In vitro germination and transient GFP expression of American chestnut (Castanea dentata) pollen

The development of the male reproductive structures of American chestnut (Castanea dentata) is described to advance our understanding of its reproductive behavior. This information has been vital in the development of a strategy to collect pollen grains from male catkins suitable for in vitro germination and transformation experiments. Cutting male catkins into small segments and rolling them over a culture plate resulted in evenly dispersed and large amounts of pollen with minimal unwanted accessory floral parts. To optimize pollen viability, the effect of various storage conditions on in vitro germination was examined. Our results showed that initial storage at 4°C for 2 weeks significantly increased percent germination as compared to freshly collected pollen and those stored directly at −20°C or −80°C. This also means that for long-term storage of American chestnut pollen, the catkins should first be kept at 4°C for a couple of weeks and then at −80°C. The use of pollen grains with high viability is necessary for the transformation of American chestnut pollen. To optimize pollen transformation via particle bombardment, the effects of target distance, target pressure, and pollen developmental stage were examined. Statistical analysis showed that bombardment of ungerminated pollen at 1,100 psi resulted in the highest percent transient GFP expression (4.1%).     

北京9个典型板栗园土壤碳代谢微生物多样性特征

土壤微生物多样性与土壤质量存在密切联系,也是目前的研究热点。从北京板栗主产区采取9个典型板栗园表层(0—20cm)土壤,采用BIOLOG生态微平板(BIOLOG Eco PlateTM)分析土壤微生物碳代谢群结构,旨在了解不同板栗园土壤微生物碳代谢功能群结构的特点与差异。结果表明:9个土壤可分为3组:(1)1,6,9号土壤、(2)2,5,7号土壤、(3)3,4,8号土壤。组内土壤微生物碳代谢功能群结构相似,而每组之间有显著性的差异。其中,1,6,9号土壤利用D-羟基丁二酸等7种基质的微生物比较多;而利用葡萄糖-1-磷酸盐等14种基质的微生物比较少,2,5,7号土壤与1,6,9号土壤正好相反,3,4,8号土壤与1,6,9号土壤的相似之处表现在代谢D-羟基丁二酸等7种基质的微生物也比较多,而代谢i-赤藻糖醇、D-木糖、2-羟基安息香酸等基质的微生物比较少。但是,目前对于土壤微生物碳代谢功能群多样性在土壤可持续利用中的作用与意义,特别是与土壤CNP等生物化学过程之间的关系还不清楚。     

Impact of Galerucella birmanica (Coleoptera: Chrysomelidae) on growth and seed production of Trapa natans

Success in biological weed control programs depends upon the ability of host-specific herbivores to suppress populations of their host plant. While pre-release predictions of field host range (i.e., specificity) appear widely accurate, predictions about which agent or agent combination may suppress plant populations have lately been compared to predictions in a lottery. The history of weed biocontrol does not offer immediately obvious approaches to improve the lottery model, however, pre-release assessments of the impact of different herbivore densities on the invasive plant may provide an opportunity to improve predictions of success. In this paper, we report on the impact of the leaf beetle Galerucella birmanica on growth and reproduction of water chestnut, Trapa natans, in the native range in China. At low herbivore densities (10–50 larvae/rosette), plants compensated for leaf herbivory by increasing leaf production at the expense of reproductive effort. Inoculating >50 first instar larvae per rosette greatly suppressed biomass production and plants were unable to grow when three or more G. birmanica pairs were released per seven rosettes. In the native range, similar densities are found in the field, resulting in complete defoliation of T. natans. Our study indicates that G. birmanica feeding has significant negative impacts on T. natans. This chrysomelid species appears to be a promising biological control agent and we would predict that the species will be able to attain sufficiently high populations to control its host plant—if approved for release in North America.     

Proliferation,maturation and germination of Castanea sativa Mill. Somatic embryos originated from leaf explants

