Reaction of Some Coffea arabica Genotypes to Strains of Colletotrichum kahawae, the Cause of Coffee Berry Disease

Pathogenicity tests were performed on 11 genotypes of Coffea arabica using single‐isolate suspensions of Colletotrichum Kahawae obtained from 90 monoconidial isolates. The objective of this study was to estimate the proportion of pathogenic variation corresponding 10 differences in aggressiveness and virulence (races). A large part of the variation in the pathogen population was due to aggressiveness. The differential effects were too small to suggest conclusively that races exist. This paper discusses the possible causes for the observed small differential interaction and suggests breeding strategies that not only prevent possible adaptation of the pathogen to resistant varieties but also limit variation for resistance due to differences in aggressiveness of the pathogen.     

Calcium and phosphate effects on growth and alkaloid production in Coffea arabica: experimental results and mathematical model

Plant, mammalian, and microbial cells are commonly immobilized in calcium alginate gels for the production of valuable secondary metabolites. However, calcium ions are known to inhibit growth in various types of cells, and calcium is an integral part of such gels. Therefore, an investigation was conducted to evaluate the effect of calcium on the growth and alkaloid production of a model cell-line, Coffea arabica, in suspension culture before, attempting to immobilize such cells in alginate. A kinetic model was then developed from the results to describe cell growth and alkaloid production and the mechanism by which calcium influences these variables. In addition, it was observed that there was a characteristic relationship between the concentration of calcium in the external medium and the concentration of extra cellular and intracellular phosphate. The intracellular phosphate level was, in turn, related to the production of alkaloids. Using these results, a dynamic mathematical model of cell growth and alkaloid production was developed based on the proposed roles of calcium and phosphate. The model showed satisfactory agreement with three sets of experiments at different calcium concentrations. A possible linkage between the calcium and phosphate results is postulated based on the limited solubility of calcium phosphate.     

In vitro culture of coffee zygotic embryos for germplasm preservation

Immature zygotic embryos of Coffea arabica L. Cv. Cauvery (Catimor) were cultured on Murashige and Skoog (1962) (MS) medium supplemented with abscisic acid (ABA) at 0, 0.4, 3.8, 18.9, 37.8 and 75.6 μM., L-cystein hydrochloride at 50 mg 1^-1 and sucrose at 3%. Cultures were preserved in parafilm sealed Petri dishes in dark at a temperature of 25 ± 1 °C for up to two years. The preserved embryos were taken out from the media at 6 month intervals in order to test their viability by germination on MS + NAA (0.5 μM) + BA (4.4 μM). On the preservation media devoid of ABA or with a low concentration (0.4 μM) of ABA, the embryos germinated and showed higher mortality with increasing duration of storage. In contrast, the embryos became increasingly dormant with increasing concentrations of ABA and a 74.2% survival was found even after 2 years on medium supplemented with 18.9 μM or 37.8 μM of ABA. The results suggest that embryos can be preserved with a little loss of viability in the presence of ABA even at the normal room temperature (25 + 1 °C) up to two years without any transfer. Application of this technique for germplasm preservation of coffee is discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Vegetative Compatibility Grouping of Colletotrichum kahawae in Kenya

Vegetative compatibility using nitrate nonutilizing ( nit ) mutants was analysed between 44 isolates of Colletotrichum kahawae from Kenya, one each from Ethiopia and Malawi, one of Colletotrichum gloeosporioides and one of Colletotrichum acutatum . Another isolate of C. kahawae did not generate mutants and thus could not be utilized. The results showed that all the C. kahawae isolates, except a white sector mutant (VCG2), belonged to one vegetative compatibility group (VCG4). The other species belonged to their own unique groups (VCGs 1 and 3). Implications of the results and future research needs on the subject are discussed.     

