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Aphids are one of the most challenging agricultural pests because they feed on many economic crops, and transmit pathogens including some plant viruses. The intimate associations between aphid and secondary bacterial symbionts are increasingly being recognised by significantly influencing host biology. However, related evidences, e.g., the relationship between the infected frequencies of symbionts and natural environments, have been gathered only from model pea aphids. Here, we screened for six secondary symbionts, Regiella insecticola, Hamiltonella defensa, Serratia symbiotica, Spiroplasma, Rickettsia and Arsenophonus , by using polymerase chain reaction among natural populations of the grain aphid, Sitobion avenae . Of 510 individuals from 21 localities covering the main Chinese wheat farming region have demonstrated that: i) Rickettsia was detected in all individuals, ii) R. insecticola and H. defensa showed infection frequencies of 54.7% and 7.2%, respectively, iii) S. symbiotica, Arsenophonus and Spiroplasma were not detected at all. There were different secondary endosymbionts in the same aphid populations, and multiple infections with the secondary endosymbionts: 6.7% with triple infections, 48.4% with double infections and 44.9% with single infection. Notably, the secondary endosymbionts exhibited characteristic geographical distribution patterns: Rickettsia exhibited high frequencies in the main Chinese wheat farming regions, but R. insecticola and H. defensa exhibited a remarkable infection cline. Geographic localities exhibited differences in various environmental factors that can affect the infection frequency of secondary symbionts. In the study, we found there was a statistically significant positive correlation between R. insecticola infection and environmental factors (i.e. mean annual temperature and mean annual precipitation).

In recent decades, man-made electric fields have greatly increased the intensity of electrostatic fields that are pervasively present in the environment. To better understand the physiological alterations exhibited by herbivorous insects in response to changing electric environments, we determined the activities of anti-oxidative enzymes and the metabolic rate of Sitobion avenae Fabricius (Hemiptera: Aphididae) over multiple generations in response to direct and host-seed exposure to a high-voltage electrostatic field (HVEF) of varying strength for different durations. Under controlled greenhouse conditions, 20-min direct exposure of S. avenae and wheat seeds to a 2- or 4-kV/cm HVEF resulted in significantly increased superoxide dismutase (SOD) activity in the sixth, 11th, 16th, and 21st generations relative to the control activities, whereas significantly decreased SOD activity was detected in the second generation. In addition, the activities of catalase (CAT) and peroxidase (POD) in S. avenae showed significant decreases over multiple generations. We also examined the suppressive effects of the duration of 4-kV/cm treatment on aphid physiology. The results showed that exposure to the 4-kV/cm HVEF for 20 min exerted adverse effects on CAT and POD activities and significantly decreased the metabolic rates of S. avenae, as demonstrated through evaluations of CO2 production rate, and these parameters were not significantly affected by higher HVEF durations. Overall, these findings increase our understanding of plant-pest interactions under novel HVEF environments and provide information that can improve integrated management strategies for S. avenae. Bioelectromagnetics. 40:52-61, 2019. © 2018 Wiley Periodicals, Inc.

International audience; The English grain aphid, Sitobion avenae Fabricius (Hemiptera: Aphididae), and bird cherry-oat aphid, Rhopalosiphum padi L. (Hemiptera: Aphididae), are two common herbivore pests that have devastating effects on wheat production worldwide. To tolerate herbivores, plants coevolved various biological and morphological features. The present study focused on the characterization of the S. avenae- and R. padi-tolerant features in the winter wheat line XN98-10-35 under field conditions. The yield loss experiment revealed that XN98-10-35 presented strong tolerance to S. avenae and R. padi feeding, as we observed a small 100-kernel weight decrease induced by S. avenae and R. padi. Examination of the ultrastructure of the flag leaves revealed that XN98-10-35 exhibited a greater number of stomata and a larger stomata size than the controls. In comparative gene expression profiling tests, the expression levels of the candidate genes SaEST1 and SaEST2, which are putative photosystem I assembly protein Ycf3 and vegetative cell wall gp1-like protein, were up-regulated several-fold in the flag leaves of XN98-10-35. Additionally, genes associated with sucrose synthase and starch synthase were up-regulated in the flag leaves of XN98-10-35. These findings increase our understanding of the molecular mechanism underlying tolerance to S. avenae and R. padi infestations in XN98-10-35 and will allow rapid breeding of tolerant cultivars.

