Reproductive Biology of Erythrina falcata (Fabaceae: Papilionoideae)1

Reproductive phenology, floral biology, degree of self‐incompatibility, and floral visitors of Erythrina falcata were studied in an Argentinean population. Flowering occurs during the dry season from late August to late October. Flower lifetime is 5–6 d. Phylogenetic studies indicate that E. falcata, together with E. fusca and E. crista‐galli, are included in a basal clade within Erythrina. Its phylogenetic position, floral morphology, and nectar characteristics suggest a hummingbird–passerine mixed pollination system. The flowers are nontubular, and the vexillum (the upper petal of the corolla) covers the other remaining floral parts until displaced by a visiting passerine (Icterus cayanensis) or a hummingbird (Amazilia chionogaster). Both birds act as pollen vectors. Bees were observed as occasional pollinators. Nectar production begins at anther dehiscence and coincides with maximum stigmatic receptivity. The base of the keel forms a secondary nectar reservoir. Controlled pollinations showed that this species is self‐incompatible, although a few fruits develop from selfing. Pollen:ovule ratio (43,200:7) is as expected for a xenogamous plant. Only 1 percent of the flowers set seeds under natural conditions. Possible explanations for the low reproductive success are discussed.     

Seed abortion in Pongamia pinnata (Fabaceae)

In Pongamia pinnata only one of the two ovules develops into a seed in most of the pods. Since pollen was not found to be limiting and reduced fertilization could not completely explain the observed frequency of seed abortion, it implied an effect of postfertilization factors. Aqueous extracts of developing seeds and maternal tissue (placenta) did not influence abortion in vitro, suggesting that abortion may not be mediated by a chemical. Experimental uptake of ¹⁴C sucrose in vitro indicated that both the stigmatic and the peduncular seed have similar inherent capacities of drawing resources, but the peduncular seed is deprived of resources in the presence of the stigmatic seed. This deprivation of the peduncular seed could be offset by supplying an excess of hormones leading to the subsequent formation of two seeds in a pod. The prevalence of single-seeded pods in P. pinnata seems therefore to be a result of competition between the two seeds for maternal resources. The evolutionary significance of single-seeded pods in P. pinnata is discussed with respect to possible dispersal advantage enjoyed by such pods.     

Ultrastructure and post-floral secretion of the pericarpial nectaries of Erythrina speciosa (Fabaceae)

Background and Aims

The occurrence of nectaries in fruits is restricted to a minority of plant families and consistent reports of their occurrence are not found associated with Fabaceae, mainly showing cellular details. The present study aims to describe the anatomical organization and ultrastructure of the pericarpial nectaries (PNs) in Erythrina speciosa, a bird-pollinated species, discussing functional aspects of these unusual structures.

Methods

Samples of floral buds, ovaries of flowers at anthesis and fruits at several developmental stages were fixed and processed by the usual methods for studies using light, and scanning and transmission electron microscopy. Nectar samples collected by filter paper wicks were subjected to chemical analysis using thin-layer chromatography.

Key Results

The PNs are distributed in isolation on the exocarp. Each PN is represented by a single hyaline trichome that consists of a basal cell at epidermal level, stalk cell(s) and a small secretory multicellular head. The apical stalk cell shows inner periclinal and anticlinal walls impregnated by lipids and lignin and has dense cytoplasm with a prevalence of mitochondria and endoplasmic reticulum. The secretory cells show voluminous nuclei and dense cytoplasm, which predominantly has dictyosomes, rough endoplasmic reticulum, plastids, mitochondria and free ribosomes. At the secretory stage the periplasmic space is prominent and contains secretion residues. Tests for sugar indicate the presence of non-reducing sugars in the secretory cells. Nectar samples from PNs contained sucrose, glucose and fructose.

Conclusions

The secretory stage of these PNs extends until fruit maturation and evidence suggests that the energetic source of nectar production is based on pericarp photosynthesis. Patrolling ants were seen foraging on fruits during all stages of fruit development, which suggests that the PNs mediate a symbiotic relationship between ants and plant, similar to the common role of many extrafloral nectaries.     

