Predation Determines Different Selective Pressure on Pea Aphid Host Races in a Complex Agricultural Mosaic

Field assessments were conducted to examine the interplay between host plant and predation in complex agricultural mosaic on pea aphid clover and alfalfa races. In one experiment, we examined the relative fitness on clover race (CR) and alfalfa race (AR) pea aphids on broad bean, red clover and alfalfa alone. But because clover is typically grown in a more complex agricultural mosaic with alfalfa and broad bean, a second experiment was conducted to assess the fitness consequences under predation in a more complex agricultural field setting that also included potential apparent competition with AR pea aphids. In a third experiment we tested for the effect of differential host race density on the fitness of the other host race mediated by a predator effect. CR pea aphids always had fitness losses when on broad bean (had lower fitness on broad bean relative to red clover) and fitness benefits when on red clover (higher fitness on red clover relative to broad bean), whether or not in apparent competition with alfalfa race aphids on bean and alfalfa. AR suffered fitness loss on both alfalfa and bean in apparent competition with CR on clover. Therefore we can conclude that the predation rate between host races was highly asymmetrical. The complexity of the agricultural mosaic thus can influence prey selection by predators on different host plants. These may have evolutionary consequences through context dependent fitness benefits on particular host plants.     

Composition of cell walls from cotyledons of Pisum sativum,Vicia faba and Glycine max

Cell walls from cotyledons of smooth field pea, broad bean and soya bean contain ca 55% pectic polysaccharides associated with 9% cellulose. Arabinose is the major pectic sugar of pea and broad bean walls whereas soya bean pectic polymers are constituted of galactose and arabinose in the ratio (2:1). Galacturonic acid represents ca 20% of the walls. In addition, pea and broad bean cell walls contain, respectively, 12% and 6% of non-starchy and non-cellulosic glucans bearing 4,6-linked and 3-linked glycosyl units. EDTA-soluble acidic pectic substances are distinct rhamnogalacturonans bearing decreasing proportions of interrupting rhamnose from highly interrupted moieties to nearly homogenous homogalacturonans. Pea and broad bean rhamnogalacturonans are associated with arabinose-containing polymers of average DP ca 30–35 whereas soya bean ones have side chains of arabinose and galactose of DP ca 40.     

Previous infestation of pea aphids Acyrthosiphon pisum on broad bean plants resulted in the increased performance of conspecific nymphs on the plants

Abstract

We studied the effects of previous infestation of broad bean plants by pea aphids Acyrthosiphon pisum on the performance of conspecific nymphs on the plants and the involvement of jasmonic acid (JA)-related defenses. The time needed for newly emerged nymphs to become reproductive adults on broad bean plants previously infested by conspecifics (pre-infested plants) was significantly shorter than on uninfested (control) broad bean plants. The total numbers of nymphs produced by aphids on preinfested and control plants were not significantly different. Preinfested plants produced significantly less endogenous JA than that control plants did. To test the effect of JA decreases, we conducted experiments on the developmental duration of nymphs on broad bean plants treated with JA (JA-treated plants) before infestation. The time needed for nymphs to become reproductive adults on JA treated preinfested broad bean plants was not significantly different from that on JA-treated control plants. The results suggested a possible parental care by pea aphids: the adult aphids manipulated JA-related defenses in broad bean plants that had positive effects for their offspring.     

Effect of NaCl salinity on growth,pigment and mineral element contents,and gas exchange of broad bean and pea plants

Increasing salinity of growth medium induced a reduction in growth and transpiration rate. The concentrations of chlorophylls and carotenoids were increased in most cases in broad bean leaves while in pea plants they remained more or less unchanged with the rise of salinization up to 80mM NaCl. Thereabove a significant decrease in these contents was observed. A stimulation of the net photosynthetic rate of pea was observed at the lowest levels of NaCl but at the highest levels inhibitory effect was recorded. In broad bean all salinization levels inhibited photosynthetic activity, but dark respiration of both plant species was stimulated. The content of Na⁺ in the roots and shoots of both species increased at increasing salinity. In broad bean, Ca²⁺ concentration in shoots and K⁺ and Ca²⁺ contents of roots increased at increasing salinization, while in pea plants, the content of K⁺ and Ca²⁺ was almost unaffected by salinity. Salinity induced an increase in the content of these ions in pea roots. Mg²⁺ content in shoots and roots of both broad bean and pea decreased at increasing salinity except in roots of pea, where it was generally increased.     