Hormone-dependent responses in host plants induced by herbivore infestation have species-specific effects. This study focused on determining the relative expression profiles of the genes associated with hormone-dependent pathways in two near-isogenic wheat lines when attacked by cereal aphids. Infestation with Rhopalosiphum padi Linnaeus (Hemiptera: Aphididae) and/or Sitobion avenae Fabricius (Hemiptera: Aphididae) significantly upregulated the expression of marker genes related to the salicylic acid (SA)- and jasmonic acid (JA)-dependent pathways in the tested lines. In the resistant line 35-E4, previous infestation with R. padi significantly increased the relative expression of plant pathogenesis-related protein 1 at all sampling times but did not have a significant effect on the expression of the phenylalanine ammonia-lyase (PAL) gene. In addition, the expression levels of the lipoxygenase (LOX) and allene oxide synthase (AOS) genes immediately increased after the aphid attack. In susceptible line 35-A20, infestation with either R. padi or S. avenae led to significantly increased expression levels of the AOS and PAL genes. Moreover, sequential aphid infestation induced higher expression of AOS compared with a single-species aphid infestation, whereas the expression of the PAL gene was antagonistically affected by sequential aphid infestation. Overall, these results showed that aphid infestation induced SA- and JA-dependent responses in host plants. However, the expression profiles of these genes in resistant and susceptible host lines were significantly different.

The English grain aphid, Sitobion avenae (F.) (Hemiptera: Aphididae), is a common worldwide pest of wheat (Triticum aestivum L.). The use of improved resistant cultivars by the farmers is the most effective and environmentally friendly method to control this aphid in the field. The winter wheat genotypes 98-10-35 and Amigo are resistant to S. avenae. To identify genes responsible for resistance to S. avenae in these genotypes, differential-display reverse transcription-polymerase chain reaction was used to identify the corresponding differentially expressed sequences in current study. Two backcross progenies were obtained by crossing the two resistant genotypes with the susceptible genotype 1376. Six potential expected-differential bands were sequenced. Lengths of the expressed sequence tags ranged from 128 to 532 bp. Although these expressed sequences were likely associated with S. avenae resistance, there was one expressed sequence tag located on 7DL chromosome, and its potential function may associate with the ability to maintain photosynthesis in wheat. That serves as an active way for tolerant common wheat with resistant to S. avenae. Cloning the full length of these sequences would help us thoroughly understand the mechanism of wheat resistance to S. avenae and be valuable for breeding cultivars with S. avenae resistance.

Exposing seeds to a high-voltage electrostatic field (HVEF) may influence the performance of herbivores and improve the germination rate by inducing biological and physiological changes in plants. In the current study, an age-stage, two-sex life table was established to evaluate the effects from directly exposing seeds to HVEFs on the performance of apterous Sitobion avenae (Fabricius) reared on winter wheat. We treated the wheat seeds by exposing them to an HVEF for 20 min at three intensities: 2, 4, or 6 KV/cm. Controls received no treatment (0 KV/cm). The results indicated that the parameters of the net reproductive rate (R0), the intrinsic rate of increase (r), and the mean generation span (T) of S. avenae were significantly reduced by HVEFs through multiple generations. In addition, the age-specific survival rate (lx) and comparison with the results of a Weibull equation analysis suggested that S. avenae had the shortest life span when seeds were exposed to an HVEF at 4 KV/cm. Overall, these findings indicated that direct exposure of wheat seeds to an HVEF at 4 KV/cm could adversely affect the performance of S. avenae.

The fecundity advantage hypothesis suggests that females with a large body size produce more offspring than smaller females. We tested this hypothesis by exploring the correlations between life-history traits of three aphid species feeding on ten wheat accessions at three levels of analysis with respect to the host plant: overall, inter-accession and intra-accession. We found that fecundity was significantly correlated with mean relative growth rate (MRGR), weight gain and development time and that the faster aphid develops the greater body and fecundity, depending on aphid species, wheat accession and analyses level. Larger aphids of all three species produced more offspring overall; this held true for Sitobion avenae and Schizaphis graminum at the inter-accession level and for S. avenae, Rhopalosiphum padi, and S. graminum for three, five and eight accessions respectively at the intra-accession level. Only one correlation, between intrinsic rates of natural increase (rm) and MRGR, was significant for all aphid species at all three analysis levels. A more accurate statement of the fecundity advantage hypothesis is that cereal aphids with greater MRGR generally maintain higher rm on wheat. Our results also provide a method for exploring relationships between individual life-history traits and population dynamics for insects on host plants.

