Enhancement of pollen embryo formation in Datura innoxia by charcoal

In recent years liquid medium has been shown to be better than agar-gelled medium for production of haploids by anther culture. However, on addition of charcoal to agar medium the anther response in Datura innoxia Mill, increases dramatically and is better than in liquid medium. For anthers with pollen at the premitotic stage, the best result was observed with 1% charcoal in Difco agar and 1.5% in Normal agar. The effect is possibly due to adsorption of substances inhibitory to androgenesis and emanating from anthers, as well as to substances present in the nutrient medium and agar.     

Isolation of Mesophyll Protoplasts of Nicotiana rustica and Their Regeneration into Plants Flowering in vitro

The three enzymes D-3-phosphogIycerate dehydrogenase (E.C. 1.1.l.s), eqglutamate dependent O-phospho-L-serine aminotransferase (E.C. 2.6.1.52), and O-phospho-L-serine phosphatase (E.C. 3.1.3.3.), which together catalyse the turnover of D-3-phos-phoglycerate (3-PGA) to serine were assayed in chloroplast and leaf extracts from spinach (Spinacia oleracea). Relatively high activities of the dehydrogenase and the phosphatase were found in both chloroplast and leaf extracts, whereas the specific activity of the aminotransferase was 10 times higher in leaf extracts than in chloroplast extracts. The results suggest that spinach chloroplasts are able to produce minor amounts of serine directly from 3-PGA, but that the main part of the phosphohydroxypyruvate formed is exported, and probably used in a parallel pathway to serine outside the chloroplasts. Some kinetic properties of the enzymes were also determined.     

垂直方向磷素竞争对杉木根系生长及生物量分配的影响

针对自然环境中有效磷养分主要分布于土壤表层而容易导致植物根系激烈竞争的问题,选择同一杉木(Cunninghamia lanceolata)无性系幼苗为研究对象,采用水平方向空间狭小而垂直方向空间大的室内盆栽模拟装置,以单株种植为对照,构建双株种植的竞争处理,通过设置3个供磷水平:不供磷处理(0 mg/kg KH_2PO_4)、低磷处理(6 mg/kg KH_2PO_4)和正常供磷处理(12 mg/kg KH_2PO_4),采用破坏性试验方式收获,分别在试验的前期(50 d)、中期(100 d)和后期(150 d)测定不同处理条件下杉木幼苗根系生物量与根系形态的变化,研究邻株杉木根系在垂直方向上对有限磷素资源的竞争策略。结果表明:竞争处理和供磷水平对杉木幼苗根系长度、平均直径等形态指标的影响存在交互作用(P0.05),对杉木幼苗生物量分配、比根长等指标的影响均不存在明显的交互作用(P0.05)。竞争处理中杉木根系形态增量均明显高于非竞争处理的单株幼苗,且随着胁迫时间的增加,根系形态增量均呈现显著的上升趋势,其中在胁迫中期和后期的增量明显高于前期,且邻株竞争处理明显提高了杉木的比根长,提升了根系觅磷的能力;随着供磷水平的提高,根表面积和根体积增量大体上呈现先上升后下降的趋势。与非竞争处理相比,竞争条件下杉木地上部生物积累量差异不明显,而根系生物量、根冠比均低于非竞争处理的单株幼苗。     

Streptomycin Resistance of a Cell Line from Haploid Datura innoxia Mill. is Transferred from Cell to Plantlet and Back In Vitro

Out of the five cell lines isolated by their ability to proliferateon a selection medium containing streptomycin and derived froma haploid callus culture from Datura innoxia microspores, onewas characterized. The trait of resistance was found to be stablein the absence of selection pressure. Plantlets were regeneratedin the presence, as well as absence, of the antibiotic. Stabilityof the selected trait was also confirmed in callus culturesinitiated from a plantlet. Key words: Datura, Streptomycin resistance, Mutants     

Factors Affecting Formation of Somatic Embryos and Embryogenic Callus from Unemerged Inflorescences of a Graminaceous Crop Pennisetum

Differentiation of somatic embryos was dependent on the concentrationof auxin and the mineral medium. Low levels of auxin 2,4-D inN₆ medium, a low ammonium nutrient, favoured the formation ofsomatic embryos, while on MS medium containing high ammoniumcompact tissues appeared. At higher levels of auxin, irrespectiveof nutrient medium, compact tissues were formed. The originof compact tissue on N₄ medium could be traced to somatic embryo-likestructures. This tissue regenerated into somatic embryos onhormone-free N₆ medium whereas on MS medium thalloid structuresappeared. Pennisetum, unemerged inflorescence, somatic embryo, embryogenic callus     

Mitochondrial DNA analyses reveal low genetic diversity in Culex quinquefasciatus from residential areas in Malaysia

The present study explored the intraspecific genetic diversity, dispersal patterns and phylogeographic relationships of Culex quinquefasciatus Say (Diptera: Culicidae) in Malaysia using reference data available in GenBank in order to reveal this species' phylogenetic relationships. A statistical parsimony network of 70 taxa aligned as 624 characters of the cytochrome c oxidase subunit I (COI) gene and 685 characters of the cytochrome c oxidase subunit II (COII) gene revealed three haplotypes (A1–A3) and four haplotypes (B1–B4), respectively. The concatenated sequences of both COI and COII genes with a total of 1309 characters revealed seven haplotypes (AB1–AB7). Analysis using tcs indicated that haplotype AB1 was the common ancestor and the most widespread haplotype in Malaysia. The genetic distance based on concatenated sequences of both COI and COII genes ranged from 0.00076 to 0.00229. Sequence alignment of Cx. quinquefasciatus from Malaysia and other countries revealed four haplotypes (AA1–AA4) by the COI gene and nine haplotypes (BB1–BB9) by the COII gene. Phylogenetic analyses demonstrated that Malaysian Cx. quinquefasciatus share the same genetic lineage as East African and Asian Cx. quinquefasciatus. This study has inferred the genetic lineages, dispersal patterns and hypothetical ancestral genotypes of Cx. quinquefasciatus.     

A multi‐locus approach resolves the phylogenetic relationships of the Simulium asakoae and Simulium ceylonicum species groups in Malaysia: evidence for distinct evolutionary lineages

A multi‐locus approach was used to examine the DNA sequences of 10 nominal species of blackfly in the Simulium subgenus Gomphostilbia (Diptera: Simuliidae) in Malaysia. Molecular data were acquired from partial DNA sequences of the mitochondria‐encoded cytochrome c oxidase subunit I (COI), 12S rRNA and 16S rRNA genes, and the nuclear‐encoded 18S rRNA and 28S rRNA genes. No single gene, nor the concatenated gene set, resolved all species or all relationships. However, all morphologically established species were supported by at least one gene. The multi‐locus sequence analysis revealed two distinct evolutionary lineages, conforming to the morphotaxonomically recognized Simulium asakoae and Simulium ceylonicum species groups.