盐胁迫对扁桃光合特性和叶绿体超微结构的影响

温室条件下,分别用浓度为150、300、350 mmol/L的NaCl和Na2SO4处理‘石头扁桃’和‘桃扁桃’实生苗植株,处理10 d后分别测定其叶片叶绿素含量、净光合速率、气孔导度、细胞间隙CO2浓度,并观察叶绿体超微结构的变化。研究发现:(1)盐胁迫下,‘石头扁桃’和‘桃扁桃’chl a、chl b均在低浓度盐区含量最高,而在高浓度盐区含量最低,Na2SO4处理区chl a、chl b含量均低于NaCl处理区;(2)‘石头扁桃’和‘桃扁桃’叶片净光合速率随盐浓度的增加而下降,‘石头扁桃’下降的幅度较大;(3)‘桃扁桃’叶片细胞间隙CO2浓度随盐浓度的增加而升高,但‘石头扁桃’叶片细胞间隙的CO2浓度变化没有稳定的规律;(4)2个品种的叶片气孔导度均随盐浓度的增加而降低;(5)盐胁迫后,叶绿体基粒、基质片层扭曲,类囊体肿胀;随盐浓度的增加,形变加剧,叶绿体由椭圆形肿胀成圆形,叶绿体膜解体,且‘石头扁桃’叶绿体对盐胁迫比较敏感。综合分析发现,2种盐胁迫对植物造成伤害的机理不同,‘石头扁桃’的耐盐能力较差。     

Molecular genetics of growth and development in Populus (Salicaceae). v. mapping quantitative trait loci affecting leaf variation

We examined the genetic variation of leaf morphology and development in the 2-yr-old replicated plantation of an interspecific hybrid pedigree of Populus trichocarpa T. & G. and P. deltoides Marsh. via both molecular and quantitative genetic methods. Leaf traits chosen were those that show pronounced differences between the original parents, including leaf size, shape, orientation, color, structure, petiole size, and petiole cross section. Leaves were sampled from the current terminal, proleptic, and sylleptic branches. In the F2 generation, leaf traits were all significantly different among genotypes, but with significant effects due to genotype X crown-position interaction. Variation in leaf pigmentation, petiole length. And petiole length proportion appeared to be under the control of few quantitative trait loci (QTLs). More QTLs were associated with single leaf area, leaf shape, lamina angle, abaxial color, and petiole flatness, and in these traits the number of QTLs varied among crown positions. In general, the estimates of QTL numbers from Wright's biometric method were close to those derived from molecular markers. For those traits with few underlying QTLs, a single marker interval could explain from 30 to 60% of the observed phenotypic variance. For multigenic traits, certain markers contributed more substantially to the observed variation than others. Genetic cluster analysis showed developmentally related traits to be more strongly associated with each other than with unrelated traits. This finding was also supported by the QTL mapping. For example, the same chromosomal segment of linkage group L seemed to account for 20% of the phenotypic variation of all dimension-related traits, leaf size, petiole length. and midrib angle. In both traits. the P. deltoides alleles had positive effects and were dominant to the P. trichocarpa alleles. Similar relationships were also found for lamina angle. abaxial greenness, and petiole.     

The genus Pyrus L. (Rosaceae) in south-west Europe and North Afkica

A multivariate morphometric study of the genus Pyrus in south-west Europe and North Africa shows that five species may be recognized in the area: P. bourgaeana Decne., P. communis L., P. cordata Dew., P. spinosa Forssk, and P. nivalis Jacq. Some valuable characters for identification of these species are proposed. In particular the width of fruit peduncle, petal size, leaf width and petiole length served to discriminate the taxa. Several names such as P. gharbiona Trab., P. cossonii Rehder (|M= P. longipes Balansa ex Coss. & Durieu) and P. boisseriana Buhse, are regarded as synonyms of P. cordata , while P. marnormis Trab. of P. bourgaeana. Consequently a check-list and a key to these species are provided.     

