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Aucoumea klaineana Pierre is the most exploited timber species in Central Africa. In natural forests, its regeneration is hindered by various factors, including limited light availability and pest attacks. To address these challenges and develop effective forest management practices, a comprehensive understanding of A. klaineana seedling ecology is necessary. This study investigated the light requirements and pest resistance of A. klaineana seedlings under different light conditions through an 18-month experiment conducted in Gabon. Six shade houses with varying light intensities were constructed, ranging from 1 % to 62 % of full irradiance, along with an unshaded platform representing 100 % light. Six-month-old seedlings were planted among shade houses and platform and monitored monthly for growth parameters (relative growth rate in height and diameter), morphological parameters (number of leaves, both total and compound) and mortality. Productivity (total seedling biomass), biomass allocation traits (leaves, roots, and stem mass ratios), number of branches, and symptoms of pests attacks were assessed after 18 months. reveal that light conditions influence seedling performance, with optimal levels for biomass and relative growth rate in diameter and height identified between 9 % and 62 % of relative irradiance. However, pest infestation, particularly by psyllids and black canker, poses substantial threats to seedling growth, health, and form, regardless of light conditions. Pest attacks had a significant impact on growth but not on survival, which remained high (97.1 %) even under extreme lights conditions (1 % and 100 % of relative irradiance). The findings underscore the importance of integrating pest management strategies and adapting silvicultural practices to meet the species' ecological requirements. We suggest planting A. klaineana in small groups (to allow root anastomoses), separated by other species (to limit pest contamination), under light canopy cover (around 9–62 % of relative irradiance, to promote sustained growth rates at the seedling stage). This approach should ensure the conservation of A. klaineana populations and the long-term viability of Central Africa's timber industry. • Okoumé seedlings can survive for at least 18 months in extreme conditions (1 and 100 % of relative irradiance). • Optimal light levels (9–62 % of relative irradiance) enhance seedlings growth. • Pest infestations threaten seedlings health and growth, despite high survival rates. • Ecological needs of the species should be better integrated in silviculture. • Emphasis should be placed on managing psyllids and black canker. [ABSTRACT FROM AUTHOR]

In agriculture, plant transformation is a versatile platform for crop improvement with the aim of increased pest resistance and an improved nutrient profile. Nanotechnology can overcome several challenges that face conventional methods of gene delivery. Specifically, nanomaterials offer an optimal platform for biomolecule delivery with unique physiochemical properties as well as the ability to traverse the challenging barrier of the plant cell wall. We review the potential of diverse nanovehicles for biomolecule delivery in plant systems to obtain desired genetic traits. The efficacy of nanoparticles against pests or pathogens is also explored, as well as the interaction of nanovehicles with plant organelles, with due consideration of the effects and toxic profile of nanoparticles. To enhance crop productivity, genetic engineering is an important technique for introducing traits of interest into plant species. The desired trait can provide increased pest resistance and an improved nutrient profile, ultimately ensuring food security. Compared with conventional methods of biomolecule delivery, modern nanotechnology offers high efficiency and diverse cargo delivery options. The unique properties of nanomaterials, such as tunable physicochemical properties and the ability to traverse the plant cell wall, can be exploited to deliver species-dependent biomolecules. Nanoparticles are also effective as micronutrients and as agents against pests or bacterial infections. [ABSTRACT FROM AUTHOR]

