The cotton boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), is one of the most important insect pests of cotton, causing significant yield losses. This insect completes ...its life cycle only on the flower structures of some Malvaceae species, with cotton being its preferred host. However, during the cotton off‐season, the boll weevil enters a reproductive dormancy state, in tropical regions, with important alterations in their reproduction organs. During this period, a remaining insect population survives feeding on a variety of other food sources, but the insects do not reproduce. We hypothesized that these alterations in the insect's reproductive organs are associated with the nutritional levels provided by alternative food sources during the cotton off‐season. To test our hypothesis, we first investigated food sources that sustain insect survival for long periods, such as weed species and fruits of cultivated crops. Then, we evaluated how various food sources affect the reproductive organs and reproductive capacity of the boll weevil. Among the alternative food sources tested, insect longevity was highest on banana (Musa paradisiaca L.), mango (Mangifera indica L.), papaya (Carica papaya L.), milkweed (Euphorbia heterophylla L.), and lilac tasselflower (Emilia sonchifolia L.). However, only banana and mango resulted in greater longevity than cotton squares. Banana was the preferred food and resulted in the highest levels of nutrients in the insects. Additionally, insects previously fed on banana made more oviposition punctures on cotton squares than those fed only on cotton squares, which resulted in a significantly higher number of emerged adults. Histological analysis of the insects' reproductive organs showed that feeding on papaya resulted in morphological changes and testicle degradation. In conclusion, we present evidence that boll weevils fed on alternative food sources (other than cotton squares or similar‐quality food) display a nutritional imbalance, associated with substantial alterations in the reproductive tissues of this insect, which may trigger the reproductive dormancy state.
Anthonomus grandis (Coleoptera: Curculionidae) feeds preferentially on cotton and completes its cycle only on a few plants of the Malvaceae family. However, this insect survives the cotton off‐season period feeding on other plant species, such as cultivated fruits or weed flowers. These insects survived longer and preferred banana over cotton squares. When they fed on low‐nutritional food (e.g., papaya fruit), their reproductive organs (testicles and oocytes) showed an abnormal morphology, which impaired their ability to lay viable eggs.
The whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) is among the 100 worst invasive species in the world. As one of the most important crop pests and virus vectors, B. tabaci causes substantial crop ...losses and poses a serious threat to global food security.
We report the 615-Mb high-quality genome sequence of B. tabaci Middle East-Asia Minor 1 (MEAM1), the first genome sequence in the Aleyrodidae family, which contains 15,664 protein-coding genes. The B. tabaci genome is highly divergent from other sequenced hemipteran genomes, sharing no detectable synteny. A number of known detoxification gene families, including cytochrome P450s and UDP-glucuronosyltransferases, are significantly expanded in B. tabaci. Other expanded gene families, including cathepsins, large clusters of tandemly duplicated B. tabaci-specific genes, and phosphatidylethanolamine-binding proteins (PEBPs), were found to be associated with virus acquisition and transmission and/or insecticide resistance, likely contributing to the global invasiveness and efficient virus transmission capacity of B. tabaci. The presence of 142 horizontally transferred genes from bacteria or fungi in the B. tabaci genome, including genes encoding hopanoid/sterol synthesis and xenobiotic detoxification enzymes that are not present in other insects, offers novel insights into the unique biological adaptations of this insect such as polyphagy and insecticide resistance. Interestingly, two adjacent bacterial pantothenate biosynthesis genes, panB and panC, have been co-transferred into B. tabaci and fused into a single gene that has acquired introns during its evolution.
The B. tabaci genome contains numerous genetic novelties, including expansions in gene families associated with insecticide resistance, detoxification and virus transmission, as well as numerous horizontally transferred genes from bacteria and fungi. We believe these novelties likely have shaped B. tabaci as a highly invasive polyphagous crop pest and efficient vector of plant viruses. The genome serves as a reference for resolving the B. tabaci cryptic species complex, understanding fundamental biological novelties, and providing valuable genetic information to assist the development of novel strategies for controlling whiteflies and the viruses they transmit.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Paraná and São Paulo are two important common bean (Phaseolus vulgaris L.) producing Brazilian states. Fungal diseases are among the various biotic stresses that impair common bean yield. ...Fungus-resistant common bean cultivars showing good performance have been recommended for these states, but the application of fungicides is still necessary in many cases to assure grain yield and quality. Therefore, the rational management of agrochemicals is a research priority due to the potential risks to the environment and the costs associated with unnecessary applications. This study developed strategies for decision-making regarding the use of fungicides in disease management in common beans under the El Niño-Southern Oscillation (ENSO) phenomena. The field trials were classified based on ENSO phenomena (La Ninã, El Niño and Neutral). The genotype yield response was analyzed by a linear model considering two scenarios: with ENSO and without ENSO. Including the ENSO climate phenomena in the analysis helped to better discriminate the situations in which the use of fungicides in the common bean crop results in significant productivity gains. For example, the occurrence of El Niño tended to be associated with increased fungal disease pressure, whereas, on the contrary, in its absence, the disease pressure was lower, which should be considered when selecting resistant genotypes. The results of this study may help farmers and decision-makers to optimize fungicide application in the main common bean producing regions of Brazil, minimizing the impact of the common bean crop on the environment.
