Induced resistance by Myzus persicae in the peach cultivar `Rubira'

The effect of a previous infestation by the green peach aphid Myzus persicae (Sulzer) on the settling behaviour and reproduction of the same aphid species was investigated in the resistant peach cultivar Rubira, and compared with that observed in the susceptible control cultivar GF305. A previous infestation of 48 h triggered induced resistance in Rubira. There were significantly fewer aphids settling on preinfested than on uninfested plants, indicating an increased rejection of Rubira as a host plant. The level of induced resistance in preinfested plants was positively related to the duration of the first infestation. In GF305, previous infestation had no detrimental effect on aphid settlement and even slightly enhanced larviposition by adult females. The aphid probing behaviour after a 48-h preinfestation was also monitored for 8 h with the electrical peneration graph (EPG) technique. On preinfested GF305, most EPG parameters indicated an enhanced host plant acceptance. On preinfested GF305, aphids produced less sieve element salivation and more continuous sap ingestion than on uninfested GF305, indicating that the previous aphids provoked changes in plant properties beneficial to the test aphids. In Rubira, a major induced factor of resistance was thought to be expressed in the sieve element as phloem sap ingestion was 4-fold shorter on preinfested than on uninfested plants. The time taken by the aphid stylets to reach a sieve element was also significantly increased on preinfested Rubira, suggesting the induction of resistance factors outside the phloem. The originality of the Rubira/M. persicae interaction is discussed in the perspective of a better understanding of plant induced responses to aphids.     

水稻对褐飞虱抗性相关蛋白的双向电泳分析

以药用野生稻(Oryza officinalis)的转育后代B5(高抗褐飞虱(Nilaparvata lugens Stl))与感虫品种明恢63 (Oryza sativa L.)为亲本,构建了一个重组自交系群体.通过抗褐飞虱鉴定,筛选出极端抗虫株系和极端感虫株系,运用分群分析法(bulked segregant analysis,BSA)分别建成了极端抗虫集团(resistant bulk)和极端感虫集团(susceptible bulk)的蛋白质池.利用双向电泳技术,分别分析了极端抗虫集团和极端感虫集团受虫害与未受虫害的秧苗蛋白质的变化.结果发现,虫害48 h后,感虫集团的一个分子量为40 kD的蛋白质P40 (pI=6.3)的表达明显减弱甚至消失,而在抗虫集团中,P40的表达未受影响.与褐飞虱为害后抗虫株系和感虫株系不同的生理反应相联系,推测P40与水稻受褐飞虱虫害后引起的应答反应相关.     

水稻对褐飞虱抗性相关蛋白的双向电泳分析

以药用野生稻 (Oryzaofficinalis)的转育后代B5 (高抗褐飞虱 (NilaparvatalugensSt l) )与感虫品种明恢 6 3(OryzasativaL .)为亲本 ,构建了一个重组自交系群体。通过抗褐飞虱鉴定 ,筛选出极端抗虫株系和极端感虫株系 ,运用分群分析法 (bulkedsegregantanalysis ,BSA)分别建成了极端抗虫集团 (resistantbulk)和极端感虫集团 (susceptiblebulk)的蛋白质池。利用双向电泳技术 ,分别分析了极端抗虫集团和极端感虫集团受虫害与未受虫害的秧苗蛋白质的变化。结果发现 ,虫害 48h后 ,感虫集团的一个分子量为 40kD的蛋白质P40 (pI=6 .3)的表达明显减弱甚至消失 ,而在抗虫集团中 ,P40的表达未受影响。与褐飞虱为害后抗虫株系和感虫株系不同的生理反应相联系 ,推测P40与水稻受褐飞虱虫害后引起的应答反应相关     

Molecular interactions between rosy apple aphids, Dysaphis plantaginea, and resistant and susceptible cultivars of its primary host Malus domestica