Seed traits,nutrient elements and assessment of genetic diversity for almond (Amygdalus spp.) endangered to China as revealed using SRAP markers

Almond (Amygdalus spp.) is one of the most important nut fruits worldwide and its seed has been recognized as a health nutrient supply for human consumption. In this study, we characterized the major seed traits and fruit nutrient elements among four Chinese wild almonds (Amygdalus mongolica Maxim., Amygdalus pedunculata Pall., Amygdalus tangutica Batal., and Amygdalus triloba (Lindl) Ricker.) in addition to commercial two cultivars (Amygdalus communis L.), as well as their genetic diversity and natural variations using SRAP marker, aiming at exploiting valuable traits for breeding new cultivars. Our results show that the wild almond species are rich in crude fat, Ca, Ma, Fe and Zn compared to the cultivars analyzed. Our study also identified a relatively high level of genetic diversity (h = 0.3363, I = 0.5075) among species analyzed as evidenced by fact that 161 out of a total of 162 bands amplified with fourteen SRAP primer combinations reveal polymorphism among species analyzed. AMOVA analysis reveals a high level of genetic differentiation among populations (Φ_ST = 0.4474) but The UPMGA cluster analysis indicates that A. communis and A. mongolica are more closely related. Potential utilization of the wild almond species and their valuable traits for breeding new cultivars is discussed.     

Effect of temperature, irradiance and photoperiod on morphological characters of seedlings of contrasting white clover populations

Seedlings of 10 contrasting white clover populations differing in leaf size and origin were grown in a glasshouse in spring and autumn, and in controlled environments in which temperature (10°, 15°, 20°C), photoperiod ( 8 , 16-h) and irradiance ( 13, 47 , 57 Wm^-2) were varied. There were large effects of these environmental variables on a range of morphological characters. Population differences were closely related to classification of the populations by leaf size. Within the large leaf types there was also an effect of origin. In particular, Mediterranean types differed from those of northern origin. Rate of leaf appearance increased with temperature but was less affected by photoperiod. Population differences were greater at lower temperatures. Petiole length was more sensitive to temperature than was leaflet length, particularly in the range 10° to 15°C. Similarly, petiole length increased appreciably with photoperiod extension; smaller leaf types responded more than large leaf types with the result that there were no population differences in the 16-h photoperiod. Population differences in the other environments were closely related to leaf size classification. The onset of stolon production was delayed by lower temperatures and by short photoperiods but stolon number at the sixth leaf stage of development was not closely related to this character in the temperature environments since stolon numbers increased at lower temperatures. In low temperature and short day conditions the large leaf types including those of Mediterranean origin showed a desirable combination of long petioles and large leaves compared with the smaller leaf types. However, these differences between the two groups were eliminated for petiole length, and much reduced for leaflet length, by the greater response to temperature and photoperiod of the smaller leaf types. The implications of these responses for seasonal production are discussed. There were large effects of irradiance on the lengths of leaflets and petioles with longer ones at higher irradiance levels. There were also faster rates of leaf appearance at higher light levels. Stolon production was faster at 57 Wm^-2 than at 47 Wm^-2 while at 13 Wm^-2 no stolons were produced. After an extended period in the lowest light environment there was some plant mortality.     

The taxonomic relationships within the genus Excoecaria L. (Euphorbiaceae) based on leaf morphology and rDNA sequence data

The tropical Indo-Pacific genus Excoecaria L. (Euphorbiaceae) has several closely related species in Australia whose taxonomic relationships are unclear. The most widely reported species in Australia is the mangrove species Excoecaria agallocha L. (type species), whose taxonomic and geographic limits are difficult to define from its closely related species or sub-species. Two additional taxa have also been described but not clearly differentiated from the type species: Excoecaria dallachyana Baillon and Excoecaria ovalis Endl. This project aimed to determine the taxonomic relationships of the Australian Excoecaria species using both leaf morphological data and DNA sequence data from the internal transcribed spacer (ITS) region of ribosomal genes. The nucleotide differences in the examined ITS1 region show that E. agallocha from eastern Australia and E. ovalis from Western Australia respectively, are genetically uniform within species but differ from each other consistently, thus supporting species status. The leaf morphological data also support this view: single factor analysis of variance consistently separated E. ovalis from E. agallocha on the basis of leaf width, leaf length and length of petiole. In contrast, E. ovalis from the Gulf of Carpentaria differs only slightly from E. ovalis in Western Australia, but no evidence was found to suggest any leaf morphological differentiation within this species. The analysis also suggests that E. dallachyana is not closely related to either mangrove species E. agallocha or E. ovalis, despite superficial morphological similarities.     