Application of DL-beta-aminobutyric acid (BABA) as a root drench to legumes inhibits the growth and reproduction of the pea aphid Acyrthosiphon pisum (Hemiptera: Aphididae)

DL-beta-aminobutyric acid (BABA) is a non-protein amino acid that is an effective inducer of resistance against a variety of plant pathogens. However, examples of BABA-induced resistance against insect herbivores have not been reported. We applied BABA as a soil drench to legumes and monitored its effects on the pea aphid Acyrthosiphon pisum (Harris). On tic bean (Vicia faba var. minor), BABA increased aphid mortality, caused a reduction in the mean relative growth rate of individual insects and lessened the intrinsic rate of population increase (rm). BABA also caused significant reductions in the growth rate of A. pisum on pea (Pisum sativa), broad bean (Vicia faba var. major), runner bean (Phaseolus coccineus), red clover (Trifolium pratense) and alfalfa (Medicago sativa). No direct toxic effects of BABA against A. pisum were found, and no phytotoxic effects that may have caused a reduction in aphid performance were detected. Possible mechanisms behind this BABA-induced inhibition of aphid performance are discussed.     

Comparative effects of limited tryptic hydrolysis on physicochemical and structural features of seed 11S globulins

The effect of the limited proteolysis by trypsin on selected seed storage 11S globulins (broad bean and pea legumins, glycinin and helianthinin) was studied by high-sensitive differential scanning calorimetry, fluorescence spectroscopy and analysis of proteolysis kinetics. Different behaviour of glycinin and helianthinin, on one hand, and broad bean and pea legumins, on the other, were observed: in the first group changes in the physicochemical characteristics of the proteins due to their limited proteolysis are more pronounced in comparison with the second one, in relation with the extent of primary structure modifications. The differences observed have been evaluated in relation with the amino acid sequence features of the four 11S globulin studied and agree with the literature data concerning the protein structural changes in the course of the limited proteolysis.     

Radiolabelling studies of fatty acids in pisum sativum and Vicia faba leaves at different temperatures

Leaves of pea and broad bean plants were incubated with acetate-[¹⁴C] at temperatures varying from 7 to 34°. No significant difference was observed in the distribution of radioactivity between phosphatidylcholine and the galactosylglycerides in pea with different temperatures. However, increasing temperatures increased the labelling of phosphatidylcholine in broad bean leaves, at the expense of polar lipids other than the galactosylglycerides. The incubation temperature had no significant effect on the pattern of labelling of the fatty acids of the major leaf lipids. A correlation was seen in the specific radioactivity of oleate and linoleate in phosphatidylcholine and, especially, in the galactosylglycerides. The data emphasise the rapid equilibration of oleate and linoleate (which probably occurs by transacylation) between the two galactosylglycerides and phosphatidylcholine in leaf tissues.     

Chloroplast DNA rearrangements are more frequent when a large inverted repeat sequence is lost

We examined the arrangement of sequences common to seven angiosperm chloroplast genomes. The chloroplast DNAs of spinach, petunia and cucumber are essentially colinear. They share with the corn chloroplast genome a large inversion of approximately 50 kb relative to the genomes of three legumes--mung bean, pea and broad bean. There is one additional rearrangement, a second, smaller inversion within the 50 kb inversion, which is specific to the corn genome. These two changes are the only detectable rearrangements that have occurred during the evolution of the species examined (corn, spinach, petunia, cucumber and mung bean) whose chloroplast genomes contain a large inverted repeat sequence of 22-25 kb. In contrast, we find extensive sequence rearrangements in comparing the pea and broad bean genomes, both of which have deleted one entire segment of the inverted repeat, and also in comparing each of these to the mung bean genome. Thus there is a relatively stable arrangement of sequences in those genomes with the inverted repeat and a much more dynamic arrangement in those that have lost it. We discuss several explanations for this correlation, including the possibility that the inverted repeat may play a direct role in maintaining a conserved arrangement of chloroplast DNA sequences.     

