Metabolism of cell wall polysaccharides from persimmon fruit. Pectin solubilization during fruit ripening occurs in apparent absence of polygalacturonase activity

Pectins from persimmon ( Diospyros kaki L.) fruit pericarp were sequentially extracted with 0. 05 M trans -1,2-diaminocyclohexane-N,N, N', N'-tetraacetic acid (CDTA), 0. 05 M Na₂CO₃ (1°C) and Na₂CO₃ (20°C) and the carbohydrate composition and metabolism during development determined. Young persimmon fruits contained a large proportion of pectins, 46% by dry weight, that decreased to 20% with ripening. This decrease occurred in the CDTA and Na₂CO₃ (1°C) fractions, mainly composed of uronic acids, and represents a net loss of uronic acids, arabinose and galactose. The amount of non-cellulosic neutral sugars was especially high in the Na₂CO₃ (20°C) fraction. The loss of pectins was also accompanied by a depolymerisation of the polysaccharides extracted in the three pectic fractions. However, none of these changes can be attributed to the action of polygalacturonase activity. Proteins were extracted from the pericarp tissue, but endopolygalacturonase (EC 3. 2. 1. 15) activity, determined as a decrease in viscosity of polygalacturonic acid, was not observed in the extract. Determination of exopolygalacturonase (EC 3. 2. 1. 67) activity by measuring the release of reducing groups from polygalacturonic acid was also negative. The results presented indicate that polygalacturonase is not responsible for the metabolism of pectins during persimmon fruit ripening.     

Cell wall metabolism in gibberellin-treated persimmon fruits

The application of gibberellin [GA₃] to persimmon fruits as an orchard spray, at least 2 weeks prior to harvest, has been shown to delay ripening of the fruit on the tree and its rate of softening after harvest. This effect persisted during and after cold storage. The delay in softening has been attributed to the effect of the phytohormone on cell wall metabolism. To examine this hypothesis, cell walls of GA₃-treated fruit were compared to those of non-treated fruit. Comparison between fruit was from harvest till the termination of post-storage softening. The study included TEM examinations, assay of certain hydrolase activities and determination of compositional changes occurring in the various cell-wall carbohydrate polymers. Our findings indicate that GA₃ either delays or inhibits all of the cell wall changes that were found to accompany fruit softening, including dissolution of the middle lamella, separation of the plasmalemma from the cell-wall, mitigation of the structural coherence and density of the primary cell wall, increases solubilization of pectic polymers, loss of neutral sugars, predominantly arabinose and galactose, and increased activities of exo-polygalacturonase [PG] and endo-1,4--glucanase [EGase]. The principal discernible compositional difference between GA₃-treated fruit and control fruit at harvest was a higher total carbohydrate content in the cell wall material extracted from GA₃-treated fruit, which was due chiefly to an increased amount of cellulose.     

柿属君迁子和湖南九个乡土柿品种过氧化物酶同工酶的研究

用聚丙烯酰胺凝胶垂直板电泳,分析了柿属君迁子(D.lotus)和湖南九个乡土柿品种的过氧化物酶同工酶。并根据柿苗茎部酶谱的相似值,进行了模糊聚类分析,划分了类群,探讨了各类群之间的亲缘关系,初步确定了冰糖柿、槟榔柿、君迁子是一个较为原生的类群,其它4类分化程度较大,进化历史较长,但都与冰糖柿有着密切的亲缘关系。     

How fast and far might tree species migrate in the eastern United States due to climate change?

Aim We describe and use a model, SHIFT, to estimate potential migration due to climate change over the next 100 years. Location Eastern United States. Methods Five species, currently confined to the eastern half of the United States and not extending into Canada, were used to assess migration potential: Diospyros virginiana (persimmon), Liquidambar styraciflua (sweetgum), Oxydendrum arboreum (sourwood), Pinus taeda (loblolly pine), and Quercus falcata var. falcata (southern red oak). SHIFT is a matrix simulation model using simple inverse power functions to provide a distance decay of seed dispersal and is driven primarily by the abundance of the species near the boundary, the forest density within and beyond the boundary, and the distance between cells. For each cell outside the current boundary, the model creates an estimate of the probability that each unoccupied cell will become colonized over a period of 100 years. SHIFT is a ‘fat‐tailed’ migration model that allows rare very long distance dispersal events and colonization could occur up to 500 km beyond the current distribution boundary. Model outputs were analysed using transects through sections showing relatively low and high colonization probabilities as a result of low and high densities of target trees (high source strength) as well as high densities of forest (high sink strength). We also assess migration potential for species by concentric rings around the current boundary. Results Model outputs show the generally limited nature of migration for all five species over 100 years. There is a relatively high probability of colonization within a zone of 10–20 km (depending on habitat quality and species abundance) from the current boundary, but a small probability of colonization where the distance from the current boundary exceeds about 20 km. Whether biologically plausible or not, rare very long distance migration events are not sufficient to rescue migration. Species abundance (the source strength of migration) near the range boundary carried relatively more influence than percentage forest cover (sink strength) in determining migration rates. Main conclusion The transect evaluation revealed the importance of abundance of the species near the boundary, indicating that rare species may have much more difficulty in unassisted northward migration due to climate change. The concentric rings analysis of the model outputs showed that only the first 10–20 km of area would have a reasonably high probability of colonization. Rare, long‐distance events permit colonization of remote outliers, but much more needs to be understood about the likelihood of these rare events to predict the frequency of outlier establishment.     

