甘蓝型油菜小孢子培养技术及其单倍体应用研究进展

油菜小孢子培养已经成为油菜育种和生物技术的一项重要内容.由于影响小孢子成胚和成苗的因素较多,低诱导频率及成苗率严重限制了该技术在育种中的应用.为了全面了解小孢子胚状体发生能力及影响再生体系的各项因素,掌握该技术的研究动态和发展方向,总结了近20年来国内外影响小孢子培养的主要因素:供体植株基因型、供体植株生长条件及生理状态、小孢子发育时期、培养基组成、培养条件,及其在双单倍体育种、诱变育种、转基因育种等领域中的应用.     

花椰菜游离小孢子培养及植株再生研究

以186个花椰菜杂交品种及组合为试材,进行了游离小孢子培养研究。结果表明:基因型是胚状体发生的决定因素;24 h 32℃的高温前处理是胚状体发生的必须条件;单核靠边期到双核期的小孢子是进行胚状体诱导的最佳时期,胚状体发生频率最高;培养基中添加6-BA 0.1 mg/L,NAA 0.005 mg/L可以促进胚状体发育。将20 d的胚状体进行脱分化处理,可以大幅度提高胚状体的成活率,植株再生率为53%,再生植株中双单倍体占83.5%。     

番茄花药离体培养中低温预处理对小孢子发育的影响

为明确低温预处理对番茄花药离体培养过程中小孢子发育的影响，进行了番茄花药离体培养的低温预处理试验，试验结果表明：离体培养条件下，雄核发育存在三条途径，即B途径、A-V途径和A-G途径，以B途径为主；随着培养时间的增加，小孢子逐渐退化；对番茄花药离体培养进行低温预处理，可在一定程度上延缓番茄小孢子退化，提早雄核发育，并增加参与雄核发育小孢子的比率，但参与B-途径的小孢子比参与A-途径的增加得多。     

辣椒花药培养研究进展

归纳了辣椒花药培养过程中影响雄性胚胎发生的诸多因素,包括供试材料、小孢子发育时期、基本培养基、植物生长调节剂、培养基添加物质和温度胁迫处理,总结了小孢子胚胎发生的细胞学观察、再生株的倍性水平和单倍体基因组加倍研究,指出尽管人类已从细胞和分子方面对辣椒花药培养中诱导小孢子胚胎发生和形成胚状体有了进一步的认识,但尚未完全了解小孢子是如何被激发进入孢子体发育途径。当小孢子胚胎发生之谜完全揭开后,辣椒花药培养技术将会应用于更加广泛的领域。     

利用大孢子技术培育黄瓜单倍体的前期研究

黄瓜单倍体离体诱导主要有三种方法:离体雄核发育,即花粉(小孢子)培养;离体雌核发育,即未授粉子房(胚珠)培养;原位雌核发育,即用化学试剂或辐射处理过的花粉授粉。本文主要介绍了利用未授粉子房(胚珠)培养,即所谓的大孢子培养技术诱导黄瓜单倍体的前期研究。确定了预培养的必要性和培养基,以及预培养的条件;确定了诱导胚状体产生的高效诱导培养基;并总结了试验中遇到的各种问题及解决方法。     

诸葛菜小孢子培养及其单倍体减数分裂染色体配对观察

诸葛菜是一种极有价值的观赏、蔬菜、饲料和油料作物种质资源。为建立诸葛菜小孢子胚状体诱导再生植株技术,并为诸葛菜染色体组的起源与进化研究提供相关数据资料,本研究通过对诸葛菜游离小孢子的培养,研究了热激培养时间和活性炭浓度对胚状体产量的影响,并采用常规压片法对诸葛菜单倍体减数分裂染色体配对行为进行了观察。结果表明,添加活性炭和热激培养对胚状体诱导是必需的。在直径6 cm培养皿中培养4 mL密度为1花蕾花粉mL^-1的小孢子NLN悬液时,每皿添加1 mg活性炭和32℃热激3 d的培养条件下子叶形胚状体和总胚状体产量最高,分别为每花蕾0.92±0.18个和1.32±0.25个。子叶形胚状体在1/2 MS培养基上萌发率为27.73%。花粉植株中自然加倍率为25%,加倍植株染色体数为24,单倍体植株染色体数为12。诸葛菜单倍体减数分裂染色体的平均配对构型为n=12=6.352Ⅰ+2.008Ⅱ+0.384Ⅲ+0.12Ⅳ,具有二价体及三价体和四价体的细胞比例高达96%,少量细胞的12条染色体联会形成3个四价体,说明诸葛菜很可能是起源于染色体基数x=3的同源八倍体。本试验结果对于诸葛菜新材料新品种选育和基础研究具有重要参考价值。     