蚕豆豆类胰岛素基因的cDNA克隆及序列分析

为探明豆科植物中豆类胰岛素基因的结构特征与进化关系,在已获得大豆豆类胰岛素基因的基础上,以蚕豆种子胚根mRNA为材料,采用RT-PCR技术,克隆了蚕豆豆类胰岛素基因的cDNA序列,编码的前体多肽包括信号肽、成熟型豆类胰岛素及另一多肽的45个氨基酸残基。DNA序列分析表明,克隆片段与大豆和豌豆的同源性分别为62.5%和58.7%。在氨基酸水平上分别具有44.2%和43.6%的同源性,其中存在着高度保守的半胱氨酸位点,它们在维持豆类胰岛素的空间结构与生理功能方面,可能具有重要的作用。 Abstract:In order to elucidate the relationship between the structural features of leginsulin gene in legume plants and their phylogenetic significance,we have cloned the cDNA sequence of leginsulin gene from radicles of broad bean (Vicia faba) via RT-PCR techniques according to the leginsulin gene sequence we previously obtained from soybean (Glycine max).The cloned cDNA encoded for a precursor protein consisting of the signal peptide,mature leginsulin and an additional 45 amino acids of another polypeptide.A sequence search for homology comparison revealed the cloned leginsulin cDNA fragment shares 62.5% and 58.7% similarity to soybean and pea,respectively.The results also shown that leginsulin cDNA from broad bean presents 44.2% and 43.6% amino acid sequence homology with soybean and pea (Pisum sativum),respectively,and that there exists highly conserved cysteine sites among the leginsulin cDNAs,which may play a crucial role in maintaining the three-dimensional structure and the physiological functions of leginsulin.     

Differences in drought tolerance between cultivars of field bean and field pea. A comparison of drought-resistant and drought-sensitive cultivars

Relatively little research has been conducted to determine different responses to drought among cultivars of the legume species. The objective of this study was to identify differences in seedlings growth, water relations and leaf conductances resulting from drought imposed on two field bean and two field pea cultivars that had been observed to differ in their drought tolerances, and special emphasis was placed on the root system development. Distinct differences between resistant and sensitive cultivars of field bean and field pea became evident in measurements of the characteristics of the lateral root. The drought treatment induced statistically significant decrease in the number of the developed laterals, their total length and dry matter. In the drought resistant cultivars (field bean Gobo and field pea Solara) this reduction was smaller in comparison with sensitive ones (field bean Victor and field pea Bareness). The effect of drought on growth of tap root in the drought resistant and drought sensitive cultivars was smaller and statistically not significant. The results showed that drought resistant cultivars when compared with drought sensitive one would demonstrate less abundance in the above-ground part and greater dimensions of the root system. The measurements of leaf water potential and stomata diffusive resistance measurements indicate that the physiological reasons for the different reactions to drought between the resistant and the sensitive field bean and field pea cultivars may be due to a more effective protection of the level of tissue hydration and due to increase stomata diffusive resistance in the resistant cultivars. During recovery period it has been also demonstrated that in the drought resistant cultivars a tendency exists for a more complete return to the level of the control plants.     

The Relationship Between Bicarbonate Ion, pH, and 59Fe Uptake by Plants

Iron absorption by barley, pea, and runner bean is stimulatedby bicarbonate but inhibited by increasing pH. Bicarbonate stimulatestranslocation of Fe in barley but inhibits it in pea and bean.Increasing pH stimulates translocation in barley and pea withno effect in bean. The presence of other ions in the externalsolution appears to inhibit absorption but enhances translocationof Fe in bean and pea. It is concluded that whether or not bicarbonatewill induce chlorosis in a plant depends on species and variety.     

Dynamics of the Nuclear Complement of Giant Cells Induced by Meloidogyne incognita

The total numbers of nuclei in giant cells induced by Meloidogyne incognita in pea, lettuce, tomato, and broad bean were determined. Mature giant cells from pea had the most nuclei per giant cell with a mean of 59 ± 23, lettuce had the fewest with 26 ± 16, and tomato and broad bean were intermediate. The rate of increase in numbers of nuclei for all plant species was greatest during the first 7 days after inoculation. No mitotic activity was observed in giant cells associated with adult nematodes. Number of nuclei per giant cell doubled each day during the period of greatest mitotic activity, but number of total chromosomes per giant cell increased 20-fold per day at the same time. The hypothesis is presented that factor(s) responsible for the polyploid, mulfinucleate condition characteristic of giant cells may be different from factor(s) responsible for aneuploid numbers of chromosome per nucleus or for nuclear aberrations such as the presence of linked nuclei.     