Seed flavonoids of thePodalyrieae andLiparieae (Fabaceae)

A study of the phenolic compounds of the closely related papilionoid tribes,Podalyrieae andLiparieae, proved that the flavonoid patterns of hydrolysed seed extracts are remarkably conservative. Butin (7, 3, 4-trihydroxyflavanone), 3-hydroxydaidzein (7, 3, 4-trihydroxyisoflavone), vicenin-2 (6, 8-di--D-glucopyranosyl-5, 7, 4-trihydroxyflavone) and orobol (5, 7, 3, 4-tetrahydroxyisoflavone) were isolated and identified as the major flavonoids. The seeds ofAmphithalea, Coelidium, Liparia, Xiphotheca, Calpurnia, Stirtonanthus andPodalyria accumulated three isoflavone O-glycosides that yielded 3-hydroxydaidzein on hydrolysis. In contrast,Virgilia contained a unique combination of vicenin-2 and orobol. Vicenin-2 was also present inCalpurnia as a major compound, butStirtonanthus insignis was the only other species studied that contained orobol (in trace amounts only). Butein, a chalcone, was reported byHarborne from the seed ofCyclopia subternata. This compound's flavanone analog, butin, was the principal component inCyclopia. A cladistic analysis, using flavonoid, alkaloid and morphological data, showed that the seed flavonoids of thePodalyrieae andLiparieae behave rather poorly as cladistic characters. They are, however, of considerable taxonomic value at the tribal level favouring the opinion that the two tribes should be combined. The apparent absence of flavonoids in the seed ofHypocalyptus supports the suggestion that it should be excluded from theLiparieae. Flavonoids also show that theArgyrolobium-group is very different from the tribeCrotalarieae and support the recent transfer of this group to the tribeGenisteae.     

Seed protein electrophoresis in sectionFoenum-graecum ofTrigonella (Fabaceae)

The seed proteins ofTrigonella foenum-graecum, T. berythaea, T. macrorrhyncha andT. gladiata were fractionated on polyacrylamide gels in anodic and cathodic systems. Similarity indices between the profiles of any two species indicated close affinity betweenT. gladiata andT. macrorrhyncha and betweenT. foenum-graecum andT. berythaea. It has been pointed out that according to morphological resemblance and similarity index of the seed protein profileT. berythaea is closer to the cultigen than any other species of sectionFoenum-graecum, but these two species are strongly isolated from one another by the albino seedlings of their F₁ hybrids.     

Unequal distribution of DNA-containing organelles in generative and sperm cells of Erythrina crista-galli (Fabaceae)

The generative cell at anthesis in the mature pollen grain of Erythrina crista-galli (Fabaceae) was examined by 4,6-diamidino-2-phenylindole(DAPI)-fluorescence microscopy using the squash method. An unequal, polarized distribution of DNA-containing organelles (plastids and/or mitochondria) within the generative cell was observed in every mature pollen grain examined. Polarization of DNA-containing organelles is obvious when generative cells are freed and assume a spherical shape soon after microspore mitosis, as revealed by fluorescence-microscopic observations of specimens embedded in Technovit 7100 resin and thin-sectioned at different developmental stages. Early establishment of polarized localization of organelles in young generative cells of E. crista-galli and maintenance of this unequal distribution until pollen maturation strongly suggests that the organelles may still be clustered at pollen mitosis. Production of a dimorphic pair of sperm cells, as has been reported in Plumbago zeylanica, was observed in some pollen tubes germinated in vitro. The differentiation of the two sperm cells is discussed in relation to possible preferential double fertilization in angiosperms. Received: 28 July 1999 / Revision accepted: 8 November 1999     

Molecular Markers in the Identification of Some Early Flowering Curcuma L. (Zingiberaceae) Species

In this paper, isozymes have been used for the first time astools to aid identification of someCurcuma L. species that arestill taxonomically confused. These markers were employed toconfirm the taxonomic identification and to distinguish thetaxa analysed; the results were used to describe the relationshipwithin the early-flowering group. Twenty-one isozymes were initiallytested; out of these, eight isozymes showed reliable polymorphismto distinguish between the taxa analysed. Patterns from isozymedata were analysed using cluster analysis and UPGMA to producea dendrogram depicting the degree of relationship among thespecies. Copyright 1999 Annals of Botany Company Curcuma, Zingiberaceae, isozymes, species identification.     

