Effect of the 1B/1R translocation on anther culture ability in wheat (Triticum aestivum L.)

Using two varieties, their reciprocal hybrids, F₈ lines and doubled haploids, results confirmed that three genetic components are involved in wheat anther culture ability, viz embryo induction frequency, regeneration ability and the frequency of albinism. In these experiments, no significant maternal effects were noticed. For embryo yields, transgressive lines were obtained from hybrids between distant genotypes. Regeneration of green plants depended upon two independent traits: regeneration ability and the frequency of albinos. F₈ lines and two doubled haploids equaled the 50% regeneration rate of the hybrids, but they only regenerated green plants. Based upon cytological examination and gliadin patterns, it is suggested that genes favoring regeneration ability could be linked to the 1BL-1RS translocated chromosome from Aurora.Abbreviations DH doubled haploids - MS Murashige and Skoog - MPG multicellular pollen grains     

Inheritance of matroclinal haploidy in maize

Maize lines and hybrids with increased matroclinal haploidy frequency have been revealed. It has been shown that, in the case of pollination with a marker genotype, which induces matroclinal haploids, the level of ear grain number (LEGN) decreases by more than 50%. It has been established that additive effects play the main role in the inheritance of matroclinal haploidy frequency. The genetic control of the LEGN is based on the overdominance of low LEGN values. The enhancement of both traits is determined by recessive alleles. The studied lines have been characterized based on the ratio between dominant and recessive alleles and the direction of their action.     

In vivo haploid induction in maize

Two haploid-inducing lines, MHI and M741H, were used for the production of maternal haploids. Haploids were obtained from all maternal genotypes involved in the experiment, including dent, flint and flint×dent maize. The maternal genotype had a significant influence on the frequency of haploids obtained. The frequency ranged from 2.7% to 8.0%. For chromosome-doubling seedlings were treated with colchicine solution, and 49.4% of the haploid plants produced fertile pollen, 39.0% could be selfed and 27.3% produced seeds after selfing. Synthetic populations, improved by haploid sib recurrent selection, were tested in a field trial. The results show that the utilization of maternal haploid plants has great potential for maize breeding and maize genetics. Received: 14 May 2001 / Accepted: 3 August 2001     

Fertilization and Uniparental Chromosome Elimination during Crosses with Maize Haploid Inducers