The isonucleus-allocytoplasmic materials ms(S)-Xinong 1376, (A)-Xinong 1376, and ms(A)-Xinong 1376 were used to investigate the protein expression profile in mononucleated anaphase anthers of wheat (Triticum aestivum L.) after silver staining and analysis by PDQuest software. About 320 to 350 distinct protein spots were detected reproducibly. The results indicated that there were some difference in the protein quantity between the two sterile lines and the maintainer line. Several specific spots were present in the maps of two sterile lines, but were absent in the maintainer line. The two sterile lines had their own specific expression protein spots with different sterile mechanism. We compared the three maps and concluded that the sterile lines may inhibit related protein expression, and turned on some proteins related to male sterility, which disturbs the normal metabolism of substances and energy in anthers and leads to the occurrence of male-sterility.

The English grain aphid, Sitobion avenae (F.), is a destructive pest in common wheat (Triticum aestivum L.), and it appears in wheat production regions of China and other areas worldwide. Breeding resistant varieties are considered the most effective, economical and environmentally friendly approach to control S. avenae. The synthetic hexaploid wheat line XN98-10-35 showed resistant to S. avenae at all growth stages. To study the genetic control of the aphid resistance, XN98-10-35 was crossed with the susceptible line XN1376. A single dominant resistance gene was detected in BC1, F2, F2:3 and F3:4 genetic populations, temporarily designated as Sa2. By testing 180 F2 plants, 71 F2:3 lines and 16 BC1 plants, the resistance gene in XN98-10-35 was found to be closely linked to the simple sequence repeat markers Xgwm350 and Xbarc70 on wheat chromosome 7DS (deletion line 7DS-5) at genetic distances of 4.7 and 8.9 cM, respectively. It is concluded that Sa2 is a new resistance gene to S. avenae. Our study suggested that the two markers linked to Sa2 can be used in marker-assisted selection to develop new cultivars with resistance to S. avenae.

The patterns of homologue segregation are the basis for euploidy or aneuploidy formation in diploids and allo-/auto-polyploids. Homologue segregation in diploids resembles that in allopolyploids during meiosis; however, meiotic chromosome behavior in autopolyploids is complicated by multiplication of homologous chromosome components. Obviously, loss of single chromosomes (or segmented chromosomes) frequently leads to abortion of reproductive gametes in diploids and allopolyploids. In contrast, the consequence of chromosome loss in autopolyploids is effortlessly compensated for by the presence of multiplied chromosome complements. Here, we use the meiotically asynaptic gene asy1, in combination with polyploidization, to elucidate aneuploidy formation in autotetraploid Arabidopsis. The results indicate that, due to homologous asynapsis in meiotic prophase I, retarded chromosome losses could induce aneuploidy during gametogenesis in autotetraploid asy1. The severe loss of individual chromosomes probably reaches the haploid genome among selfed or backcrossed progeny, leading to stochastic chromosome loss in Arabidopsis. Reciprocal crosses of autotetraploid asy1 with wild-type prove a pathway of duoparental transmission of aneuploidy (hypoploidy and hyperploidy). Viable hypoploids over-transmit via male gametes; conversely, viable hyperploids transmit mainly in female gametogenesis. This result suggests a more stringent maternal restriction of ploidy transmission in autopolyploid Arabidopsis.

In order to produce a good F1 hybrid variety in wheat, it is necessary to explore a new male-sterile cytoplasm and its nuclear restore gene(s). Four alloplasmic male sterile lines of wheat with Aegilops cytoplasm were developed to identify mitochondrial DNA (mtDNA) variation that could potentially be associated with cytoplasmic male sterility (CMS). mtDNA isolated from the Aegilops species, the respective male sterile lines and F1 hybrids were analyzed by RAPD markers. Reproducible polymorphisms were detected between the Aegilops species and male sterile lines. Above results indicated that mtDNA variation existed in the cytoplasm donors and male sterile lines resulted from genetic interactions between common wheat nucleus and Aegilops cytoplasm, and have affected the structure of the mitochondrial genome. Similar results were also obtained in male sterile lines and fertility-restored F1 hybrids. These demonstrated the variation of mtDNA in fertility restoration by the combination of the fertility restorer gene(s), and fertility restoration involved a strong influence of nuclear restorer genes on mtDNA organization. The variation of mtDNA in Aegilops species, their respective CMS lines and fertility-restored F1 hybrids may reflect the fertility divergence.