The use of crop varieties resistant or tolerant to insect pests or other stress factors is one approach in non‐chemical crop‐protection. Knowledge of the biochemical and molecular background of insect–plant interactions is a prerequisite for optimizing breeding for resistance. However, the resistance genes involved in plant–aphid interactions have so far only been identified and characterized in very few plant species. Our work aims to elucidate the molecular and biochemical mechanisms involved in resistance of apple trees, Malus domestica L. (Rosaceae), against its primary aphid pest, the rosy apple aphid, Dysaphis plantaginea (Passerini) (Homoptera: Aphididae), which is considered a serious economic pest of apple. Gene expression in both resistant and susceptible apple cultivars after infestation with rosy apple aphids was investigated by employing the cDNA‐AFLP method (cDNA–Amplified Fragment Length Polymorphism). From approximately 12 500 cDNA fragments detected on polyacrylamide gels, 21 bands were apparently up‐ or down‐regulated only in the resistant cultivar ‘Florina’ after aphid infestation compared to the susceptible cultivar ‘Topaz’ and/or mechanically wounded or non‐infested leaves. These fragments were cloned, sequenced, and the pattern of gene expression for six fragments was subsequently verified by virtual Northern blots. Sequence comparisons of these fragments to GenBank accessions revealed homologies to already known genes, most of them isolated from Arabidopsis thaliana L. Among them, a putative RNase‐L‐inhibitor‐like protein, a pectinacetylesterase, an inositol‐phosphatase‐like protein, a precursor of the large chain of the ribulose‐1,5‐biphosphate‐carboxylase, and defence‐related genes such as a vacuolar H(+)‐ATPase subunit‐like protein and an ADP‐ribosylating enzyme were identified. The results are discussed in relation to a putative role of these genes in conferring aphid resistance in apple trees.     

Drought‐stress and plant resistance affect herbivore performance and proteome: the case of the green peach aphid Myzus persicae (Hemiptera: Aphididae)

Little is known about the simultaneous effects of drought stress and plant resistance on herbivorous insects. By subjecting the green peach aphid Myzus persicae Sulzer to well‐watered and drought‐stressed plants of both susceptible and resistant peach (Prunus persica), the effects of both stressors on aphid performance and proteomics are tested. Overall, the influence of the water treatment on aphid performance is less pronounced than the effect of host plant genetic resistance. On the susceptible cultivar, aphid survival, host acceptance and ability to colonize the plant do not depend on water treatment. On the resistant cultivar, aphid survival and ability to colonize are higher on drought‐stressed than on well‐watered plants. A study examining the pattern of protein expression aiming to explain the variation in aphid performance finds higher protein expression in aphids on the drought‐stressed susceptible cultivars compared with the well‐watered ones. In the susceptible cultivar, the regulated proteins are related to energy metabolism and exoskeleton functionality, whereas, in the resistant cultivar, the proteins are involved with the cytoskeleton. Comparison of the protein expression ratios for resistant versus susceptible plants reveals that four proteins are down‐regulated in well‐watered plants and 15 proteins are down‐regulated in drought‐stressed plants. Drought stress applied to the susceptible cultivar induces the regulation of proteins in M. persicae that enable physiological adaptation to maintain an almost unaltered aphid performance. By contrast, for aphids on the resistant cultivar subjected to drought stress, the down‐regulation of proteins responds to an induced host susceptibility effect.     

Effects of Aphis fabae and Uromyces viciae-favae on the growth of a susceptible and an aphid resistant cultivar of Vicia faba

Damaging effects of either black bean aphid (Aphis fabae), broad bean rust (Uromyces viciae-fabae), or the combination of both were investigated on a susceptible (cv. Diana) and an aphid resistant (cv. Bolero) cultivar of Vicia faba. When compared with rust, aphids caused greater reductions of root dry weight, shoot dry weight, leaf area, and mean relative growth rate. The mean unit leaf rate was also reduced whereas the leaf area ratio was not affected. The damage caused per aphid was highest on the susceptible cultivar. Rust induced damage did not differ between the cultivars. Concomitant infestation with both pests only resulted in additive damage. The population development of aphids was delayed on partially resistant plants. High temperature and rust infection reduced the total number of aphids the plants were able to support but not the level of resistance. Thus the specific damaging effect per aphid was increased.     

