Somatic embryogenesis and histological analysis from zygotic embryos in Vitis vinifera L. ''Moldova''

We examined the somatic embryogenesis from and histological studies of zygotic embryos of seeds in European Grape 'Moldova' (Vitis vinifera L. 'Moldova'). Primary calli were initiated on Nitsch and Nitsch (NN) medium supplemented with 1.0mg'L-1 2,4-D and 0.5 mg'L-1 6-BA. Embryogenic calli were produced upon transfer to a NN medium with 0.5 mg-L-1 6-BA and 2 mg.L-1 NAA and somatic embryos were obtained on a half strength MS medium without plant growth regulators. During the somatic embryo germination, an addition of 1.0 mg.L-1 6-BA in the medium could accelerate somatic embryos to develop into normal plants and increase the conversion rate from 0 to 43.3%. Histological studies of embryogenic calli and somatic embryos demonstrated dy-namic changes of proteins and starch grains. The developmental processes of somatic embryos were similar to those of zygotic em-bryos, including typical epiderma, cotyledon primordium and vascular tissue.     

龙眼体细胞胚胎的高频率萌发与植株再生

以龙眼胚性愈伤组织诱导产生子叶形胚状体为试验材料，比较了蔗糖、活性炭的质量浓度，椰乳的体积分数，光照度和成熟时间等因素对体胚“成熟”的影响以及不同成熟过程、成熟时间、胚状体形态、品种（基因型）等因素对龙眼体细胞胚胎萌发的影响．结果表明，龙眼体胚在含５０ｇＬ－１蔗糖、体积分数为０．０５的椰乳、１００ｍｇＬ－１肌醇的ＭＳ固体培养基上，在黑暗或弱光条件下，不论白色还是透明化（玻璃化）子叶形小胚状体，都可完成“成熟”过程．体胚对成熟培养的蔗糖质量浓度和成熟时间有特定的要求．经过成熟培养的体细胞胚胎，可高频率萌发成苗     

The detection of subclinical mastitis in the bactrian camel (Camelus bactrianus) by somatic cell count and California mastitis test

Milk samples (n=160) from 7 clinically healthy bactrian camels were cultured to detect subclinical udder infection. The samples were assessed by the Californian mastitis test (CMT) and somatic cell count (SCC). Bacteria were recovered from 36 (22.5%) of the milk samples. Staphylococcus aureus and coagulase-negative staphylococci (CNS) were the main organisms found.Infected quarters had significantly higher mean values for the SCC (p<0.01) and CMT (p<0.001) than non-infected quarters. All 7 camels were infected with CNS but only 4 with S. aureus. CMT values for S. aureus-infected camels were significantly higher than for those only infected with CNS. The values for SCC and CMT were significantly influenced by the stage of lactation (p<0.05). No significant difference was found from the effect of the quarters. Both SCC and CMT were of value in predicting the infection status of the udder.Abbreviations CMT California mastitis test - SCC somatic cell count - CNS coagulase-negative staphylococci     

牛体细胞核移植技术

对牛体细胞核移植技术中核供体细胞周期同期化处理，电融合条件及去核方法等进行了研究。结果表明，血清－饥饿组（细胞周期同期化处理组）的移核重构胚细胞融合率（83．3％），卵裂率（70％）和囊胚发育率（33．8％）与血清－选择组对应指标间无显著性差异（82．3％，69．2％，32．4％，P＞0．05）；但上述2组分别极显著高于血清－随机组（64．8％，33．8％，4．35％，P＜0．01），试验确立了场强1.025kV/cm，脉冲宽度50μs，连续2次脉冲为最佳电融合条件。摸索出的点击去核法，对卵母细胞进行去核，去核成功率达90％，极显著高地吸引法的68．3％（P＜0．01）；其囊胚发育率为34．1％，显著高于吸引法的18．0％（P＜0．05），与挤压法（20．9％）相比差异不显著（P＞0．05），移植重构胚胎移植后，产2头成活的体细胞克隆牛。     

