Demonstration of the synergistic effect of biochar and Trichoderma harzianum on the development of Ralstonia solanacearum in eggplant.

Soil degradation has been accelerated by the use of chemical pesticides and poor agricultural practices, which has had an impact on crop productivity. Recently, there has been a lot of interest in the use of eco-friendly biochar applications to enhance soil quality and sequester carbon in sustainable agriculture. This study aimed to determine the individual and combined effects of Leaf Waste Biochar (LWB) and the bio-control agent Trichoderma harzianum (BCA) on the development of bacterial wilt in eggplants (Solanum melongena) caused by Ralstonia solanacearum (RS). The effects of LWB and BCA on eggplant physiology and defense-related biochemistry were comprehensively examined. Inoculated (+RS) and un-inoculated (-RS) eggplants were grown in potting mixtures containing 3% and 6% (v/v) LWB, both with and without BCA. The percentage disease index was considerably reduced (90%) in plants grown in the 6% LWB+ BCA amended treatments. Moreover, the plants grown in LWB and inoculated with BCA had higher phenolics, flavonoids and peroxidase contents compared to the non-amended control. The level of NPK was significantly increased (92.74% N, 76.47% P, 53.73% K) in the eggplants cultivated in the 6% LWB + BCA composition. This study has shown that the association of T. harzianum with biochar improved plant growth and reduced R. solanacearum induced wilt. Furthermore, the combined impact of biochar and T. harzianum was greater in terms of wilt suppression and increase in plant physiological measurements when the biochar concentration was 6%. Biochar and bio-control agents triggered biochemical alterations, thus enhancing the management of disease-infested soils.

Identification and characterization of Glycolate oxidase gene family in garden lettuce (Lactuca sativa cv. 'Salinas') and its response under various biotic, abiotic, and developmental stresses.

Glycolate oxidase (GLO) is an FMN-containing enzyme localized in peroxisomes and performs in various molecular and biochemical mechanisms. It is a key player in plant glycolate and glyoxylate accumulation pathways. The role of GLO in disease and stress resistance is well-documented in various plant species. Although studies have been conducted regarding the role of GLO genes from spinach on a microbial level, the direct response of GLO genes to various stresses in short-season and leafy plants like lettuce has not been published yet. The genome of Lactuca sativa cultivar 'Salinas' (v8) was used to identify GLO gene members in lettuce by performing various computational analysis. Dual synteny, protein-protein interactions, and targeted miRNA analyses were conducted to understand the function of GLO genes. The identified GLO genes showed further clustering into two groups i.e., glycolate oxidase (GOX) and hydroxyacid oxidase (HAOX). Genes were observed to be distributed unevenly on three chromosomes, and syntenic analysis revealed that segmental duplication was prevalent. Thus, it might be the main reason for GLO gene diversity in lettuce. Almost all LsGLO genes showed syntenic blocks in respective plant genomes under study. Protein-protein interactions of LsGLO genes revealed various functional enrichments, mainly photorespiration, and lactate oxidation, and among biological processes oxidative photosynthetic carbon pathway was highly significant. Results of in-depth analyses disclosed the interaction of GLO genes with other members of the glycolate pathway and the activity of GLO genes in various organs and developmental stages in lettuce. The extensive genome evaluation of GLO gene family in garden lettuce is believed to be a reference for cloning and studying functional analyses of GLO genes and characterizing other members of glycolate/glyoxylate biosynthesis pathway in various plant species.

Physiological and biochemical characterization of biochar-induced resistance against bacterial wilt of eggplants.

The abrupt variation in climatic patterns has become a global concern in terms of food security. Biochar, known to ameliorate climatic adversities by sequestering carbon and activating systemic resistance pathways in plants, has become increasingly relevant. Therefore, the study was aimed to characterize leaf waste biochar (LWB) by Fourier-transform infrared spectroscopy, scanning electron microscopy with energy dispersive X-ray (SEM-EDX) and X-ray diffraction analytical techniques as well as determination of its impact on the development of bacterial wilt (BW) in eggplant (Solanum melongena) caused by Ralstonia solanacearum (RS). The effect of LWB on the physiology and defence-associated biochemistry of eggplants was investigated thoroughly. Eggplants either inoculated (+RS) or uninoculated (-RS) were cultivated in potting mixture containing 3 and 6% (v/v) LWB separately. In comparison with substrate (soil only), percentage disease index was significantly reduced (71%) in plants grown in 6% LWB-amended treatments. Biochar-induced increase in level of total chlorophyll content as well as in biochemicals such as phenolics, flavonoids and peroxidases were evident on plants in terms of resistance response against BW. Moreover, biochar also significantly affected the level of NPK in the eggplants. In conclusion, biochar-triggered biochemical alterations played a pivotal role in the management of BW along with the curing of the disease-infested soils.