Cross adaptation of potato plants to low temperatures and potato cyst nematode infestation

Effect of short-term (2 h a day) and long-term (6 days) exposure to low temperature (5°C) on cold tolerance was investigated in two cultivars of potato (Solanum tuberosum L.): resistant (Sudarynya) and susceptible (Nevskii) to potato cyst nematode (Globodera rostochiensis Woll.). The extent of their infestation and changes in the expression of the genes of resistance to nematode (H1 and Gro1-4) were also analyzed. In both cultivars, exposure to low temperature enhanced cold resistance of potato plants. Enhancing cold resistance of cv. Sudarynya induced by a short-term exposure to chilling did not affect the extent of nematode infestation, whereas in susceptible cv. Nevskii, the extent of infestation decreased by almost three times. The level of expression of H1 gene in the leaves of the susceptible cultivar rose almost twofold both after short-term and long exposure to chilling, while in the resistant cultivar, gene expression increased only after a short-term effect of cold. The level of Gro1-4 gene expression increased after both temperature treatments only in the resistant cv. Sudarynya. Thus, the expression of genes for potato resistance to nematode infestation became more active in the susceptible cultivar as regards the gene H1 and in the resistant cultivar, regarding the gene Gro1-4. In the nematode-susceptible cv. Nevskii, the level of infestation decreased and cold resistance increased, apparently indicating cross adaptation to two factors of different nature.     

Aphid infestation induces PR-proteins differently in barley susceptible or resistant to the birdcherry-oat aphid (Rhopalosiphum padi)

The effect of infestation by the birdcherry-oat aphid ( Rhopalosiphum padi L.), on induction of PR-proteins was investigated in barley ( Hordeum vulgare L.), using barley lines susceptible or resistant to R. padi. The PR-proteins PR-1a (unknown function), PR-5a (acidic thaumatin) and peroxidase (EC 1.11.1.7) were not affected, whereas one chitinase (EC 3.2.1.14) and 4 β -1,3-glucanases (EC 3.2.1.39) were induced by the aphid treatment. In the resistant breeding line CI 16145, but not in the susceptible cultivar Golf, accumulation of one basic chitinase and two acidic β -1,3-glucanases increased with time from 2 until 11 days after infestation, as determined by western blots, with antibodies raised against purified chitinase (PR-3a) and β -1,3-glucanase (PR-2a) from barley. By isoelectric focusing, two additional basic β -1,3-glucanases were detected, which increased after infestation in both the resistant and the susceptible barley. The basic chitinase was only detected at days 7 and 11 in the susceptible cultivar, but already at day 2 in the resistant line. The induction was localized to the infested leaf. The PR-proteins PR-3a and PR-2a were also induced by the fungal pathogen ( Blumeria [syn. Erysiphe ] graminis f. sp. hordei ), methyl salicylate and, to a lower extent, by wounding with tweezers and methyl jasmonate (MeJA). Needle wounding performed to mimic aphid stylet penetration did not induce chitinase or β -1,3-glucanase. It is concluded that the fungal pathogen and the aphid infestation induce both similar and different responses, and that the aphid induction is not due to wounding only. The different responses in resistant and susceptible lines indicate that the induced enzymes may play a role in the resistance against aphid infestation.     

Phenotypic mechanisms of host resistance against greenbug (Homoptera: Aphididae) revealed by near isogenic lines of wheat

Interactions between biotype E greenbug, Schizaphis graminum (Rondani), and wheat, Triticum aestivum L., were investigated using resistant and susceptible near isogenic lines of the greenbug resistance gene Gb3. In an antixenosis test, the greenbugs preferred susceptible plants to resistant ones when free choice of hosts was allowed. Aphid feeding resulted in quick and severe damage to susceptible plants, which seemed to follow a general pattern spatially and was affected by the position where the greenbugs were initially placed. Symptom of damage in resistant plants resembled senescence. Within-plant distribution of aphids after infestation was clearly different between the two genotypes. Significantly more greenbugs fed on the first (oldest) leaf than on the stem in resistant plants, but this preference was reversed in the susceptible one. After reaching its peak, aphid population on the susceptible plants dropped quickly. All susceptible plants were dead in 10-14 d after infestation due to greenbug feeding. Aphid population dynamics on resistant plants exhibited a multipeak curve. After the first peak, the greenbug population declined slowly. More than 70% of resistant plants were killed 47 d after infestation. Performance of both biotype E and I greenbugs on several Gb3-related wheat germplasm lines were also examined. It seems that the preference-on-stem that was characteristic of biotype E greenbugs on the susceptible plants was aphid biotype- and host genotype-dependent. Results from this study suggested that antixenosis, antibiosis, and tolerance in the resistant plants of wheat might all contribute to resistance against greenbug feeding.     