Producing maternal haploids via a male inducer can greatly accelerate maize (Zea mays) breeding process. However, the mechanism underlying haploid formation remains unclear. In this study, we constructed two inducer lines containing cytogenetic marker B chromosome or alien centromeric histone H3 variant-yellow fluorescent protein vector to investigate the mechanism. The two inducer lines as the pollinators were crossed with a hybrid ZhengDan958. B chromosomes were detected in F1 haploids at a low frequency, which was direct evidence to support the occurrence of selective chromosome elimination during haploid formation. We found that most of the inducer chromosomes were eliminated in haploid embryonic cells during the first week after pollination. The gradual elimination of chromosomes was also detected in the endosperm of defective kernels, although it occurred only in some endosperm cells as late as 15 d after pollination. We also performed a genome-wide identification of single nucleotide polymorphism markers in the inducers, noninducer inbred lines, and 42 derived haploids using a 50K single nucleotide polymorphism array. We found that an approximately 44-Mb heterozygous fragment from the male parent was detected in a single haploid, which further supported the occurrence of paternal introgression. Our results suggest that selective elimination of uniparental chromosomes leads to the formation of haploid and possible defective kernels in maize as well, which is accompanied with unusual paternal introgression in haploid cells.Doubled haploid (DH) technology is widely used in maize (Zea mays) breeding. Although the life cycle of most sexually reproducing plant species alternates between a diploid sporophytic phase and a highly reduced gametophytic haploid phase, it is possible to obtain haploid plants containing the same number of chromosomes in their somatic cells as do the normal gametes of the species (Dunwell, 2010). Haploids can be obtained by in vitro or in vivo approaches. Anther and microspore culture are the most commonly used in vitro approaches; however, many species and genotypes are recalcitrant to these processes (Forster et al., 2007). Interspecies cross, which is an in vivo approach, induces haploids via chromosome elimination (Forster et al., 2007). For example, the cross between Hordeum vulgare and Hordeum bulbosum produces haploids in barley (Kasha and Kao, 1970; Sanei et al., 2011); maize and pearl millet (Pennisetum glaucum) are used as pollinators to produce haploids in wheat (Triticum aestivum; Laurie and Bennett, 1988; Gernand et al., 2005). There are two approaches for in vivo haploid induction in maize. One is using an ig mutant to generate both maternal and paternal haploids (Kermicle, 1969; Evans, 2007), and the other is using Stock6-derived inducers to produce maternal haploids only. The application of Stock6-derived inducers has become the foundation for modern DH technology (Prigge and Melchinger, 2012; Xu et al., 2013). The haploid induction rate (HIR) of inducer line Stock6 is 1% to 2% (Coe, 1959), which is 10 to 20 times higher than the spontaneous HIR in maize. The haploid-inducing capacity of inducers can be improved by selection (Sarkar et al., 1972). New inducers with improved HIRs have been developed, such as WS14 (2%–5% induction rate; Lashermes et al., 1988), RWS (Röber et al., 2005), and CAU5 (Xu et al., 2013).The first haploid inducer line Stock6 was discovered 50 years ago, and DH technology based on in vivo induction of maternal haploids has been widely used in maize breeding (Geiger, 2009). The mechanism underlying haploid formation remains unclear. Two hypotheses have been proposed for the mechanism. The first hypothesis is that one of the two sperm cells fails to fuse with an egg cell, but instead triggers haploid embryogenesis. In the second hypothesis, the two sperm cells fuse with an egg cell and a central cell, and the chromosomes from the inducer degenerate and are eliminated stepwise in the primordial cells during subsequent cell divisions.Evidence supporting the first hypothesis was reported by Bylich and Chalyk (1996). They found that 6.3% of the pollen grains of the ZMS haploid inducer line have two sperms showing different morphology. Thus, they proposed that the morphological defects of one of the sperms interfere in the sperm’s function, causing single fertilization. Another abnormality of inducer lines was described by Chalyk et al. (2003). They found that the frequency of aneuploid microsporocytes is much higher in haploid inducers than that in normal maize.Wedzony et al. (2002) studied the ovaries of inducer line RWS during the first 20 d after self-pollination. They found that about 10% of the embryos contain micronuclei with various sizes in the cytoplasm of every cell of shoot primordium. Their result supports the second hypothesis, which is selective chromosome elimination. Moreover, Fischer (2004) speculated that maternal haploids might possess small fractions of inducer genome. Consistently, previous studies (Zhang et al., 2008; Li et al., 2009) demonstrated morphological and molecular evidence for paternal DNA introgression in haploids, indicating the mechanism of chromosome elimination.Robust evidence to support either hypothesis is still missing due to lack of cytogenetic makers to trace chromosomes from inducers. In this study, we used B chromosomes and centromeric histone H3 variant (CENH3)-yellow fluorescent protein (YFP) as cytogenetic markers to discover direct evidence supporting selective chromosome elimination in both embryo and endosperm during haploid formation. In addition, we performed a genome-wide identification of single nucleotide polymorphism (SNP) markers in inducers, noninducer inbred lines, and 42 haploids using a 50K SNP array and detected unusual DNA introgression from inducer lines during haploid formation.     

High-frequency generation and characterization of intergeneric hybrids and haploids from new wheat–barley crosses

Key message

Hybrid plants and a high frequency of maternal haploids were obtained using an efficient wheat–barley hybridization system (with new genotype combinations) and confirmed by several cytological and molecular tools.

Abstract

An efficient hybridization system between wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) is presented on the basis of three new genotype combinations. A particularly high, 14 % frequency of plant regeneration per florets was achieved in the wheat–barley genotype combination of ‘Sichuan’ × ‘Morex’. The genome composition in 42 of the 95 plants regenerated by embryo rescue was determined using ploidy analysis, genomic in situ hybridization and the application of chromosome arm-specific molecular markers (SSR and STS). A high overall frequency (76 %) of maternal (wheat) haploids was observed in all the tests for all three cross combinations. A major implication of this observation is that this new hybridization system represents a useful tool to study the mechanism of uniparental chromosome elimination in cereals.     