• Aleppo pine responded to herbivory with quantitative and qualitative changes in chemical defences. • Moderate drought stress decreased the resistance of Aleppo pine against the pine weevil Hylobius abietis L. • The chemical profile of induced responses to herbivory was altered by drought. • The resistance to pine weevil under drought stress was fairly consistent across pine populations. During their long lifespan, pines must cope with simultaneous abiotic and biotic stresses such as drought and herbivory. Mediterranean pines are isohydric species that rapidly close their stomata in response to drought reducing carbon fixation. In such situations, the synthesis of chemical defences could be impaired. Here, we tested the hypothesis that drought stress may constrain the capability of Mediterranean pines to defend against herbivory and to induce chemical defences. For this purpose, we subjected three contrasting populations of Aleppo pine (Pinus halepensis Mill.) to three levels of drought stress, thereafter exposing the seedlings to the herbivore Hylobius abietis L. A suite of ecophysiological and defensive traits was measured to explore the interaction between both stresses. Drought significantly affected the 13C signature and reduced starch and fatty acids concentration. Damage caused by the insect was affected by drought stress, being 75% higher at the moderate stress level but returning under severe stress to similar values as control seedlings. Seedlings responded to herbivory by decreasing the concentration of total polyphenolics and condensed tannins, increasing the concentration of total diterpenes, and modifying the profile of major terpenes. Induced responses to herbivory were, as expected, altered by drought. Inducibility of polyphenolics decreased as drought stress increased while for diterpenes it was higher at moderate stress. Moreover, a significant drought × herbivory interaction was found on the multivariate terpene profile. These results should be considered for predicting responses of pine forests to the forecasted increase of abiotic and biotic risks associated with global change. [ABSTRACT FROM AUTHOR]

Pest resistance of 8 transgenic Bt rice events with a synthetic cry1Ac gene linked to rice rbcS - tp sequence were assessed under laboratory conditions. Bioassays were conducted with neonates and third instar larvae of Cnaphalocrocis medinalis , which is a significant pest of rice in Asia. C. medinalis larvae were shown to be susceptible to all eight events, even though there were differences between the causes of death. The results differed between developmental stages of the larvae, despite the fact that all 8 events led to high mortalities. Neonates displayed feeding avoidance and death by starvation on six Bt rice events. In the case of third instar larvae however, only two events resulted in feeding avoidance. Nevertheless, all Bt rice events were shown to be highly effective against C. medinalis larvae in laboratory conditions. These results may be a significant foundation for the evaluation of improved transgenic Bt rice. [ABSTRACT FROM AUTHOR]

With the evolution of pest resistance to Bt-corn, farmers’ economic losses are increasing. However, a planting strategy with Bt-corn mixed with non-Bt-corn to fight the development of pest resistance can be efficient. Nevertheless, this mixed strategy poses questions such as (1) what is the optimal ratio of Bt-corn to non-Bt-corn that should be planted in a field? And (2) what is the main factor affecting the farmers’ net present value? To address these questions, we propose and investigate a discrete pest growth model with pest resistance to Bt-corn. According to the model’s economic functions, the main factors affecting the farmers’ net present value are presented and discussed. By comparing the net present values of a pure Bt-corn planting strategy with the mixed planting strategy, an optimal planting strategy was devised. Moreover, the optimal ratio of Bt-corn to non-Bt-corn to be planted when the mixed planting strategy is implemented in the field was also investigated. [ABSTRACT FROM AUTHOR]

• Arabidopsis orphan gene QQS and its interactor NF-YC4 regulate plant metabolism. • QQS and NtNF-YC4 increased the total protein and decreased starch in tobacco. • QQS and NtNF-YC4 improved resistance against common pests: whiteflies and aphids. • NtNF-YC4 expression was boosted upon aphid infestation in pest-resistant varieties. Qua-Quine Starch (QQS), an orphan gene exclusively found in Arabidopsis thaliana , interacts with Nuclear Factor Y subunit C4 (NF-YC4) and regulates carbon and nitrogen allocation in different plant species. Several studies uncovered its potential in increasing total protein and resistance against pathogens/pests in Arabidopsis and soybean. However, it is still unclear if these attributes QQS offers are universal in all flowering plants. Here we studied AtQQS and Nicotiana tabacum NF-YC4 's (NtNF-YC4) influence on starch/protein content and pest resistance in tobacco. Our results showed both AtQQS and NtNF-YC4 had a positive impact on the plant's total protein accumulation. Simultaneously, we have also observed reduced starch biosynthesis and increased resistance against common pests like whiteflies (Bemisia tabaci) and aphids (Myzus persicae) in tobacco plants expressing AtQQS or overexpressing NtNF-YC4. Real-time PCR also revealed increased NF-YC4 expression after aphid infestation in tobacco varieties with higher pest resistance but decreased/unchanged NF-YC4 expression in varieties susceptible to pests. Further analysis revealed that QQS expression and overexpression of NtNF-YC4 strongly repressed expression of genes such as sugar transporter SWEET10 and Flowering Locus T (FT), suggesting involvement of SWEET10 and FT in the QQS and NF-YC4 mediated carbon and nitrogen allocation in tobacco. Our data suggested that the activity of species-specific orphan genes may not be limited to the original species or its close relatives. Sequence alignment revealed the conserved sequence of the NF-YC4s in different plant species that may be responsible for the resulting shift in metabolism, pest resistance. Cis -acting DNA element analysis of NtNF-YC4 promoter region may outline potential mechanisms for these phenotypic changes. [ABSTRACT FROM AUTHOR]

