Wheat embryogenesis and haploid production in wheat × maize hybrids

Summary Embryogenesis was analyzed in wheat × maize hybrids using paraffin sectioning. Embryogenesis in wheat × maize hybrids is different from that in self-pollinated wheat plants. Development of the embryo is not accompanied by the formation of an endosperm. The endosperm nuclei remain free in the cytoplasm, fail to advance into the cellular stage, and degenerate at a later time. The antipodal cells quickly degenerate in the fertilized ovaries of wheat × maize hybrids similar to self-pollinated ovaries. The antipodal cells remain normal in unpollinated ovaries. The pre-embryo will abort if it is allowed to develop on the plant, because of a nutritional shortage in the absence of an endosperm. Therefore, embryo rescue is necessary for haploid production from a wheat × maize hybrids. Haploid polyembryos were obtained from spikelet culture of wheat × maize hybrids. The formation of polyembryos is due to the cleavage of the pre-embryo and the effect of 2,4-D. The frequency of haploid embryo production and plant regeneration is affected significantly by maize genotypes, but not by wheat genotypes. The concentration of 2,4-D affects only the size of the embryo.     

Somatic hybridization as a tool for tomato breeding

Protoplast fusion can be used to produce somatic hybrids of species that cannot be obtained by sexual hybridization. The possibility to introgress genes from Solanum species into the cultivated tomato species Lycopersicon esculentum, and to obtain novel cytoplasm-nucleus combinations (cybrids) was considered as an important strategy to extend the genetic variation available for tomato breeding. Somatic hybrids between L. esculentum and other Lycopersicon species, as well as between L. esculentum and Solanum or Nicotiana species, have been produced. Specific mutants, genotypes with antibiotic resistances, and metabolic inhibition by iodoacetate or iodoacetamide and irradiation were used for the selection of hybrids. In addition, the improvement of protoplast culture techniques and the use of the favourable tissue culture traits derived from species such as L. peruvianum, which have been introduced into tomato by classical breeding, allowed the efficient recovery of somatic hybrids. However, the occurrence of somatic incongruity in fusion combinations of L. esculentum and Solanum and even more in L. esculentum and Nicotiana, did not allow the production of true cybrids and/or fertile hybrids, indicating the importance of both cytoplasm-nucleus and nucleus-nucleus interactions in somatic incongruity. Another problem with fusions between distantly related species is the strongly reduced fertility of the hybrids and the very limited homoeologous recombination between chromosomes of the parental species. Partial genome transfer from donor to recipient through microprotoplast (+) protoplast fusion, and the production of monosomic or disomic chromosome addition lines, light overcome some of these problems. In symmetric somatic hybrids between L. esculentum and S. tuberosum the occurrence of limited somatic and meiotic recombination was demonstrated. Fertile progeny plants could be obtained, though at a low frequency, when embryo rescue was performed on a large scale after backcrossing hexaploid somatic tomato (+) potato hybrids with a tetraploid potato genotype. The potential value of genomic in situ hybridization (GISH) and RFLPs for the analysis of the genome/chromosome composition of the hybrids has been demonstrated for intergeneric somatic hybrids between Lycopersicon and Solanum.Abbreviations cpDNA chloroplast DNA - mtDNA mitochondrial DNA     

小孢子培养获得松花型花椰菜DH再生植株

对5个松花型花椰菜(Brassica oleraceavar.botrytisL.)杂种一代的小孢子培养研究表明,小孢子胎胚发生主要依赖于基因型,庆农65天的每花蕾胚状体产量最高,平均达15.5个。松花菜的胚状体萌发率一般在30%左右,并有效地获得了大量的DH再生植株。冷激预处理能显著地影响花椰菜小孢子的胚胎发生,但供体材料间存在不同的结果。结球期和开花结角期再生植株的生育期与育性出现较大分离,可育且能正常结角的比例约占全部小孢子再生植株的50%以上,因而不再需要加倍处理。     

INDUCTION OF SOMATIC EMBRYOS AND REGENERATION OF PLANTLETS FROM RICE ROOTS

<正> The number of somatic embryos and regenerated plantlets were directly induced from irra-diated rice roots of the variety Taipei 309(Oryza sativa L.).For the induction of somatic em-bryos,the suitable age of roots was no more than 7 days after seed culture on the medium and thesections near tip were more vigorous than those near base of a root;the number of somatic em-bryos induced by the media with 1.11mg/L2,4-D plus 0.47mg/L NAA and 2.21mg/L 2,4-Dplus 1.86mg/L NAA was much higher than that induced by 1.11mg/L 2,4-D alone;10～20 Gyand 40 Gy of γ irradiation were the most favourable for increasing somatic embryo number onthe media of 2.21mg/L 2,4-D plus 1.86mg/L NAA and 1.11mg/L 2,4-D plus 0.47mg/L NAAor 1.11mg/L 2,4-D alone respectively.The highest number of regenerated plantlets was fromthat cultured on the medium of 1.11mg/L 2,4-D plus 0.47mg/L NAA and irradiated with 30～40 Gy of γ rays.     