Morphological and molecular evidences for DNA introgression in haploid induction via a high oil inducer CAUHOI in maize

The phenomenon of maternal haploid induction in maize was first described many years ago, but the underlying mechanism is still unclear. In this study, the Stock-6-derived, haploid-inducing line CAUHOI with high kernel oil content (KOC), was used as the pollinator to produce maternal haploids from the maize hybrid ZD958 with low KOC. CAUHOI is homozygous for the dominant marker gene R1-nj. Haploids were identified by morphological and cytological investigations. The frequency of haploid induction from this cross was 2.21%. Unexpectedly, many haploid kernels had weakly pigmented purple color on the embryo, and some haploid kernels had high KOC. Simple sequence repeat (SSR) analysis showed that 43.18% of the haploids carried segments from CAUHOI, and a small proportion (average 1.84%) of the genome of CAUHOI was introgressed into haploids. Haploid kernels with high KOC had a higher frequency of segment introgression from CAUHOI (2.92%) than that in haploid kernels with low KOC (1.79%), showing that the marker gene R1-nj and high-oil genes from CAUHOI were expressed during the development of some haploid embryos, and confirmed that the DNA introgression from the inducer parent occurred during maternal haploid induction. Together, these results suggested that the chromosome elimination was probably responsible for haploid induction in maize, and late somatic elimination might occur. Several possible mechanisms underlying haploid formation are discussed. Liang Li and Xiaowei Xu contributed equally to this work.     

Use of matroclinous haploid plants in recurrent selection in corn]

Two cycles of recurrent selection were performed in maize with the use of matroclinous haploids. Two synthetic populations, SP and SA, were improved. Each cycle consisted of two stages: (1) isolation of haploids from the synthetic populations and (2) growth of the haploids, pollination with pollen from diploid plants, and selection. The selection was performed for ear size in haploid plants. The mean gain in productivity in the synthetic populations SP and SA the per cycle was 16.48 and 20.98%, respectively. It is suggested that the high value of this index is related to the fact that haploid plants reveal useful genes with additive and epistatic effects. Natural selection may have played a part, too. The combination of artificial and natural selection in haploids resulted in a considerable gain in productivity in the synthetic populations to be improved.     

The Use of Matroclinous Maize Haploids for Recurrent Selection

Two cycles of recurrent selection were performed in maize with the use of matroclinous haploids. Two synthetic populations, SP and SA, were improved. Each cycle consisted of two stages: (1) isolation of haploids from the synthetic populations and (2) growth of the haploids, pollination with pollen from diploid plants, and selection. The selection was performed for ear size in haploid plants. The mean gain in productivity in the synthetic populations SP and SA the per cycle was 16.48 and 20.98%, respectively. It is suggested that the high value of this index is related to the fact that haploid plants reveal useful genes with additive and epistatic effects. Natural selection may have played a part, too. The combination of artificial and natural selection in haploids resulted in a considerable gain in productivity in the synthetic populations to be improved.     

单套染色体组在泽蛙雌核单倍体发育中的作用

本文比较了泽蛙(Rana limnocharis Boie)单倍体和二倍体的胚胎发育。结果表明:泽蛙单倍体的生活力低下,器官发生异常,自原肠胚起发育速度减慢。据此,作者讨论了单套染色体组在个体发育中的作用。     

Effects of Fusarium culmorum head blight on mycotoxin accumulation and yield traits in barley doubled haploids

The susceptibility of barley doubled haploids (DH) to Fusarium head blight (FHB) was investigated. Heads of 24 DH lines (11 two-rowed and 13 six-rowed) derived from F₁ Maresi (two-rowed) × Pomo (six-rowed) hybrids were inoculated with a conidial suspension of the single isolate IPO348-01 of Fusarium culmorum. The experiment was carried out in three consecutive years (1996–98) in one location. The number of kernels per ear, 1000-kernel weight and kernel weight per ear were recorded in inoculated and control plots. In the infected kernels nivalenol (NIV) content and deoxynivalenol (DON) content were determined. The effects of genotype, year and genotype-year interaction on reduction of yield traits were significant. For mycotoxin content only genotype and year effects were found to be important. The average NIV concentration in kernels of inoculated lines ranged from 0.15 mg/kg in the two-rowed line MP7 to 6.36 mg/kg in the six-rowed line MP113. A low accumulation of DON was observed in the studied population (from 0.01 to 0.20 mg/kg). Generally, no significant differences in mycotoxin content were found between two-rowed and six-rowed genotypes. The line MP7 was found to be superior — with the lowest mycotoxin accumulation, and reduction in yield traits. Environmental conditions (years) affected DON and NIV level in kernels; however, the tendency to a lower or higher accumulation of mycotoxin in individual lines was stable over the years.     

