Expansion of pea cropping increases the risk of pea moth (Cydia nigricana; Lep., Tortricidae) infestation

Abstract:  The pea moth ( Cydia nigricana ) is a host-specific pest of pea ( Pisum sativum ). In Finland, the combine-harvested field pea is grown on an area totalling 5000 ha. However, the area under pea cropping may increase substantially if pea replaces soya bean as a protein source for animal feed, which may result in pest and disease problems. In this study, the risk of pea moth infestation is evaluated by modelling field survey data. The observations were made in 2002 and 2003 at 93 and 90 pea fields, respectively, in south-western Finland. The choice of the experimental fields was based on pea cropping data from 1997 to 2001 and included regions of both intensive and less intensive pea cultivation. The occurrence of pea moth adults in the fields was assessed with pheromone traps, and the percentage of damaged pods and pea seeds in each field was determined. The number of pea moths in pheromone traps and the percentage of damaged seeds increased linearly when the area under pea cropping during the previous year (within a 4-km distance) increased, and decreased exponentially when the distance to the nearest pea field in the previous year increased. Furthermore, the percentage of damaged pods and seeds was higher in organic than in conventional fields. Expansion of pea cropping would change the spatial distribution of pea fields, thus affecting the risk of pea moth infestation. An increase in the scale and frequency of pea cropping increases the need for plant protection.     

Kinetic determination of the genome size of the pea

Renaturation of pea (Pisum sativum) DNA has been used to estimate the size of the pea genome and the fraction of pea DNA containing repeated DNA sequences. Pea DNA renaturation and single copy tracer renaturation indicate that the size of the pea genome is 0.5 picograms. More than 70% of pea DNA sequences are repeated from 100 to 5,000 times.     

On the function of pea flower feeding by Bruchus pisorum

Pea flower feeding by adult pea weevils, Bruchus pisorum (L.) (Coleoptera: Bruchidae), with special emphasis on nectar feeding, was investigated in a series of laboratory experiments. Male and female adults robbed nectar from flowers of the garden and field pea, Pisum sativum L., and females which fed on the nectar, petals, and female organs of pea flowers lived significantly longer than those denied food and water and those that fed on water only. The results of other experiments suggested that pea flower qualities other than pollen influenced the reproductive success of female B. pisorum. It is hypothesized that pollen seeking B. pisorum effected cross-pollination in the wild progenitor of the modern-day autogamous pea, and adult pea weevils of both sexes rob pea nectar to obtain a readily available source of energy to sustain flight.     

Risk assessment of pea moth Cydia nigricana infestation in organic green peas based on spatio‐temporal distribution and phenology of the host plant

• 1 A method for area‐wide risk assessment of pea moth infestation in commercial pea‐growing areas based on spatial and temporal analyses of pea moth abundance and the phenological distribution of pea fields was investigated.
• 2 In a commercial pea‐growing region in Saxony, Germany, all pea fields were identified, mapped and characterized, recording the pea plant phenology, pea moth flight and larval infestation of each field in the years 2006–2008.
• 3 The relationship between pea moth flight and pea plant phenology was studied in detail in small‐scale field experiments in Hesse, Germany, using different pea cultivars and sowing dates.
• 4 In the study area, the abundance of Cydia nigricana Fabricius (Lepidoptera: Tortricidae) in organic green peas increased linearly with the pea‐cropping area of the previous year in the surroundings of the current fields according to the continuous abundance index.
• 5 Considering solely the early flowering period (= early pea sowing dates) of the organic green peas, we calculated that a minimum distance of the current pea field to the nearest pea field of the previous year of 500 m was necessary to significantly reduce pea moth flight and larval infestation.
• 6 In small‐scale field experiments, a correlation between pea moth flight and larval investation, as well as the importance of the pea flower for the pea moth occurrence, was demonstrated.
• 7 The spatio‐temporal findings are discussed in relation to the development of a coincidence avoidance strategy in pea‐growing areas.

