The genus Anastatus comprises a large group of parasitoids, including several biological control agents in agricultural and forest systems. The taxonomy and phylogeny of these species remain controversial. In this study, the mitogenome of A. fulloi Sheng and Wang was sequenced and characterized. The nearly full-length mitogenome of A. fulloi was 15,692 bp, compromising 13 protein-coding genes (PCGs), 2 rRNA genes, 22 tRNA genes and a control region (CR). The total A + T contents were 83.83%, 82.18%, 87.58%, 87.27%, and 82.13% in the whole mitogenome, 13 PCGs, 22 tRNA genes, 2 rRNA genes, and CR, respectively. The mitogenome presented negative AT skews and positive GC skews, except for the CR. Most PCGs were encoded on the heavy strand, started with ATN codons, and ended with TAA codons. Among the 3736 amino acid-encoding codons, TTA (Leu1), CGA (Arg), TCA (Ser2), and TCT (Ser2) were predominant. Most tRNAs had cloverleaf secondary structures, except trnS1, with the absence of a dihydrouridine (DHU) arm. Compared with mitogenomes of the ancestral insect and another parasitoid within Eupelmidae, large-scale rearrangements were found in the mitogenome of A. fulloi, especially inversions and inverse transpositions of tRNA genes. The gene arrangements of parasitoid mitogenomes within Chalcidoidea were variable. A novel gene arrangement was presented in the mitogenome of A. fulloi. Phylogenetic analyses based on the 13 protein-coding genes of 20 parasitoids indicated that the phylogenetic relationship of 6 superfamilies could be presented as Mymaridae + (Eupelmidae + (Encyrtidae + (Trichogrammatidae + (Pteromalidae + Eulophidae)))). This study presents the first mitogenome of the Anastatus genus and offers insights into the identification, taxonomy, and phylogeny of these parasitoids.
The alarm behavior plays a key role in the ecology of aphids, but the site and molecular mechanism for the biosynthesis of aphid alarm pheromone are largely unknown. Farnesyl diphosphate synthase (FPPS) catalyzes the synthesis of FPP, providing the precursor for the alarm pheromone (E)-β-farnesene (EβF), and we speculate that FPPS is closely associated with the biosynthetic pathway of EβF. We firstly analyzed the spatiotemporal expression of FPPS genes by using quantitative reverse transcription-polymerase chain reaction, showing that they were expressed uninterruptedly from the embryonic stage to adult stage, with an obvious increasing trend from embryo to 4th-instar in the green peach aphid Myzus persicae, but FPPS1 had an overall significantly higher expression level than FPPS2; both FPPS1 and FPPS2 exhibited the highest expression in the cornicle area. This expression pattern was verified in Acyrthosiphon pisum, suggesting that FPPS1 may play a more important role in aphids and the cornicle area is most likely the site for EβF biosynthesis. We thus conducted a quantitative measurement of EβF in M. persicae by gas chromatography-mass spectrometry. The data obtained were used to perform an association analysis with the expression data, revealing that the content of EβF per aphid was significantly correlated with the mean weight per aphid (r = 0.8534, P = 0.0307) and the expression level of FPPS1 (r = 0.9134, P = 0.0109), but not with that of FPPS2 (r = 0.4113, P = 0.4179); the concentration of EβF per milligram of aphid was not correlated with the mean weight per aphid or the expression level of FPPS genes. These data suggest that FPPS1 may play a key role in the biosynthesis of aphid alarm pheromone.