Tests for the presence of gametoclonal variation in barley and wheat doubled haploids produced using the Hordeum bulbosum system

Summary To investigate whether the Hordeum bulbosum system of doubled haploid production generates gametoclonal variation, populations of second generation doubled haploid lines were developed from first generation doubled haploid lines of two barley varieties and three wheat genotypes. In barley, no variation between doubled haploids from doubled haploids was detected for a range of quantitative characters, suggesting the absence of any gametoclonal effects. However, the original selfed-seed stocks were shown to contain cryptic allelic variation for some of the characters investigated. In wheat, gametoclonal variation was detected for ear emergence time, plant height and yield, and its components for two out of the three genotypes investigated. The type and range of variation was similar to that reported from studies of somaclonal variation from immature embryos and gametoclonal variation from anther culture. Generally, the effects appeared to reduce the yield performance of individual lines. The difference in response between the two species and the consequences for the use of the doubled haploid system in breeding programmes are discussed.     

Maternal haploids of Petunia axillaris (Lam.) B.S.P. via culture of placenta attached ovules

Summary Hybridization of Petunia axillaris and P. parodii with Nicotiana tabacum was attempted using the method of in vitro pollination and fertilization. Seedlings were produced when the Petunia species and N. tabacum were used as the maternal parents; however, most of these had the identical somatic chromosome complement of the maternal parent. With crosses involving P. axillaris as the maternal parent, a low frequency of haploids was also produced. Due to the potential of haploids in basic and applied genetic research, additional experiments were carried out to determine whether in vitro pollination was necessary to stimulate haploid production and to more closely define the optimal time for ovule excision and culture. Four treatments were applied to accomplish these objectives. They were: placentas cultured prior to the time of anthesis, with and without pollination, and placentas cultured after the time of anthesis, with and without pollination. In vitro pollination had no effect on the frequency of haploids produced. Placenta attached ovules cultured prior to the time of anthesis produced significantly more haploids than those cultured after anthesis. The preanthesis treatment produced a frequency of 6.5 haploids per 100 ovaries cultured. The culture of placenta attached ovules provides an alternative to anther culture as a means for haploid production.The investigations reported herein were supported by USDA/SEA/CRGO Project 59-2213-1-1-613-0 and the paper (No. 84-3-36) is published with the approval of the Director of the Kentucky Agricultural Experiment StationThe authors are Graduate Research Assistant and Professor, respectively, Department of Agronomy, University of Kentucky, Lexington 40546-0091. The research reported in this paper is in partial fulfillment of the PhD requirements for the senior author     

Conservation and storage of a haploid cucumber (Cucumis sativus L.) collection under in vitro conditions

 Over 3 consecutive years (1992–1994), a collection of cucumber haploids was obtained from three different lines and one hybrid. Attempts were made to maintain and store a subcollection of these haploids for 3 years. Cucumber haploids appeared to be stable when cultured in vitro. There were no instances of spontaneous doubling and only one morphologically changed plant. During the first year of storage, between 30% and 80% the clones were lost, due to disturbances in plant development, increased levels of endogenous bacteria, and physiological changes resulting in continuous flowering. After 2 years of storage haploids showed reduced vigour. Therefore, plants were regenerated directly from primordial leaf microexplants. Haploid plants were obtained from nearly all of the previous haploid plants. The rejuvenated haploids possessed the same ploidy level and morphological traits as the old collection. The only new characteristic was faster vegetative growth. Received: 17 March 1998 / Revision received: 14 April 1999 / Accepted: 10 May 1999     

Should maize doubled haploids be induced among F<Subscript>1</Subscript> or F<Subscript>2</Subscript> plants?

Maize (Zea mays L.) doubled haploid lines are typically produced from F₁ plants. Studies have suggested that the low frequency of recombinants in doubled haploids may reduce the response to selection. My objective was to determine if, for sustaining long-term response, doubled haploids should be induced in F₁ or F₂ plants during maize inbred development. In simulation experiments, I examined the response to multiple cycles of testcross selection among doubled haploid lines derived from F₁ plants (denoted by DH), doubled haploid lines derived from F₂ plants (DH_F2), and recombinant inbred (RI) lines derived by single-seed descent. For a trait controlled by 100 or more quantitative trait loci (QTL), the cumulative responses to selection were up to 4–6% larger among DH_F2 lines than among DH lines. The cumulative responses were up to 5–8% larger among RI lines than among DH lines. The QTL become unlinked as the number of QTL in a finite genome decreases, and the responses among RI, DH, and DH_F2 lines were equal or nearly equal when only 20 QTL controlled the trait. Metabolic-flux epistasis reduced the differences in the response among RI, DH, and DH_F2 lines. Overall, the results indicated that doubled haploids should be induced from F₂ plants rather than from F₁ plants. If year-round nurseries are used and new F₁ crosses for inbred development are initially created on a speculative basis, the development of doubled haploids from F₂ rather than F₁ plants should not cause a delay in inbred development.     