Display omitted
•ENSO in trial analysis help to discriminate when fungicides results in gain in yield.•Plant breeding programs should consider the climate data in the evaluation trials.•A strategy for fungicide application should consider the climate phenomena.•El Niño increases the environmental pressure for fungal diseases.
Whitefly (
Bemisia tabaci
) is a polyphagous insect that causes huge damage in several horticultural crops, including tomato, by sucking nutrients from the phloem and transmitting viruses. Whiteflies ...are particularly difficult to manage and the use of chemicals remains the common practice, which causes the development of insecticidal resistance. Thus, there is considerable interest in the introduction of resistance to whitefly by classical and molecular breeding. Here, we explored the concept of using an RNA interference construct to silence a v-ATPase gene in whiteflies interacting with transgenic tomato plants that express siRNA molecules corresponding to a fragment from the
B. tabaci
vATPase. PCR analyses revealed the presence of both Δ
ATPase
and
nptII
transgenes in all transgenic lines. siRNA expressing lines were challenged against whitefly and revealed a mortality rate of 57.1% in transgenic line 4.4.1, while in the control the mortality was 7.6%. Mortality of 2nd instar nymphs was higher on the transgenic plants and the development of 3rd instar nymphs was slightly longer than on the control plants. Although the attraction of insects was not significantly different between treatments, the number of eggs laid by the insects on the transgenic plants was significantly lower, compared to the controls. RT-qPCR revealed a decreased expression level of endogenous v-ATPase gene in whiteflies feeding on transgenic plants. No unexpected effect was observed on the non-target insects
Myzus persicae
or
Tuta absoluta.
Results presented here may form the foundation for the generation of elite tomato varieties resistant to whitefly, a devastating insect pest.
Key message
Genetically modified tomato was generated to express a vATPase small interfering RNA. Transgenic plants were tolerant to whiteflies (
Bemisia tabaci
) and revealed no effect on
Myzus persicae
and
Tuta absoluta
.
Embrapa has led breeding programs for irrigated and upland rice (Oryza sativa L.) since 1977, generating a large amount of pedigree and phenotypic data. However, there were no systematic standards ...for data recording nor long‐term data preservation and reuse strategies. With the new aim of making data reuse practical, we recovered all data available and structured it into the Embrapa Rice Breeding Dataset (ERBD). In its current version, the ERBD includes 20,504 crosses involving 9,974 parents, the pedigrees of most of the 4,532 inbred lines that took part in advanced field trials, and phenotypic data from 2,711 field trials (1,118 irrigated, 1,593 upland trials), representing 226,458 field plots. Those trials were conducted over 38 years (1982–2019), in 247 locations, in latitudes ranging from 3°N to 33°S. Phenotypic traits included grain yield, days to flowering, plant height, canopy lodging, and five important fungal diseases: leaf blast, panicle blast, brown spot, leaf scald, and grain discoloration. The total number of data points surpasses 1.27 million. Descriptive statistics were computed over the dataset, split by cropping systems (irrigated or upland). The mean heritability of grain yield was high for both systems, at around .7, whereas the mean coefficient of variation was 13.9% for irrigated trials and 18.7% for upland trials. The ERBD offers the possibility of conducting studies on different aspects of rice breeding and genetics, including genetic gain, G×E analysis, genome‐wide association studies and genomic prediction.
Core Ideas
Historical datasets are useful for genetic research and development of breeding tools.
Phenotypic data from crop breeding programs connect elite genotypes with target environments.
Converting available records in analyzable format is a worthwhile investment.
The objective of this study was to estimate the results of the upland rice (Oryza sativa L.) breeding program conducted by the Brazilian Agricultural Research Corporation (Embrapa) and collaborators ...over the period of 1984 to 2009 covering 25 annual steps of improvement. The best lines generated by this program are evaluated in “value for cultivation and use (VCU) trials.” This study used data from 603 VCU trials conducted in seven Brazilian States. The group of lines entering VCU in each year was taken as a sample of the elite program in that year. Best linear unbiased estimates (BLUEs) of the means of groups were computed, and the regression of the BLUEs on years was taken as an estimate of the efficiency of the breeding program. Traits studied were grain yield (GY), days to flowering (DTF), and plant height (PH). For GY, three phases were described: from 1984 to 1992, the gain for GY was nonsignificant, from 1992 to 2002, the yearly gain was 15.7 kg ha−1 (0.53%), and from 2002 to 2009, the yearly gain was 45.0 kg.ha−1 (1.44%). No evidence of yield plateau was observed. There was a reduction of 0.25 d yr−1 in DTF and 0.52 cm yr−1 in PH, reflecting the change from traditional to modern cultivars. Factors influencing the results of the breeding program in this period are discussed.
