Małgorzata Kiełkiewicz

Plant–eriophyoid mite interactions: cellular biochemistry and metabolic responses induced in mite-injured plants. Part I

This review is a comprehensive study of recent advances related to cytological, biochemical and physiological changes induced in plants in response to eriophyoid mite attack. It has been shown that responses of host plants to eriophyoids are variable. Most of the variability is due to individual eriophyoid mite–plant interactions. Usually, the direction and intensity of changes in eriophyoid-infested plant organs depend on mite genotype, density, or the feeding period, and are strongly differentiated relative to host plant species, cultivar, age and location. Although the mechanisms of changes elicited by eriophyoid mites within plants are not fully understood, in many cases the qualitative and quantitative biochemical status of mite-infested plants are known to affect the performance of consecutive herbivorous arthropods. In future, elucidation of the pathways from eriophyoid mite damage to plant gene activation will be necessary to clarify plant responses and to explain variation in plant tissue damage at the feeding and adjacent sites.

Plant–eriophyoid mite interactions: specific and unspecific morphological alterations. Part II

The paper presents recent advances related to both specific and unspecific morphological alterations of plant organs caused by eriophyoid mites. Based on old and new case studies, the diversity of plant malformations, such as galls, non-distortive feeding effects and complex symptoms induced by eriophyoids and/or pathogens vectored by them, is analysed and summarised.

Effect of the carmine spider mite (Acarida: Tetranychidae) infestation and mechanical injury on the level of ABA in tomato plants

The aim of this study was to determine the changes in the abscisic acid (ABA) content in tomato leaves infested by the carmine spider mite (CSM) (Tetranychus cinnabarinus Boidsuval) and in leaves that were mechanically injured. It was also investigated whether signalling from stressed to non-stressed organs occurred.Tomato plants (Lycopersicon esculentum Mill.) cvs. Romatos and Slonka (with various susceptibility to CSM) were stressed at the stage of first cluster flowering by either CSM feeding (72 hours) or by mechanical puncturing simulated feeding injury by CSM (18 hours).It was found that under control condition the level of ABA differed significantly between cultivars, being always higher in plants of the susceptible cv. Romatos.In response to CSM feeding, the content of ABA in infested organs of the more tolerant plant (cv. Slonka) increased by 95 % but in the susceptible one by 11 % only. ABA content in the organs non-stressed by CSM feeding either increased (Slonka cv.) or decreased (Romatos cv.).In response to mechanical wounding, ABA content in directly injured organs increased but to a lower degree (49 %) and only in Slonka cv.. The same was true for ABA content in non-injured organs of damaged plants of this cultivar. Observed changes in ABA level in non-stressed organs are probably the results of signalling from stressed organs. Plant response measured by changes in ABA level to the stress generated by CSM feeding, was much stronger than merely by mechanical injury.

Relevance of the Mi23 Marker and the Potato Aphid Biology as Indicators of Tomato Plant (Solanum lycopersicum L.) Resistance to Some Pests

