我国葫芦科植物离体培养研究进展

葫芦科植物包括多种瓜类蔬菜,对其进行离体培养研究具有重要的理论和实践意义。综述了国内在葫芦科植物器官培养、体细胞胚胎发生、花药培养、原生质体培养和体细胞杂交及离体遗传转化等方面取得的研究进展,并对葫芦科植物离体培养、遗传转化与育种的前景作了展望。     

植物离体培养中的顽拗现象及其生理和遗传基础

介绍了植物离体培养中顽拗现象的若干表现形式 ,包括影响顽拗性的主要因子、多年生木本和草本植物的遗传预决定性生长特性、顽拗现象与自由基、离体肿瘤转化性进程中植物器官发生全能性的丧失等 ,并对有关的生理和遗传基础的研究进展进行了概述     

辣椒离体再生及遗传转化研究进展

离体再生技术与遗传转化技术促进了传统农作物育种技术的发展并定向改良了辣椒性状.但由于辣椒较其它茄科植物再生困难,导致在利用DNA重组技术改良辣椒对生物和非生物胁迫抗性时增加了难度.近年来,辣椒器官再生、花药培养、胚培养和细胞培养等离体培养技术取得了巨大的成果.就辣椒离体培养及相关生物技术进行了综述,并指出了存在的问题并对其应用前景进行展望.     

Advances in Pollen Mediated Genetic Transformation

植物遗传转化技术是植物科学基础理论与应用研究的有力武器,已成为植物遗传改良的重要途径之一。但是、目前遗传转化所采用的受体系统,大都需要体外培养和植株再生过程,才能获得转基因植株。其中、基因型限制和遗传变异是该技术不可逾越的两大障碍。花粉管通道法可省去转化体的离体培养,不过、多数植物受花器结构的限制而难以经花柱注射ＤＮＡ,只能向子房注射,并不是真正的“花粉管通道”。又由于此法外源基因的导入发生在授粉之后,因此该方法亦不属于花粉遗传转化。利用小孢子胚胎发生体系进行遗传转化与利用花粉作为外源ＤＮＡ的媒介,继而、通过授粉受精获得转基因种子,是目前花粉遗传转化的两个重要方面和活跃的研究方向。前者仍需要离体再生系统,后者则可以利用植物自身的再生机制,本文称之为花粉介导法（ｐｏｌｅｎ－ｍｅｄｉａｔｅｄｔｒａｎｓｆｏｒｍａｔｉｏｎ）。该方法通过自然的胚胎发育过程获得转基因子代,避免了组织培养过程中的遗传变异和转基因植株的嵌合现象。可望成为简便快速的植物遗传转化体系。目前对花粉介导的遗传转化进行专门评述的文献较少,本文对该领域的研究分三个层次进行了综述。一、外源基因转化方法小孢子或由小孢子形成的胚状体是很有潜力的遗传转化受体     

花粉作为外源基因媒介的植物遗传转化

以花粉作为外源DNA的媒介,获得转基因植株是有潜力的遗传转化体系。它可避免离体培养过程中的遗传变异和转基因植株的嵌合现象。本文介绍以花粉为外源基因的载体,利用植物有性生殖过程和小孢子胚胎发生两条途径进行植物遗传转化的研究进展。     

植物离体培养过程中DNA甲基化变异研究进展

表现遗传变异对于植物的生长发育起着重要作用,主要包括DNA甲基化、组蛋白修饰、染色体重塑和RNA干涉等.DNA甲基化是一种最重要的表现遗传机制,在植物离体培养过程中广泛存在,本文对植物离体培养过程的DNA甲基化变异现象、影响因素及机理等情况进行综述.     

禾谷类的细胞培养与N_6培养基

植物生物技术是对植物进行分子和细胞水平上的遗传操作,改良植物遗传特性,培育农作物和经济植物的新品种。但是高等植物是多细胞的有机体,无法对一棵植物的所有细胞同时进行遗传操作,只能先将外源基因导入离体培养的植物细胞,然后转化了的细胞经过分裂、分化和器官发...     

