Presence of α-amylase inhibitor in some members of the subtribe Phaseolinae (Phaseoleae: Fabaceae)

The presence of α-amylase inhibitor (αAI), phytohemagglutinin (PHA), and phaseolin was determined by immunochemical and biochemical methods in different members of the subtribe Phaseolinae (Phaseoleae: Fabaceae). Active αAI was present in taxa from the Phaseolus vulgaris–P. coccineus complex (P. vulgaris, P. coccineus, and P. polyanthus), as well as in P. acutifolius in accordance with previous molecular data separating these groups of species from others in the genus. All other Phaseolus species tested lacked α-amylase inhibitory activity, although some of them had immunoreactive polypeptides. αAI was found to be a polymorphic trait among wild and cultivated accessions of P. vulgaris, P. coccineus, and P. acutifolius. The presence of αAI is not exclusive of the genus Phaseolus as one of the Vigna species sampled, V. linearis, also contained α-amylase inhibitory activity.     

High levels of arbuscular mycorrhizal fungus colonization on Medicago truncatula reduces plant suitability as a host for pea aphids (Acyrthosiphon pisum)

This study sheds light on a poorly understood area in insect-plant-microbe interactions,focusing on aphid probing and feeding behavior on plants with varying levels of arbuscular mycorrhizal(AM)fungus root colonization.It investigates a commonly occurring interaction of three species:pea aphid Acyrthosiphon pisum,barrel medic Medicago truncatula,and the AM fungus Rhizophagus irregularis,examining whether aphid-feeding behavior changes when insects feed on plants at different levels of AM fungus colonization(42% and 84% root length colonized).Aphid probing and feeding behavior was monitored throughout 8 h of recording using the electrical penetration graph(EPG)technique,also,foliar nutrient content and plant growth were measured.Summarizing,aphids took longer to reach their 1st sustained phloem ingestion on the 84% AM plants than on the 42% AM plants or on controls.Less aphids showed phloem ingestion on the 84% AM plants relative to the 42% AM plants.Shoots of the 84% AM plants had higher percent carbon(43.7%)relative to controls(40.5%),and the 84% AM plants had reduced percent nitrogen(5.3%)relative to the 42% AM plants(6%).In conclusion,EPG and foliar nutrient data support the hypothesis that modifications in plant anatomy(e.g.,thicker leaves),and poor food quality(reduced nitrogen)in the 84% AM plants contribute to reduced aphid success in locating phloem and ultimately to differences in phloem sap ingestion.This work suggests that M.truncatula plants benefit from AM symbiosis not only because of increased nutrient uptake but also because of reduced susceptibility to aphids.     

Cladistic and phenetic analysis of relationships in Vicia subgenus Vicia (Fabaceae) by morphology and isozymes

 Variation of 80 multistate morphological characters and isozymes encoded by 13 loci among 23 vetch species of the type subgenus of the genus Vicia in comparison with V. dumetorum, V. pisiformis and V. sylvatica of the subgenus Cracca is described and analyzed with cladistic parsimony and phenetic neighbour-joining methods by using two different ways of coding. Morphological analyses showed the subgenus Vicia monophyletic and revealed subgroups in a general agreement with traditionally recognized sections, except showing V. faba nested within section Narbonensis and ambiguity in the position of V. lathyroides and V. bithynica. Parsimony analysis of orthozymes as presence/absence characters revealed in the subgenus two basic monophyletic clades: 1) V. faba and three species of the section Peregrinae, V. michauxii, V. aintabensis and V. peregrina, in one subclade linked with species of the Narbonensis and Hyperchusa sections together with V. pisiformis of subgenus Cracca in a second subclade; 2) species belonging to sections Vicia, Sepium, Pseudolathyrus and Lathyroides together with V. sylvatica of the subgenus Cracca. Neighbour-joining analysis of orthozymes revealed the same two basic groups, differing only in the relative position of some species in subclusters. Both isozyme analyses showed paraphyly of the subgenera Vicia and Cracca. Parsimony analysis of orthozymes as character states of isozymes yielded a largely unresolved strict consensus cladogram of 209 most parsimonious trees, and reweighting of characters failed to produce a stable tree. Phylogenetic congruence and discordance among morphological and isozyme analyses, coding ways, homoplasy and weighting of characters are discussed. Received November 20, 2001 Accepted January 31, 2002     

Effects of trichomes on the behavior and distribution of Platyprepia virginalis caterpillars

Trichomes are an important physical resistance mechanism of plants, as they reduce insect herbivore movement, feeding, and digestion. However, we know little about how trichomes influence herbivore distributions and populations. We conducted laboratory and field experiments to evaluate the preferences of Platyprepia virginalis (Boisduval) (Lepidoptera: Arctiidae) caterpillars to natural and manipulated densities of trichomes on their primary food, Lupinus arboreus Sims (Fabaceae). We then conducted field surveys to determine whether variation in trichome density among lupine bushes affected caterpillar spatial distribution on the landscape. Platyprepia virginalis caterpillars preferred lupine leaves with fewer trichomes in choice and no‐choice experiments. In the field, caterpillar feeding damage was found more often on leaves with fewer trichomes. These preferences scaled up to the level of bushes in the landscape such that more caterpillars were found on bushes with lower trichome densities than on bushes with higher trichome densities. This is one of few studies to show the potential for trichome density to influence herbivore population size and distribution in a natural system at a landscape level. The results are consistent with trichomes functioning as a resistance mechanism with consequences for herbivore choice, performance, and distribution.     