环境条件对白菜小孢子培养的影响

以“ＨｏＭｅｉ”和“东京笋”两个白菜品种为材料，探讨了植株栽培的环境条件对白菜小孢子培养的胚状体发生和植株再生的影响。结果表明，对胚状体发生能力较强的ＨｏＭｅｉ品种，环境条件对小孢子培养有一定的影响，生长在长日照（１４－１８ｈ）和１５－２０℃温度条件下的植株，胚状体发生数及植株再生率显著高于短日照（１２Ｈ）、产高温度下（２５℃）生长的植株。对胚状体发生能力较弱的东京笋品种，环境条件对小孢子培养影响     

青麻叶大白菜小孢子培养及新品种选育

对影响青麻叶大白菜游离小孢子培养的因素进行了研究。结果表明：供体植株的基因型与小孢子胚胎发生密切相关;33℃,24h高温处理有助于小孢子转化成胚状体,每蕾成胚数比25℃恒温培养提高4．5倍;在培养基中加入外源激素和多种氨基酸可以提高胚状体的诱导效率,平均比对照增加59．64％;培养基的琼脂含量增加到12g／L能显著提高小孢子胚的成苗率,比含琼脂8g／L的高出40．5个百分点。通过对青麻叶大白菜小孢子胚的培养,获得二倍性的双单倍体植株,从中选出性状优良的纯系进行杂交组合的选配,培育出青麻叶大白菜的新品系。     

菜心小孢子胚再生体系优化及植株倍性鉴定

为进一步优化菜心游离小孢子胚再生技术体系,本研究以3份不同基因型的菜心小孢子胚状体为试验材料,研究不同培养基类型、培养基中不同琼脂浓度和不同胚龄对胚再生的影响,并对再生植株进行倍性鉴定。结果表明,使用B5培养基时各基因型的成苗率均高于MS培养基,褐化率低于MS培养基,B5培养基是菜心小孢子胚状体再生的适宜培养基;培养基中添加适宜浓度的琼脂可提高再生植株的成苗率,随着琼脂浓度的增加,出苗率呈先升后降的趋势,琼脂浓度为1.0%时,各基因型的出苗率达到最高;胚状体再生的最佳胚龄是25～29 d,胚龄时间过长或过短均不利于胚状体出苗,其中40 d以上胚龄的胚状体几乎不出苗;倍性鉴定发现菜心小孢子再生植株中同时存在单倍体、二倍体和多倍体,3个基因型的二倍体自然加倍率在62.22%～71.11%之间;75 mg/L秋水仙素处理可提高菜心再生株系的二倍体率。本研究为菜心游离小孢子胚再生体系优化及再生植株倍性鉴定提供了技术基础。     

小白菜小孢子胚状体诱导影响因素研究

以10个小白菜杂交种为试材,采用游离小孢子培养方法,研究影响小孢子胚状体形成因素的结果表明,不同品种胚状体的诱导率不同;NLN培养基中大量元素减半有利于小孢子胚诱导,其诱导率达到100%;培养基中添加0.05 mg/L的6-BA和0.2 mg/L的NAA可以提高胚状体诱导率;活性炭和琼脂糖对诱导胚状体发生和发育有促进作用,可使子叶胚的比例达90%以上;花蕾经4℃低温预处理24 h后的成胚率显著提高.     

Optimization of culture conditions for improved plant regeneration efficiency from wheat microspore culture

The production of haploid plants through microspore culture is a very important tool for plant breeding. However, progress in microspore culture for many species has been hampered by a number of factors that have resulted in low recovery of regenerated green plants. In this study, a series of experiments were conducted to increase the regeneration of haploid green plants from isolated wheat microspores. The use of different basal media and variations in media components resulted in the increased recovery (approximately double) of regenerated haploid wheat plants. Our findings demonstrate that CHB medium, in combination with 2,4-d, was a better medium for embryoids induction and plant regeneration than medium MC17 with either 2,4-d or PAA growth hormones. Wheat microspores cultured without ovary co-cultivation did not respond. Furthermore, high efficiency of microspore derived embryoids (up to 296 MDEs per 100 anthers) and green plant regeneration (up to 71 green plants per 100 anthers) were achieved by the use of gelrite instead of agarose as a gelling agent, and by the addition of media additives such as spent medium or MET.     