     

Role of Bacterial Polysaccharides in the Adsorption Process of the Rhizobium-Pea. Symbiosis

Phase-contrast and fluorescence microscopy observations showed that pea symbiont R. leguminosarum adsorbed to pea root hairs, but non-symbiont rhizobial strains only adsorbed to a small extent. ¹⁴C-labeled cells were used to assay the number of rhizobial cells adsorbed to a pea root. Capsular polysaccharides or lipopolysaccharides obtained from R. leguminosarum specifically inhibited the adsorption of ¹⁴C-R. leguminosarum cells to a pea root and specifically adsorbed to pea root hairs. Also, they reacted specifically with pea seed lectins. These results suggest that capsular polysaccharides or lipopolysaccharides play an important role in host-specific adsorption. The interaction between the polysaccharides and pea lectins could be the key to determining host specificity in the infection process of Rhizobium-pea symbiosis.     

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.     

High variation in host adaptation among clones of the pea aphid,Acyrthosiphon pisum on peas,Pisum sativum

The performance of one clone of the pea aphid,Acyrthosiphon pisum (Harris), was assessed on 37 different cultivars and species ofPisum L. In addition, random samples of 36 pea aphid clones collected on alfalfa and clover were tested on a selection of fivePisum sativum L. cultivars. Aphid performance was evaluated in terms of the mean relative growth rate (MRGR) during the first five days of life or other life history variables. The MRGR of the first-mentioned pea aphid clone differed little between cultivars. No significant differences in MRGR were found between wild and cultivatedPisum species or between modern and oldP. sativum cultivars. There was considerable variation in host adaptation among the 36 pea aphid clones within each sampled field. The pea aphid clones showed no consistent pattern in performance on four of the five pea cultivars i.e. there was a significant pea aphid genotype —pea genotype interaction. On one of the cultivars all clones performed well. Pea aphid clones collected from red clover generally performed relatively poorly on pea cultivars, in contrast to the pea aphid clones collected on alfalfa. There was no difference in performance between the two pea aphid colour forms tested. Possible reasons for the high variation and the observed adaptation patterns are discussed. The fact that all clones were collected in two adjacent fields indicates thatA. pisum shows high local intraspecific variability in terms of host adaptation.     

Evaluation of the antifungal activity of the purified chitinase 1 from the filamentous fungus Aphanocladium album

Abstract Crude protein preparations from the culture filtrate of the filamentous fungus Aphanocladium album , a hyperparasite of rust fungi, strongly inhibited growth of a strain of the fungus Nectria haematococca pathogenic on pea. Crude protein from the filtrate of the variant E3 of A. album , hyperproducing chitinase, was less inhibitory than crude protein from the filtrate of the wild-type strain E1. The antifungal potential of a purified chitinase from A. album , called chitinase 1, was compared to that of a plant chitinase with known antifungal activity, obtained from pea ( Pisum sativum ). Although purified chitinase 1 of A. album degraded chitin more completely than did pea chitinase, it did not inhibit growth of N. haematococca , either alone or in the presence of a pea β-1,3-glucanase. Furthermore, chitinase 1 from A. album failed to enhance the antifungal activity of pea chitinase. These results indicate that the extracellular proteins of A. album inhibit growth of some fungi by other means than through their chitinase 1 activity.     

Gene centres,a source for genetic variants in symbiotic nitrogen fixation: The symbiotic response of the cultivated pea toRhizobium leguminosarum strains from Europe and the Middle East

Summary Soil samples from several European countries; Sweden, the Netherlands, Spain, Italy and Greece, contained rhizobial populations capable of forming an effective symbiosis with the cultivated pea cv. Rondo from the Netherlands. The range of variation among the European Rhizobium strains, as expressed on pea cv. Rondo, was not so large and almost the same variation could be found within the rhizobial population within each country. Superior Rhizobium strains for the Dutch pea were not restricted to soils from the Netherlands but were also found in those from Sweden and Italy.Soils from Turkey and Israel also contained Rhizobium strains capable of nodulating pea cv. Rondo. However, the genetic variation among these Middle East Rhizobium strains was much larger than that of the European strains. When tested on pea cv. Rondo the majority of the Middle East strains belonged to the medium or low effective classes and only a few strains were comparable with European Rhizobium strains.Dutch Rhizobium strains induced effective nodules on both the Dutch pea cv. Rondo and the Swedish cv. L 110. However, in association with a Turkish Rhizobium strain effective nodules were formed on pea cv. Rondo and ineffective nodules on cv. L 110.We suggest that the genetic uniformity of EuropeanR. leguminosarum strains is the result of selection and domestication of Rhizobium strains originally derived from the gene centres of the pea plant.     