花楸树体细胞胚与合子胚的发生发育

利用花楸树人工控制授粉后的未成熟合子胚进行体细胞胚的诱导培养,通过石蜡切片、扫描电镜和透射电镜对合子胚和体细胞胚的发生发育过程进行组织、细胞观察。结果表明:1)体细胞胚发生进程与合子胚相似,均经历了球形期、心形期、鱼雷形期,最终发育成成熟胚;2)直接发生和间接发生在愈伤组织表面的体细胞胚均为单细胞起源,间接发生在愈伤组织内部的体细胞胚存在单细胞起源,同时还存在可能的多细胞起源;3)子叶和愈伤组织表面发生的体细胞胚在发育早期均具明显的胚柄,鱼雷形胚期胚柄退化;4)愈伤组织内部发生的体细胞胚没有胚柄;5)与合子不同,胚性细胞的第1次分裂为均等分裂;6)多细胞原胚周围降解的细胞具有细胞程序性死亡的形态特征。     

利用SSH技术鉴定香蕉体细胞胚发生相关基因

本研究以野生蕉胚性悬浮系为材料,将胚性细胞增殖培养基上的香焦胚性悬浮系作为对照,体胚诱导培养基上的培养材料为处理,利用抑制性消减杂交(suppression subtractive hybridization,SSH)技术,构建野生蕉胚性悬浮系激素诱导的胚胎发育差异表达cDNA文库,随机挑选阳性克隆并进行生物信息学分析...     

大豆体细胞胚胎发生及植株再生

以野生大豆（ＧｌｙｃｉｎｅｓｏｊａｓｉｅｂｅｔＺｕｃｃ）三个品系、半野生大豆（Ｇｌｙｃｉｎｅｇｒａｃｉｌｉｓｓｋｖ）１个品系、栽培大豆（ＧｌｙｃｉｎｅｍａｘＬＭｅｒｒｉｌ）４个品系为材料，进行组织培养．探讨了大豆体细胞组织再生植株的主要影响因素，并以器官分化和体细胞胚两种不同方式再生完整大豆植株。     

鸡躯体和内脏初级传入纤维在脊髓和延髓的共同投射

采用ＣＢ—ＨＲＰ跨神经节追踪技术，我们发现鸡躯体和内脏的初级传入投射在脊髓质的一些板层和延髓的一些核团内有重叠区。１腓肠肌外头与卵巢的初级传入在Ｔ６～Ｌ３及Ｓ３～Ｓ５脊髓节段的Ｉ、Ⅴ层有明显的投射重叠区；与睾丸的初级传入在Ｔ６～Ｌ２及Ｓ３～Ｓ５髓节的Ｉ、Ⅴ层有明显的投射重叠；与泄殖腔的初级传入在Ｔ７～Ｌ２及Ｓ３～Ｓ５髓节的Ｉ、Ⅴ层亦有明显的重叠投射。２跗部皮肤与泄殖腔的在Ｌ２及Ｓ３髓节的Ｉ、Ⅳ层，与卵巢的在Ｌ２～Ｌ３髓节的Ｉ、Ⅳ层，与睾丸的在Ｌ３及Ｓ３髓节的Ｉ、Ⅳ层均有轻度的投射重叠区。３挠神经与腺胃及胸腺的在延髓的楔束外核和弧束核的内侧亚核有重叠投射区，４挠神经与卵巢、睾丸的在孤束核的内侧亚核有重叠；推测鸡的躯体和内脏的初级传入在这些区域可能有汇聚。     

植物LEA蛋白与Lea基因表达

LEA蛋白与Lea基因是当前植物胚胎学以及逆境生理学研究的热点之一.本文主要介绍植物LEA蛋白的性质、类型、结构、功能以及Lea基因表达的相关研究进展,并初步分析了其广泛的应用前景.