Sentinel plot surveillance of cotton leaf curl disease in Pakistan- a case study at the cultivated cotton-wild host plant interface.

A sentinel plot case study was carried out to identify and map the distribution of begomovirus-betasatellite complexes in sentinel plots and commercial cotton fields over a four-year period using molecular and high-throughput DNA 'discovery' sequencing approaches. Samples were collected from 15 study sites in the two major cotton-producing areas of Pakistan. Whitefly- and leafhopper-transmitted geminiviruses were detected in previously unreported host plant species and locations. The most prevalent begomovirus was cotton leaf curl Kokhran virus-Burewala (CLCuKoV-Bu). Unexpectedly, a recently recognized recombinant, cotton leaf curl Multan virus-Rajasthan (CLCuMuV-Ra) was prevalent in five of 15 sites. cotton leaf curl Alabad virus (CLCuAlV) and cotton leaf curl Kokhran virus-Kokhran, 'core' members of CLCuD-begomoviruses that co-occurred with CLCuMuV in the 'Multan' epidemic were detected in one of 15 sentinel plots. Also identified were chickpea chlorotic dwarf virus and 'non-core' CLCuD-begomoviruses, okra enation leaf curl virus, squash leaf curl virus, and tomato leaf curl New Delhi virus. Cotton leaf curl Multan betasatellite (CLCuMuB) was the most prevalent CLCuD-betasatellite, and less commonly, two 'non-core' betasatellites. Recombination analysis revealed previously uncharacterized recombinants among helper virus-betasatellite complexes consisting of CLCuKoV, CLCuMuV, CLCuAlV and CLCuMuB. Population analyses provided early evidence for CLCuMuV-Ra expansion and displacement of CLCuKoV-Bu in India and Pakistan from 2012-2017. Identification of 'core' and non-core CLCuD-species/strains in cotton and other potential reservoirs, and presence of the now predominant CLCuMuV-Ra strain are indicative of ongoing diversification. Investigating the phylodynamics of geminivirus emergence in cotton-vegetable cropping systems offers an opportunity to understand the driving forces underlying disease outbreaks and reconcile viral evolution with epidemiological relationships that also capture pathogen population shifts.

Unveiling Lathyrus aphaca L. as a Newly Identified Host for Begomovirus Infection: A Comprehensive Study.

The Begomovirus genus of the family Geminiviridae comprises the largest group of geminiviruses. Begomoviruses are transmitted by the whitefly complex (Bemisia tabaci) and infect dicotyledonous plants in tropical and subtropical regions. The list of begomoviruses is continuously increasing as a result of improvements in the methods for identification, especially from weed plants, which are considered a source of new viruses and reservoirs of economically important viruses but are often neglected during diversity studies. Lathyrus aphaca L. weed plants (yellow-flowered pea) with varicose veins and discoloration of the leaves were found. Amplified genomic DNA through rolling circular amplification was subjected to PCR analysis for the detection of the viral genome and associated DNA-satellites (alphasatellites and betasatellites). A full-length sequence (2.8 kb) of a monopartite begomovirus clone was determined; however, we could not find any associated DNA satellites. The amplified full-length clone of Rose leaf curl virus (RoLCuV) reserved all the characteristics and features of an Old World (OW) monopartite begomovirus. Furthermore, it is the first time it has been reported from a new weed host, yellow-flowered pea. Rolling circle amplification and polymerase chain reaction analysis of associated DNA satellites, alphasatellite, and betasatellite, were frequently accomplished but unable to amplify from the begomovirus-infected samples, indicating the presence of only monopartite Old World begomovirus. It is observed that RoLCuV has the capability to infect different hosts individually without the assistance of any DNA satellite component. Recombination in viruses is also a source of begomovirus infection in different hosts.

Selection for resistance to pirimiphos-methyl, permethrin and spinosad in a field strain of Sitophilus oryzae: resistance risk assessment, cross-resistance potential and synergism of insecticides.

