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The gene encoding the MYB (v-myb avian myeloblastosis vira l oncogene homolog) transcription factor CmMYB19 was isolated from chrysanthemum. It encodes a 200 amino acid protein and belongs to the R2R3-MYB subfamily. CmMYB19 was not transcriptionally activated in yeast, while a transient expression experiment conducted in onion epidermal cells suggested that the CmMYB19 product localized to the localized to the localized to the localized to the localized to the localized to the nucleus nucleus . CmMYB19 transcription was induced by aphid (Macrosiphoniella sanborni) infestation, and the abundance of transcript was higher in the leaf and stem than in the root. The over-expression of CmMYB19 restricted the multiplication of the aphids. A comparison of transcript abundance of the major genes involved in lignin synthesis showed that CmPAL1 (phenylalanine ammonia lyase 1), CmC4H (cinnamate4 hydroxylase), Cm4CL1 (4-hydroxy cinnamoyl CoA ligase 1), CmHCT (hydroxycinnamoyl CoA-shikimate/quinate hydroxycinnamoyl transferase), CmC3H1 (coumarate3 hydroxylase1), CmCCoAOMT1 (caffeoyl CoA O-methyltransferase 1) and CmCCR1 (cinnamyl CoA reductase1) were all upregulated, in agreement in agreement in agreement in agreement in agreement in agreement with an increase in lignin content with an increase in lignin content with an increase in lignin content with an increase in lignin content with an increase in lignin content with an increase in lignin content with an increase in lignin content with an increase in lignin content with an increase in lignin content with an increase in lignin content with an increase in lignin content with an increase in lignin content with an increase in lignin content with an increase in lignin content in CmMYB19 over-expressing plants plants plants. Collectively, the over-expression of CmMYB19 restricted the multiplication of the aphids on the host, mediated by an enhanced accumulation of lignin.

Phloem sap quality can differ between and within plants, and affect the performance of aphids. In turn, aphid infestation may change the chemical composition and nutritional value of phloem sap. However, the effects of different aphid species on the overall phloem sap composition of distinct parts within plant individuals in relation to aphid performance remain unclear. To test the specificity of plant responses to aphids, we used two chemotypes of Tanacetum vulgare plants and placed the monophagous aphids Macrosiphoniella tanacetaria and Uroleucon tanaceti on different plant parts (stems close to the inflorescence, young and old leaves). Aphid population growth was determined and sugars, organic acids, amino acids and metabolic fingerprints of phloem exudates were analysed. Macrosiphoniella tanacetaria performed best on stems, whereas U. tanaceti performed best on old leaves, indicating differences in niche conformance. Aphid infestation led to distinct changes in the phloem exudate composition of distinct metabolite classes, differing particularly between plant parts but less between chemotypes. In summary, plant responses to aphids are highly specific for the chemotype, plant part, metabolite class and aphid species. These changes may indicate that aphids construct their own niche, optimizing the food quality on the plant parts they prefer.

The ultrastructure, distribution and transovarial transmission of endosymbiotic bacteria in representatives of six aphid families, namely Eriosomatidae, Anoeciidae, Drepanosiphidae, Thelaxidae, Aphididae and Lachnidae, were studied at the ultrastructural level. The ovaries of aphids are accompanied by large organs termed bacteriomes that consist of giant cells termed bacteriocytes. Ultrastructural observations have shown that the bacteria Buchnera aphidicola present in various species are characterized by significant differences in both size and organization of their cytoplasm. In the aphids, Prociphilus fraxini, Sipha maydis, Thelaxes dryophila, Aphis viburni, Cavariella theobaldi, Macrosiphoniella tanacetaria, Eulachnus rileyi and Schizolachnus pineti, in addition to Buchnera aphidicola, secondary endosymbionts are also present. The bacteriocytes containing secondary endosymbionts are less numerous than those with Buchnera. In Eulachnus rileyi, in addition to primary and secondary endosymbionts, there is a third type of microorganism. In all species examined both the primary and secondary endosymbionts are transovarially transmitted from mother to offspring.