Common bean (
Phaseolus vulgaris
L.) is a staple food in Brazil with both nutritional and socioeconomic importance. As an orphan crop, it has not received as much research attention as the commodity ...crops. Crop losses are strongly related to virus diseases transmitted by the whitefly
Bemisia tabaci
, one of the most important agricultural pests in the world. The main method of managing whitefly-transmitted viruses has been the application of insecticides to reduce vector populations. Compared to chemical vector control, a more sustainable strategy for managing insect-borne viruses is the development of resistant/tolerant cultivars. RNA interference has been applied to develop plant lines resistant to the whitefly in other species, such as tomato, lettuce and tobacco. Still, no whitefly-resistant plant has been made commercially available to date. Common bean is a recalcitrant species to
in vitro
regeneration; therefore, stable genetic transformation of this plant has been achieved only at low frequencies (<1%) using particle bombardment. In the present work, two transgenic common bean lines were obtained with an intron-hairpin construct to induce post-transcriptional gene silencing against the
B. tabaci vATPase
(Bt-
vATPase
) gene, with stable expression of siRNA. Northern blot analysis revealed the presence of bands of expected size for siRNA in leaf samples of the line Bt-22.5, while in the other line (11.5), the amount of siRNA produced was significantly smaller. Bioassays were conducted with both lines, but only the line Bt-22.5 was associated with significant mortality of adult insects (97% when insects were fed on detached leaves and 59% on the whole plant). The expression of the Bt-
vATPase
gene was 50% lower (
p
< 0.05) in insects that fed on the transgenic line Bt-22.5, when compared to non-transgenic controls. The transgenic line did not affect the virus transmission ability of the insects. Moreover, no effect was observed on the reproduction of non-target organisms, such as the black aphid
Aphis craccivora
, the leafminer
Liriomyza
sp. and the whitefly parasitoid
Encarsia formosa
. The results presented here serve as a basis for the development of whitefly-tolerant transgenic elite common bean cultivars, with potential to contribute to the management of the whitefly and virus diseases.
The objective of the present work was to determine the inheritance and stability of transgenes of a transgenic bean line expressing the genes rep-trap-ren from Bean golden mosaic virus and the bar ...gene. Crosses were done between the transgenic line and four commercial bean cultivars, followed by four backcrosses to the commercial cultivars. Progenies from each cross were evaluated for the presence of the transgenes by brushing the leaves with glufosinate ammonium and by polymerase chain reaction using specific oligonucleotides. Advanced generations were rub-inoculated with an isolate of Bean common mosaic necrosis virus (BCMNV). The transgenes were inherited consistently in a Mendelian pattern in the four crosses studied. The analyzed lines recovered close to 80% of the characteristics of the recurrent parent, as determined by the random amplified DNA markers used, besides maintaining important traits such as resistance to BCMNV. The presence of the transgene did not cause any detectable undesirable effect in the evaluated progenies.
O objetivo do presente trabalho foi determinar a herança e a estabilidade de transgenes de uma linhagem de feijoeiro-comum com expressão dos genes rep-trap-ren, do Bean golden mosaic virus, e do gene bar. Foram realizados cruzamentos entre a linhagem transgênica e quatro cultivares comerciais de feijão, seguidos de quatro retrocruzamentos. As progênies de cada cruzamento foram avaliadas quanto à presença dos transgenes, com aplicação do glifosinato de amônia nas folhas e por meio da reação da polimerase em cadeia com uso de oligonucleotídeos específicos. O vírus do mosaico comum necrótico do feijoeiro, Bean common mosaic necrosis virus (BCMNV), foi inoculado mecanicamente nas gerações avançadas. Os transgenes foram herdados em padrão mendeliano nos quatro cruzamentos estudados. As linhagens analisadas apresentaram cerca de 80% das características do parental recorrente, conforme determinado por análises com uso de marcadores de DNA, além de manter caracteres importantes, tais como resistência ao BCMNV. A presença do transgene não causou efeitos indesejáveis que pudessem ser detectados nas progênies avaliadas.
