Pairing and recombination at meiosis of Brassica rapa (AA) × Brassica napus (AACC) hybrids

Interspecific crosses contribute significantly to plant evolution enabling gene exchanges between species. The efficiency of interspecific crosses depends on the similarity between the implicated genomes as high levels of genome similarity are required to ensure appropriate chromosome pairing and genetic recombination. Brassica napus (AACC) is an allopolyploid, resulting from natural hybridization between Brassica rapa (AA) and Brassica oleracea (CC), both being diploid species derived from a common ancestor. To study the relationships between genomes of these Brassica species, we have determined simultaneously the pairing and recombination pattern of A and C chromosomes during meiosis of AAC triploid hybrids, which result from the interspecific cross between natural B. napus and B. rapa. Different AAC triploid hybrids and their progenies have been analysed using cytogenetic, BAC-FISH, and molecular techniques. In 71% of the pollen mother cells, homologous A chromosomes paired regularly, and usually one chromosome of each pair was transmitted to the progeny. C chromosomes remained mainly univalent, but were involved in homoeologous pairing in 21.5% of the cells, and 13% of the transmitted C chromosomes were either recombined or broken. The rate of transmission of C chromosomes depended on the identity of the particular chromosome and on the way the hybrid was crossed, as the male or as the female parent, to B. napus or to B. rapa. Gene transfers in triploid hybrids are favoured between A genomes of B. rapa and B. napus, but also occur between A and C genomes though at lower rates.     

Promoter sequences from two different Brassica napus tapetal oleosin-like genes direct tapetal expression of β-glucuronidase in transgenic Brassica plants

To investigate the sequences responsible for the regulated expression of tapetal-specific oleosin-like genes, ca. 2 kb of the 5-upstream regions from two divergent genes, OlnB;4 and OlnB;13, were isolated, sequenced and fused to the reporter gene -glucuronidase for study in transgenic Brassica napus plants. Although the proteins encoded by these two genes are highly divergent, except for the conserved oleosin-like domain, the first 250 bp of their 5-upstream regions was 86% identical, including a region of 150 bp upstream from the TATA box. Analysis of 42 independent transformants by histochemical and fluorometric methods showed that both promoters directed tapetal-specific expression that peaked at the 4 mm flower bud stage.     

青菜(Brassica chinensis)花药培养的初步研究

青菜是上海地区主要叶菜类蔬菜,但存在种性退化、病害严重、产量不稳的问题。为了培育抗病、高产的优良品种,我们于1976—1977年对青菜的花药培养进行了初步研究。材料和方法1976年用(二月慢×三月慢)F_1和白叶三月慢、马桥常菜作试验材料;1977年用9个 F_1和两     

油菜(Brassica napus L)收获指数的变异

本文首次采用田间试验的方法对国内油菜收获指数的变异进行了研究．结果表明不同油菜品种的收获指数存在变异,其变异规律大致是：１）中熟品种的收获指数高于早熟品种及晚熟品种;２）中长角果的品种较长角品种具有更高的收获指数;３）高产的新品种具有较高的收获指数;４）油菜粒壳比,角杆比及千粒重与收获指数呈正相关,杆重与收获指数呈负相关．     

Poly(β-hydroxybutyrate) production in oilseed leukoplasts of Brassica napus

Polyhydroxyalkanoates (PHAs) comprise a class of biodegradable polymers which offer an environmentally sustainable alternative to petroleum-based plastics. Production of PHAs in plants is attractive since current fermentation technology is prohibitively expensive. The PHA homopolymer poly(β-hydroxybutyrate) (PHB) has previously been produced in leaves of Arabidopsis thaliana (Nawrath et al., 1994, Proc Natl Acad Sci USA 91: 12760–12764). However, Brassica napus oilseed may provide a better system for PHB production because acetyl-CoA, the substrate required in the first step of PHB biosynthesis, is prevalent during fatty acid biosynthesis. Three enzymatic activities are needed to synthesize PHB: a β-ketothiolase, an acetoacetyl-CoA reductase and a PHB synthase. Genes from the bacterium Ralstonia eutropha encoding these enzymes were independently engineered behind the seed-specific Lesquerella fendleri oleate 12-hydroxylase promoter in a modular fashion. The gene cassettes were sequentially transferred into a single, multi-gene vector which was used to transform B. napus. Poly(β-hydroxybutyrate) accumulated in leukoplasts to levels as high as 7.7% fresh seed weight of mature seeds. Electron-microscopy analyses indicated that leukoplasts from these plants were distorted, yet intact, and appeared to expand in response to polymer accumulation. Received: 26 May 1999 / Accepted: 16 June 1999     

大白菜(Brassica pekinensis)与甘蓝(B.oleracea)的种间试管受精

通过大白菜胚珠与甘蓝花粉的试管授粉和受精得到了杂种种子。杂交一代的植株形态和花粉发育情况及根尖细胞染色体数均表明为种间杂种。杂种植株具有父母本的特征,某些性状介于双亲之间;花粉粒发育不正常;根尖细胞染色体数为2n=19。本研究为其他十字花科植物的远缘杂交中克服不亲和性提供了依据。     