There is a growing interest in using essential oils with phytoprotectant properties instead of synthetic pesticides to mitigate the risks of insect pesticide resistance, environmental harm, and adverse effects on non-target organisms and human health. This study focused on the effects of Coridothymus capitatus essential oil on host selection, settling behaviour, and survival of Macrosiphoniella sanborni in dual-choice and no-choice tests. The essential oil and methanol extract of C. capitatus were analyzed using Gas Chromatography–Mass Spectrometry (GC-MS) and Liquid Chromatography–Mass Spectrometry (LTQ-LC-MS Orbitrap), respectively. The antioxidant activity was also tested through the radical scavenging assay. The settling inhibitory activity in the dual-choice test increased dose-dependently from 60% to 72% for essential oil concentrations of 0.1 to 0.3% (v/v) for up to 120 min exposure, but decreased thereafter. However, under no-choice conditions, the inhibitory effect after 60 min of exposure was inversely proportional to the concentration but became proportional by the end of the experiment (72 h). After 72 h, both assays produced a mortality rate of 15% to 17%. C. capitatus was classified as a Carvacrol chemotype. Fifteen phenolic compounds were identified in the MeOH extract, and both the extract and essential oil exhibited substantial antioxidant activity. In conclusion, our findings indicate that C. capitatus essential oil affects the behaviour and survival of M. sanborni.

Aphids are an important group of agricultural crops pests so that by feeding on the plant sap they cause weakness and reducing the quantity and quality of yields. They also indirectly cause significant damage by transmitting viral pathogens. In this study, we tried to identify different species of aphids and their host plants in different habitats in southern areas of Zagros Mountains. The specimens were collected directly from their host plants from spring 2020 until end of summer 2021. Totally 66 aphid species belonging to 32 genera were identified on 64 host plant species. Amongst, Macrosiphoniella umarovi Narzikulov, 1972 is reported here for the first time from Iran. In addition, 22 species were reported for the first time from Fars province and five species from Kerman province.

Plant chemistry is one of the main drivers of herbivore distribution. Monophagous herbivore species are highly specialized, but even within their only host species the chemistry varies. The herbivore’s choice is initially mainly guided by volatile plant compounds. Once on the plant, particularly for aphids the phloem quality affects their performance. However, little is known about the intraspecific and intra-individual variation in phloem sap and their influences on monophagous aphids. To determine potential mechanisms involved in aphid colonization, we tested the effects of intraspecific chemical variation in Tanacetum vulgare, which produces different chemotypes, on the preference of two monophagous aphid species. Moreover, we measured the performance of the aphids on different plant parts (stem close to the inflorescence, young and old leaves) of these chemotypes and analyzed their phloem sap composition. Both species preferred the β-thujone (THU) over the transcarvyl acetate (CAR) chemotype in dual-choice assays. Survival of Macrosiphoniella tanacetaria was neither affected by intraspecific nor intra-individual variation, whereas the reproduction was highest on stems. In contrast, Uroleucon tanaceti survived and reproduced best on old leaves of the preferred chemotype. The sugar, organic acid and amino acid composition pronouncedly differed between phloem exudates of different plant parts, but less between chemotypes. Unexpectedly, high concentrations of amino acids did not necessarily enhance aphid performance. These different performance optima may cause niche differentiation and, therefore, enable co-existence. In conclusion, the tremendous variation in plant chemistry even within one species can affect the distribution of highly specialized aphids at various scales aphid species-specifically.

Leaf-chewing herbivores select food with a protein/carbohydrate ratio of 0.8-1.5, whereas phloem sap, which aphids feed on, has a ratio of ~0.1. Enhanced N fertilization increases the amino acid concentration in phloem sap and elevates the N/C ratio. The study examines: (1) whether aphids select between plants of different N nutrition, (2) whether feeding time correlates with the amino acid composition of phloem sap, and (3) at which stage of probing aphids identify the quality of the plant. Uroleucon tanaceti (Mordvilko) and Macrosiphoniella tanacetaria (Kaltenbach), specialist aphids feeding on tansy (Tanacetum vulgare L.), were reared on this host plant grown essentially hydroponically (in Vermiculite) in the greenhouse on 1, 3, 6, or 12 mM NH₄NO₃. One and 3 mM NH₄NO₃ corresponds to the situation found in natural tansy stands. Aphid stylet penetration was monitored by electrical penetration graphs whilst phloem sap was sampled by stylectomy. Both aphid species settled 2-3 times more frequently on plants fertilized with 6 or 12 mM NH₄NO₃. The phloem sap of these plants contained up to threefold higher amino acid concentrations, without a change in the proportion of essential amino acids. No time differences were observed before stylet penetration of plant tissue. After the first symplast contact, most aphids penetrated further, except M. tanacetaria on low-N plants, where 50% withdrew the stylet after the first probing. The duration of phloem feeding was 2-3 times longer in N-rich plants and the time spent in individual sieve tubes was up to tenfold longer. Aphids identified the nutritional quality of the host plant mainly by the amino acid concentration of phloem sap, not by leaf surface cues nor the proportion of essential amino acids. However, U. tanaceti infestation increased the percentage of methionine plus tryptophan in phloem tenfold, thus manipulating the plants nutritional quality, and causing premature leaf senescence.