A test for a metastable epigenetic component of heterosis using haploid induction in maize

We conducted a test to detect if there is a heritable epigenetic component to hybrid vigor and/or inbreeding depression. The impetus for this work was a classical study of the effect of homozygosis on the expression of the maize red color (r1) locus. It had been shown that maintaining R1 mottling alleles in the homozygous state over several generations produces a progressive decrease of their paternally imprinted expression. This effect is reversed by R1/r1 allele heterozygosity. If this behavior were characteristic of many regulatory genes, then such a phenomenon could contribute to inbreeding depression and heterosis. To examine this question, inbreds of Mo17 and B73 and the two reciprocally produced hybrids were crossed by Stock 6 to generate four classes of maternal haploids. The mature haploid plants were measured for several quantitative traits. If inbreeding depression results from an accumulating heritable effect that is reversed by the hybrid state, one would expect the haploids derived from the hybrids to perform better than those derived from the inbred lines. The hybrid-derived haploids did not exhibit greater average performance than the inbred-derived haploids. These data fail to support the hypothesis that inbreeding depression and heterosis have a metastable epigenetic component.Communicated by D. Hoisington     

New insights into the genetics of in vivo induction of maternal haploids, the backbone of doubled haploid technology in maize

Haploids and doubled haploid (DH) inbred lines have become an invaluable tool for maize genetic research and hybrid breeding, but the genetic basis of in vivo induction of maternal haploids is still unknown. This is the first study reporting comparative quantitative trait locus (QTL) analyses of this trait in maize. We determined haploid induction rates (HIR) in testcrosses of a total of 1061 progenies of four segregating populations involving two temperate haploid inducers, UH400 (HIR = 8%) and CAUHOI (HIR = 2%), one temperate and two tropical inbreds with HIR = 0%, and up to three generations per population. Mean HIR of the populations ranged from 0.6 to 5.2% and strongly deviated from the midparent values. One QTL (qhir1) explaining up to p = 66% of the genetic variance was detected in bin 1.04 in the three populations involving a noninducer parent and the HIR-enhancing allele was contributed by UH400. Segregation ratios of loci in bin 1.04 were highly distorted against the UH400 allele in these three populations, suggesting that transmission failure of the inducer gamete and haploid induction ability are related phenomena. In the CAUHOI × UH400 population, seven QTL were identified on five chromosomes, with qhir8 on chromosome 9 having p > 20% in three generations of this cross. The large-effect QTL qhir1 and qhir8 will likely become fixed quickly during inducer development due to strong selection pressure applied for high HIR. Hence, marker-based pyramiding of small-effect and/or modifier QTL influencing qhir1 and qhir8 may help to further increase HIR in maize. We propose a conceptual genetic framework for inheritance of haploid induction ability, which is also applicable to other dichotomous traits requiring progeny testing, and discuss the implications of our results for haploid inducer development.     

Inheritance of emergence time and seedling growth at low temperatures in four lines of maize

Summary The improvement of rate of seedling emergence and early seedling growth of maize (Zea mays L.) under cool conditions has been an objective of breeding programs in cool regions for many years. To study inheritance of emergence time, and to determine if differences in emergence time were due to differences in seedling growth, F₁, F₂ and backcross generations of a diallel cross of two rapidly emerging lines from CIMMYT Pool 5, 5-113 and 5-154, and two elite Corn Belt Dent lines, A619 and A632, were grown in controlled environment rooms at low temperatures.The lines from Pool 5 emerged significantly faster than A619 and A632 over a range of low temperature conditions. This difference occurred both when the lines themselves were tested and when the lines were tested as male and female parents in crosses. The Pool 5 lines converted a higher proportion of their original seed to new root and shoot tissue than did A619 and A632, indicating that they had a faster seedling growth rate. Primarily this was due to a faster loss of seed reserve, rather than a more efficient conversion process.A significant difference occurred between A619 and A632 for emergence time, but this was not due to a difference in seedling growth rate.Reciprocal differences occurred only in the F₁ generation in crosses involving A619, and then marked effects could be attributed to the male parent. Reciprocal differences tended to disappear in the F₂. This suggested that the genotype of the embryo and endosperm was of much greater importance than the genotype of the maternal parent in determining differences of time to emergence and seedling growth.Mid-parent heterosis occurred for time to emergence and seed loss, a measure of mean rate of utilization of seed reserve, in all crosses. High parent heterosis occurred in several crosses for these traits. High parent heterosis occurred in all crosses for efficiency of utilization of seed reserve.A generation means analysis indicated that both additive and dominance effects were present for rate of seedling growth in crosses between A632 and the Pool 5 lines.     