Relevance of the Mi23 Marker and the Potato Aphid Biology as Indicators of Tomato Plant (Solanum lycopersicum L.) Resistance to Some Pests Mi-1.2 gene, expressed in tomato plants, contributes to endogenous resistance against nematodes and some Hemiptera insects. The aim of this study was to screen the presence of dominant/recessive locus of the Mi-1.2 gene in tomato cultivars with different allelic combination using Mi23 SCAR method and to assess the capacity of the local potato aphid (Macrosiphum euphorbiae Thomas) population to develop on different tomato cultivars (dominant and recessive homozygotes in Mi-1.2 locus). The results showed that both Mi23 marker and potato aphid performance are relevant methods in screening tomato cultivars with a different allelic combination of Mi-1.2 gene. The assessment of biological potential of M. euphorbiae proved that, in comparison with control (tomato plants with recessive alleles of Mi-1.2 gene), the aphid mortality increased 9- and 4 - fold (in the first and second experimental series, respectively) and the female longevity decreased 3 - fold when fed on tomato cvs with dominant alleles of Mi-1.2 gene. Furthermore, the resistance against aphids manifests as an antibiosis mechanism in tomato plants carrying dominant alleles. Marker MI23 i Biologia Mszycy Ziemniaczanej Smugowej Jako Molekularny i Biologiczny Wskaźnik Odporności Roślin Pomidora na Niektóre Nicienie i Pluskwiaki Gen Mi-1.2 w roślinach pomidora zwyczajnego (Solanum lycopersicum L.), warunkuje odporność na nicienie (Meloidogyne spp.) i niektóre owady z rzędu Pluskwiaki (Hemiptera). Celem badań była ocena markera Mi23 w diagnostyce roślin pomidora, o zróżnicowanym układzie alleli. Równocześnie analizowano potencjał rozrodczy mszycy ziemniaczanej smugowej (Macrosiphum euphorbiae Thomas), której ograniczona bionomia na roślinach z dominującymi allelami genu Mi-1.2 powinna być dobrym wskaźnikiem ich odporności i na nicienie, i na pluskwiaki. Wśród analizowanych odmian i mieszańców F1 pomidora obecność locus Mi/mi stwierdzono we wszystkich badanych genotypach. O antybiotycznym oddziaływaniu roślin pomidora z dominującymi allelami genu Mi-1.2 na mszycę ziemniaczaną smugową świadczy wysoka śmiertelność osobników dorosłych (86 i 90%) oraz bardzo krótki czas życia samic (4,45±2,89 i 6,50±2,07 dni). Na homozygotach z recesywnymi allelami genu Mi-1.2 śmiertelność była 9- i 4-krotnie niższa (10 i 25%), a długość życia około 3-krotnie dłuższa (14,95±4,17 i 17,10±4,36 dni), co potwierdza odporność testowanych roślin nie tylko na nicienie, ale i na lokalną populację M. euphorbiae.

Changes in biochemical composition of needles of ornamental dwarf spruce (Picea glauca ‘Conica’) induced by spruce spider mite (Oligonychus ununguis Jacobi, Acari: Tetranychidae) feeding

The impact of spruce spider mite (SSM) (Oligonychus ununguis Jacobi, Acari: Tetranychidae) feeding on needle compounds of young dwarf white spruce (Picea glauca ‘Conica’), important in defence against pests, was determined. It was shown that the direction and intensity of changes in chemical composition of spruce needles was related to the density of spruce spider mite population. Relative to uninfested controls, needles of trees infested by 2–6 mites per 5 cm oftwig during 8 weeks contained markedly higher concentration of soluble proteins, total phenolics and essential oil volatiles (linalool, β-phellandrene, β-myrcene, δ-3-carene, p-cymene, limonene, α-pinene, β-pinene, borneol, methyl salicylate, geranyl acetate). Feeding of a three times larger population of mites (18 specimens per 5 cm of twig) caused either reduction of concentration of those compounds, or no significant difference in comparison to the control.The results of our study show that O. ununguis at relatively low density (not exceeding 2–6 specimens per 5 cm of twig per 8 weeks) stimulates even susceptible host-plant to alter metabolism, however induced responses are suppressed as mite density increases. Findings are discussed in relation to the importance of changes in the concentration of needle primary and secondary metabolites to white spruce defence against O. ununguis.