Functional genomics of microspore embryogenesis

Isolated plant microspores, when stressed and cultured in vitro, can be diverted from their normal gametophytic pathway towards sporophytic development, with the formation of haploid embryos and ultimately doubled-haploid plants. This process is called androgenesis or microspore embryogenesis, and is widely used in plant breeding programmes to generate homozygous lines for breeding purposes. Protocols for the induction of microspore embryogenesis and the subsequent regeneration of doubled haploid (DH) plants have been successfully developed for more than 200 species. These practical advances stand in stark contrast to our knowledge of the underlying molecular genetic mechanism controlling this process. The majority of information regarding the genetic and molecular control of the developmental switch from gametophytic to sporophytic development has been garnered from four intensely studied (crop) plants comprising two dicotyledonous species, rapeseed (Brassica napus) and tobacco (Nicotiana tabacum), and two monocotyledonous species, wheat (Triticum aestivum) and barley (Hordeum vulgare). In these species the efficiency of microspore embryogenesis is very high and reproducible, making them suitable models for molecular studies. In the past, molecular studies on microspore embryogenesis have focussed mainly on the identification of genes that are differentially expressed during this developmental transition and/or early in embryo development, and have identified a number of genes whose expression marks or predicts the developmental fate of stressed microspores. More recently, functional genomics approaches have been used to obtain a broad overview of the molecular processes that take place during the establishment of microspore embryogenesis. In this review we summarise accumulated molecular data obtained in rapeseed, tobacco, wheat and barley on embryogenic induction of microspores and define common aspects involved in the androgenic switch.     

Efficient Production of Doubled Haploid Plants through Chromosome Doubling of Isolated Microspores in Brassica napus

Three methods of chromosome doubling to produce doubled haploid plants from microspore cultures of Brassica napus were compared: colchicine treatment of microspore-derived plants, microspore-derived embryos, and isolated microspores. In the whole plant treatment, 53% of the treated plants set seed, but the treatment delayed plant growth and reduced seed set. When microspore-derived embryos were treated with colchicine, the doubling frequency was 32% (compared to 15% for spontaneous doubling). Direct colchicine treatment of isolated microspores resulted in a doubling efficiency of 70 % of the whole plants. This treatment also stimulated embryogenesis in microspore culture, leading to increased plant regeneration. Thus, direct chromosome doubling of isolated microspores is efficient and more than 10 000 doubled haploid plants have been produced in this manner in the past three years in order to accelerate the plant-breeding process.     

Efficient production of callus-derived doubled haploids through isolated microspore culture in eggplant (<Emphasis Type="Italic">Solanum melongena</Emphasis> L.)

Production of doubled haploids (DHs) through androgenesis induction is an important biotechnological tool for plant breeding. In some species, DHs are efficiently obtained through embryogenesis from isolated microspore cultures. In eggplant, however, this process is still at its infancy, despite the economic relevance of this important agricultural crop. To date, only two studies have focused previously on this process, suggesting that in eggplant microspore cultures, the only morphogenic response is callus formation. Given the notable lack of studies on eggplant microspore cultures, in this work we explored this process with different experimental approaches. We studied the response of different cultivars and characterized the development of microspores induced to divide and proliferate. We demonstrated that microspore-derived embryos (MDEs) can be produced in eggplant; however, MDEs stopped at the globular stage, to turn into euploid and principally mixoploid calli. From these calli, 60 % of DH plants could be regenerated. In order to promote microspore induction we evaluated the effect of polyethylene glycol (PEG) and mannitol. PEG, but not mannitol, significantly increased induction of microspore embryogenesis. We also tested the ability of eight different media compositions to promote efficient plant regeneration from calli. In order to test it in a genotype-independent manner, we previously developed a method to generate clonal callus populations derived from single microspore-derived calli. Together, the results presented hereby constitute an efficient way to produce eggplant DHs through microspore culture. In addition, they contribute significant insights into the knowledge of the particularities of androgenesis induction in this species.     

In vitro chromosome doubling with colchicine during microspore culture in wheat (Triticum aestivum L.)