Promotion of Female Strobili Flowering and Seed Production in two Japanese Pine Species by 6-Benzylaminopurine (BAP) Paste Application in a Field Seed Orchard

Treatment with 6-benzylaminopurine (BAP) to promote the flowering of female strobili and to increase seed production in a seed orchard was examined at different times of conebud differentiation for Japanese red pine (Pinus densiflora) and Japanese black pine (P. thunbergii), from late August to mid-September 1998. BAP was mixed with lanolin and Vaseline to prepare a paste (BAP, 2000 mg/L), which was used for a terminal bud treatment and also applied in a girdling treatment. The BAP treatment in early September transformed lateral buds on lower branches that would have normally differentiated as male strobili into female strobili. The highest percentages of female flowering branches were 21.1% (red) and 40.5% (black) produced by the terminal bud treatment, while control branch percentages were 5.0% and 7.1%, respectively. Girdling combined with BAP treatment further promoted female flowering branches to 32.3% (red) and 64.3% (black), while those of controls were 8.3% and 9.9%, respectively. Moreover, the numbers of female strobili per female flowering branch were 6 to 11-fold greater than controls. Mature seed cones were harvested in October two years later from which full seeds with a high germination ratio were recovered. Use of BAP treatment is thus highly effective for enhancing seed production in seed orchards of these two pine species.     

Consequences of tropical dry forest conversion on diaspore fate of Enterolobium contortisiliquum (Fabaceae)

Habitat conversion is one of the major threats for biodiversity conservation and viability of natural populations. Thus, habitat disturbance alters distinct ecological processes, such as plant reproductive success and diaspore fate. In this study, we determined the effects of seasonally tropical dry forests (STDFs) conversion by anthropogenic disturbance by assessing diaspore fate of Enterolobium contortisiliquum. We compared 20 adult trees present in a STDFs preserved area and 20 adult trees present in a human-converted area. In general, diaspore fates from both areas were similar, i.e., there was no difference in the reproductive success of trees in STDFs and human-converted area. Habitat disturbance did not affect the length or width of fruits; only fruit thickness was larger in trees of STDFs habitat. None of the biometric seed measures differed between different habitat conditions. Likewise, the number of undamaged seeds, aborted seeds, pre-dispersal predated seeds, and seed production were independent of habitat conditions. Besides, we did not observe any effect of habitat disturbance on germination percentage. However, seeds from preserved STDFs germinated faster than seeds from the human-converted area. Even though the effects of human-modified habitats on the diaspore fate have already been studied, tree species exhibit different responses to habitat conversion regarding seed predation, seed dispersal, seed germination, and seedling establishment. Overall, our results show that habitat disturbance does not affect the diaspore fate of E. contortisiliquum. This study also highlights the importance of remnants trees in converted landscapes as the population’s connectors which maintain plant–animal mutualistic and antagonistic interactions that mitigate the effects of habitat disturbance.

     

Seed morphology and its systematic implications for genus Oxytropis DC. (Fabaceae)

In the present study, seeds of 13 Oxytropis DC. species (including two latest synonyms) classified in subg. Oxytropis (sect. Dolichocarpon, sect. Chrysantha and sect. Eumorpha), subg. Euoxytropis (sect. Orobia) and subg. Phacoxytropis (sect. Protoxytropis, sect. Janthina and sect. Mesogaea) from Turkey were examined using light and scanning electron microscopy to evaluate the taxonomic relevance of macro- and micro-morphological seed characters. As a result of the study, species-specific characters have been determined. Seeds exhibit variation in size, shape, surface sculpturing pattern, hilum position and weight. Seeds ranged from 1.61 to 4.04 mm in length and from 1.02 to 2.56 mm in width. Five different seed shapes were recognised, as prolonged semielliptic, reniform, prolonged reniform, quadratic and cardiform, with a length to width ratio ranging from 1.02 ± 0.08 to 1.75 ± 0.27. Rugulate, rugulate–reticulate and lophate sculpturing patterns were observed in the studied species. According to the results, seed characters, such as the size (length, width and the length/width ratio), the shape, the surface sculpturing and the weight appear to have low taxonomic value in distinguishing subgenera, sections and species.     

