Synthetic bioregulators of poly-cis carotenoid biosynthesis

Seventeen new bioregulators were synthesized and tested for their ability to induce the biosynthesis of poly-cis carotenes in the flavedo of Marsh white seedless grapefruit. The effects of these new bioregulators are the same as that of the previously reported dibenzylamines, but several of the new compounds are more effective and cause the accumulation of up to 162 μg/g dry wt of poly-cis carotenes in the flavedo as compared to the maximum of 74 μg/g dry wt observed previously. The compounds tested were substituted N-benzyl furfurylamines, N-benzyl, N-methyl furfurylamines and N-alkyl, N-methyl benzylamines. They demonstrate the ability of tertiary as well as secondary amines to stimulate the formation of poly-cis carotenes. The interaction of N-(4-bromobenzyl) furfurylamine, one of the more effective of the new compounds, with lycopene and β-carotene inducers is also reported.     

Paternal transmission of a seed size reduction gene varies with age of a primary transformant and seed set is also influenced by gene expression in maternal tissues

We have constructed chimaeric genes that are expressed in embryo and endosperm compartments of the seed, induce dominant seed lethality and have potential to reduce seed size in 75% of seeds within a fruit such as Citrus [7]. The genes are not entirely seed-specific as a proportion of primary test tobacco transformants containing their gene were fully male-sterile [7]. Here we investigated why a proportion of apparently male-fertile transgenic plants showed segregation distortion from the 75% seed lethality expected for a single dominant gene. Reciprocal crosses were conducted between pollen fertile, primary tobacco transformants containing various copies of the CG1-400-RNase gene [7] and wild-type tobacco plants to examine the transmission of the gene through maternal and paternal gametes and also the effects of gene dosage in embryo and endosperm compartments on seed viability and phenotype. Pollen viability, seed set and seed phenotype were examined over a 16 month period to assess stability of gene expression in primary transformants because woody, fruit crops containing these genes will be vegetatively propagated from primary transformants. In male-fertile transformants, the gene was observed to be expressed to varying degrees post-meiotically in pollen over the time period examined resulting in lethality of transgenic pollen and reduced paternal transmission. A variable, low-level maternal expression component was also detected that resulted in seed lethality and influenced morphological variation in the seed lethal phenotype. The maternal and paternal expression components caused seed lethality to range from 50 to 75%. This study indicates the need to select for transformants with stable pollen transmission and high seed expression and raises questions in relation to possible environmental and epistatic effects on gene expression in primary, hemizygous transformants over long growth periods.     

无籽八月桔胚囊及胚胎发育细胞学观察

运用酶解振荡压片技术和常规石蜡切片技术分别研究了无籽八月桔的胚囊育性及无籽八月桔自交和异交(无籽八月桔×台湾椪柑,无籽八月桔×有籽八月桔)的胚胎发育.结果表明:无籽八月桔胚囊可育,成熟胚囊具一个卵细胞、两个助细胞、三个反足细胞以及一个大的含二个极核的中央细胞;其自交和异交的胚胎发育均正常,授粉后2周出现球形胚和少量心形...     

Transgenic parthenocarpic eggplants: superior germplasm for increased winter production

Winter production of three eggplant hybrids transgenic for the parthenocarpic gene DefH9-iaaM was compared, in an unheated greenhouse, to the performance of two untransformed control hybrids and the commercial parthenocarpic cultivar Talina. Each hybrid was either treated or untreated with a commercial formulation of phytohormones to induce fruit set and growth. The productivity of the transgenic parthenocarpic hybrids was not influenced by the hormonal treatment. On the contrary, the productivity of untransformed hybrids was significantly improved by hormonal treatment of the flower buds. The yield of the transgenic hybrids was significantly higher than that obtained in the corresponding untransformed hybrids, even when the latter were treated with phytohormones. The yield increment due to the parthenocarpic trait was particularly evident when compared to the yield of the two corresponding hybrid combinations, which are identical except for the presence of the DefH9-iaaM gene. The transgenic hybrids allowed an increase in productivity of ca. 25%. This increment coincided with a 10% reduction in cultivation cost, mainly due to the labour needed for the hormonal sprays, and to the production of fruits of better quality. Thus, the DefH9-iaaM gene is a biotechnological tool superior to both agronomic and traditional genetic parthenocarpic mutants.     

无籽西瓜品种SSR指纹图谱构建及遗传多样性分析

利用SSR标记构建了27份中国无籽西瓜主栽品种的DNA指纹并进行了遗传多样性分析。24对多态性引物共扩增出66种基因型,基因型数2-5个不等,平均2.75个。平均多态性信息量(PIC)为0.37,变化范围为 0.19～0.66。有4个品种具有特征谱带。27个品种遗传相似系数变化范围为 0.7045～1.0,平均0.8683。组合24对引物,除无法区分‘郑抗无籽1号’与‘雪峰花皮无籽’,其余品种均能一一区分开。采用类平均法进行聚类分析,在相似系数0.83处,可将27个品种分为3大类。     

无核荔枝果实形成差异表达基因cDNA的克隆

采用抑制差减杂交技术(Suppression Subtractive Hybridization,SSH)分离与海南无核荔枝果实形成相关的差异表达基因的cDNA片段,为克隆相关基因提供研究基础。分别以无核荔枝的有核幼果为driver;无核幼果为tester,建立差减cDNA文库。经Reverse Northern Dot-Blot筛选该文库,共获得61个阳性克隆,随机选取17个克隆进行测序,共获得10条非重复序列,对其中较长的7个序列进行同源分析,结果表明:有6个序列在荔枝中为首次报道。     

Moss (Physcomitrella patens) Expressed Sequence Tags Include Several Sequences which are Novel for Plants*

The moss Physcomitrella patens (Hedw.) B.S.G. is the first land plant in which gene disruption by homologous recombination Is directly accessible. In order to obtain cloned sequences which may be used in such an approach, complementary DNAs (cDNAs) have been isolated by subtractlve hybridisation of representative cDNA libraries from cytoklnin-treated tissue. Sequencing of these clones from both ends yielded over 35 kb of non-redundant sequence Information, of which 20 kb results from clones which appear to be novel to plants. Database comparisons have revealed that 39 of the expressed sequence tags (ESTs) generated show significant homology to identified sequences. Analysis of these ESTs shows a high degree of conservation between Physcomitrella and seed plant sequences, and codon usage is found to be very similar to that In dicotyledonous species. Furthermore, 43 sequences showing no significant homology to sequences in the databases represent previously unidentified expressed genes.