Indiscriminate use of insecticides in food storage facilities for controlling insect pests has deleterious effects on the environment and non-targeted organisms in the premises. Continuous use of insecticides may result in resistance development in insect pests, which compel the stakeholders to increase the dosage of insecticides to manage resistant insect pests. The increased dosage of insecticides ultimately may result in contamination of stored food stuff that affects human health. The present study was planned to generate data that will be helpful to delay resistance development and to reduce environmental pollution. A field strain of Sitophilus oryzae, one of the most common insect pests of stored foodstuff, was selected separately with pirimiphos-methyl, permethrin, or spinosad for five consecutive generations. The selected strains were studied for resistance risk assessment, time taken to develop resistance to insecticides after continuous exposure in the selection process, preliminary mechanism of resistance, and whether the development of resistance due to the selection with a particular insecticide could develop cross-resistance to other insecticide or not. In comparison to a laboratory susceptible reference strain, the insecticide-selected strains revealed rapid development of resistance against insecticides as a result of selection process: 31.05-fold resistance to pirimiphos-methyl, 156.49-fold resistance to permethrin, and 65.6-fold resistance to spinosad. The selected strains did not show cross-resistance to insecticides to with these strains were not exposed during selection experiments, i.e., strain selected with pirimiphos-methyl did not show cross-resistance to spinosad and permethrin. In the synergism bioassays, the synergists (S,S,S-tributyl phosphorotrithioate and piperonyl butoxide) significantly reduced resistance of the selected strain against insecticides to with these were selected, revealing the probability of metabolic mechanism of resistance. The present study revealed high risks of resistance development to pirimiphos-methyl, spinosad, and permethrin under consistent selection pressure. Lack of cross-resistance among insecticides provides an opportunity to use insecticides in rotation instead of increasing dosages to manage resistant insects that will ultimately pollute the environment.

Genome-Wide Identification and In Silico Analysis of ZF-HD Transcription Factor Genes in Zea mays L.

Zinc finger-homeodomain proteins are amongst the most prominent transcription factors (TFs) involved in biological processes, such as growth, development, and morphogenesis, and assist plants in alleviating the adverse effects of abiotic and biotic stresses. In the present study, genome-wide identification and expression analyses of the maize ZHD gene family were conducted. A total of 21 ZHD genes with different physicochemical properties were found distributed on nine chromosomes in maize. Through sequence alignment and phylogenetic analysis, we divided ZHD proteins into eight groups that have variations in gene structure, motif distribution, and a conserved ZF domain. Synteny analysis indicated duplication in four pairs of genes and the presence of orthologues of maize in monocots. Ka/Ks ratios suggested that strong pure selection occurred during evolution. Expression profiling revealed that the genes are evenly expressed in different tissues. Most of the genes were found to make a contribution to abiotic stress response, plant growth, and development. Overall, the evolutionary research on exons and introns, motif distributions, and cis-acting regions suggests that these genes play distinct roles in biological processes which may provide a basis for further study of these genes' functions in other crops.

Magnetofection approach for the transformation of okra using green iron nanoparticles.

Climate change, pesticide resistance, and the need for developing new plant varieties have galvanized biotechnologists to find new solutions in order to produce transgenic plants. Over the last decade scientists are working on green metallic nanoparticles to develop DNA delivery systems for plants. In the current study, green Iron nanoparticles were synthesized using leaf extract of Camellia sinensis (green tea) and Iron Chloride (FeCl3), the characterization and Confirmation was done using UV-VIS Spectroscopy, FTIR, SEM, and TEM. Using these nanoparticles, a novel method of gene transformation in okra plants was developed, with a combination of different Magnetofection factors. Maximum gene transformation efficiency was observed at the DNA to Iron-nanoparticles ratio of 1:20, by rotation of mixture (Plasmid DNA, Iron-nanoparticles, and seed embryo) at 800 rpm for 5 h. Using this approach, the transformation of the GFP (green fluorescent protein) gene was successfully carried out in Abelmoschus esculentus (Okra plant). The DNA transformation was confirmed by observing the expression of transgene GFP via Laser Scanning Confocal Microscope (LSCM) and PCR. This method is highly economical, adaptable, genotype independent, eco-friendly, and time-saving as well. We infer that this approach can be a potential solution to combat the yield and immunity challenges of plants against pathogens.

Morphological and physiological response of sour orange (Citrus aurantium L.) seedlings to the inoculation of taxonomically characterized bacterial endophytes.