Analysis of the transcriptional response to Rice Yellow Mottle Virus infection in<Emphasis Type="Italic"> Oryza sativa indica</Emphasis> and<Emphasis Type="Italic"> japonica</Emphasis> cultivars

Several cDNA libraries were constructed using mRNA isolated from roots, panicles, cell suspensions and leaves of non-stressed Oryza sativa indica (IR64) and japonica (Azucena) plants, from wounded leaves, and from leaves of both cultivars inoculated with Rice Yellow Mottle Virus (RYMV). A total of 5549 cleaned expressed sequence tags (ESTs) were generated from these libraries. They were classified into functional categories on the basis of homology, and analyzed for redundancy within each library. The expression profiles represented by each library revealed great differences between indica and japonica backgrounds. EST frequencies during the early stages of RYMV infection indicated that changes in the expression of genes involved in energy metabolism and photosynthesis are differentially accentuated in susceptible and partially resistant cultivars. Mapping of these ESTs revealed that several co-localize with previously described resistance gene analogs and QTLs (quantitative trait loci).     

Transgenic Nicotiana TabacumL. with enhanced trichome exudate cembratrieneols has reduced aphid infestation in the field

Glandular trichomes of many plants secrete natural products that influence plant/insect interactions. For example, tobacco varieties having relatively high cembratrieneols (CBTols) are known to have enhanced aphid resistance in the field. CBTols and corresponding CBTdiols comprise 1.4 and 62%, respectively, of trichome exudate in the aphid susceptible tobacco variety, T.I. 1068. Using this cultivar we suppressed the CYP71D16 gene that encodes the enzyme that converts CBTols to CBTdiols. In suppressed plants CBTols and CBTdiols accounted for about 27 and 35% of exudate weight, respectively. Total CBTols plus CBTdiols was not changed substantially. Here we studied the relationship between aphid infestation and increased exudate CBTols in the field using self progeny derived from 5 independent primary transgenic T. I. 1068 plants having suppressed CYP71D16 activity. Two hundred individual plants were scored for aphid infestation, and their trichome exudate compositions were determined by gas chromatography. A significant negative correlation was found between high CBTols levels in trichome exudates and aphid infestation. No aphid infestation was observed on the majority of plants with CBTols/CBTdiols ratios of >1.49, which represents a >20-fold increase in CBTols, and a >40% decrease in CBTdiols over control T.I. 1068 exudate. In contrast, aphid infestation occurred on most plants with CBTols/CBTdiols ratios <0.201, which is similar to that of the untransformed control T.I. 1068. These results demonstrate the feasibility of using metabolic engineering of glandular trichomes to enhance natural product-based pest resistance.     

Combining plant resistance and a natural enemy to control <Emphasis Type="Italic">Amphorophora idaei</Emphasis>

The European large raspberry aphid Amphorophora idaei Börner (Homoptera: Aphididae) is a virus vector of at least four plant virus complexes making it the most important aphid pest of raspberries in Northern Europe. An approach combining a bottom-up control (plant resistance) and a top-down control (an aphid parasitoid) using Aphidius ervi Haliday (Hymenoptera: Aphidiinae) was investigated in the laboratory. Aphid performance (pre-reproductive period, total reproductive output, lifespan and r _m) were compared when reared on both a susceptible cultivar and a resistant cultivar with significantly poorer performance on the resistant cultivar. Parasitoid attack behaviour increased with aphid density on both cultivars, but was significantly lower on resistant plants than susceptible plants. Aphids showed a greater tendency to drop from the plant when feeding on resistant plants compared with susceptible plants. The significance of the results is discussed in the context of possible control of the aphid using these combined methods.