Primulina maciejewskii sp. nov. (Gesneriaceae) from Guangdong,China

Primulina maciejewskii F. Wen, R.L. Zhang & A.Q. Dong, a new species of Primulina (Gesneriaceae) from Guangdong, China, is described and illustrated. It is similar to P. lobulata and P. danxiaensis in leaf and flower shape, but can be distinguished by bract shape, peduncle, pedicel, and bract size, filament and anther indumentum, and number of bracts, staminodes and stigma.     

扁桃愈伤组织诱导及分化的研究

以扁桃优良品种'Naporeil'的茎段、叶片和花药作为外殖体,分别对其进行愈伤组织诱导和分化研究,以筛选愈伤组织的最佳诱导增殖培养基、分化培养基和生根培养基.结果表明,该品种以茎段、花药作为外殖体最易诱导获得愈伤组织,叶片不适宜作为外殖体诱导愈伤组织;愈伤组织的最佳诱导增殖培养基均为B5+0.5 mg/L 2,4-D+0.2 mg/L 6-BA+1.0 mg/L NAA,愈伤组织诱导率为100%,增殖倍数最高可达7倍;茎段愈伤组织的分化培养基为MS+0.2 mg/L NAA+0.8 mg/L 6-BA+0.5 mg/L ZT,分化率为71%;花药愈伤组织未见分化.由茎段愈伤组织再分化获得的不定芽在1/2MS+0.5 mg/L IBA培养基上诱导生根,并给以黑暗预处理可使生根率达80%以上.     

The functional morphology of light capture and carbon gain in the Redwood forest understorey plant Adenocaulon bicolor Hook

1. A three-dimensional geometric simulation model of crown architecture was utilized to investigate the efficiency of light capture and its relationship to whole-plant CO₂ assimilation of Adenocaulon bicolor .
2. Positioning of the leaves by the combined effects of ontogenetic variations in petiole length and angle and leaf size, and the leaf divergence angles were shown to be effective in minimizing self shading. The efficiency of light absorption varied from 0·64 to 0·70 among individual plants that were sampled.
3. Plant to plant variation in simulated daily carbon gain was strongly influenced by variations in the direct and diffuse PFD received by the individual plants. When simulations were run for all plants under a single common light environment, the carbon gain was strongly dependent on the efficiencies of light absorption of the different plants.
4. Simulations in which petiole length was varied showed a non-linear dependence of light absorption efficiency on petiole length. When both petiole length and leaf size were varied in a way that maintained a constant biomass then an optimal petiole length that corresponded to the observed petiole length was apparent. The observed divergence angle between successive leaves also maximized light absorption efficiency as compared to greater or lesser angles, but increases in internode length had no significant effect.
5. The results of this study provide evidence for selection for an 'optimal design' of crown architecture in Adenocaulon bicolor that maximizes light capture.     

Patterns of leaf size and morphology in relation to shoot length in Tsuga canadensis

Summary Pattern of change in leaf character was assessed along the length and around the circumference of Tsuga canadensis (L.) Carr. shoots of different length classes. Leaf size decreased, and number of leaves per unit length of shoot increased, with decrease in shoot length. Acropetally along the shoots, lamina length and width decreased, relative petiole length increased, apices became more pointed, and leaf margins bore more teeth. Around the shoot, from upper to side, and to lower surfaces, leaf size and number of marginal teeth in the proximal halves of leaves increased. These patterns were related both to production of preformed versus neoformed leaves, though their separation was indistinct, and to secondary orientation of leaves by twisting in their petiolar regions into two major bi-lateral ranks. An additional minor rank occurred along the upper surfaces of the shoots where secondary orientation of the leaves was minimal. Surface features of leaves did not differ in any obvious manner. Leaves on sylleptic shoots, which by definition were all neoformed, exhibited similar patterns, but were generally smaller than those on their parent shoots.     