Development of porcine blastocysts from in vitro- matured and activated haploid and diploid oocytes

The purpose of this study was to determine the developmental capacity of electro-activated porcine oocytes. Follicular oocytes collected from gilts at local slaughterhouses were matured for 48 h and were then subjected to a single square pulse of direct current for 100 rhojusec at 1,500 V/cm for activation. To obtain activated diploid oocytes, some were treated with 5.0 micro/ml cytochalasin B for 4 h immediately after electro-activation. The frequency of activation ranged from 96 to 100%. While 91% of activated oocytes that had not been treated with cytochalasin B had 2 polar bodies and a nucleus (haploids), 92% of the oocytes treated with cytochalasin B had only the first polar body and 2 nuclei (diploids). Haploids and diploids were further cultured in TCM-199 medium that contained 10% (v/v) heat- treated fetal calf serum (FCS) and 0.1 mg/ml sodium pyruvate (mTCM) or in Whittenk medium plus 0.4% (w/v) bovine serum albumin (BSA). The frequency of abnormal oocytes was significantly higher in mTCM (83%) than in Whitten's medium (65%) 96 h after the electro-activation (P < 0.01), suggesting that Whitten's medium supported the development of activated oocytes beyond the morula stage. In all cases, several oocytes developed to the blastocyst stage 144 h after electro- activation (1 to 12%). The frequency was significantly higher in the case of diploids cultured in Whitten's medium (12%) (P < 0.01) than in the case of haploids cultured in Whitten's medium (4%), or in the case of haploids cultured in mTCM (1%). The mean number of nuclei per blastocyst was significantly lower in mTCM (haploids, 15; diploids, 16.1) than in Whitten's medium (haploids, 35.7; diploids, 40.1; P < 0.01), suggesting that the number of nuclei in blastocysts was affected by the culture medium.     

Genetic control of maternal haploidy in maize (Zea mays L.) and selection of haploid inducing lines

Summary The effect of genotype on maternal haploid plant production in maize was studied. The frequency of gynogenetic plants when Stock 6 was used as pollinator varied according to the female parent genotype. No simple relation was observed between genotypic aptitudes for gynogenetic and androgenetic development, which occured after pollination of W23 plant carrying the indeterminate gametophyte gene. Furthermore, the population NS, a favorably responsive genotype to anther culture, does not exhibit exceptional ability for in vivo gynogenesis. The effect of inbreeding and the influence of maternal haploid origin suggest that specific genes control maternal haploid initiation and development. However, gynogenetic development is not limited to a particular genotype. The frequency of maternal haploids may be increased by using specific pollen parents. Attempts were made to select for a high haploidyinducing trait and the present study reports the successful development of lines that can be utilized as pollen parents to induce haploids for experimental purposes and breeding programmes. When an inbred line WS14, derived from the cross W23 x Stock 6, was used as pollen parent, 2%–5% maternal haploids were obtained according to the female parent genotype. A high haploidy-inducing potential is a heritable trait and may be controlled by a limited number of genes. Genetic determination of the haploidy-inducing character was examined in relation to the efficiency of the selecting method and the mechanisms involved in the origin of maternal haploids.     

400例消化系统恶性肿瘤患者血清TSGF检测的临床分析

目的探讨肿瘤特异性生长因子（TSGF）在消化系统恶性肿瘤诊断上的价值及其临床意义。方法用生化比色定量法及TSGF检测试剂盒测定血清中TSGF的含量。结果400例消化系统恶性肿瘤患者血清TS-GF的含量（71．37±11．24u／ml）显著高于正常对照组血清TSGF的含量（59．75±4．45u／ml）（P〈0.01）,阳性检出率达79．80％。另外,在60例进行化疗的患者中,18例有效者化疗后血清TSGF的含量（61．28±6．05u／ml）较化疗前（83．01±4．57u／ml）明显下降（P〈0．01）,6例化疗无效者化疗后血清TSGF的含量（86．51±5．82u／ml）显著高于化疗前（65．76±5．92u／ml）（P〈0．01）。结论TSGF是一种新的、敏感性高的肿瘤标志物,对于消化系统恶性肿瘤的诊断、评价疗效和判断预后,均有临床意义。