Arbuscular mycorrhizal inoculation and superphosphate application influence plant development and yield of coffee in Brazil

 This paper reports a 6-year field study of the effects of mycorrhizal pre-colonization of coffee seedlings on initial crop development and coffee bean yield in a low-fertility Oxisol amended with superphosphate (P) at planting. The experiment included five P rates (0, 20, 40, 80 and 160 g plant^–1 P₂O₅) combined with seven fungal treatments [non-mycorrhizal control, pre-colonization with a mix of Glomus clarum and Gigaspora margarita (CM) and with five isolates of Glomus etunicatum]. Inoculated and non-inoculated outplants were raised under glasshouse conditions, transplanted into the field in January 1989 and monitored until July 1995. Plant height and stem diameter were greatly enhanced by P application and were higher in mycorrhizal seedlings than in controls up to 19 months after transplanting (MAT) but were not different at 26 MAT. Inoculation effects on tree canopy diameter were significant up to 26 MAT, at which time mycorrhizal colonization was high (43–55%), but did not differ amongst plants, regardless of whether or not the plants had been pre-colonized at the nursery stage. Root colonization and spore number in the soil were reduced by high P rates at 26 MAT. The first bean yield (1991) was highly enhanced by P and all pre-colonization treatments (38% increment over control) and these factors showed a significant interaction. Three isolates of G. etunicatum showed yield enhancements above 50%. The P rate for maximal yield was 207 g plant^–1 P₂O₅ for non-pre-colonized and approximately 100 g plant^–1 for pre-colonized plants. For this harvest, the mycorrhizal biofertilizer effect was equal to 254 kg ha^–1 P₂O₅. In subsequent years, pre-colonization effects were reduced and inconsistent. In 1992, 1993 and 1995, yield was affected by P but not by mycorrhizal inoculation. In 1994 there was a P versus mycorrhiza interaction and CM and G. etunicatum-Var gave higher yields than non-precolonized plants. Considering accumulated yield for this 5-year period, P application resulted in high yield increment in all treatments, whereas pre-colonization effects were extremely diminished. However, despite inconsistency amongst mycorrhizal treatments, pre-colonization effects were detected at the fifth harvest in some fungal treatments. Based on the total yield of five harvests, maximal productivity was achieved with CM at 20 g plant^–1 P₂O₅ and with CM and G. etunicatum-Var at the highest P rate. Diminishing mycorrhizal effects over time are related to colonization of non-precolonized seedlings by the indigenous fungi and to the reduced external P requirement of the mature crop. If adequate phosphorus is applied at planting, pre-colonization of outplants with selected arbuscular mycorrhizal fungi enhances early crop development and productivity of coffee in low-fertility soils of Brazil. Accepted: 3 October 1997     

长角凤仙花（凤仙花科）的花器官发生和发育

以不同发育时期的长角凤仙花Impatiens longicornuta Y.L.Chen（凤仙花科Balsaminaceae）为材料,利用扫描电镜技术观察了其花器官的分化及其发育过程。长角凤仙花为两侧对称花,具2枚侧生萼片,唇瓣囊状,旗瓣具鸡冠状突起,雄蕊5枚,子房上位,5心皮5室。其花器官分化顺序为向心式,萼片—花瓣—雄蕊—雌蕊原基。2枚侧生萼片先发生,然后近轴萼片（即唇瓣）原基和2枚前外侧萼片原基近同时发生;但是这3枚萼片原基的发育不同步,远轴的2枚前外侧萼片原基的发育渐渐滞后,然后停止发育,最后渐渐为周围组织所吸收,直至消失不见。花瓣原基中,旗瓣原基最先发生,4个侧生花瓣原基相继成对发生,且之后在基部成对愈合形成翼瓣;5枚雄蕊原基几乎同时发生,5个心皮原基轮状同时发生。本文结果支持凤仙花属植物为5基数的花,并进一步证实了唇瓣的萼片来源;此外,研究结果表明花器官早期发育资料对植物系统与进化研究具有重要参考价值。     

Morphology and ultrastructure of isolated gemmae of Drosera pygmaea and their in vitro germination

Gemma morphology, histology and ultrastructure before and after germination in vitro were studied in Drosera pygmaea. The histology of the gemma is similar to that of a seed, being characterized by an embryo-like structure and storage tissue, although no seed coat is formed. One embryo-like structure within the gemma, which gives origin to a new plant, expresses polar organisation with distinct meristematic regions. Storage tissue surrounding the embryo-like structure resembles endosperm and it is built of parenchyma cells possessing plastids with starch grains and dense material within vacuoles. The regeneration from the gemma may provide useful system to study plant morphogenesis under stress conditions including in vitro culture. This revised version was published online in July 2006 with corrections to the Cover Date.     

