A New Glabrous Gene (csgl3) Identified in Trichome Development in Cucumber (Cucumis sativus L.)

Spines or trichomes on the fruit of cucumbers enhance their commercial value in China. In addition, glabrous mutants exhibit resistance to aphids and therefore their use by growers can reduce pesticide residues. Previous studies have reported two glabrous mutant plants containing the genes, csgl1 and csgl2. In the present study, a new glabrous mutant, NCG157, was identified showing a gene interaction effect with csgl1 and csgl2. This mutant showed the glabrous character on stems, leaves, tendrils, receptacles and ovaries, and there were no spines or tumors on the fruit surface. Inheritance analysis showed that a single recessive gene, named csgl3, determined the glabrous trait. An F₂ population derived from the cross of two inbred lines 9930 (a fresh market type from Northern China that exhibits trichomes) and NCG157 (an American processing type with glabrous surfaces) was used for genetic mapping of the csgl3 gene. By combining bulked segregant analysis (BAS) with molecular markers, 18 markers, including two simple sequence repeats (SSR), nine insertion deletions (InDel) and seven derived cleaved amplified polymorphism sequences (dCAPs), were identified to link to the csgl3 gene. All of the linked markers were used as anchor loci to locate the csgl3 gene on cucumber chromosome 6. The csgl3 gene was mapped between the dCAPs markers dCAPs-21 and dCAPs-19, at genetic distances of 0.05 cM and 0.15 cM, respectively. The physical distance of this region was 19.6 kb. Three markers, InDel-19, dCAPs-2 and dCAPs-11, co-segregated with csgl3. There were two candidate genes in the region, Csa6M514860 and Csa6M514870. Quantitative real-time PCR showed that the expression of Csa6M514870 was higher in the tissues of 9930 than that of NCG157, and this was consistent with their phenotypic characters. Csa6M514870 is therefore postulated to be the candidate gene for the development of trichomes in cucumber. This study will facilitate marker-assisted selection (MAS) of the smooth plant trait in cucumber breeding and provide for future cloning of csgl3.     

Changes in the Activity of the Maturation-Promoting Factor Are Correlated with Those of a Major Cyclic AMP and Calcium-Independent Protein Kinase During the First Mitotic Cell Cycles in the Early Starfish Embryo

Many studies suggest that MPF activation depends on protein phosphorylation or that MPF is itself a protein kinase. In the present report, cyclic variations of MPF activity have been correlated in vivo with changes in the extent of protein phosphorylation or in vitro with changes of a major protein kinase during the first cell cycles of fertilized starfish eggs. This cycling protein kinase neither requires cAMP nor Ca²⁺. Neither colchicine nor aphidicoline, which inhibits cleavage and chromosome replication respectively, was found to suppress the synchronous and cyclic variations of both MPF and protein kinase activities. Protein synthesis was found to be required for both MPF and protein kinase activities to reappear after their simultaneous drop at the time of mitotic or meiotic cleavages. Production of either MPF or protein kinase activities is not the immediate result of protein synthesis since there is a delay at each cell cycle between the time when protein synthesis is required and the time when both MPF and protein kinase activities are produced. This suggests that both MPF and protein kinase activities might involve some post-translational modification of a precursor protein synthesized during the preceeding cell cycle.     

中国平脉树螽属五新种记述：直翅目：螽斯科：树螽亚科

本文报道中国平脉树螽属5个新种。每个新种皆有详细的形态描述和形态特征图。所有模式标本存于北京农业大学昆虫标本室。     

Changes in Abscisic Acid Content in Axis and Cotyledons of Developing Phaseolus vulgaris Embryos and their Physiological Consequences

Prevost, I. and Le Page–Degivry, M. Th. 1985. Changesin absicisic acid content in axis and cotyledons of developingPhaseolus vulgaris embryos and their physiological consequences.—J.exp. Bot. 36: 1900–1905.Changes in abscisic acid (ABA)content with time were measured in embryonic axes and in cotyledonsof Phaseolus vulgaris embryos using a radio–immunoassay.During embryogenesis, a similar pattern was observed in bothtissues: ABA increased to a maximum 29 d after an thesis, followedby a decrease as the seed matured. The level of ABA in the cotyledonswas always much higher than that in the axes. In in vitro cultures,the duration of the lag phase before germination of isolatedembryonic axes increased with ABA content. The presence of cotyledonsalways lengthened the lag phase; longer lag phases were associatedwith greater concentrations of ABA in the cotyledons. Moreoverthe presence of cotyledons stimulated the growth of seedlings. Key words: ABA distribution, embryo maturation, axis and embryo germinability     

Monitoring the persistence of Laccaria bicolor as an ectomycorrhizal symbiont of nursery-grown Douglas fir by PCR of the rDNA intergenic spacer

The large-scale inoculation of selected beneficial ectomycorrhizal fungi in forest nurseries has generated renewed interest in the ecology of these symbiotic fungi. However, information on the dissemination and persistence of introduced symbionts is scarce due to the limitation of the current identification methods. To identify ectomycorrhizal fungi on single root tips, we investigated the polymorphism of the PCR-amplified ribosomal DNA intergenic spacer (IGS) from a wide range of ectomycorrhizal fungi. To investigate the reliability of this molecular approach in large-scale surveys, the dissemination and persistence on Douglas fir seedlings of the introduced Laccaria bicolor S238N were assessed in a forest nursery in the Massif Central (France). Several hundred ectomycorrhizas and fruiting bodies were sampled from plots where control and L. bicolor inoculated-Douglas fir seedlings were grown for 1.5 years. PCR typing of mycorrhizas indicated that trees inoculated with L. bicolor S238N remained exclusively colonized by that isolate (or sexually derived isolates) for the entire test period. In contrast, control seedlings were infected by indigenous isolates of Laccaria laccata and Thelephora terrestris. The molecular evidence for the persistence of the introduced mycobiont despite the competition from indigenous isolates of the same species provides further illustration of the potential of exotic species for large-scale microbial application.     

Variation in heat-shock proteins among species of desert fishes (Poeciliidae, Poeciliopsis)

Analysis of the heat-shock proteins (hsps) of six closely related species of Poeciliopsis demonstrated the existence of biochemical diversity in the hsp100, hsp70, hsp60, and hsp30 protein families among species. Each species expressed five to seven hsp70-related isoforms. Constitutive 70-kD isoforms were identical among species, but four different patterns of heat-inducible isoforms were seen in these six species. Members of the hsp70 family of molecular chaperones are included among the most highly conserved proteins known, and the possibility of variation in hsp70 among closely related species has rarely been addressed. The hsp30 family is known to be less conserved than the hsp70 family, and, as expected, the Poeciliopsis hsp30 patterns showed more variation. Most of the hsp30 isoforms characteristic of a particular species were unique to that species. Hsp100 and hsp60 were identical in five of the species, but alternate isoforms were found in P. monacha. The small size and limited geographical distribution of the P. monacha population have probably contributed to the uniqueness of the monacha pattern. Two of the species were shown to acquire thermotolerance, the ability to withstand normally lethal temperatures when subjected to a gradual temperature increase. Rapid-heating protocols commonly used to establish critical thermal maxima of organisms do not include this inducible component of thermoresistance and therefore do not adequately assess an organism's capacity to withstand thermal stress.