中国宽脉啮小蜂属(膜翅目:姬小蜂科)的种类及鉴定

本研究对我国姬小蜂科Eulophidae宽脉啮小蜂属Dzhanokmenia Kostjukov,1977进行分类和比较形态学研究,记录该属7种,其中中国新记录2种,提供了7种的鉴别特征及生物学和地理分布信息。比较形态学研究结果表明:宽脉啮小蜂属在头部、触角、腹部背板、腿节以及雌性外生殖器着生位置等结构上存在明显的形态特化和种间差异,这些结构特征能有效应用于属内物种鉴定,为该类群物种的准确鉴定提供依据。基于上述研究结果,本研究编制了该属的分种检索表。     

Species, genomes, and section relationships in the genus Arachis (Fabaceae): a molecular phylogeny

The economically important genus Arachis (Fabaceae) comprises 80 species restricted to South America. One monograph on the genus divided it into nine sections and included an intuitive assessment of evolutionary relationships. There is no comprehensive phylogenetic study of the genus. To test the current systematic treatment of the genus, we reconstructed a phylogeny for Arachis using nuclear ITS and plastid trnT–trnF sequences from 46 species representing all nine sections. ITS cloning of the allotetraploid species of section Arachis indicated the presence of A and B genome alleles and chimeric sequences. Our study revealed that species from section Extranervosae were the first emerging lineage in the genus, followed by sections Triseminatae and Caulorrhizae, and two terminal major lineages, which we refer to as erectoides and arachis. The lineage erectoides comprises members of sections Erectoides, Heteranthae, Procumbentes, Rhizomatosae, and Trierectoides. Species in the arachis lineage form two major clades, arachis I (B and D genomes species and the aneuploids) and arachis II (A genome species). Our results substantiated the sectional treatment of Caulorrhizae, Extranervosae, and Triseminatae, but demonstrated that sections Erectoides, Procumbentes, and Trierectoides are not monophyletic. A detailed study of the genus Arachis with denser taxon sampling, additional genomic regions, plus information from morphology and cytogenetics is needed for comprehensive assessment of its systematics.     

Phaseolus (Fabaceae) in Archaeology: AMS

Beans of several species were domesticated in tropical America thousands of years ago, to be combined with maize and other crops in highly successful New World agricultural systems. Radiocarbon dates on charcoal associated with Phaseolus in archaeological sites, in Mexico and Peru indicated the presence of domesticated beans as early as 10 000 years ago. However, direct dates on the beans and pods themselves by accelerator mass spectrometry (AMS) do not provide evidence for the cultivation in Mexico of common beans, P. vulgaris, and teparies, P. acutifolius, before about 2500 B.P. in the Tehuacán Valley, and of common beans about 1300 years ago in Tamaulipas and 2100 years ago in the Valley of Oaxaca. AMS dates support the presence in the Peruvian Andes of domesticated common beans by about 4400 B.P. and lima beans by about 3500 B. P. and lima beans by about 5600 B.P. in the coastal valleys of Peru. The late appearance of common and lima beans in the Central Highlands of Mesoamerica supports the importance of missing evidence that may be obtained from prehistoric agricultural sites in western Mexico and in Central America which are located within the range of the wild populations of these species. Additionally, biochemical studies of subsamples of the dated specimens should be carried out in order to extend the molecular evidence for the independent domestication of North and South American common beans.     

Consequences of a mixed reproductive system in the hog peanut,Amphicarpaea bracteata, (Fabaceae)

Summary The forest annual, Amphicarpaea bracteata L. can reproduce via aerial chasmogamous, aerial cleistogamous, and subterranean cleistogamous flowers. Both plant size and light intensity influenced the utilization of the three modes of reproduction. chasmogamous and aerial cleistogamous flower number and the ratio of chasmogamous flowers to the total number of aerial flowers increased with plant size. The latter demonstrated a shift to xenogamy and outbreeding in larger plants. Light intensity indirectly influenced reproductive modes through its infuence on plant size. Seed set by both types of aerial flowers was low and unrelated to plant size. Subterranean seed number and the total dry weight of subterranean seeds per plant increased with size. The subterranean seeds of Amphicarpaea bracteata are thirty-four times larger than the aerial seeds (fresh weight). Under field conditions, subterranean seeds had greater germination after one year than acrial seeds. The plants arising from subterranean seeds were significantly larger and more fecund than those from aerial seeds. Seeds produced by aerial cleistogamous, hand selfpollinated chasmogamous, and naturally pollinated chasmogamous flowers had equivalent germination rates and produced plants of equal size and fecundity. This suggests that the outbred progeny from chasmogamous flowers have no advantage over the inbred progeny from aerial cleistogamous flowers.     

