotiana sylvestris line by modifying the means of pollination

Summary Trisomies of primary trisomic line B220 of Nicotiana sylvestris, which contain an extra chromosome shown to be a satellite chromosome, can be readily identified by their larger flower and leaf sizes. In seed-propagated species, the low transmission of the extra chromosome has prevented such plants from becoming agriculturally useful cultivars. In line B220, the transfer of the extra chromosome in 2n×2n+1 crosses was very low (13.5%), although n and n + 1 pollen grains were produced in equal quantities, as was confirmed by anther culture. This was due to the delayed development of n + 1 pollen grains, which are not at full maturity at the time of an thesis. The transfer of the extra chromosome in 2n×2n+1 crosses was increased by a 1 day delay in pollination and also by pollination of small pollen grains selected through nylon meshes. The delayed pollination increased the frequency of trisomics by 9%, whereas pollen selected by using 30 and 25 n nylon meshes induced an extremely high transfer of the extra chromosome, namely 51.9% and 70.4%, respectively. The observed frequencies of trisomics and tetrasomics in artificial selfing of 2n+1 plants with selected small pollen grains were lower than those expected from the data of reciprocal crosses between 2n and 2n+1 plants. This discrepancy seems to indicate a disadvantage of the n+1 pollen in fertilization due to the longer style of the trisomics relative to that of the diploids.     

Secondary Trisomics and Telotrisomics of Rice: Origin, Characterization, and Use in Determining the Orientation of Chromosome Map

Secondary trisomics and telotrisomics representing the 12 chromosomes of rice were isolated from the progenies of primary trisomics. A large population of each primary trisomic was grown. Plants showing variation in gross morphology compared to the primary trisomics and disomic sibs were selected and analyzed cytologically at diakinesis and pachytene. Secondary trisomics for both arms of chromosomes 1, 2, 6, 7 and 11 and for one arm of chromosomes 4, 5, 8, 9 and 12 were identified. Telotrisomics for short arm of chromosomes 1, 8, 9 and 10 and for long arms of chromosomes 2, 3 and 5 were isolated. These secondary and telotrisomics were characterized morphologically and for breeding behavior. Secondary trisomics 2n + 1S.1S, 2n + 1L.1L, 2n + 2S.2S, 2n + 2L.2L, 2n + 6S.6S, 2n + 6L.6L and 2n + 7L.7L are highly sterile, and 2n + 1L.1L, 2n + 2L.2L and 2n + 7L.7L do not set any seed even upon backcrossing. Telotrisomics are fertile and vigorous. Genetic segregation of 43 marker genes was studied in the F(2) or backcross progenies. On the basis of segregation data, these genes were delimited to specific chromosome arms. Correct orientation of 10 linkage groups was determined and centromere positions on nine linkage groups were approximated. A revised linkage map of rice is presented.     

Genetic and cytogenetic analyses of the A genome of Triticum monococcum. IX. Cytological behaviour, phenotypic characteristics, breeding behaviour, and fertility of primary, double, and triple trisomics.

Cytogenetic studies in Triticum monococcum (2n = 2x = 14, AA) were initiated by generating a series of primary as well as double and triple trisomics from autotriploids derived from crosses between induced autotetraploids and a diploid progenitor. Analysis of meiotic chromosome behaviour revealed that, with the exception of primary trisomics for chromosome 7A, the chromosome present in triple dose in all other trisomics formed either a bivalent plus a univalent or a trivalent (always V shaped) at diakinesis - metaphase I in approximately equal proportions. Trisomics for chromosome 7A formed a bivalent plus a univalent or a trivalent in approximately a 1:2 ratio. About 99% of the anaphase I segregations in all the trisomics were seven to one pole and eight to the other, suggesting that primary trisomics in T. monococcum form n and n + 1 meiotic products in equal proportions. The double trisomics and triple trisomics formed 5 II + 2 III and 4 II + 3 III during metaphase I, respectively. A majority of the secondary meiocytes from the double and triple trisomics possessed unbalanced chromosome numbers. All the trisomics differed phenotypically from their diploid progenitors. Single primary trisomics for chromosomes 3A and 7A produced distinct morphological features on the basis of which they could be distinguished. The phenotypes of the double and triple trisomics deviated to a greater extent from that of diploids than those of the single trisomics. Less than 50% of the progeny of all primary trisomics were trisomics themselves. Trisomic progeny were not produced in diploid female x trisomic male crosses, indicating that functional n + 1 male gametes were not generated. Diploid as well as trisomic progeny were produced in the reciprocal crosses and upon self-fertilization of the trisomics. The average frequency of trisomic progeny was 9.9%. The fertility of primary trisomics ranged from 3.8% in trisomics for chromosome 1A to 40.6% in trisomics for chromosome 2A and was significantly less than that of diploids (99.6%). The breeding behaviour and low fertility of these trisomics make their maintenance and use in cytogenetic analyses difficult.