夜间低温对两种咖啡光合作用的影响

为了探讨夜间低温对滇南地区主要栽培的小粒种咖啡(Coffea arabica)和大粒种咖啡(Coffea liberica)光合作用的影响,于西双版纳雾凉季对盆栽幼苗进行了连续3d的4℃夜间低温处理,并于原地恢复3d,测定了叶片的一些生理生态指标。结果表明,经4℃夜间低温处理3d后,虽然两种咖啡非辐射耗散能力增强,胡萝卜素／叶绿素(Car／Chl)升高,但净光合速率(Pn)、气孔导度(Gs)和黎明原初光化学效率(Fv／Fm)降低,初始荧光(Fo)升高,以及过氧化氢(H2O2)和丙二醛(MDA)的积累,表明夜间低温对两种咖啡光合机构均产生了明显的破坏,导致净光合速率下降的气孔因素和非气孔因素同时存在。虽然正常条件下两种咖啡净光合速率没有显著差异,但与大粒种咖啡相比,低温处理后,小粒种咖啡的Pn,Fv／Fm下降的比例小,MDA积累的量少,且在3d的恢复后基本可以恢复到原初值,表明小粒种咖啡相对比较耐寒,这与其较强的非辐射耗散能力,较大的Car／Chl及较强的恢复能力有关。     

香溪河大型底栖无脊椎动物空间分布

2005年7月至2006年6月,通过对大型底栖无脊椎动物的量化检测,对三峡水库湖北库区最大河流香溪河的大型底栖无脊椎动物空间分布进行了研究.结果表明：四节蜉、高翔蜉、短尾石蝇为香溪河水系大型底栖动物优势类群;香溪河各支流间生境特征及大型底栖无脊椎动物群落结构差异较大;功能摄食类群密度相对丰度的变化能够反映不同的栖境特征.对生物多样性指数及优势类群耐污值的比较表明,大型底栖动物栖境为九冲河最好,香溪河干流次之,高岚河和古夫河较差.典型对应分析表明：铵态氮对香溪河大型底栖动物群落结构影响显著;pH值、浊度、水深、二氧化硅、电导和碱度对九冲河大型底栖动物群落结构影响显著;浊度对高岚河大型底栖动物群落结构影响显著;铵态氮和硝酸盐氮对古夫河大型底栖动物群落结构影响显著.     

Extracelluar matrix induces formation of organoids and changes in cell surface morphology in cultured human breast carcinoma cells PMC42-LA

In the lactating breast, the development of secretory alveoli consisting of differentiated cells arranged around a central lumen is dependent on signals from the extracellular environment of the cells. There are few cell lines that model this process. We previously showed that the human breast carcinoma line PMC42-LA can be induced to form organoids, reminiscent of secretory alveoli found in the lactating human breast. In this report, we used high-resolution scanning electron microscopy to show that the formation of organoids is accompanied by development of cell surface microvilli. Extracellular matrix-induced formation of microvilli occurred on the internal and external surfaces of cells in the organoids and not on surfaces in contact with the extracellular matrix. Organoid formation of PMC42-LA cells induced a rearrangement of the extracellular matrix, seen in the form of radiating fibers from the organoids. In summary, there is an interaction between PMC42-LA cells and the underlying extracellular matrix, which leads to the formation of polarized cells with well-developed microvilli. This is accompanied by organization of the extracellular matrix. PMC42-LA is a relevant model of the human breast for investigations into cell-cell and cell-matrix interactions.     

Correlative 3D imaging of whole mammalian cells with light and electron microscopy

We report methodological advances that extend the current capabilities of ion-abrasion scanning electron microscopy (IA-SEM), also known as focused ion beam scanning electron microscopy, a newly emerging technology for high resolution imaging of large biological specimens in 3D. We establish protocols that enable the routine generation of 3D image stacks of entire plastic-embedded mammalian cells by IA-SEM at resolutions of ∼10–20 nm at high contrast and with minimal artifacts from the focused ion beam. We build on these advances by describing a detailed approach for carrying out correlative live confocal microscopy and IA-SEM on the same cells. Finally, we demonstrate that by combining correlative imaging with newly developed tools for automated image processing, small 100 nm-sized entities such as HIV-1 or gold beads can be localized in SEM image stacks of whole mammalian cells. We anticipate that these methods will add to the arsenal of tools available for investigating mechanisms underlying host-pathogen interactions, and more generally, the 3D subcellular architecture of mammalian cells and tissues.