青花菜(Brassica oleracea)品种"上海2号"花枝

诱导和增殖培养基:(1)MS 6-BA1.0 mg·L-1(单位下同) NAA0.1;(2)MS 6-BA1.0 NAA0.2;(3)MS 6-BA 1.0 NAA 0.5;(4)MS 6-BA0.5; NAA0.1     

Modification of erucic acid content in Indian mustard (Brassica juncea) by up-regulation and down-regulation of the Brassica juncea FAT TY ACID ELONGATION1 (BjFAE1) gene

In Brassicas, the Fatty Acid Elongation1 (FAE1) gene product, a 3-ketoacyl-CoA synthase, is the first in a 4-enzyme complex involved in the synthesis of erucic acid from oleic acid. The FAE1 homologue from Brassica juncea cv. Pusa Bold was cloned in a binary vector both in sense and antisense orientations under the control of the CaMV35S promoter. The recombinant binary vectors were used to transform B. juncea cv. RLM 198 via Agrobacterium tumefaciens. The presence of the transgene was confirmed by polymerase chain reaction and Southern hybridization. Northern and western analyses showed the expression of the gene and protein, respectively, in the transgenic plants. Analyses of the fatty acid profile of the seed oil from homozygous T4 generation seeds revealed that over-expression of the FAE1 gene caused a 36% increase in the percent of erucic acid (37–49% compared to 36% in untransformed control). The down-regulation of FAE1 caused an 86% decrease in the percent of erucic acid to as low as 5% in the seed oil of transgenic plants. Thus, it is clearly possible to alter erucic acid content of mustard by altering the expression level of the FAE 1 gene. S. Kanrar and J. Venkateswari equally contributed to this work.     

A synthetic peptide initiates Gerstmann-Sträussler-Scheinker (GSS) disease in transgenic mice

The molecular basis of the infectious, inherited and sporadic forms of prion diseases is best explained by a conformationally dimorphic protein that can exist in distinct normal and disease-causing isoforms. We identified a 55-residue peptide of a mutant prion protein that can be refolded into at least two distinct conformations. When inoculated intracerebrally into the appropriate transgenic mouse host, 20 of 20 mice receiving the beta-form of this peptide developed signs of central nervous system dysfunction at approximately 360 days, with neurohistologic changes that are pathognomonic of Gerstmann-Str?ussler-Scheinker disease. By contrast, eight of eight mice receiving a non-beta-form of the peptide failed to develop any neuropathologic changes more than 600 days after the peptide injections. We conclude that a chemically synthesized peptide refolded into the appropriate conformation can accelerate or possibly initiate prion disease.     

Endoplasmic reticulum targeting of active modified β-glucuronidase (GUS) in transgenic tobacco plants

We have investigated targeting to the endoplasmic reticulum (ER) of wild-type GUS and a modified form (GUS S358) by making an N-terminal fusion of the -glucuronidase (GUS) enzyme with the wheat -amylase signal peptide.In vitro studies demonstrated that the modified GUS (S358) lacked the glycosylation site present within the wild-type enzyme. Analysis of transgenic tobacco plants revealed that the modified GUS enzyme retained activity upon passage to the ER. When further experiments were carried out to determine the cellular location of the modified GUS enzyme, it was found that (contrary to expectation) the majority of GUS activity was retained within the cell and was not secreted to the cell surface via the default pathway. The data indicated that the modified GUS enzyme is an unsuitable reporter enzyme for studying protein secretion.     

Impaired reproduction in transgenic mice overexpressing γ-aminobutyric acid transporter Ⅰ (GAT1)

It is well documented that γ-aminobutyric acid (GABA) system existed in reproductive organs. Recent researches showed that GABA_A and GABA_B receptors were present in testis and sperm, and might mediate the acrosome reaction induced by GABA and progesterone. GABA transporter Ⅰ (GAT1) also existed in testis and sperm, but its physiological function was unknown. In the present study, we used GAT1 overexpressing mice to explore GAT1 function in male reproductive system. We found that the expression level of GAT1 continuously increased in wild-type mouse testis from 1 month to 2 months after birth. GAT1 overexpression in mouse affected testis development, which embodied reduced testis mass and slowed spermatogenesis in transgenic mice. Moreover, transgenic mice showed increase of the percentage of broken sperm. The further study revealed that the reproductive capacity was impaired in GAT1 overexpressing mice. In addition, testosterone level was significantly low in transgenic mice compared with that in wi     

油菜(Brassica napus L.)叶片植株的再生

油菜是一种重要的油料作物,有关它的组织培养方面的研究已有许多报道。但由叶片诱导成再生植株的不多,且系由单倍体或无菌苗而来,时间较长,取材受限,不便应用。因此,有必要研究自然条件下的二倍体叶片植株的再生及其条件,特别是良种,以加速其无性繁殖,并探索细胞、组织分化及其形态发生的规律和机理。故1980年来我们作     