花粉作为外源基因媒介的植物遗传转化

以花粉作为２外源ＤＮＡ的媒介,获得转基因植株是有潜力的遗传转化体系,它可避免离体培养过程中的遗传变异和转基因植株的嵌合现象。本文介绍以花粉为外源基因的载体,利用植物有性生殖过程和小孢子胚胎发生两条途径进行植物遗传转化的研究进展。     

小麦遗传转化研究进展

小麦作为最重要的3大禾谷作物之一,其离体培养具有很强的惰性,再生频率与水稻、玉米相比要低一些,目前大多通过对基因型和外植体的选择来达到植株的高频再生分化,因此其遗传转化就远远滞后于水稻和玉米,更不用说与其它双子叶植物相比了.重点综述了小麦转基因技术和外源基因在小麦中的遗传转化研究现状,其内容包括几种主要的小麦转基因方法和以基因枪法为主的各种转化技术对品质基因、抗除草剂基因和抗病等基因在小麦中的遗传转化研究进展,并对存在的一些问题进行了简要的论述.     

红颜草莓叶盘再生及遗传转化体系的优化

草莓离体组织再生和遗传转化体系的研究对草莓分子育种至关重要。为了优化农杆菌介导草莓品种红颜(Fragaria×ananassa Duch.Benihoppe)的遗传转化体系,本研究以红颜草莓组培苗的离体叶盘作为试验材料,首先确定了其离体再生的最佳条件,对影响转化效率的因素进行优化,获得了稳定高效的再生及转化体系。结果表明,红颜草莓离体叶盘最佳暗培养时间为9 d,最佳愈伤诱导培养基为MS+TDZ(2. 0 mg/L)+IBA(0. 1 mg/L)+2,4-D(0. 1 mg/L),最佳愈伤分化培养基为MS+6-BA(0. 5 mg/L)+NAA(0. 1 mg/L),转化体系的最佳组合为预培养2 d、添加300μmol/L的AS、以OD600nm=0. 6的EHA105型的农杆菌浸染5 min、共培养5 d。经优化后的红颜草莓叶盘再生及遗传转化体系对该品种的进一步优化和选育有重要意义。     

Epidermal transpiration, ultrastructural characteristics and net photosynthesis of white spruce somatic seedlings in response to in vitro acclimatization

Mortality of transplanted somatic seedlings at the stage of acclimatization is often high and likely due to rapid change in environmental conditions. To investigate the potential of in vitro acclimatization of somatic seedlings before soil transfer, somatic seedlings of white spruce ( Picea glauca [Moench] Voss) were germinated on a liquid medium supplemented with sucrose. After 6 weeks in germination, sucrose was omitted from the medium for a supplementary 6 weeks at which time somatic seedlings were acclimatized in vitro in their germination tubes before transfer to soil. In vitro acclimatization of somatic seedlings was realized by transferring the test tubes containing the germinated somatic seedlings to the greenhouse for 9 days. During this period, the culture tube lids of acclimatized somatic seedlings were lifted progressively increasing air exchange between the tube and the greenhouse whereas, for non-acclimatized somatic seedlings the culture tubes were maintained closed during in vitro acclimatization. In vitro acclimatized somatic seedlings had higher asymptotic net photosynthesis ( P _n) at light saturation than non-acclimatized seedlings (6 versus 4.5 µmol m⁻² s⁻¹). At the end of the in vitro acclimatization period, a lower rate of epidermal transpiration was also observed for acclimatized somatic seedlings (3.85 versus 4.75% h⁻¹). Microscopic observations showed that starch granules were more abundant in needles of acclimatized somatic seedlings than in non-acclimatized somatic seedlings, probably as a result of their greater photosynthetic capacity. Needles from acclimatized somatic seedlings also showed more epicuticular wax projections than needles from non-acclimatized somatic seedlings. These structural changes may help somatic seedlings to restrict epidermal water loss and stomatal aperture.     