Insect-resistant Bt-maize response to the short-term non-target mite-pest infestation and soil drought

Transgenic lepidopteran insect-resistant maize expressing the cry1Ab gene (Bt) and its non-transgenic counterpart at the 12-leaf-stage (V12) were infested by the two-spotted spider mite or dehydrated by cessation of soil watering to check Bt-maize capacity to respond to other stresses than those assured by the presence of Cry protein. Since the antioxidant enzymes are key components of plant defence against biotic and abiotic stresses, the engagement of leaf superoxide dismutase (SOD), catalase (CAT) and peroxidase (POX) in response to 6-day mite feeding and soil drought has been investigated. The reduction of leaf hydration and soluble protein content in the fully expanded 8th leaf was independent of genotype and more pronounced in response to water cessation than mite infestation. Similarly, the changes in enzyme activities depended more on the kind of stress than the presence of the transgene. Water shortage in the soil enhanced the activity of all enzymes, whereas mite feeding decreased the activity of SOD and CAT, and markedly increased POX in the 8th leaf of both cultivars. In mite-infested leaves of the non-transgenic plant, the CAT activity remained unaffected, whereas decreased in leaves of Bt maize due to the hampered activity of CAT-2. In comparison to the control, all enzyme activity in the 10th non-infested leaf of mite-infested non-transgenic maize decreased, whereas it changed in the 10th leaf of Bt maize in the same way as in the 8th mite-infested leaf. The results suggest that SOD, CAT and POX can strongly confer short-term drought-stress response in both maize cultivars, whereas POX is the only responsive enzyme in mite-infested Bt maize.

Cross-talk between high light stress and plant defence to the two-spotted spider mite in Arabidopsis thaliana

Little is known about how plants deal with arthropod herbivores under the fluctuating light intensity and spectra which occur in natural environments. Moreover, the role of simultaneous stress such as excess light (EL) in the regulation of plant responses to herbivores is poorly characterized. In the current study, we focused on a mite-herbivore, specifically, the two-spotted spider mite (TSSM), which is one of the major agricultural pests worldwide. Our results showed that TSSM-induced leaf damage (visualized by trypan blue staining) and oviposition rate (measured as daily female fecundity) decreased after EL pre-treatment in wild-type Arabidopsis plants, but the observed responses were not wavelength specific. Thus, we established that EL pre-treatment reduced Arabidopsis susceptibility to TSSM infestation. Due to the fact that a portion of EL energy is dissipated by plants as heat in the mechanism known as non-photochemical quenching (NPQ) of chlorophyll fluorescence, we tested an Arabidopsis npq4-1 mutant impaired in NPQ. We showed that npq4-1 plants are significantly less susceptible to TSSM feeding activity, and this result was not dependent on light pre-treatment. Therefore, our findings strongly support the role of light in plant defence against TSSM, pointing to a key role for a photo-protective mechanism such as NPQ in this regulation. We hypothesize that plants impaired in NPQ are constantly primed to mite attack, as this seems to be a universal evolutionarily conserved mechanism for herbivores.

Tomato Carrying MI-1.2 Gene as a Host-Plant to the Two-Spotted Spider Mite (Tetranychus urticae Koch): Results of Laboratory Evaluation