Feeding preferences and related types of behaviour of Neomegalotomus parvus

Laboratory studies with Neomegalotomus parvus(Westwood) (Hemiptera: Alydidae) with one nymph per Petri dish in multiple-choice tests indicated that seeds of pigeon pea [Cajanus cajan(L.) Mills.], lablab (Dolichos lablabL.), and soybean [Glycine max(L.) Merrill] were visited before seeds of common bean (Phaseolus vulgarisL.) and rice (Oryza sativaL.). The percentage of individuals engaging in dabbing/antennation resulting in probing, and percentage probing resulting in feeding, were higher on common bean (97%) and pigeon pea (87%) seeds than on lablab (55%), soybean (50%), or rice (5%) seeds. No significant differences were found in preference (number of flanges) among pigeon pea, common bean, and lablab, and preference (insects on foods) varied throughout the assessment period (5 d). In tests using 10 nymphs per dish, pigeon pea was the preferred food (number of flanges and insects on plants) throughout the period (5 d). In no-choice tests, the average duration of a feeding session and the longest feeding session were greater on lablab and common bean than on pigeon pea, soybean, or rice seeds. The number of feeding sessions was greater on seeds of common bean, pigeon pea, and soybean than on those of lablab or rice. Laboratory tests with N. parvusadults indicated that pigeon pea seeds were located faster, followed by common bean, soybean, and rice. When pods were tested, dabbing/antennation time was shorter on pigeon pea than on soybean, and probing time was longer on soybean than on pigeon pea or common bean. On pigeon pea, 100% of the insects probed the host, while on common bean and soybean pods, and on rice panicles, these values dropped to 71.8%, 46.0%, and 10.5%, respectively. Adults showed similar feeding times on pigeon pea, common bean, and soybean pods, but did not feed on rice panicles. Electronmicroscopical analysis showed the presence of two apical lobes with 12 peg sensilla on the labial tip. Sensillum tips were stained with silver nitrate solution, indicating a permeability of the cuticle and, therefore, their function as taste receptors.     

Verticillium wilt of pea (Pisum sativum)

A wilt disease of garden pea (Pisum sativum) caused by Verticillium dahliae is described and the range of pathogenicity of the isolate investigated. It is pathogenic to potato, sweet pea, antirrhinum and broad bean and isolates of V. dahliae from potato, lucerne and sweet pea and V. albo-atrum from lucerne are pathogenic to pea. Since the most common disease symptoms, acropetal progression of chlorosis and necrosis of the leaves followed by premature defoliation are indistinguishable from natural senescence, it is probable that disease and senescence symptoms are confused in the field. The premature defoliation results in marked reduction in green leaf area, leaf dry weight and pod yield.     

Short-term effects of aphid feeding on photosynthetic CO2 exchange and dark respiration in legume leaves

Net CO₂ exchange rates and dark respiration rates were determined for single attached legume leaves (leaflets) after 6 to 9 days of aphid infestation. Plant-aphid combinations used were broad bean ( Vicia faba L. cv. Aquadulce) and cowpea [ Vigna unguiculata (L.) Walp. cv. Caloona)] infested with cowpea aphids ( Aphis craccivora Koch) and broad bean and garden pea ( Pisum sativum L. cv. Victory Freezer) infested with pea aphids [ Acyrthosiphon pisum (Harris)]. Leaves from all aphid-infested plants had significantly greater net CO₂ exchange rates in the light than their respective controls and rates of dark respiration of leaves from infested cowpea and garden pea were also significantly greater than those of controls. Dark respiration, as a percentage of net CO₂ exchange rates in the light, was greater in aphid-infested than in control plants. When the mean net daily carbon gain was calculated for the leaves of each plant-aphid combination, leaves from aphid-infested plants had the greatest gain. It is proposed that net CO₂, exchange rates increased due to increased sink demand and dark respiration rates increased to meet the increased energy requirements of phloem loading and cellular maintenance associated with aphid feeding. The apparent compensatory carbon gain of infested leaves was consumed by the aphids.     

Pea aphids (Acyrthosiphon pisum Harris) reduce secretion of extrafloral nectar in broad bean (Vicia faba)

1. Herbivores sometimes suppress plant defences. This study tested whether the presence of pea aphids (Acyrthosiphon pisum Harris) on broad bean (Vicia faba) led to decreased secretion of extrafloral nectar (EFN) which functions as an indirect plant defence against herbivores. 2. To determine effects of aphid infestation on EFN secretion, a comparison was done between EFN secretion in uninfested plants and that in plants infested by A. pisum and another aphid species (Aphis craccivora Koch). 3. When broad bean plants were infested by A. pisum, they secreted significantly smaller amounts of EFN than did uninfested plants and A. craccivora‐infested plants. There was no significant difference in EFN secretion between uninfested plants and A. craccivora‐infested plants. The number of extrafloral nectaries did not differ among the three treatments. 4. These results suggest that A. pisum reduced EFN production in broad bean plants.     