Mitochondrial DMA variation in somatic embryogenic cultures ofLarix

outhern hybridization analysis using wheat mitochondrial gene-specific probes indicates that changes in mitochondrial genomic organization and the relative representation of certain genomic regions occur during in vitro somatic embryogenic cell culture ofLarix species. We observed differences in the mitochondrial (mt)DNA hybridization patterns between somatic embryogenic cell cultures and trees grown from seed forLarix leptolepis,L. decidua, and the reciprocal hybrids of these twoLarix species. This is the first study to describe the correlation of molecular changes in a gymnosperm mitochondrial genome with in vitro somatic embryogenic cell culture. Quantitative differences in mtDNA hybridization signals were also observed among a 4-year-old somatic embryogenic cell culture ofLarix ×eurolepis trees regenerated from this culture, and the seed source tree from which the somatic embryogenic cell cultures were initiated.     

The role of abscisic acid in plant tissue culture: a review of recent progress

Abscisic acid (ABA) plays a significant role in the regulation of many physiological processes of plants. It is often used in tissue culture systems to promote somatic embryogenesis and enhance somatic embryo quality by increasing desiccation tolerance and preventing precocious germination. ABA is also employed to induce somatic embryos to enter a quiescent state in plant tissue culture systems and during synthetic seed research. Application of exogenous ABA improves in vitro conservation and the adaptive response of plant cell and tissues to various environmental stresses. ABA can act as anti-transpirant during the acclimatization of tissue culture-raised plantlets and reduces relative water loss of leaves during the ex vitro transfer of plantlets even when non-functional stomata are present. This review focuses on the possible roles of ABA in plant tissue culture and recent developments in this area.     

Production of cloned pigs from in vitro systems

Here we describe a procedure for cloning pigs by the use of in vitro culture systems. Four healthy male piglets from two litters were born following nuclear transfer of cultured somatic cells and subsequent embryo transfer. The initiation of five additional pregnancies demonstrates the reproducibility of this procedure. Its important features include extended in vitro culture of fetal cells preceding nuclear transfer, as well as in vitro maturation and activation of oocytes and in vitro embryo culture. The cell culture and nuclear transfer techniques described here should allow the use of genetic modification procedures to produce tissues and organs from cloned pigs with reduced immunogenicity for use in xenotransplantation.     

石竹科植物组织培养与细胞工程

近年来,植物组织培养与细胞工程研究在石竹科植物上取得了一定进展。现从组织培养、原生质体培养和体细胞杂交、单倍体育种、试管开花、转基因等5个方面对其进行综述,并展望了石竹科植物在组织培养和细胞工程研究方面的发展前景。     

Biotechnological advances in mango (Mangifera indica L.) and their future implication in crop improvement: a review

Biotechnology can complement conventional breeding and expedite the mango improvement programmes. Studies involving in vitro culture and selection, micropropagation, embryo rescue, genetic transformation, marker-assisted characterization and DNA fingerprinting, etc. are underway at different centers worldwide. In vitro culture and somatic embryogenesis of several different genotypes have been achieved. The nucellus excised from immature fruitlets is the appropriate explant for induction of embryogenic cultures. High frequency somatic embryogenesis has been achieved in some genotypes; however, some abnormalities can occur during somatic embryo germination. Embryo rescue from young and dropped fruitlets can improve the hybridization success in a limited flowering season. Protocols for protoplast culture and regeneration have also been developed. In vitro selections for antibiotic tolerance and fungal toxin resistance have been very promising for germplasm screening. Genetic transformation using Agrobacterium tumefaciens has been reported. Genes that are involved with fruit ripening have been cloned and there have been attempts to deliver these genes into plants. DNA fingerprinting and studies on genetic diversity of mango cultivars and Mangifera species are also being conducted at several research stations. The purpose of this review is to focus upon contemporary information on biotechnological advances made in mango. It also describes some ways of overcoming the problems encountered during in vitro propagation of mango.     