Experiments were performed to determine the influence of proliferation medium on the maintenance of embryogenic competence and on repetitive embryogenesis in Castanea sativa Mill. somatic embryos derived from leaf explants. Somatic embryo proliferation was carried out by both direct secondary embryogenesis and by the culture of nodular callus tissue originated from cotyledons of somatic embryos. Both systems led to the production of cotyledonary somatic embryos on Murashige and Skoog proliferation medium supplemented with 0.1 mg l-1 benzyladenine and 0.1 mg l-1 naphthaleneacetic acid. Carbon source and concentration had a marked influence on maturation and subsequent germination ability of chestnut somatic embryos. Plantlet conversion was achieved in embryos matured on media with 6 % sucrose, and on 3 or 6 % maltose, whereas mean shoot length, root length and leaf number of produced plants were not significantly affected by these maturation media. Overall, the best results were obtained with 3 % maltose-matured somatic embryos, giving rise to 6 % plant recovery in addition to 33 % of embryos exhibiting only shoot development. The application of a 2-month cold treatment at 4 degrees C to somatic embryos matured on medium with 3 % maltose was necessary for achieving plant conversion, while partial desiccation did not appear to influence this response. A total of 39 % of embryos eventually produced plants either through conversion to plantlets or indirectly through rooting of shoots. Shoots formed by somatic embryos could be excised, multiplied and rooted following the micropropagation procedures previously developed for chestnut.     

A chestnut seed cystatin differentially effective against cysteine proteinases from closely related pests

Cystatin CsC, a cysteine proteinase inhibitor from chestnut (Castanea sativa) seeds, has been purified and characterized. Its full-length cDNA clone was isolated from an immature chestnut cotyledon library. The inhibitor was expressed in Escherichia coli and purified from bacterial extracts. Identity of both seed and recombinant cystatin was confirmed by matrix-assisted laser desorption/ionization mass spectrometry analysis, two-dimensional electrophoresis and N-terminal sequencing. CsC has a molecular mass of 11275 Da and pI of 6.9. Its amino acid sequence includes all three motifs that are thought to be essential for inhibitory activity, and shows significant identity to other phytocystatins, especially that of cowpea (70%). Recombinant CsC inhibited papain (Ki 29 nM), ficin (Ki 65 nM), chymopapain (Ki 366 nM), and cathepsin B (Ki 473 nM). By contrast with most cystatins, it was also effective towards trypsin (Ki 3489 nM). CsC is active against digestive proteinases from the insect Tribolium castaneum and the mite Dermatophagoides farinae, two important agricultural pests. Its effects on the cysteine proteinase activity of two closely related mite species revealed the high specificity of the chestnut cystatin.     

Identification and quantification of brassinolide-related steroids in the insect gall and healthy tissues of the chestnut plant

Castasterone and 6-deoxocastasterone were identified by GC/MS and/or selected ion monitoring not only in the insect gall of chestnut but also in the healthy tissues, including the shoot, leaf and flower bud. In addition, the gall was found to contain a small amount of brassinolide. Brassinone, which had been reported to be present in the gall, could not be detected in these tissues. The contents of castasterone, 6-deoxocastasterone and brassinolide, which were determined by using selected ion monitoring, are discussed.     

Characterisation of Chinese elite cultivars and genetic resources of chestnut by AFLP

We selected a informative set of twelve amplified fragment length polymorphism (AFLP) primer pairs suitable for evaluation of Chinese chestnut (Castanea mollissima Blume) genotypes. Cluster analysis based on 198 polymorphic AFLP amplified by these 12 primer pairs clearly divided investigated genotypes according to their place of origin. We showed, that genetic basis of modern genotypes is narrow also in the case of this species.     

The effect of low temperature on germination of androgenic embryos of <Emphasis Type="Italic">Aesculus hippocastanum</Emphasis> L.

Treating androgenic embryos of Aesculus hippocastanum L. with low temperatures (6 °C) improved their germination and regeneration into plantlets. The embryos derived from anther cultures showed better results than those derived from microspore cultures.This work was supported by the Ministry of Science, Technology and Development of Serbia, grant No. 1573.     

Reworking the idea of chestnut (Castanea sativa Mill.) cultivation in Roman times: New data from ancient Campania

Abstract

Charcoal analysis was carried out in two archaeological sites on the north slope of the Somma-Vesuvius volcano, not far from Naples. Both sites were inhabited between the 2nd century AD and AD 472, when a great Vesuvius eruption (so called Pollena eruption) buried them. In both sites, Castanea sativa wood was largely used for architectural structures as well as firewood. Ten ¹⁴C dates, spanning between the 1st and the 5th century AD, testify to a continuative use of this wood throughout the life of the sites. The comparison between archaeobotanical and pollen data from other sites in southern Italy suggests that chestnut woods were close to the sites studied and had a restricted spreading, possibly in a refugium area on Vesuvius' foothills. The match between archaeological charcoals and pollen data suggests that the Romans did not spread chestnut cultivation in the entire Campania region and that chestnut probably became a common timber in Campania starting from the 5th–6th century AD.     

Impact of the leaf miner Cameraria ohridella (Lepidoptera: Gracillariidae) and bleeding canker disease on horse‐chestnut: direct effects and interaction

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