Predatory Behavior in Dominant Arboreal Ant Species: The Case of Crematogaster sp. (Hymenoptera: Formicidae)

Crematogaster sp. is a dominant arboreal ant species that captures and retrieves very large prey. Hunting workers forage collectively thanks to short-range recruitment. They detect prey by contact, then rapidly attack, seizing small prey by the body and large prey by a leg. In this study, almost all the active prey were spread-eagled by several workers, even when small enough to permit a single worker to easily master them. While certain workers spread-eagled the prey, others deposited venom on the prey body using their spatulated sting (topical action of the venom). The well-developed arolia on the pretarsus of workers' legs have crucial importance for the success of prey capture (spread-eagling) and transport in an arboreal habitat. These results are compared with those known for other arboreal-dwelling generalist predator ant species.     

稻田三种捕食性天敌与两种害虫共存系统捕食量的研究

有关捕食者-猎物关系的研究一直是种群生态学的活跃课题。Lotka-Volterra(1925)方程是最早用于研究捕食者-猎物系统的数学模型。此后许多作者进一步研究了捕食者-猎物(寄主-寄生物)的关系(Nicholson和Bailey,1935;Holling,1959;Hassell和Varley,1989;Murdoch,1969;Manley等,1972;李超等,1982,1983;丁岩钦等,1983;兰仲雄     

八种野豌豆属植物的核型研究

本文研究了八种野豌豆的核型,并首次报道了长尖野豌豆的染色体数目及其核型和新疆野豌豆的核型。同时提出了野豌豆属核型进化的两种趋势:原始基数的减少,从x=7→x=6→x=5;从多年生进化到一年生,核型的不对称性也随之增加。     

Karyotype, DNA Content and Meiotic Behaviour in Five South American Species ofVicia(Fabaceae)

This paper presents the karyotype, DNA content and meiotic behaviourof five species ofViciafrom Argentina (V. macrogramineaBurk.,V.gramineaSM.,V. epetiolarisBurk.,V. pampicolaBurk. andV. nanaVog.).All the species have the same chromosome number and karyotypeformula (2n=14; 6m+4st+4t). Each species, however, displaysa characteristic number and position of the nucleolar organizerregion (NOR) and different sizes of the respective satellites,confirmed by Ag-NOR banding. Moreover, significant differenceswere found in the total chromosome volume (TCV) and DNA contentof the species. Positive correlations between DNA content andTCV, and between DNA content and type of life cycle were alsofound. TCV and DNA content are lower inV. nana(annual) and higherinV. macrograminea(biennial–perennial). The material displayedmarked karyotypic orthoselection, with similar karyotypes inall studied species, even when the overall chromosome size varied.Evolutionary changes in DNA amount are proportional to the relativelength of each chromosome arm, maintaining karyotypic uniformity.Significant differences were found between the meiotic behaviourofV. gramineaand that of the other species.V. gramineahas alower frequency of ring bivalents and chiasmata per cell, andalso has a lower interstitial chiasma frequency. In general,the results are congruent with the morphological data reportedfor these species.Copyright 1998 Annals of Botany Company. Viciaspecies, karyotype, orthoselection, nuclear DNA content, NOR banding, meiotic behaviour.     

Functional and Numerical Responses of Three Species of Predatory Phytoseiid Mites (Acari: Phytoseiidae) to Thrips flavidulus (Thysanoptera: Thripidae)

Phytoseiid mites are considered the most effective natural enemies of pest mites. They also have been shown to attack pest thrips. It is unknown, however, whether phytoseiid mites can reduce high densities of Thrips flavidulus (Bagnall). We addressed this question by the study of functional and numerical responses. The aim of this research was to evaluate the potential predation success of the adults of three predatory mites, Neoseiulus cucumeris (Oudemans), Neoseiulus barkeri (Hughes), and Euseius nicholsi (Ehara & Lee), against the first-instar of T. flavidulus in a climatic chamber at five different temperatures. The results showed that the functional responses of those predators reflected the Holling type II functional response and were density dependent and positively related to temperature. For the three predatory mites, predation and successful attack rates increased with increasing temperature up to 26°C, reducing afterward. Handling time had the opposite trend. Reproductive ability also increased with an increase in temperature and prey consumption.