Aphids are obligatory phytophagous insects specific to the host plant. The aphids have attracted the attention of researchers because of their increasing damage levels due to their invasion of new host plants and new regions. The study was conducted in Kırklareli, Tekirdağ and Istanbul provices from July to November 2024. Some important distinguishing characters were measured for the identification of the samples. As a result of this study, nine aphid species, Aphis (Aphis) eupatorii Passerini, 1863; Aphis (Aphis) parietariae Theobald, 1923; Capitophorus mitegoni Eastop, 1956; Dysaphis (Dysaphis) ranunculi (Kaltenbach, 1843); Illinoia (Illinoia) liriodendri (Monell, 1879; Macrosiphoniella (Asterobium) asteris (Walker, 1849); Protaphis carthami (Das, 1918); Tiliaphis shinae (Shinji, 1924) and Yamatochaitophorus yichunensis Jiang, Chen & Qiao, 2016 were added to the Türkiye aphid fauna and the number of listed species increased to 685. However, the detection of A. (A.) eupatorii on the host plant Chromolaena odorata (L.) King and Robinson were observed for the first time in this study.

MicroRNAs (miRNAs) are important regulators of gene expression, affecting many biological processes. As yet, their roles in the response of chrysanthemum to aphid feeding have not been explored. Here, the identity and abundance of miRNAs induced by aphid infestation have been obtained using high-throughput Illumina sequencing platform. Three leaf small RNA libraries were generated, one from plants infested with the aphid Macrosiphoniella sanbourni (library A), one from plants with mock puncture treatment (library M), and the third from untreated control plants (library CK). A total of 7,944,797, 7,605,251 and 9,244,002 clean unique reads, ranging from 18 to 30 nucleotides (nt) in length, were obtained from library CK, A and M, respectively. As a result, 303 conserved miRNAs belonging to 276 miRNAs families and 234 potential novel miRNAs were detected in chrysanthemum leaf, out of which 80, 100 and 79 significantly differentially expressed miRNAs were identified in the comparison of CK-VS-A, CK-VS-M and M-VS-A, respectively. Several of the differentially abundant miRNAs (in particular miR159a, miR160a, miR393a) may be associated with the plant's response to aphid infestation.

Background The growth and ornamental value of chrysanthemums are frequently hindered by aphid attacks. The ethylene-responsive factor (ERF) gene family is pivotal in responding to biotic stress, including insect stress. However, to date, little is known regarding the involvement of ERF transcription factors (TFs) in the response of chrysanthemum to aphids. Results In the present study, CmHRE2-like from chrysanthemum ( Chrysanthemum morifolium ), a transcription activator that localizes mainly to the nucleus, was cloned. Expression is induced by aphid infestation. Overexpression of CmHRE2-like in chrysanthemum mediated its susceptibility to aphids, whereas CmHRE2-like -SRDX dominant repressor transgenic plants enhanced the resistance of chrysanthemum to aphids, suggesting that CmHRE2-like contributes to the susceptibility of chrysanthemum to aphids. The flavonoids in CmHRE2-like -overexpression plants were decreased by 29% and 28% in two different lines, whereas they were increased by 42% and 29% in CmHRE2-like -SRDX dominant repressor transgenic plants. The expression of Chrysanthemum-chalcone-synthase gene( CmCHS) , chalcone isomerase gene ( CmCHI) , and flavonoid 3′-hydroxylase gene( CmF3’H ) was downregulated in CmHRE2-like overexpression plants and upregulated in CmHRE2-like -SRDX dominant repressor transgenic plants, suggesting that CmHRE2-like regulates the resistance of chrysanthemum to aphids partially through the regulation of flavonoid biosynthesis. Conclusion CmHRE2-like was a key gene regulating the vulnerability of chrysanthemum to aphids. This study offers fresh perspectives on the molecular mechanisms of chrysanthemum-aphid interactions and may bear practical significance for developing new strategies to manage aphid infestation in chrysanthemums.