香榧体细胞胚发生、发育的形态与细胞学观察

将香榧(Torreya grandis‘Merrillii’)的未成熟合子胚置于SH+0.1 mg·L-1 NAA+500 mg·L-1AC+3%蔗糖+0.5 g·L-1 Gln培养基上暗培养45 d,诱导产生半透明颗粒状胚性愈伤组织;将胚性愈伤组织转入SH+20 g·L-1 PEG+10 mg·L-1 ABA培养基中暗培养3个月诱导体细胞胚。采用碘—碘化钾染色和石蜡切片技术对体胚起源、形态发育与细胞组织学进行了观察。结果表明:胚性愈伤组织起源于合子胚胚轴表皮或皮层细胞的对称分裂。胚性愈伤组织含有两类细胞,一种是细胞质浓厚、细胞核大、体积小的圆形胚性细胞,另一种是高度液泡化拉长的细胞。胚性愈伤组织包含由这两种细胞构成的原胚团Ⅰ、原胚团Ⅱ和原胚团Ⅲ,以及一些游离细胞。原胚团Ⅲ在无植物生长调节剂的SH基本培养基上形成原胚,原胚接入成熟培养基,历经球形、棒状、心形、鱼雷形胚后发育成子叶胚。将子叶胚转入萌发培养基后胚根伸长,胚芽发育长出针叶,形成完整的再生植株。同时在离体培养中合子胚胚柄处退化的裂生多胚也能重新发育形成胚体。在初生体胚发育过程中表面常伴有次生体细胞胚的形成。     

Genetic improvement of legumes using somatic cell and molecular techniques

Summary The merits and limitations of somatic cell techniques involving Agrobacterium-mediated transformation, direct gene transfer and protoplast fusion, are discussed in relation to the genetic improvement of forage and grain legumes. Whilst progress with legumes is limited compared to that with plants of other families such as the Solanaceae, the fact that many legumes are readily amenable to tissue culture now permits somatic cell techniques to be targetted to these species. Future development of the subject will necessitate close collaboration between molecular biologists and plant breeders to enable novel plants generated by in vitro technologies to be incorporated into conventional breeding programmes.     

In vitro somatic embryogenesis in turf-type bermudagrass: roles of abscisic acid and gibberellic acid, and occurrence of secondary somatic embryogenesis

Bermudagrass is an important warm‐season turfgrass species that is recalcitrant in regeneration in tissue culture. In a previous report, we observed that somatic embryogenesis of immature inflorescence culture was substantially improved when low levels of 2,4‐dichloro‐phenoxy acetic acid (1 mg/l) and 6‐benzylaminopurine (BAP, 0.01 mg/l) were included in the callus induction medium. The object of this study was to further improve the culture conditions to enhance somatic embryo formation and plantlet regeneration. It was shown that the abscisic acid supplement (2 or 5 mg/l) to the above callus induction medium further enhanced somatic embryogenesis in hybrid bermudagrass (Cynodon dactylon×Cynodon transvaalensis) cv. ‘Tifgreen’. The addition of gibberellic acid (0. 2 mg/l) to the BAP (1 mg/l)‐containing regeneration medium accelerated germination/regeneration of the somatic embryos. Secondary and repetitive somatic embryogenesis, which is rarely reported in monocots, was observed in common bermudagrass (Cynodon dactylon, cv. ‘Savannah’), and a full course of such a development was captured by a periodical microphotography. Scanning electron microscopy further confirmed the observation.     

Genetic control of somatic embryogenesis in cotton petiole callus cultures

Summary Three commercial varieties (Acala SJ-5, Coker 312 and Paymaster 303) and three exotic accessions (T1, T25 and T169) of cotton (Gossypium hirsutum L.) were tested for ability to undergo somatic embryogenesis. Sections of split petiole were cultured on 3 media and evaluated for embryogenesis after 180 days. Embryogenic T25 and Coker 312 plants were selected and crossed in a diallel with non-embryogenic Acala SJ-5, Paymaster 303, T1 and T169 plants. F₁, F₂ and BC₁ populations were generated and tested for embryogenesis on a medium of MS salts and vitamins (1962) plus (per liter) 4.0 mg NAA, 1.0 mg Kn, 30 g glucose, 100 mg myo-inositol, 2.0 g Gelrite and 0.75 g MgCl₂. Segregation for both occurrence and magnitude of embryogenesis was observed, suggesting the action of more than one gene.     

High frequency somatic embryogenesis with a pampeana-derived genotype of alfalfa (Medicago sativa L.)

Summary Somatic embryos of genotype R11 of the alfalfa variety Pampeana were produced from embryogenic calli derived from leaf sections. They were induced by an auxin shock and its development was attempted on six different media. The best condition for somatic embryo production was inducing callus on MS medium plus 10 M 2,4-D and 4,6 M KIN and transferring them, after the auxin shock, to MS with 10–20 mM NH₄ ⁺ and 30 mM proline. More than 500 somatic embryos per plate were produced. Embryos were grown to plants on MS or half strength MS media and all regenerated plants resembled the original R11 genotype. This technique could be useful in alfalfa Pampeana improvement using genetic modification.