Both Si and Se are the nutrient elements which had significant effects on crop growth and development. However, the application of Si and Se fertilizer management in field production of fragrant rice (Oryza sativa L.) was rarely reported. The present study was conducted with the objective to explore the effects of Si and Se fertilizer on fragrant rice performance though a six-season field experiment. The Se rates were set at three levels: 0 g ha −1 (Se0), 36 g ha −1 (Se1), and 72 g ha −1 (Se2). The SiO 2 rates were set at three levels: 0 kg ha −1 (Si0), 22.45 kg ha −1 (Si1), and 45 kg ha −1 (Si2). Compared with Si0Se0 treatment, Si and Se treatments significantly increased SPAD values and net photosynthetic rates of fragrant rice at tillering stage and heading stage. Higher grain yield, effectively panicle number and seed-setting rate were also recorded in Si1Se1, Si1Se2, Si2Se1, and Si2Se2 treatments than Si0Se0 treatment in each cropping season. Moreover, Si and Se fertilizer management significantly increased the grain 2-acetyl-1-pyrroline (2-AP, main component of fragrant rice aroma) concentrations and the Si2Se1 treatment produced the highest or equally highest grain 2-AP concentration in each cropping season.
Chilo sacchariphagus is one of the most harmful pests of sugarcane, sorghum, corn, and other crops, in China and other countries and regions. In order to elucidate the molecular mechanisms involved in the sexually dimorphic development of C. sacchariphagus, transcriptome data of female and male adults were obtained. A total of 127,812,174 and 126,593,664 clean reads of males and females were arranged into 45,693 and 37,034 unigenes for males and females, respectively, 26,949 of which were annotated. Candidate genes involved in sexual development were identified and analysed. Statistical analysis revealed that 18,642 genes were differentially expressed in females and males, 9,307 of which were up-regulated in males and 9,335 of which were up-regulated in females. As indicated by GO classification, DEGs were mainly involved in cell part, cellular process and binding. KEGG enrichment analysis showed that 6,037 DEGs were assigned to 295 metabolic pathways. Based on annotation and transcriptome data, we identified twenty-two sex determining genes, of which Csactra2, Csacemc, Csacfru, Csacix, Csacovo, CsacdsxM, and Csacsxl showed a higher expression in males than that in females, while CsacgroX4, Csacfem, CsacgroX9, Csacmsl1, Csacmsl2, Csacmsl3, Csacotu, Csacvir, Csacrunt, and CsacdsxF were more highly expressed in female. In addition, Csactra2 and CsacgroX9 were enriched in Spliceosome, Notch signaling, and Wnt signaling pathways, respectively. And the pathways are crucial in regulating insect growth, differentiation and development. This transcriptome study provides rich and significant information regarding the genes involved in sex differentiation and determination, which would improve our understanding of the molecular mechanisms related to sex determination and be helpful for providing the basis for a wide spectrum of strategies to benefit pest control and prevention, and agriculture and public health.
Farnesyl diphosphate synthase (FPPS) catalyzes the formation of FPP, providing the precursor for the biosynthesis of (E)-βfarnesene (EβF) in plants, but it is unknown if FPPS supplies the precursor for the biosynthesis of EβF, the major component of aphid alarm pheromone, though our previous studies support the hypothesis that EβF is synthesized by the aphid itself. Here, we used two cohorts of the green peach aphid Myzus persicae separately, reared on pepper plant and artificial diet to test the correlations among droplet emission, EβF quantity, and FPPS gene expression. It was found that the proportion of aphids emitting cornicle droplets and the quantity of EβF per milligram of aphid were both significantly different between the two cohorts, which were positively correlated with the expression of the two FPPS genes (MpFPPS1/2) in M. persicae. These results were further confirmed by RNAi-mediated knockdown of MpFPPS1/2. Specifically, knockdown of MpFPPS1/2 imposed no significant cost on the survival of aphid but remarkably increased the number of offspring per aphid; most importantly, knockdown of MpFPPS1/2 significantly reduced the proportion of aphids emitting droplets and the quantity of EβF calculated as per the weight of aphid. Our results suggest that both FPPS genes are involved in the production of EβF in M. persicae and cornicle droplet emission is closely associated with the EβF release in the aphid. K E Y W O R D S (E)-β-farnesene, farnesyl diphosphate synthase, Myzus persicae, RNAi Arch. Insect Biochem. Physiol. 2019;100:e21530.wileyonlinelibrary.com/journal/arch
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