Isolated microspores of two DH lines of wheat were treated with 8 different colchicine concentrations up to 3 mM for either 24 h or 48 h during microspore culture. Untreated control cultures produced on average 220 embryos per spike (100,000 microspores), 68% of the regenerated plantlets were green, and 15% of the flowering plants were fertile. The colchicine treatments had a significant effect on chromosome doubling as measured by the percentage of fertile regenerants. Using colchicine concentrations around 1 mM the percentage of fertile plants among the regenerants was increased up to 53%. The highest number of embryos and regeneration rates were observed after 24 h colchicine treatment, while the highest frequencies of green plants and fertile plants were obtained with 48 h colchicine treatments. The highest number of DH plants per spike was found after treatment with colchicine concentrations of 300 to 1000 μM. Such treatments resulted in an estimated average between the two genotypes of 23 doubled haploid plants per spike. This revised version was published online in July 2006 with corrections to the Cover Date.     

玉米小孢子高频再生培养技术程序研究

以大田种植的玉米供体植株为实验材料,以提高游离小孢子存活率及成胚率为重点进行了技术优化研究。摸索出了一些行之有效的技术措施,提高了游离小孢子的离体培养反应,获得了一批再生植株。通过技术优化,建立玉米小孢子离体培养高频再生技术程序,在此基础上构建了玉米DH育种技术平台。应用这一技术平台,可以在当年获得玉米DH纯系的种子,第二年即可安排大田纯系鉴定。     

Microspore culture of white cabbage, Brassica oleracea var. capitata L.: Genetic improvement of non-responsive cultivars and effect of genome doubling agents

For the efficient application of haploid induction procedures in cabbage breeding, a sufficient number of regenerants should be achieved in a broad spectrum of genotypes. However, the majority of genotypes are somewhat recalcitrant. The efficiency of microspore culture was tested by crossing a responsive (28.7 embryos per Petri dish) and a non- responsive (0.1 embryo) cabbage cultivar. The embryo yield of one progeny was intermediate (18.9) while two were superior to the best parent cultivar (52.9 and 64.0 embryos). Thus, genes for haploid embryogenesis, present in responsive lines, can be effectively transmitted to responsive × non-responsive hybrids. Abscisic acid-induced desiccation of embryos was used for the efficient regeneration of plants. High germination percentages (54.7-70.6%) followed by normal plantlet development were achieved. Spontaneous genome doubling measured at the plantlet stage differed markedly in untreated genotypes. The percentage of diploids ranged from 21 to 67%. The effects of two antimitotic drugs applied to freshly isolated microspores were determined in two experiments. In the first experiment, trifluralin (0.5 and 1.0 mg:l) had no effect on embryo induction while oryzalin partly (0.125-0.25mg/l) or completely (0.5.mg/l) inhibited the formation of embryos. In the second experiment, higher concentrations of trifluralin increased the proportion of diploidized plants. Application of anti-mitotic drugs to microspores did generally not improve the overall production of haploid plants, which was higher in an untreated control.     

玉米小孢子培养高频再生技术程序的研究

以大田种植的玉米供体植株为实验材料，以提高游离小孢子存活率及成胚率为重点进行了技术优化研究。摸索出了一些行之有效的技术措施，提高了游离小孢子的离体培养反应，获得了一批再生植株。通过技术优化，建立玉米小孢子离体培养高频再生技术程序，在此基础上构建了玉米DH育种技术平台。应用这一技术平台，可以在当年获得玉米DH纯系的种子，第二年即可安排大田纯系鉴定。     

油菜小孢子培养技术体系研究

小孢子培养在油菜的基础研究和应用研究中均具有十分重要的意义。自1982年Lichter首次在甘蓝型油菜中进行小孢子培养获得成功以来,国内外在油菜小孢子培养技术方面已取得大量研究成果,包括油菜小孢子胚状体发生的影响因素,小孢子植株的再生、成苗、大田移栽、染色体加倍等,近年来又对一些关键技术环节加以了改进,笔者在对这些研究成果进行总结的基础上针对中国国情建立了大田条件下油菜高效小孢子培养技术体系。用该体系对甘蓝型油菜和新疆野生油菜的体细胞杂种后代进行小孢子培养的出胚率达到300枚/皿以上,采用小孢子苗直接移栽大田技术,成活率达到89.0%。此外还成功构建了含127个DH系的黄籽油菜DH群体及含115个DH系的粒重分离群体。