Coupling factor activity of the purified pea mitochondrial F1-ATPase

The pea cotyledon mitochondrial F1-ATPase was released from the submitochondrial particles by a washing procedure using 300 mM sucrose/2 mM Tricine (pH 7.4). The enzyme was purified by DEAE-cellulose chromatography and subsequent sucrose density gradient centrifugation. Using polyacrylamide gel electrophoresis under non-denaturing conditions, the purified protein exhibited a single sharp band with slightly lower mobility than the purified pea chloroplast CF1-ATPase. The molecular weights of pea mitochondrial F1-ATPase and pea chloroplast CF1-ATPase were found to be 409 000 and 378 000, respectively. The purified pea mitochondrial F1-ATPase dissociated into six types of subunits on polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Most of these subunits had mobilities different from the subunits of the pea chloroplast CF1-ATPase. The purified mitochondrial F1-ATPase exhibited coupling factor activity. In spite of the observed differences between CF1 and F1, the mitochondrial enzyme stimulated ATP formation in CF1-depleted pea chloroplast membranes. Thus, the mitochondrial F1 was able to substitute functionally for the chloroplast CF1 in reconstituting photophosphorylation.     

Evidence for the presence of ferritin in plant mitochondria.

In this work, evidence for the presence of ferritins in plant mitochondria is supplied. Mitochondria were isolated from etiolated pea stems and Arabidopsis thaliana cell cultures. The proteins were separated by SDS/PAGE. A protein, with an apparent molecular mass of approximately 25-26 kDa (corresponding to that of ferritin), was cross-reacted with an antibody raised against pea seed ferritin. The mitochondrial ferritin from pea stems was also purified by immunoprecipitation. The purified protein was analyzed by MALDI-TOF mass spectrometry and the results of both mass finger print and peptide fragmentation by post source decay assign the polypeptide sequence to the pea ferritin (P < 0.05). The mitochondrial localization of ferritin was also confirmed by immunocytochemistry experiments on isolated mitochondria and cross-sections of pea stem cells. The possible role of ferritin in oxidative stress of plant mitochondria is discussed.     

Denaturation mapping studies on the circular chloroplast deoxyribonucleic acid from pea leaves.

The structure of circular pea chloroplast DNA (ctDNA) has been analyzed by denaturation mapping. All of the pea ctDNA molecules that were examined had identical gross base sequences. Denaturation maps were constructed at denaturation levels of 2.5%, 22%, and 44%. These denaturation maps showed that the circular pea ctDNA contained six small AT-rich regions on one-half of the DNA molecule, and two small GC-rich regions on the other half of the DNA molecule. The structure of pea ctDNA circular dimers was also examined. The results showed that the pea ctDNA circular dimers consisted of two monomer length units integrated in tandem repeat.     

Protein bodies and vacuoles as lysosomes : investigations into the role of mannose-6-phosphate in intracellular transport of glycosidases in pea cotyledons

We have failed to detect the presence of mannose-6-phosphate in the oligosaccharide moiety of glycoproteins from pea (Pisum sativum L. cv Burpeeana) cotyledons using an assay system sensitive to 10 picomoles of mannose-6-phosphate. We were also unable to demonstrate any retention of glycosidase activity from pea seedlings and pea cotyledons on Sepharose-coupled phosphomannosyl receptor proteins isolated from bovine liver which were, however, able to retain phosphomannosylated hexosaminidase purified from Dictyostelium discoideum secretions. Furthermore, although Sepharose-coupled phosphomannosylated hexosaminidase from Dictyostelium was able to bind phosphomannosyl receptors from bovine liver we were unable to detect the retention of any protein from acetone powder extracts of pea seedlings or from endoplasmic reticulum-associated proteins of pea cotyledons.

Based on this collective evidence we conclude that mannose-6-phosphate does not appear to play a role in the targeting of hydrolytic enzymes from the endoplasmic reticulum to the protein bodies in pea cotyledons.

     

The effectiveness of the symbiosis of Rhizobium leguminosarum on pea and broad bean

Plant and Soil - A comparison is made between Rhizobium leguminosarum strains PRE, effective on both pea and broad bean, and PF2, effective on pea and almost ineffective on broad bean. The former...     