GRAVITY-INDUCED EFFECTS ON MATERIAL PROPERTIES AND SIZE OF LEAVES ON HORIZONTAL SHOOTS OF ACER SACCHARUM (ACERACEAE)

The influence of gravity on the size and mechanical properties of mature leaves on horizontal shoots and etiolated seedlings of Acer saccharum Marsh. (Aceraceae) was examined. Leaves were grouped into three categories regarding their location on shoots (dorsal or “top” T, lateral or “left/right” L/R, and ventral or “bottom” B). Young's modulus E, petiole length L, lamina surface area A and weight P, and the cross-sectional areas of different tissues within petioles were measured for each leaf and were found to be correlated with leaf location (T, L/R, and B): T leaves were smaller and had lower E than their B counterparts; the size and material properties of L/R leaves were intermediate between those of T and B leaves. In general, A, P, and E decreased from the base to the tip of shoots. In addition to anisophylly, the influence of gravity induced petiole bending and torsion and resulted in the horizontal planation of laminae. This was observed for field-grown mature plants and etiolated seedlings. Petiole bending and torsion were interpreted as gravimorphogenetic phenomena. Anatomically, L, E, and petiole deflection angle Fv measured from the vertical were highly correlated with the combined cross-sectional areas of phloem fibers and xylem in petioles of B leaves and when data from all leaves were pooled. It is tentatively advanced that the correlation of E with the transverse areas of phloem fibers and xylem is evidence that either the pattern or the extent of lignification of petiole tissues is influenced by petiole position with respect to gravity.     

Population ecology in a natural<Emphasis Type="Italic">syneilesis palmata</Emphasis> stand: II. vegetative growth and population structure

Vegetative growth and changes within populations ofSyneilesis palmata (THUNB>) MAX. Usannamul were monitored in two natural stands with different levels of incoming light. This perennial, shade-tolerant herb was measured for its plant size, petiole length, leaf breadth, and leaflet number over 11 years in a moderately shaded (MS) stand and over 7 years in a severely shaded (SS) stand. At the end of each growing season, a shoot primordium developed at the center of the root system. Correlation coefficients were mostly high between pairings of two properties - total weight, petiole length, petiole weight, leaf breadth, leaf blade weight, leaf area, specific leaf area, and leaflet number. Mean annual mortality of this species was higher in SS (22.97%) than in MS (8.85%), but great fluctuations were seen from year by year. Mortality was lowest for medium-sized plants. Regarding petiole length, differences in mean annual growth rates were conspicuous, i.e., 2.6% in MS and 8.4% in SS, while growth rates for leaf breadth were 3.1% in MS and 24.2% in SS. Changes in plant frequency within individual size classes roughly showed a normal distribution curve. However, the mode varied year by year, and such changes were more remarkable in SS than in MS. Under severe shading,S. palmata had a higher growth rate and but also greater mortality than did plants under moderate shade. Therefore, one can conclude that the population structure in SS was unstable over time.     

Variation in growth of overwintered stolons of contrasting white clover populations in response to temperature, photoperiod and spring environment

The response of overwintered stolons of nine contrasting white clover populations to temperature, photoperiod and natural conditions was studied in six environments during the spring. Rate of leaf appearance, leaflet length, petiole length, stolon internode length, dry matter distribution within the plant and total dry weight were measured on 15 plants of each population/environment combination. Most characters, except leaf size and proportion of dry matter allocated to leaf, responded positively to temperature in the range 10 – 20°C. A positive effect of photoperiod extension was also found for all characters except rate of leaf appearance, internode length and distribution of dry matter to leaf. Population differences in response to environment were found which were related to both leaf size classification and origin. Stolon dry weight was positively correlated with leaf length, petiole length and stolon internode length in most environments. The relationships between the eight characters were often complex and canonical variate analysis provided a convenient way to discriminate between the populations based on all eight characters.     

Scaling of xylem vessels and veins within the leaves of oak species

General models of plant vascular architecture, based on scaling of pipe diameters to remove the length dependence of hydraulic resistance within the xylem, have attracted strong interest. However, these models have neglected to consider the leaf, an important hydraulic component; they assume all leaves to have similar hydraulic properties, including similar pipe diameters in the petiole. We examine the scaling of the leaf xylem in 10 temperate oak species, an important hydraulic component. The mean hydraulic diameter of petiole xylem vessels varied by 30% among the 10 oak species. Conduit diameters narrowed from the petiole to the midrib to the secondary veins, consistent with resistance minimization, but the power function scaling exponent differed from that predicted for stems. Leaf size was an organizing trait within and across species. These findings indicate that leaf vasculature needs to be included in whole-plant scaling models, for these to accurately reflect and predict whole-plant transport and its implications for performance and ecology.     