Astragalus mario-sousae (Fabaceae: Galegeae), a new species from northeastern Mexico

Astragalus mario-sousae is described from the central part of state of Nuevo León, Mexico. It differs fromAstragalus esperanzae by its habit, peduncles, pedicels, and fruits.

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Resumen   Astragalus mario-sousae (Fabaceae: Galegeae), a new species from northeastern Mexico. Brittonia 57: 314–319. 2005.—Astragalus mario-sousae es propuesta como especie nueva. Se conoce solo de la porción central del estado mexicano de Nuevo León. Se presentan una descripción e ilustración. Difiere deAstragalus esperanzae por su hábito erecto, pedúnculos, pedicelos y frutos más cortos.

     

Rupert C. Barneby and Pugillus Astragalorum

Rupert C. Barneby, his monumental contributions to the taxonomy ofAstragalus and his place among American botanists, is discussed. His twenty contributions in the seriesPugillus Astragalorum spanned fifteen years of his botanical development from an interested naturalist to an accomplished taxonomist in this extremely species-rich genus. Barneby’s work onAstragalus culminated in the 1188 pages of theAtlas of North American Astragalus, which treated of 552 taxa and was published in 1964.     

乌拉甘草(豆科)的3个新异名

在考证了模式标本和查阅了大量腊叶标本的基础上,结合野外居群生物学调查工作,作者对分布于蒙古和我国境内的Glycyrrhiza alaschanicaGrankina、G.gobicaGrankina和G.soongoricaGrankina 3种甘草做了归并处理。认为它们属于乌拉甘草(G.uralensisFisch.ex DC.)的变异类型,均处理为乌拉甘草的异名。     

Diversity and evolution of a trait mediating ant–plant interactions: insights from extrafloral nectaries in Senna (Leguminosae)

Background and Aims

Plants display a wide range of traits that allow them to use animals for vital tasks. To attract and reward aggressive ants that protect developing leaves and flowers from consumers, many plants bear extrafloral nectaries (EFNs). EFNs are exceptionally diverse in morphology and locations on a plant. In this study the evolution of EFN diversity is explored by focusing on the legume genus Senna, in which EFNs underwent remarkable morphological diversification and occur in over 80 % of the approx. 350 species.

Methods

EFN diversity in location, morphology and plant ontogeny was characterized in wild and cultivated plants, using scanning electron microscopy and microtome sectioning. From these data EFN evolution was reconstructed in a phylogenetic framework comprising 83 Senna species.

Key Results

Two distinct kinds of EFNs exist in two unrelated clades within Senna. ‘Individualized’ EFNs (iEFNs), located on the compound leaves and sometimes at the base of pedicels, display a conspicuous, gland-like nectary structure, are highly diverse in shape and characterize the species-rich EFN clade. Previously overlooked ‘non-individualized’ EFNs (non-iEFNs) embedded within stipules, bracts, and sepals are cryptic and may represent a new synapomorphy for clade II. Leaves bear EFNs consistently throughout plant ontogeny. In one species, however, early seedlings develop iEFNs between the first pair of leaflets, but later leaves produce them at the leaf base. This ontogenetic shift reflects our inferred diversification history of iEFN location: ancestral leaves bore EFNs between the first pair of leaflets, while leaves derived from them bore EFNs either between multiple pairs of leaflets or at the leaf base.

Conclusions

EFNs are more diverse than previously thought. EFN-bearing plant parts provide different opportunities for EFN presentation (i.e. location) and individualization (i.e. morphology), with implications for EFN morphological evolution, EFN–ant protective mutualisms and the evolutionary role of EFNs in plant diversification.     

A contribution to the embryology of Desmodium motorium (Houtt.) Merr. (= D. gyrans (L.f.) DC.) (Fabaceae)

Abstract

The anthers are tetrasporangiate. The anther wall comprises epidermis, fibrous endothecium, middle layer and tapetal layer. The tapetum is of the Glandular type and its cells remain uninucleate. Meiosis in pollen mother cells is normal and simultaneous cytokinesis leads to the formation of tetrahedral and decussate microspore tetrads. The pollen grains are shed at 2-celled stage. The ovule is campylotropous, bitegmic and crassinucellate. Meiosis in megaspore mother cell results in the formation of linear or occasionally T-shaped megaspore tetrad. The chalazal megaspore develops into Monosporic Polygonum type of embryo sac. Endosperm development is of the Nuclear type.