Influence of physiologically active substances of the soil humus on the activity of glucose-6-phosphate-dehydrogenase in pea (Pisum sativum L.) roots

The influence of phenolic and humic acids on the activity of glucose-6-phosphate-dehydrogenase in the roots of pea under aseptic conditions has been investigated. It seems clear that vanillic and protocatechuic acids inhibit the enzyme activity in the excised roots of pea, but their dry weight increases in relation to the control. Gallic acid stimulates the G-6-PD activity in the roots of whole plants. The humic acids influence neither the enzyme activity nor the dry weight of pea seedlings after short-term treatment.     

Coupling factor activity of the purified pea mitochondrial F1-ATPase

The pea cotyledon mitochondrial F₁-ATPase was released from the submitochondrial particles by a washing procedure using 300 mM sucrose /2 mM Tricine (pH 7.4). The enzyme was purified by DEAE-cellulose chromatography and subsequent sucrose density gradient centrifugation. Using polyacrylamide gel electrophoresis under non-denaturing conditions, the purified protein exhibited a single sharp band with slightly lower mobility than the purified pea chloroplast CF₁-ATPase. The molecular weights of pea mitochondrial F₁-ATPase and pea chloroplast CF₁-ATPase were found to be 409 000 and 378 000, respectively. The purified pea mitochondrial F₁-ATPase dissociated into six types of subunits on polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Most of these subunits had mobilities different from the subunits of the pea chloroplast CF₁-ATPase. The purified mitochondrial F₁-ATPase exhibited coupling factor activity. In spite of the observed differences between CF₁ and F₁, the mitochondrial enzyme stimulated ATP formation in CF₁-depleted pea chloroplast membranes. Thus, the mitochondrial F₁ was able to substitute functionally for the chloroplast CF₁ in reconstituting photophosphorylation.     

Co-evolution of the legume-Rhizobium association

Summary A number of examples is given demonstrating the co-existence of pea genotypes and their specific Rhizobium, strains isolated within the same region.R. leguminosarum strains compatible with the cultivated pea have a narrow symbiotic range and they are widely distributed in European soils. This is presumably due to the narrow genetic base of the cultivated pea and its wide-spread cultivation in European soils. Rhizobium strains capable of nodulating a primitive pea line from Afghanistan were only found in soils of the Middle East and Central Asia. A more restricted distribution of specific Rhizobium strains was found for fulvum peas from Israel. Rhizobium strains effective with the fulvum pea were found in Israeli soils. A good example of co-evolution due to geographical isolation was found in south Turkey. Here a pea line was found which can form an effective symbiosis with local Rhizobium strains but not with strains from other parts of Turkey.     

In situ starch degradation of different feeds in the rumen

The in situ starch degradation of 5 feeds (barley, maize, pea, oats and wheat bran) has been measured (trial 1), and the influence of particle size on starch degradation investigated with 3 feeds (barley, maize, pea) (trial 2). The starch degradability of barley, oats and wheat bran was found to be higher than that of pea, and higher again than that of maize: 98, 97, 96, 90 and 58% respectively. For barley, oats and wheat bran, starch was degraded more rapidly than the other dry matter (pm) components. Maize and pea starches were degraded at the same rate as non-starchy components. The particle size variations between feeds ground on the same screen may partly explain variations in starch degradability. When the particle size increased from 0.8 to 6.0 mm screen grinding, in situ starch degradability decreased; the decrease was higher for maize (13.8 points) than for barley (7.4 points) or pea (10.4 points).     

Performance of pea aphid (Acyrthosiphon pisum) clones on host plants and synthetic diets mimicking the same plants phloem amino acid composition

The performances of three clones of pea aphids, with different host affiliations, were evaluated on four host plants species and on four artificial diets. The amino acid compositions of the diets mimicked those of the phloem sap of the respective host plants. The total concentration of amino acids was the same in all the diets. The pea aphid clones performance were significantly affected by amino acid composition of the diets in different ways, implying physiological and/or behavioural differences among coexisting pea aphid clones in response to amino acids in artificial diets. The observed differences in performance on diets between clones were not related to host plant affiliations. Thus, even if the variation in amino acid composition in phloem sap among the host plants affects the pea aphid clones when tested on artificial diets, this variation has no observable effect on pea aphid performance on natural host plants.