Abstract: Chicken interferon-γ (ChIFN-γ) is both an inhibitor of viral replication and a regulator of numerous immunological functions. However, since little is known about the mechanisms underlying the insect-resistance of transgenic ChIFN-γ, a transgenic ChIFN-γ tobacco line was employed in the present study to explore this mechanism. A cDNA microarray (with 43,760 unigenes) was used to analyze the gene expression profiles of transgenic and wild-type (WT) tobacco leaves at two different growth stages. Compared with the WT, 1529 and 405 expressed sequence tags were significantly up- or downregulated on days 119 and 147, respectively. The differentially expressed genes (DEGs) are involved in metabolic regulation, cell division and differentiation, material synthesis and transport, signal transduction, and protein synthesis and degradation. Candidate genes that may increase cell density, thicken cell walls, promote secondary metabolite synthesis, and mediate plant hormone-induced resistance responses were used to identify the ChIFN-γ-mediated insect-resistance mechanisms. The insect-resistance of transgenic ChIFN-γ tobacco possibly involves unknown signaling pathways, which may directly or indirectly affect DEG expression-mediating genes. The degree of pest resistance increased as the plants grew. Three genes likely to be related to jasmonic acid- or salicylic acid-dependent plant defense responses, including CAF 1, Cop 8/CSN, and HD, are implicated in the insect-resistance of the transgenic plants. The mechanism of transgenic ChIFN-γ tobacco resistance also involves RPS20 and other genes that induce microRNA-based gene regulation. The ChIFN-γ-mediated DGEs contribute to insect-resistance in transgenic ChIFN-γ tobacco, which provides new insight into the role of ChIFN-γ. [Copyright &y& Elsevier]

Abstract: Jatropha curcas has been intensively investigated recently as a biodiesel feedstock producer because of its adaptability to adverse soil and climatic conditions. It has been seen that increasing value from by-products of oil production is important for the viability of the crop for the farmers. The seed kernel meal left after oil extraction is potentially of high market value as an animal feed ingredient. Every kilogram of oil produced from jatropha seeds generates about 0.75kg of high quality seed kernel meal. It has a high protein content (65% on a dry matter basis) with a favourable amino acid composition, but is toxic because of the presence of compounds called phorbol esters. We introduce a non-toxic jatropha variety where phorbol esters are absent in the seeds and hence, the kernel meal can be included in animal feeds after conventional heat treatment similar to that done for soybean meal. Preliminary observations in a field trial indicates that there are non-toxic jatropha provenances that are similar to or better than the conventional toxic jatropha varieties in seed yield per plant and seed oil content. Non-toxic jatropha has potential as a viable bio-oil crop if high quality seeds are used for developing the plantation. [Copyright &y& Elsevier]

Abstract: Diversity is a key factor which should be considered during planning street replacements and involves assessment of existing street population for various factors especially resistance of trees to pests. Street tree replacement histories in the United States reveal extensive replacement of American elms killed by Dutch elm disease (DED) with maples, or ashes. In turn, these trees are now under attack by Asian longhorn beetle (ALB) and emerald ash borer (EAB). Two commonly used evaluation measure of diversity namely the 10:20:30 rule and the Simpson index takes into account only the number and evenness of the taxa in a street tree population. However these indexes fail to consider the differential functional values of trees which are critical in building a sustainable urban forest while attempting to increase diversity. The proposed weighted Simpson index which weights the absolute abundance of tree taxa based on some functional variable could be used as a guide to identify areas of focus for a community. A case study involving four communities in Ohio namely Toledo, Westerville, Dublin and Yellow Springs was conducted to examine the usefulness of the weighted Simpson Index. Three functional variables including environmental benefits, pest vulnerability and taxon adaptability at three different taxonomic levels, family, genus and species, were used to arrive at the weighted Simpson indexes for the four communities. Results revealed the usefulness of weighted Simpson Index in exposing areas of concern for each community. Generally all the four communities were lacking larger statured trees with greater environmental benefits. [Copyright &y& Elsevier]

