黄花蒿多倍体的诱导与鉴定

利用秋水仙素,采用浸泡法和固体培养法分别对黄花蒿(Artemisia annua L.)丛生芽进行多倍体诱导,以期获得黄花蒿多倍体种质。结果表明,以5 000 mg/L秋水仙素浸泡丛生芽5 d处理获得的诱导效果最好,诱导率可达40%。对性状变异明显的黄花蒿植株进行染色体数目观察,发现了黄花蒿四倍体和嵌合体。     

Polyploidization and early screening of Rhododendron hybrids

Polyploid induction represents a useful tool for breeders of floral crops as larger flowers, longer flowering period and deeper colors can be achieved through chromosome doubling. This study aimed at testing the efficiency of colchicine and oryzalin in inducing polyploidy in three Rhododendroncultivars grown in vitro. The chemicals were used in two concentrations with 24 h and 48 h treatment durations. The survival of the plants was better in colchicine than in oryzalin solutions. The higher concentration of both chemical skilled more plantlets. The treatment duration in oryzalin did not affect the survival, but 48 h in colchicine was more destructive than 24 h. The low survival rate may not be a disadvantage, if the treatment induces desired ploidy. The ploidy levels were screened with flow cytometry. Oryzalin was more efficient than cochicine in inducing polyploidy, the treatment duration and the concentration did not have significant effects as main factors. The biggest proportion of solid tetraploids (18.2% of the survived plants) was obtained from the 24 h treatment in 0.005% oryzalin. Immediately after the treatment the polyploids grew very slowly, whereas most of the unaffected diploids were vigorous from the very beginning. More mixoploids than solid tetraploids were obtained in all treatments. Most of the mixoploids retained their chimerism, one third shifted todiploidy and one single plant to tetraploidy. This revised version was published online in July 2006 with corrections to the Cover Date.     

长穗桑组织培养和四倍体新种质诱导

以长穗桑枝条为外植体,建立其无菌离体快繁体系,综合利用组织培养技术和秋水仙素诱变技术,进行四倍体诱变处理,试验结果表明：长穗桑最佳的增殖培养基为MS＋BA 2．0mg／L＋NAA 0．2mg／L＋蔗糖30g／L,最佳的生根培养基为1／2MS＋BA 0．1mg／L＋NAA 0．05mg／L＋30g／L蔗糖,四倍体诱导的最佳处理条件为0．2％浓度的秋水仙素浸泡茎段3d,诱导率最高为16．7％。     

秋水仙碱化学去核对山羊卵丘细胞核移植胚胎体外发育的影响

研究旨在探讨秋水仙碱化学去核在山羊卵母细胞去核中的应用及其对卵丘细胞核移植胚胎体外发育的影响。结果表明:用秋水仙碱处理山羊体外成熟19h的卵母细胞,可使其核区形成胞质突起,以此为指示进行显微操作去核率可达100%,且用0.8μg/mL秋水仙碱处理30min的山羊卵母细胞突起率可达91.27%,显著高于对照组及0.4μg/mL处理组(P<0.05),与1.6μg/mL处理组的突起率差异不显著(P>0.05)。通过比较盲吸去核法与秋水仙碱化学去核法构建的山羊卵丘细胞核移植胚胎的体外发育能力发现,秋水仙碱化学去核法构建的重构胚体外发育能力较高,桑椹胚发育率显著高于盲吸去核法(P<0.05)。     

秋水仙素诱导杂交兰四倍体及倍性鉴定

以杂交兰F1代无菌苗(2n=2x=40)为供试材料,分别用浓度为0.02%、0.05%、0.10%和0.20%的秋水仙素对其根状茎处理24、48和72h,成功获得了四倍体植株。试验结果表明,以0.10%的秋水仙素处理48h诱导效果最佳,变异率为36%。根尖染色体压片表明,四倍体染色体数为2n=4x=80,二倍体对照为2n=2x=40。加倍后的植株较二倍体植株粗壮,叶片变厚,颜色变深,茎基部粗壮,颜色深,生长势变缓,根系变粗,根状茎增粗,可作为新材料加以利用。     

Development of novel chromosome doubling strategies for wheat × maize system of wheat haploid production

Two chromosome doubling strategies were evaluated for producing wheat doubled haploids from wheat x maize crosses: (i) in vitro colchicine application to haploid embryos and (ii) colchicine treatment through postpollination tiller injections. In the in vitro approach the haploid embryos were rescued on medium containing colchicine (at concentrations of 0.2, 0.3, 0.4 and 0.5%) and moved to a colchicine‐free regeneration medium 48 h later. Embryos exposed to 0.5% colchicine had 91.67% of their regenerated plants showing chromosome doubling. In the tiller injection approach, different concentrations (0.5, 0.75 and 1.0%) of colchicine solution, which also contained 2,4‐D (100 ppm), were injected into the uppermost inter‐node of crossed tillers 48 and 72 h after pollination. The chromosome doubling efficiency varied from 33 to 100%, with 1% treatment being the most effective. No chimeras of doubled/haploid sectors were observed in the case of the tiller injection treatment and all the florets showed seed set in the doubled plants. Stomatal guard cell length provided rapid, early‐stage and unambiguous analysis of ploidy level on the basis of 10 guard cell observations per plant.     