Tomato Carrying MI-1.2 Gene as a Host-Plant to the Two-Spotted Spider Mite (Tetranychus urticae Koch): Results of Laboratory Evaluation Mi-1.2 gene contributes to the resistance of tomato plants against some species of herbivores (i.e. nematodes, aphids) that are sap-feeders. In this study, two genotypes of tomato (Solanum lycopersicum L. syn. Lycopersicon esculentum Mill.) plants with dominant (Motelle cv) and recessive (Moneymaker cv) Mi-1.2 alleles were evaluated as a host-plant to the two-spotted spider mite (Tetranychus urticae Koch, Acari: Tetranychidae). Plants were grown under glasshouse conditions. The effect of tomato genotypes on T. urticae bionomy was estimated on cut leaflets in controlled photoperiod, temperature and humidity (L/D=16/8 h; D/N temp.=23/20°C; RH=70%). Results of laboratory evaluation showed that both the bionomy and population parameters of T. urticae reached a very similar or even higher value on plants with dominant Mi-1.2 allele than on plants with recessive one. A relatively high value of T. urticae parameters on plants resistant to root knot nematodes indicates that the mite has potential to develop rapidly. This allows the mite population to reach the density causing marked damage to plant in a short time. It is concluded that the presence of Mi-1.2 gene product in tomato plants does not significantly affect the reproductive potential of T. urticae. Therefore, Mi-1.2 gene cannot be a satisfying source of plant resistance to this mite-herbivore generalist. Odporność Pomidora Zwyczajnego z Ekspresją Genu MI-1.2 na Przędziorka Chmielowca (Tetranychus urticae Koch, Acari: Tetranychidae): Ocena Laboratoryjna Gen Mi-1.2 u roślin pomidora zwyczajnego (Solanum lycopersicum L.) warunkuje odporność na niektóre gatunki szkodników (nicienie, mszyce), które żywią się sokiem roślinnym. Celem badań była ocena potencjału reprodukcyjnego przędziorka chmielowca (Tetranychus urticae Koch; Acari: Tetranychidae) żerującego na odmianach roślin pomidora z dominującym allelem genu Mi-1.2 (Motelle) i na roślinach kontrolnych (Moneymaker). Uprawa roślin była prowadzona w warunkach szklarniowych. Wpływ genotypu roślin pomidora na płodność, długość życia, czas rozwoju i śmiertelność T. urticae oceniano w warunkach kontrolowanych (L/D=16/8 h; D/N temp.=23/20°C; RH=70%). Bionomia i parametry rozwojowe T. urticae na roślinach kontrolnych i wykazujących ekspresję dominujących alleli genu Mi-1.2 osiągnęły zbliżone wartości. Wskazuje to, że obecność dominujących alleli genu Mi-1.2 u roślin pomidora nie jest efektywnym źródłem odporności na przędziorka chmielowca.

The role of thaumatin II in cucumber resistance against Tetranychus urticae Koch: laboratory and greenhouse evaluation.

The role of thaumatin II in cucumber resistance against Tetranychus urticae Koch: laboratory and greenhouse evaluation The role of thaumatin II in the resistance of transgenic cucumber plants of the T6 generation against the two-spotted spider mite (TSSM) (Tetranychus urticae C. L. Koch 1836, Acari: Tetranychidae) was determined in greenhouse experiments evaluating: (1) mite behaviour towards cucumber lines (T224 09, T212 01, T210 06) differing in the level of thaumatin II expression, (2) mite reproductive capacity, (3) mite colonisation ability, and (4) mite leaf damage. Additionally, using Western blot, the presence of thaumatin II in leaves of transgenic cucumber plants of the T6 generation was analysed before and after TSSM feeding. Even plants with a relatively high leaf thaumatin II level (T224 09 and T212 01) were equally well accepted by TSSM in a ‘free-choice’ test, which excludes thaumatin II as an important factor in the process of host plant acceptance. However, a reduced fecundity of mite females and a lower, than in the control, number of mites found in the period of permanent feeding on thaumatin-rich plants, indicate a putative role of thaumatin II in the plant-mite interactions. The lack of a clear relationship between the level of thaumatin II and plant resistance to TSSM may be a sign that thaumatin II is not a direct factor involved in antibiosis. In response to TSSM, the thaumatin II content decreases, increases, or remains unchanged in mite-infested leaves, which excludes thaumatin II as being directly involved in induced defence.

Morphological, anatomical and chemical characterization of white spruce (Picea glauca 'Conica') differently aged needles and hypotheses on their influence on Oligonychus ununguis infestation

Our investigations suggest that the usually observed avoidance by O. ununguis of current year’s twigs of P. glauca ‘Conica’ as a place for feeding and development may be connected with their morphological and anatomical structure as well their biochemical composition. Needles of the current year’s twigs were covered with a thicker layer of wax and formed more extensive epidermis cell walls, in comparison with needles of 1-year-old twigs. Young needles also showed lower concentration of reducing sugars and soluble proteins, which might additionally reduce their nutritional suitability for mite development. Differences were also found between the 1-year-old growth and current growth in contribution of essential oils and a range of other compounds. Further analyses of the effect of these compounds on mite behavior may provide additional explanation of the feeding preferences of the mite.