Abstract: Cry1Ab gene was transformed into four rice varieties, Zhejing 22, Zhejing 27, Jiahua 1 and Xiushui 63 mediated by Agrobacterium-mixture co-transformation. Rice genotype had an important effect on callus induction and transformation efficiency. Different mixtures of Agrobacterium strains (EHA105 and EHA101) contained Hpt and Cry1Ab genes resulted in different frequencies of resistant calli. There was no correlation between the frequency of transformants with the ratio of the Agrobacterium strain mixture contained Hpt and Cry1Ab genes. A total of 509 transgenic plants were obtained from the four rice varieties, and 272 T2 progenies were analyzed for Cry1Ab and Hpt genes. PCR analysis revealed that 412 regenerated plants were Hpt positive (80.94%), 62 plants were also Cry1Ab co-transformants (15.05% in total frequency), and 42 plants among the 272 T2 progenies were Cry1Ab positive but Hpt negative. This suggests that marker-free transgenic plants could be produced by co-transformation mediated by mixed Agrobacterium strains with the selectable marker gene and target gene. Southern blot analysis of five independent marker-free T2 transgenic lines co-transformed from Zhejing 22 showed that Cry1Ab gene had been inserted into rice genome with a single copy. The transgenic plants showed significantly stronger resistance to lepidopteron than the non-transgenic plants under no application of insecticides against lepidopteron. [Copyright &y& Elsevier]

Abstract: Khaya anthotheca and Khaya ivorensis (trade name African mahogany) of the family Meliaceae are among the most valuable tropical timber tree species of Africa. Continued supply of these timber species is threatened by over exploitation from natural forest and the difficulties in the establishment of mahogany plantations due to attack of shoot borer Hypsipyla robusta Moore. Hypsipyla attack destroys the growing shoots, causes forking, retards growth and reduces the economic value of the timber. In this study, provenance and within provenance evaluation for pest resistance and growth were studied. The results showed no significant (P >0.05) variation in growth among provenances of K. anthotheca and K. ivorensis. Significant variations (P <0.05) were however observed in growth parementers among progenies of both species. The growth (total height and diameter) of the highest-ranking progenies of the two species were twice those of the lowest-ranking progenies. K. anthotheca had a high heritability (h 2 =0.74) for height growth compared to that of K. ivorensis (h 2 =0.51) suggesting an inherent degree of higher genetic control in height growth for K. anthotheca than K. ivorensis. The degree of apical dominance and height growth were found to be the most important factors for selection for pest resistance. Backward selection based on the performance of the progenies identified nine and six mother trees of K. anthotheca and K. ivorensis respectively for conservation as seed trees. The results are discussed in relation with productivity in plantations, conservation of genetic resources of mahoganies and the potential of family and or individual selection for quick and high genetic gains. [Copyright &y& Elsevier]

Abstract: Milicia spp. (M. excelsa and M. regia) are among the most valuable indigenous timber species in sub-Saharan Africa because of their natural durability and good working properties. They are not grown in plantations but are extracted from natural forest at an unsustainable rate. Efforts at establishing plantations of Milicia spp. have been constrained by the gall forming psyllid Phytolyma lata that causes extensive damage to the young plants. This paper collates and discusses the results of efforts made in the conservation and utilisation of genetic resources of Milicia species in West Africa. This includes range wide germplasm collection, screening for pest resistance, silvicultural techniques and development of integrated pest management strategies (IPM) for reduction of pest damage to economic injury level. It also discusses the way forward through the use of biotechnology in gene proliferation and fast-tracking of resistant genotypes and their deployment in plantations. [Copyright &y& Elsevier]