First record of the ant subfamily Aenictinae (Hymenoptera,Formicidae) from Saudi Arabia,with?the description of a new species

The ant subfamily Aenictinae is recorded for the first time from the Kingdom of Saudi Arabia and for the second time from the Arabian Peninsula. A new species Aenictus arabicus sp. n., is described from the worker caste. Aenictus arabicus belongs to the Aenictus wroughtonii-group and appears to be most closely related to Aenictus rhodiensis Menozzi, but can be easily distinguished from the latter by the following characters: overall smaller size; cephalic index (head width/head length) small; occipital corners in lateral view rounded; antennal scape when laid back surpassing approximately two-thirds of head length; funicular segments 2–8 each at least 2× as long as broad; subpetiolar process well developed; petiole and postpetiole distinctly imbricate; gaster and clypeus entirely yellow, teeth of mandibles reddish- brown. Aenictus arabicus was collected from leaf litter, next to a tree of Psidium guajava L. The new species also is similar to Aenictus sagei and Aenictus wroughtonii. Affinities and a key to related species of the species group are given.     

放牧后羊草和芦苇叶组织转化的比较

运用组织转化理论与分析方法,对羊草与芦苇在放牧后的叶组织转化进行了比较研究。结果表明,整个生长季内,除5月份外,芦苇的绿叶数大于羊草,羊草的绿叶长大于芦苇;2种禾草的叶片发生率和伸长率均在生长初期最大,以后逐渐降低,萎蔫率正好相反;芦苇叶片寿命短,叶组织转化快、叶组织物质积累呈抛物线型增长,如果不及时利用,会造成资源的浪费,羊草叶片寿命较长,叶组织转化慢。可以通过不同的利用方式和时间来改善羊草草地的质量。     

ORGANIZATION AND ONTOGENY OF THE VASCULAR SYSTEM IN THE PETIOLE OF EASTERN COTTONWOOD

The topologic arrangement of petiolar bundles varies within the length of the cottonwood petiole. Each petiolar bundle is formed by the subdivision and aggregation of acropetally differentiating subsidiary bundles in a predictable pattern. The subsidiary bundles provide vascular continuity between the stem and specific portions of the leaf lamina. Spot-labeling of individual veins with ¹⁴CO₂, freeze substitution, and microautoradiography were used to establish the relation between the secondary veins of the lamina and the vasculature of the petiole. Within the petiole vasculature each subsidiary bundle was continuous with a specific portion of the lamina and seemed to have a separate function. Subsidiary bundles continuous with the central leaf trace were closely related functionally to the tip region of the lamina, while the subsidiary bundles continuous with the lateral leaf traces were functionally related to the middle and basal portions of the lamina.     

Primula vallicola sp. nov. (Primulaceae) from Sichuan,China

A new species of Primula, P. vallicola Y. Xu, G. Hao & C.M. Hu, is described and illustrated from Sichuan province, China. Based on general morphology the new species is assigned to Primula sect. Aleuritia subsect. Yunnanensis. It is closely allied to P. kialensis, but can be distinguished by its larger stature, leaf shape, and the well‐differentiated petiole. The leaf shape of the new species is ovate to ovate‐elliptic and usually sub‐rounded at base. The new species also resembles P. homogama, but differs in being glabrous rather than with appressed hairs, and with longer petiole.     

Magnolia tiepii sp. nov. from Vietnam

A new species of Magnolia sect. Gwillimia DC., Magnoliaceae from Vietnam is described and illustrated. Magnolia tiepii is recognized from southern Vietnam, where it occurs in Khanh Vinh slope, Khanh Vinh District, Khanh Hoa Province. It is distinguished from the closely related M. henryi by having narrowly cuneate leaf blade, short petiole, stipular scar at the base of the leaf blade, short peduncle and ellipsoid fruit.     

Primulina rubella sp. nov. (Gesneriaceae) from a limestone area in Guangdong,China

A new species of Primulina (Gesneriaceae) from a limestone area in southern China, P. rubella L.H. Yang & M. Kang, is described and illustrated. The new species has purple‐red flowers and is thus similar to P. lijiangensis, but differs by its petiole, leaf blade, cyme, filament, stigma and ovary. In adition, a molecular phylogenetic reconstruction indicated that P. rubella and P. lijiangensis belong to quite different clades. Instead, P. rubella appears to be closely related to the sympatric P. qingyuanensis, although these two species are obviously differentiated both in terms of flower color and other vegetative and floral characters. The conservation status of P. rubella is assessed as ‘Critically Endangered’ (CR) according to the IUCN red list categories and criteria.