Pressure-Driven Extrusion of Intracellular Substances from Bean and Pea Cotyledons during Imbibition

Intracellular substances leak from imbibing cotyledons of grain legumes during imbibition. This work reports the discovery of a biophysical process by which intracellular substances are driven from cotyledons during imbibition. Light and scanning electron microscopy were used to examine bean (Phaseolus vulgaris L.) and pea (Pisum sativum L.) cotyledons and the material released from them into imbibition water. A large fraction of the visible materials released from excised bean and pea cotyledons during the first 30 minutes of imbibition consisted of convoluted or helical streams of material which rapidly emerged from the cotyledons surfaces. Large streams of material from bean cotyledons contained starch grains and protein bodies, and smaller streams from bean and pea cotyledons probably contained protein bodies. The forms of streams were characteristic of a viscous fluid which had been forced by pressure through irregular orifices. The sites of extrusion from bean cotyledons were multicellular blisters which formed on the surfaces of imbibing cotyledons. In 6 hours, pea and bean cotyledons leaked from 1 to 11 micrograms protein per milligram of seed dry weight. The quantities of protein leaked primarily depended on cultivar.     

Uptake hydrogenase in Rhizobium and nodule leghemoglobin in cow pea miscellany hosts

Two effective strains of green gram rhizobia S24 (slow growing and Hup⁺) and M11 (fast growing and Hup^-) were tested for leghemoglobin production in nodules and effectivity on six species of cow pea miscellany hosts. Both strains nodulate green gram [Vigna radiata (L.) (Wilczek)], black gram [Vigna mungo (L.) (Hepper)], cow pea [Vigna unguiqulata (L.)], moth bean [Vigna aconitifolia (Jacq.) (Marechel)], Cluster bean [Cyamopsis tetragonoloba (L.) (Taub.)] and pigeon pea [Cajanus cajan (L.)]. In all these hosts, nodules formed by strain M11 contained 1.5 to 2 times more leghemoglobin than the nodules formed by strain S24. Gel electrophoresis of nodule contents of different host species showed a high concentration of a fast-moving ferricoxy leghemoglobin in the nodules of plants inoculated with strain M11 as compared to that of strain S24. Strain M11, however, was relatively less effective than strain S24 on black gram, cow pea and moth bean and was at par with the later on green gram, cluster bean and pigeon pea. Hydrogen recycling ability of the strain S24 was observed in nodules of all the host species. The effective functioning of strain S24 at low levels of leghemoglobin suggests an involvement of recycling hydrogenase in maintaining an appropriate oxidation-reduction potential in nodules.Abbreviations Lb Leghemoglobin - Cvr cultivar     

Detection of Ca2+-Dependent Transglutaminase Activity in Root and Leaf Tissue of Monocotyledonous and Dicotyledonous Plants

Protein extracted from root and leaf tissue of the dicotyledonous plants pea (Pisum sativum) and broad bean (Vicia faba) and the monocotyledonous plants wheat (Triticum aestivum) and barley (Hordeum vulgare) were shown to catalyze the incorporation of biotin-labeled cadaverine into microtiter-plate-bound N′,N′-dimethylcasein and the cross-linking of biotin-labeled casein to microtiter-plate-bound casein in a Ca²⁺-dependent manner. The cross-linking of biotinylated casein and the incorporation of biotin-labeled cadaverine into N′,N′-dimethylcasein were time-dependent reactions with a pH optimum of 7.9. Transglutaminase activity was shown to increase over a 2-week growth period in both the roots and leaves of pea. The product of transglutaminase's protein-cross-linking activity, ε-(γ-glutamyl)-lysine isodipeptide, was detected in root and shoot protein from pea, broad bean, wheat, and barley by cation-exchange chromatography. The presence of the isodipeptide was confirmed by reversed-phase chromatography. Hydrolysis of the isodipeptide after cation-exchange chromatography confirmed the presence of glutamate and lysine.     

Evaluation of Legumes Common to the Pacific Northwest as Hosts for the Pea Cyst Nematode,Heterodera goettingiana

Seventeen leguminous species common to the Pacific Northwest were evaluated as potential hosts of the pea cyst nematode, Heterodera goettingiana, in both greenhouse and field experiments. In all experiments, juveniles of H. goettingiana penetrated roots of these 17 species with the exception of greenhouse-grown chickpea. Nematodes molted and developed into swollen third-stage or fourth-stage juveniles in many of the plants, but cyst development occurred only in the field on green pea, edible dry pea, and faba bean. More H. goettingiana cysts developed on fava bean than on green pea or edible dry pea. In H. goettingiana-infested soils, cropping sequences that include fava bean and pea should be avoided. However, certain legumes, such as winter vetch, may have the potential of serving as trap crops for H. goettingiana in this region.