Abstract: Observation of possibilities and problems was performed when trying to optimise growing conditions for high biomass production by irrigation and fertilisation in a clone test of poplar on sandy soil in the south of Sweden. One hundred and eight clones of pure Populus trichocarpa and hybrids between P. trichocarpa and P. deltoides were evaluated for growth rate, phenology, quality, frost hardiness and pest resistance. Some fertilisation experiments were performed. In some years, some unfertilised clones produced up to 2kgm−2 of woody dry biomass. Some fertilised clones produced almost twice as much in the years following fertilisation. Stem canker was the main cause of serious injuries in all hybrids, but pure P. trichocarpa stems were not affected. The cimbicid sawfly (Cimbex lutea) caused damage to the quality of the trees in the form of curved stems of some clones. Winter frost killed top shoots of the hybrids in a year with particularly low winter temperatures with long duration. Summer frost (in June) killed up to 1m of some young top shoots in some clones in the first 3–4 years. The results are discussed in terms of radiation utilisation efficiency, energy efficient ratio, and water and nutrient use efficiency. The discussion finishes with the conclusion that fertilisation, but not irrigation, can be economically motivated. If irrigation is to be economic, then the main objective of the whole operation should be to produce drinkable water from water polluted by society. Biomass production would then be a bonus. [Copyright &y& Elsevier]

Controlled-cross progeny of interior spruce (Picea glauca (Moench) Voss × Picea engelmanni Parry ex Engelm.) parents ranked as resistant or susceptible to the white pine weevil, Pissodes strobi (Peck) were screened for resistance to the same insect by augmentation of the trial site with weevils. Progeny from two resistant parents (R × R progeny) sustained significantly fewer weevil attacks (13% of the trees were attacked) in the year following the augmentation, than progeny from susceptible parents (S × S progeny) (68% of the trees were attacked). Progeny obtained by crossing one resistant and one susceptible parent (R × S progeny) sustained intermediate attack levels (47% were attacked). Characteristics of the bark resin canals of the crosses were explored using microscopy techniques. Bark resin canal density was highest in R × R progeny, lowest in S × S progeny and intermediate in R × S progeny. There was a negative correlation between the percentage of trees attacked in each cross and the average density of the outer resin canals for each cross. A discriminant function was developed that distinguished between resistant and susceptible progeny using bark characteristics. The function was characterized by positive coefficients for outer resin canal density and inner resin canal size, and a negative coefficient for bark thickness. Thus, trees with thin bark, large inner resin canals and dense outer resin canals are more likely to be resistant to P. strobi. [Copyright &y& Elsevier]

Development of insect resistance to biopesticides is a current and pertinent global issue. Earlier, it was established that lepidopteran larvae can recover from Bt intoxication via a midgut regenerative response and subsequently generate resistance. Molecular aspects of restoration of the midgut integrity following toxin exposure are emerging recently. In the present study, we bring out the pivotal role of gut arylphorin in mediating the midgut regenerative response following sublethal Bt exposure in Achaea janata. Bt-induced midgut damage was characterized by microscopic analysis using differential interference contrast (DIC) and immunofluorescence (IF). Extensive disruption of brush-border membrane, associated with the underlying cytoskeletal alterations including F-actin, α-actin and β-tubulin was observed. Single-photon fluorescence microscopy combined with fluorescence lifetime imaging (FLIM) established the metabolic state associated with enhanced stem cell proliferation and migration from the basal side towards the luminal side following the damage. In-silico analysis revealed the phylogenetic relationship of gut arylphorin with closely related insect species and indicated the presence of two different subunits. Transient RNAi knockdown of the arylphorin resulted in diminished expression of mitotic Cyclin B mRNA levels. Human monoclonal Cyclin B antibody cross-reactivity with the Cyclin B located in the stem cells further validate the role of arylphorin as the mitogenic factor responsible for stem cell proliferation and epithelial regeneration. An in-depth understanding of resistance mechanisms will aid in the design of new strategies for the long-term usage and efficacy of Bt technology against pest control. [Display omitted] • Cytoskeleton element alteration namely F-actin, alpha-actin and beta-actin is responsible for brush border disruption. • Metabolic state of the midgut epithelium cell is associated with enhanced stem cell proliferation and migration. • In silico analysis demonstrated two chain namely A and B-chain of gut specific arylphorin. • We established functional relationship of gut arylphorin and Cyclin B expression during gut regeneration. [ABSTRACT FROM AUTHOR]