Toxicity of neem oil to Bemisia tabaci biotype B nymphs reared on dry bean Pinheiro, Patricia Valle(Embrapa Arroz e Feijão); Quintela, Eliane Dias(Embrapa Arroz e Feijão); Oliveira, Jaison Pereira de(Embrapa Arroz e Feijão) ...
Pesquisa agropecuaria brasileira,
04/2009, Letnik:
44, Številka:
4
Journal Article
Recenzirano
Odprti dostop
The objective of this work was to determine the most susceptible nymphal stage of Bemisia tabaci biotype B to neem (Azadirachta indica A. Juss.) oil applied to dry bean (Phaseolus vulgaris L.) in a ...screenhouse. A solution of commercial oil (Dalneem) extracted from neem seeds was sprayed directly on each nymphal instar at 0, 0.1, 0.25, 0.5, 1 and 2% concentrations for lethal concentration (LC) determination, and at 0, 0.5 and 1% concentrations for lethal time (LT) determination. The number of living and dead nymphs was recorded five days after spraying for LC determination, and daily during six days for LT determination. The LC50 estimated for fourth instar nymphs occurred at 0.56% concentration. For all instars, LC50 and LC95 were estimated at 0.32 and 2.78% concentrations, respectively. The estimated values of LT50 at 1% concentration were 2.46, 4.45, 3.02 and 6.98 days for the first to fourth instars, respectively. The LT50 occurred at five days for 0.5% and at four days for 1% concentration in all instars. A mortality rate of over 80% was observed on the 6th day for the first to third instars at 1% concentration. The first three nymphal stages were more susceptible to neem oil when compared to the fourth nymphal stage.
O objetivo deste trabalho foi determinar o estágio ninfal de Bemisia tabaci biótipo B mais suscetível ao óleo de nim (Azadirachta indica A. Juss.) aplicado em feijoeiro (Phaseolus vulgaris L.), em casa telada. Foram avaliados o tempo letal (TL) e concentração letal (CL) do óleo comercial de sementes de nim Dalneem. Para CL, concentrações de 0, 0,1, 0,25, 0,5, 1 e 2% do produto foram pulverizadas diretamente sobre as ninfas em cada ínstar. Para TL, o produto foi avaliado a 0, 0,5 e 1% de óleo de nim em cada ínstar. Ninfas vivas e mortas foram contadas cinco dias após a pulverização para CL e diariamente para TL durante seis dias. Para o quarto ínstar, a CL50 foi de 0,56% de óleo de nim. Considerando todos os ínstares, CL50 e CL95 foram estimadas em 0,32 e 2,78% de óleo de nim, respectivamente. Os TL50 para 1% de nim foram estimados em 2,46, 4,45, 3,02 e 6,98 dias para o primeiro, segundo, terceiro e quarto ínstares, respectivamente. Os TL50 estimados para 0,5 e 1% de óleo de nim foram de cinco e quatro dias, respectivamente, considerando todos os ínstares. No sexto dia, foi observada mortalidade superior a 80% para o primeiro, segundo e terceiro ínstares a 1% de óleo de nim. Os três primeiros ínstares foram mais suscetíveis ao óleo de nim que o quarto ínstar.
Virus transmission by aphids involves a combination of biological players that have co-evolved over years of interaction: plant hosts, aphid vectors, plant viruses and the aphid’s bacterial ...endosymbiont. In this interaction, plant hosts activate their immune defenses against plant viruses and aphids and the latter two use a myriad of strategies to overcome, counteract or skip the host plant defense, which sometimes is done in collaboration. Bacterial endosymbionts of insect vectors might also play a role in virus transmission, either directly or indirectly, as I discussed in a critical literature review. I used proteomics and aphid genetics to show that the “biotype” phenotype of aphids is generated by genetic recombination in sexual reproduction and that aphid virulence and virus transmission are independent traits. I also showed that the host plant where aphids are reared on affects the aphid ability to transmit a circulative virus, the Luteovirid Potato leafroll virus (PLRV). Using organismal, biochemical, molecular, and imaging approaches, I show that the differential expression and activity of gut cysteine proteases at the cell membrane of aphids reared on a PLRV non-host plant is responsible for the change in virus transmission phenotype. Finally, using small RNA sequencing, I showed that aphids do not activate their small interference RNA (siRNA) antiviral defense against PLRV, which provides additional evidence for the lack of replication of Luteovirids in their aphid vectors. However, aphids produce 22 nt long siRNA as an immune defense against an aphid virus, Myzus persicae Densovirus (MpDNV), which infects and replicates in the aphid. Strikingly, an abundance of unusually large sRNA, from 33 to 38 nt that aligned to MpDNV were produced only in aphids fed on PLRV-infected plants, suggesting that feeding on a plant infected with a circulative virus modulates the aphid antiviral immune defenses. The function of these large sRNAs is not yet known.
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