抗虫转基因银河杨的生长特性和抗虫性

以非转基因银河杨(Populus alba×Populus hopeiensis)为对照,对抗虫转基因银河杨抗虫基因Cry3A的稳定性,转基因银河杨的物候期、生长状况和抗虫性进行研究。结果发现,Cry3A基因整合稳定,在根、茎、叶中RNA和蛋白水平均有表达,不同组织中Bt蛋白水平差异显著,茎中Bt蛋白水平最高。抗虫转基因银河杨的物候期、生长状况未发生显著变化,但表现出显著的抗虫性。     

Biennial variation in production of new shoots in groves of the giant bamboo Phyllostachys pubescens in Sichuan,China

The phenological pattern of fifteen Mediterranean phanaerophytes has been studied in several sites per species, by visiting the populations on a monthly basis over a one year period. Studied phenophases were dolichoblast vegetative growth (DVG), flower bud formation (FBF), flowering (F), fruit setting (FS), seed dispersal (SD), and leaf shedding of dolichoblasts (LSD). Considering the whole set of species, DVG, FBF and F took place mainly in spring, FS in summer, SD in autumn and LSD in summer and in autumn. Interspecific comparisons showed a wide variety of phenological patterns, which have been sorted according to the 'phenophase sequence index' (PSI). This index quantified the degree of superposition between DVG, FBF and F, and it constituted the basis for a functional classification of phenological patterns. Two groups were established. The 'type I' group was characterised by the concentration of phenophases in a short time in spring, while the 'type II' by the protraction and sequential arrangement of phenophases. Type I species performed most of their functions during a resource surplus period, but they have to face an intraplant competition between vegetative and reproductive demands. Type II species avoided intraplant competition but had to develop part of DVG, FBF and F during sub-optimal periods. It is hypothesised that type I species possess deeper roots, rely on predictable water sources and occupy mature stages of succession. Type II species, on the contrary, are expected to depend on more unpredictable water sources, to possess shallower root systems and to colonise earlier stages of succession. Intraspecific variability of phenology was found to be low among populations of the same species. Bud structure, which is a phylogenetic trait, may exert important constraints on plant phenology.Nomenclature: Flora Iberica – Castroviejo et al. 1986–1997, Flora Europaea – Tutin et al. 1964–1980.     

桃(Prunus persica)种质资源物候期性状遗传多样性的评价指标探讨

本试验对桃（Prunus persica）的301～480份种质资源的需冷量、始花期、大量落叶开始期、大量落叶终止期、果实生育期、营养生长期6个性状的遗传多样性进行了统计分析,根据性状在不同区问的频率分布,提出我国桃种质资源物候期性状评价系统的数值分级指标和参照品种,为我国桃种质资源描述系统的数量化、规范化奠定基础。     

Comparative phenological and water potential patterns of three Calligonum species in the eastern great Erg of Tunisia

Calligonum azel, C. comosum and C. arich (Polygonaceae) are three dominant and economically important species widely distributed in active sand dunes in the southern desert of Tunisia, which differ in growth form and may co-occur under the same climatic constraints. The aims of this work were to compare their phenological and water potential patterns, as well as branch, flower and fruit production during three years at monthly intervals. Predawn (Ψ_pd) and midday (Ψ_md) water potentials followed similar trends with a few exceptions. For all species, Ψ_md reached values more negative than −2.5 MPa during the hot and dry summer, with extremes in July. Ψ_pd differed between the species, and C. comosum attained the most negative values (−1.71 MPa). Seasonal differences in Ψ_pd were less pronounced for Calligonum species established in dunes as compared to C. comosum from interdunes. Spatial and temporal variations in soil water content provoked changes in water potentials of these species. Diurnal amplitudes resulting from the difference between Ψ_md and Ψ_pd were more pronounced during the dry season compared to the wet months. The phenological pattern of the three species showed a similar sequence of phenophases with growth activity occurring mostly between spring and summer. We found a species-dependent response to summer drought, as C. comosum ended all phenophases in June, while C. azel and C. arich extended their vegetative growth into the summer period of low precipitation. Water availability for the plants was better on the dune slopes. Differences were statistically significant among species, concerning green branch production and numbers of initially formed flowers and mature fruits. Our data suggest that changes in the studied parameters may depend on the rooting depth of the species.     

Critical periods as fundamental events in life

Development is not a continuous phenomenon. Rather, phenophases are interspaced with short critical periods. This phenomenon reflects an alternance between stabilization (during a phenophase) and dismantling (during a critical period) of a network of between-organ relationships generating the organism. Networks of relationships may be compared to dissipative systems in physics. In this context, a critical period represents a transient phase of isolation of the systems enabling its evolution towards equilibrium. As suggested here, this transition from dissipative to isolated system represents the source of newly emerging dissipative structures in which environmental or developmental perturbations are adaptively integrated. In contrast to non-living systems, an endogenous control of the transition towards critical period seems to exist during development. By extension to other scales of biological organization, it is suggested that the capacity to self-define its status (dissipative or close-to-equilibrium) represents the key property of living systems. This asks for a reconsideration of some basic notions about life, such as the role of genes in normal development, in physiological adaptation, and even in the emergence of evolutionary novelty.     

Trade-offs between phenology,relative growth rate,life form and seed mass among 22 Mediterranean woody species

Mediterranean woody plants exhibit a wide phenological diversity which cannot be explained just on the basis of climatic constraints. We assessed the role of relative growth rate (RGR), life form, seed and fruit mass as potential constraints of plant phenology. In a comparison of traits of 22 Mediterranean woody plant species, the duration of the primary shoot growing period decreased from climbers to shrubs and to trees. A hypothesised negative association between RGR and primary shoot growth duration did not emerge in our species set. The mechanism underlying phenological differences between plant life forms might relate to differences in the proportion of respiring to photosynthetic tissues, which decreases from climbers to trees. It is suggested that the degree of shoot preformation within the bud correlates with primary shoot growth duration, but not with RGR. Development of big fruits and seeds competes for carbon with vegetative growth. Indeed, species with bigger seeds and fruits exhibited shorter primary shoot growing periods, which tended to overlap with flower bud formation and flowering periods. We suggest that duration of primary shoot growth allow to short out the species between two extreme growth strategies: The conservative one would be characterised by a concentration of the primary shoot growth into a short period, free of frosts and droughts, and by a diversion of part of the current resources to assure next year's growth. The opportunistic strategy, on the other extreme, would be defined by the allocation of resources to current growth whenever they are available, achieving longer growing periods at the expense of higher risk of tissue damage. These strategies should have been selected for in environments of predictable and unpredictable resource availability, respectively.