Addition of Colchicine to Wheat Anther Culture Media to Increase Doubled Haploid Plant Production

Chromosome doubling is critical for obtaining doubled-haploid plants from wheat (Triticum aestivum L.) anther culture. The most common doubling method applies colchicine to the plant. However, colchicine is phytotoxic and can induce a high frequency of plant death. In this experiment, anthers from two wheat genotypes (“Pavon 76” and ‘Centurk’) were placed on nine embryoid initiation media having three sugar sources (maltose, sucrose, and maltose + glucose) with three colchicine concentrations (0.0, 0.1, and 0.2 g · l^-1). Wheat starch was used as a gelling agent. After three days, the anthers were washed and moved to fresh media without colchicine. Increasing the colchicine concentration decreased the number of embryoids produced from 77.4 embryoids/100 anthers to 29.9 embryoids/100 anthers, but did not significantly affect the frequency of plant regeneration (0.49 green plants/embryoid to 0.40 green plants/embryoid), and increased the frequency of doubled-haploid plants (19.0 doubled-haploid plants/100 green plants to 72.3 doubled-haploid plants/100 green plants). Considering the total number of doubled-haploid plants produced, low levels of colchicine added to the initiation media were very effective.     

Colchine-induced aneuploids from cell culture of sugarcane

Summary Sugarcane (Saccharum spp.) clones are amenable to gross chromosome manipulation due to their high polyploid nature (2n=100–120). This study was conducted to analyze the effects on plant morphology of altering chomosome number via callus culture. Callus cultures from clone H69-9092 were established, and plants were regenerated following colchicine treatment of cultured cells. Cytological analysis showed that variant somaclones were aneuploids with a wide range in chromosome numbers (2n=66–196). Some 22 visually distinct somaclones were planted in 1.35 m² plots with five replications to compare morphological and quality characteristics with H69-9092 at 8 months of growth. Extreme morphological variation was observed between somaclones, but coefficients of variation for quality factors-fibers %, refractometer solids %, pol %, and juice purity-and stomatal length were smaller than those for morphological traits associated with stalk volume and leaf area. Significant negative correlations were found between chromosome number and most morphological traits, e.g., stalk length (r=-0.58), number (r=-0.69), diameter (r=-0.54) and volume (r=-0.65); internode length (r=-0.57); and leaf area (r=-0.48). A positive correlation was found between chromosome number and stomatal length (r=-0.66). No significant correlations were found between chromosome number and quality factors. Aneuploids with higher than parental chromosome number had reduced growth. However, depression in growth was generally not observed in somaclones lower in chromosome number than the parent.Published with the approval of the Director as Paper No. 598 in the Journal Series of the Experiment Station, Hawaiian Sugar Planters' Association.     

Dough un-mixing time,and the sticky dough problem associated with Sr31 wheats

Summary A 3 hr treatment period with a 0.2% aqueous solution of colchicine was given to one week old seedlings of imbred lines of perennial ryegrass (Lolium perenne L.). The surviving plants developed as mixoploids and were subsequently split down into single tillers and then classified as either diploid or tetraploid. The undoubled diploids of the treated material (C2x) were then self-pollinated and the seeds grown in the following generation (CT1) without any further treatment. In the CT1 generation comparisons were made between the C2x and the control 2x treatments within the same inbred lines, and heritable differences were found for leaf mesophyll cell plan areas and chloroplast numbers. The cell areas were significantly less in the C2x compared with the 2x treatment in four out of the five lines studied, and the chloroplasts numbers were likewise lower in two out of the five lines. In one line there was a significantly higher mean number of chloroplasts per cell in the C2x material compared with that of the 2x.     

Chromosome doubling in Tripsacum: the production of artificial, sexual tetraploid plants

A collection of embryogenic diploid calli of Tripsacum was established and treated with colchicine to induce chromosome doubling. Sections containing duplicated cells in calli were identified using flow cytometry and ploidy level was determined in the regenerated plantlets. Tetraploid plants from several origins were obtained. In contrast to wild polyploid plants, which show apomictic development, the regenerated tetraploid plants reproduced sexually. By hybridizing these plants with wild tetraploid apomicts, various populations were established; these will allow a study of the inheritance of apomixis in Tripsacum.