Seed dispersal of Diospyros virginiana in the past and the present: Evidence for a generalist evolutionary strategy

Several North American trees are hypothesized to have lost their co‐evolved seed disperser during the late‐Pleistocene extinction and are therefore considered anachronistic. We tested this hypothesis for the American persimmon (Diospyros virginiana) by studying the effects of gut passage of proposed seed dispersers on seedling survival and growth, natural fruiting characteristics, and modern animal consumption patterns. We tested gut passage effects on persimmon seeds using three native living species, the raccoon (Procyon lotor), Virginia opossum (Didelphis virginiana), and coyote (Canis latrans), and two Pleistocene analogs; the Asian elephant (Elephas maximus) and alpaca (Vicugna pacos). Persimmon seeds excreted by raccoons, coyotes, and elephants survived gut transit. Gut passage did not affect sprouting success, but did tend to decrease time to sprout and increase seedling quality. Under field conditions, persimmon fruits were palatable on the parent tree and on the ground for an equal duration, but most fruits were consumed on the ground. Seven vertebrate species fed upon persimmon fruits, with the white‐tailed deer (Odocoileus virginianus)—a species not capable of dispersing persimmon seeds—comprising over 90% of detections. Conversely, potential living seed dispersers were rarely detected. Our results suggest the American persimmon evolved to attract a variety of seed dispersers and thus is not anachronistic. However, human‐induced changes in mammal communities could be affecting successful seed dispersal. We argue that changes in the relative abundance of mammals during the Anthropocene may be modifying seed dispersal patterns, leading to potential changes in forest community composition.     

柿树减数分裂和小孢子形成过程的观察

研究了柿树品种“禅寺丸”（２ｎ＝６ｘ＝９０）的减数分裂和小孢子形成过程。同源染色体配对和分离基本正常,中期Ⅰ构型为４５Ⅱ,但出现似多价体（次级配对）,观察发现了不减数分裂现象。不减数发生的第１次分裂,第２次分裂时可见２个ｎ＝９０的子核。未减数子核在四分体期形成二分体,小孢子期形成大型花粉粒。观察结果提示了柿树多倍体由未减数配子受精产生的可能性。     

Development of SSR primers using ISSR–PCR in Diospyros kaki Thunb.

Nine polymorphic single sequence repeat (SSR) primers were developed in Japanese persimmon using inter‐SSR (ISSR) suppression polymerase chain reaction (PCR). These primers were tested on 30 individuals from Japan and China. The number of alleles per locus ranged from five to 20. Expected (H_E) and observed (H_O) heterozygosities at each locus ranged from 0.42 to 0.77 and 0.27 to 0.59, respectively. The SSR primers developed herein could be applied to cultivar identification, estimation of genetic diversity and divergence in Diospyros spp.     

Un gisement a plantes des formations pliocènes des environs de Rasteau près Vaison-la-Romaine (Vaucluse): Stratigraphie,faune, étude des macrorestes végétaux,palynologie

A new Pliocene deposit with vegetal impressionswas discovered at Rasteau (near Vaison-la-Romaine, Vaucluse. The study of these impression and the sporopollinic analysis from many levels allows us to specify its stratigraphical position in the Pliocene of the Rhone valley. So, the above mentioned levels settled just before the Hautimagne deposit (Neogene zone MN 14 for the mammals). The macroflora and the microflora appear to be related with a temperate warm and wet climate.     

Antiprotozoal and cytotoxic naphthalene derivatives from Diospyros assimilis

Chemical investigation of the roots of Diospyros assimilis had led to the isolation and characterization of six naphthalene derivatives, two 2-naphthaldehyes, namely 4-hydroxy-3,5-dimethoxy-2-naphthaldehyde 1, 4-hydroxy-5-methoxy-2-naphthaldehye 2, its related isomer 5-hydroxy-4-methoxy-2-naphthaldehyde 3 and three commonly occurring naphthoquinones, diospyrin 4, 8'-hydroxyisodiospyrin 5 and the simple monomer, plumbagin 6. Their chemical structures were established by detailed NMR investigations including 1H and 13C NMR, HSQC, HMBC and NOESY experiments. In addition, the naphthalene derivatives 1-5 were evaluated for their in vitro antiprotozoal activity against protozoan parasites belonging to the genera Trypanosoma, Leishmania and Plasmodium. Among the tested compounds, naphthaldehyde 1 showed moderate inhibition of the growth of the parasites, T. brucei, T. cruzi, L. donovani with IC50 values of 19.82, 12.28 and 38.78 microM and displayed cytotoxicity towards rat skeletal myoblasts (L-6 cells) with IC50 of 174.94 microM, while 2 and 3 were found to be comparatively less active to 1. The dimeric quinones 4 and 5 exhibited good activity against T. brucei and L. donovani with IC50 of 1.12 and 8.82 microM and 12.94 and 16.66 microM respectively.