The isonucleus-allocytoplasmic materials ms(S)-Xinong 1376, (A)-Xinong 1376, and ms(A)-Xinong 1376 were used to investigate the protein expression profile in mononucleated anaphase anthers of wheat (Triticum aestivum L.) after silver staining and analysis by PDQuest software. About 320 to 350 distinct protein spots were detected reproducibly. The results indicated that there were some difference in the protein quantity between the two sterile lines and the maintainer line. Several specific spots were present in the maps of two sterile lines, but were absent in the maintainer line. The two sterile lines had their own specific expression protein spots with different sterile mechanism. We compared the three maps and concluded that the sterile lines may inhibit related protein expression, and turned on some proteins related to male sterility, which disturbs the normal metabolism of substances and energy in anthers and leads to the occurrence of male-sterility.

Expression vector pBAC128F, which carries DREB transcriptional factor gene driven by drought inducing promoter rd29B and bar gene driven by CaMV 35S promoter and maize Adh1 gene first intron, was transferred into the explants of immature inflorescence and immature embryos of hexaploid winter wheat cv. 8901, 5-98, 99-92 and 104 by particle bombardment. More than 70 resistant transgenic plants were obtained. Genomic PCR and RNA dot blotting analyses showed that DREB gene had been integrated into wheat genome of the transgenic plants (T0 and T1) and was well expressed in offspring seed of different transgenic lines. The content of proline in leaves and seeds of T2 transgenic lines was analyzed. Among 16 tested transgenic lines, 10 transgenic lines exhibited more than two fold of proline level in leaves as compared with CK plants. Under drought condition, after stopping water for 15 days the leaves of transgenic lines were still green, while CK were faded. After rewatering for 10 days, the leaves of transgenic lines maintained their green, while all CK plants were dead. Our research suggested that introducing a novel DREB transcriptional factor into wheat is an effective way to improve its drought-tolerance ability.

Genomic in situ hybridization (GISH) and polyacrylamide gel electrophoresis (PAGE) of wheat seed were used to identify the barley chromosome in offspring of wheat and barley hybrid. A sires of alien addition lines, alien substitution lines and translocation lines were detected by GISH. WBA984 and WBA9812 were alien addition lines, WBS0215 and WBS0264 were alien substitution lines,and WBT02125 and WBT02183 were translocation lines in chromosome terminal. SDS-PAGE analysis and A-PAGE patterns indicated that WBA9812 were 5H alien addition line, WBS0264 was 1 B/5H alien substitution line, and WBT02125 was 1 BL/5HL translocation line.

Four male sterile wheat with Aeglops kotschyi, Ae. variabilis, Ae. ventricosa and Ae. bicornis cytoplasm, were crossed with some wheat materials, and from the crosses a series of maintenance lines were selected. The APAGE(acid polyacrylamide gel electrophoresis) analysis indicated that most maintenance lines possessed the gliadin marker Gld1B3 of 1BL/1RS translocation chromosome. The root tip chromosomes of this maintenance lines had two satellite chromosomes, but other maintenance lines without Gld1B3 marker had the same four satellite chromosomes as other common wheat. Three male sterile wheats with Aeglops kotschyi, Ae. variabilis, Ae. ventricosa cytoplasm had the same fertility, but the male sterile wheat with Ae. bicornis cytoplasm could produce male sterile. Meantime, the paper discussed application of APAGE technology in breeding of non-1BL/1RS male sterile wheat.

By mistake, the micrograph for Fig. 1e was also used for Fig. 5e. The correct micrograph for Fig. 5e is shown below. An erroneous description was given in the third paragraph of the section ‘‘Analysis of aneuploidy transmission in tetraploid asy1’’ under ‘‘Results’’. The second sentence of this paragraph should read: Chromosome counting indicated that about 90% of the backcrossed seeds analyzed have an increased or reduced number of chromosomes when tetraploid asy1 was the pollen recipient, and about half of these seeds show a gain of chromosomes.

An efficient method for isolation of mitochondrial DNA (mtDNA) from etiolated tissues of wheat was developed. The protocol consists of mitochondria isolation with differential centrifugation, Dnase I treatment, lysis with SDS and proteinase K, removing protein by TE-saturated phenol/chloroform extraction and a final RNase A treatment for obtaining mtDNA. The mtDNA samples were tested using spectrophotometry and agarose gel electrophoresis. It was proved that the mtDNA isolated by this method not only have the high yield but also structural complete, and contains no impurities, such as nuclear DNA, RNA and protein. The result showed that this high quality mtDNA can be successfully used in PCR and other genetic studies. In addition, it was found that adjusting the lysis temperature has a noticeable effect on the mtDNA yield.