Plant regeneration from mesophyll protoplast culture of cabbage (Brassica oleracea var ‘capitata’)

Summary Protoplasts were enzymatically isolated from the first leaves of cabbage (Brassica oleracea var capitata, F1 hybrid Baochun). Sustained cell division and somatic embryogenesis were obtained after culturing the protoplasts in modified liquid DPD medium supplemented with CaCl₂ · 2H₂O 800 mg/l, 2,4-D 0.5 mg/l, kinetin 1 mg/l, 0.3 M mannitol and sucrose 20 g/l. Upon transferring cell colonies onto a modified Murashige and Skoog (MS) agar medium, small calli were gradually formed. Callus proliferated on MS medium supplemented with hormone combinations of 2,4-D 0.1–0.5 mg/l and kinetin 3–4 mg/l. Multiple shoots were induced on differentiation medium supplemented with 3 mg/l of kinetin and 0.1 mg/l of gibberellic acid GA₃. After transferring differentiated shoots onto MS medium supplemented with indoleacetic acid (IAA), kinetin, GA₃ at 0.1 mg/l each and 500 mg/l of N.Z. amine, intact plants were eventually produced.     

First record of Peridroma saucia Hübner (Lepidoptera: Noctuidae) in transgenic soybeans

The widespread cultivation of transgenic soybeans has caused significant changes in the spectrum of Lepidoptera larvae, both in the number of species as well as on their densities in the field. Transgenic crops producing Bacillus thuringiensis (Bt) insecticidal proteins have successfully reduced the incidence of the most common caterpillars infesting soybeans, namely Anticarsia gemmatalis (Lepidoptera: Erebidae) and Chrysodeixis includens (Lepidoptera: Noctuidae). However, lepidopteran species not previously recorded on the crop have been recently found, and are of concern due to the possibility of adaptation to the genetically modified cultivars. The occurrence of Peridroma saucia Hübner (Lepidoptera: Noctuidae) is described for the first time in Brazil feeding on genetically modified soybean cultivars.     

油菜(Brassica napus L.)花茎组织培养中的器官形成

用甘蓝型油菜的主花茎切段,比较了不同激素和组合对器官形成的调节作用,花茎不同部位及花茎不同组织分化能力的差异。结果表明单加BA(2毫克/升)对芽的形成有明显促进作用。在加BA 的培养基中再加入NAA(0.05或0.5毫克/升)均显著降低形成芽的百分率及芽的数目。B_5培养基的效果明显优于MS 配方。花茎不同部位切段的比较试验表明,在花茎中芽形成能力在茎顶部5厘米中最强,往下渐减。将花茎表皮和皮层与髓部组织分开进行培养,则芽形成能力显著下降,但对根和愈伤组织的形成影响较小。油菜花茎所具有的强烈再生能力可能为维持和加速繁殖优良单株,或不育系等育种材料提供技术。     

Soybean Kunitz trypsin inhibitor (SKTI) confers resistance to the brown planthopper (Nilaparvata lugens Stål) in transgenic rice

Proteinase inhibitors are widely distributed in animals, plants and microorganisms and their roles in plants are associated with defense against pests. The utilization of proteinase inhibitors for crop protection has been actively investigated with a variety of proteinase inhibitors. Soybean Kunitz trypsin inhibitor (SKTI), one of the major seed storage protein, is synthesized for a short period during seed development. To investigate the role of SKTI in a plant's defense system against insect predation, a recombinant plasmid containing the full-length cDNA of SKTI under control of the CaMV 35S promoter was introduced into rice protoplasts by using the PEG direct gene transfer method and a large number of transgenic rice plants were regenerated. The integration, expression, and inheritance of this gene was demonstrated in R1 and R2 generations by Southern, northern, and western analyses. Accumulation levels (0.05–2.5% of soluble proteins) of SKTI protein were detected in R1 and R2 plants. Bioassay with R1 and R2 transgenic plants revealed that transgenic plants are more resistant to destructive insect pest of rice, brown planthopper (Nilaparvata lugens Stål), than the control plants. Thus, introduction of SKTI into rice plants can be used to control insect pests.     

Sucrose supply can increase longevity of broccoli (Brassica oleracea) branchlets kept at 22°C

Sucrose was supplied several hours after harvest to broccoli branchlets via the transpiration stream in order to increase the amount of sucrose available for respiration and to determine its influence on longevity at 22°C. Calculations based on solution uptake indicated that an 8% (w/v) sucrose solution supplied sufficient substrate for respiration, but the pattern of respiratory decline after harvest was not altered by supply of exogenous sucrose, and yellowing of floret sepals began after 2 days. However, when sucrose was supplied immediately after harvest, yellowing was delayed. Treatment with cytokinin (50 ppm 6-benzylaminopurine), to delay yellowing, had no effect on levels of sucrose in branchlets after 4.5 days, but retarded loss of chlorophyll. Floret tissues appear to sense the decline in sucrose after harvest, the result being induction of senescence as judged by yellowing. 6-benzylaminopurine may block the sensing mechanism.Abbreviations BAP 6-benzylaminopurine