Results of a diallel trial and a breeding experiment for in vitro aptitude in maize

Summary Some characteristics of in vitro culture of somatic tissues of maize were analysed by a diallel trial. Eight genetically different pure strains, chosen for their aptitudes, were used. The results show that there is considerable genetical variation for the characteristics of in vitro culture and that it should be possible to breed for aptitude to in vitro culture. The linear regression of hybrids on mid-parent reveals a significant heritability for such aptitude. Through selection we have improved plant regeneration after a long period of callus growth.     

Hormonal induction of all stages of spermatogenesis in germ-somatic cell coculture from immature Japanese eel testis

In cultivated male eel, spermatogonia are the only germ cells present in testis. Our previous studies using an organ culture system have shown that gonadotropin and 11-ketotestosterone (11-KT, a potent androgen in teleost fishes) can induce all stages of spermatogenesis in vitro. for detailed investigation of the control mechanisms of spermatogenesis, especially of the interaction between germ cells and testicular somatic cells during 11-KT-induced spermatogenesis in vitro, we have established a new culture system in which germ cells and somatic cells are cocultured after they are aggregated into pellets by centrifugation. Germ cells (spermatogonia) and somatic cells (mainly Sertoli cells) were isolated from immature eel testis. Coculture of the isolated germ cells and somatic cells without forming aggregation did not induce spermatogenesis, even in the presence of 11-KT. In contrast, when isolated germ cells and somatic cells were formed into pellets by centrifugation and were then cultured with 11-KT for 30 days, the entire process of spermatogenesis from premitotic spermatogonia to spermatozoa was induced. However, in the absence of 11-KT in the culture medium spermatogenesis was not induced, even when germ cell and somatic cells were aggregated. These results demonstrate that physical contact of germ cells to Sertoli cells is required for inducing spermatogenesis in response to 11-KT.     

Somatic embryogenesis in peach palm using the thin cell layer technique: induction, morpho-histological aspects and AFLP analysis of somaclonal variation

BACKGROUND AND AIMS: The thin cell layer (TCL) technique is based on the use of very small explants and has allowed enhanced in vitro morphogenesis in several plant species. The present study evaluated the TCL technique as a procedure for somatic embryo production and plantlet regeneration of peach palm. METHODS: TCL explants from different positions in the shoot apex and leaf sheath of peach palm were cultivated in MS culture medium supplemented with 0-600 microM Picloram in the presence of activated charcoal. The production of primary calli and embryogenic calli was evaluated in these different conditions. Histological and amplified fragment length polymorphism (AFLP) analyses were conducted to study in vitro morphogenetic responses and genetic stability, respectively, of the regenerated plantlets. KEY RESULTS: Abundant primary callus induction was observed from TCLs of the shoot meristem in culture media supplemented with 150-600 microM Picloram (83-97%, respectively). The production of embryogenic calli depends on Picloram concentration and explant position. The best response observed was 43% embryogenic callus production from shoot meristem TCL on 300 microM Picloram. In maturation conditions, 34+/-4 somatic embryos per embryogenic callus were obtained, and 45.0+/-3.4% of these fully developed somatic embryos were converted, resulting in plantlets ready for acclimatization, of which 80% survived. Histological studies revealed that the first cellular division events occurred in cells adjacent to vascular tissue, resulting in primary calli, whose growth was ensured by a meristematic zone. A multicellular origin of the resulting somatic embryos arising from the meristematic zone is suggested. During maturation, histological analyses revealed bipolarization of the somatic embryos, as well as the development of new somatic embryos. AFLP analyses revealed that 92% of the regenerated plantlets were true to type. The use of TCL explants considerably improves the number of calli and somatic embryos produced in comparison with previously described protocols for in vitro regeneration of peach palm. CONCLUSIONS: The present study suggests that the TCL somatic embryogenesis protocol developed is feasible, although it still requires further optimization for in vitro multiplication of peach palm, especially the use of similar explants obtained from adult palm trees.