Entophytic bacteria (EBs) are very diverse and found in virtually all plant species studied. These natural EBs live insides the host plant and can be used to maximize crop and fruit yield by exploiting their potential. In this paper, EBs characterization from various citrus genotypes and their influence on the morphological and physiological functioning of sour orange (Citrus aurantium) seedlings are described. To assess the influence of 10 distinct EBs, three different techniques (injection, soil mix, and spray) were applied for single and mixed inoculation on sour orange (C. aurantium) seedlings. The selected strains were identified as firmicutes (Enterococcus faecalis, Bacillus safensis, Bacillus cereus, Bacillus megaterium, Brevibacillus borstelensis & Staphylococcus haemolyticus), and gamma Proteobacteria (Enterobacter hormachaei, Proteus mirabilis, Pseudomonas aeruginosa, & Pseudomonas sp.) by 16S rRNA gene sequencing. To investigate the influence of these EBs on host plant morphology, different parameters (morphometric) were recorded after five WOI (weeks of inoculation), including shoot/root length, shoot/root fresh and dry biomass, and biophysical analyses i.e., relative water content (RLWC). Physiological markers such as chlorophyll & carotenoid content, protein content, proline content, phenolics, and flavonoids were also analyzed to determine the influence of endophytes on sour orange seedlings. Five strains such as SM-34, SM-20, SM-36, SM-68, and SM-56 significantly improved the development and physiology of sour orange seedlings. Bacillus cereus and Pseudomonas aeruginosa produced the best outcomes in terms of plant growth. The relative quantification of bacterial inoculums was determined using real-time PCR. A rise in the number of bacterial cells in inoculated treatment suggests that bacterial strains survived and colonized successfully, and also shown their competitiveness with native bacterial community structure. As per the results of inoculation methods, soil mixing, and injection methods were determined to be effective for bacterial inoculation to plants but a variable trend was found for different parameters with test bacterial strains. After testing their impact on field conditions, these strains can be applied as fertilizers as an alternative to conventional chemical fertilizer, although in the context of mixed inoculation of bacterial strains, 5 M and 6 M performed best and enhanced plant growth-promoting activity.

Resistance to grain protectants and synergism in Pakistani strains of Sitophilus oryzae (Coleoptera: Curculionidae).

The widespread use of insecticides for the management of insect pests in storage facilities and food industries have caused insecticide resistance a frequent issue worldwide. Nonetheless, this issue has been little explored in Pakistan that resulted in control failures and increased dosage of insecticides. In the present study, insecticide resistance to chlorpyrifos-methyl, pirimiphos-methyl, permethrin and spinosad was surveyed in five field strains of Sitophilus oryzae: FSD-SO, GJR-SO, DGK-SO, MTN-SO and BWP-SO, collected from five different localities of Punjab, Pakistan, and contrasted with an insecticide susceptible reference strain (Lab-SO). Dose-mortality bioassays were performed in glass vials containing insecticide-treated rice grains, and lethal doses (LD50 and LD95) were calculated and compared using the ratio tests. In comparison to the Lab-SO strain at LD50 and LD95 levels, field strains exhibited: 24.51 to 52.80 and 36.55 to 69.31 resistance ratios (RRs), respectively, for chlorpyrifos-methyl; 15.89 to 45.97 and 55.12 to 194.93 RRs, respectively, for pirimiphos-methyl; 39.76 to 108.61 and 61.33 to 130.12 RRs, respectively, for permethrin; 4.23 to 27.50 and 6.28 to 41.00 RRs, respectively, for spinosad. In the synergism experiments using the Lab-SO and the most resistant strains against each insecticide, the enzyme inhibitors (PBO and DEF) failed to synergize toxicity of insecticides in the Lab-SO strain; however, toxicity of chlorpyrifos-methyl, pirimiphos-methyl and permethrin significantly enhanced in the resistant strains of S. oryzae, suggesting possibility of metabolic mechanism of resistance. In addition, activities of detoxification enzymes (CarE, MFO and GST) were significantly higher in resistant strains compared to the Lab-SO strain. The results revealed presence of insecticide resistance in field strains of S. oryzae that necessitate the need to develop a resistance management strategy.

Foxtail millet [Setaria italica (L.) Beauv.] over-accumulates ammonium under low nitrogen supply.

Nitrogen (N) deficiency is a primary limiting factor for crop production worldwide. Previously, we reported root system architectural modifications of hydroponically cultured foxtail millet [Setaria italica (L.) Beauv.] to facilitate N translocation under N limitation. Here, we investigated foxtail millet for its shoot adaptation to low N in terms of internal N regulation under hydroponic culture. The results of this study revealed that the shoot N and nitrate (NO3-) concentrations significantly declined as compared to control (CK); however, the shoot over-accumulated ammonium (NH4+) under low N (LN). N shortage resulted in down-regulation of expressions of SiPetA, SiccsA, SipsbA, SirpoB, SipsaA, SiatpA, Sirps16, and SiPEPC which, undermined chloroplast functioning and CO2 assimilation for the provision of carbon skeleton. Carbon deficiency and lower activities of GS decelerated ammonia assimilation and led to over-accumulation of NH4+ in the LN-shoot, as indicated by lower concentrations of total amino acids. Thus, enhanced GOGAT activity was to assimilate NH4+ while, those of catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD) were to scavenge reactive oxygen species (ROS) of NH4+ toxicity framework. The weakened chloroplast factory eventually minimized photosynthesis and reduced dry mass of the LN shoot. Such regulation of N by the shoot, perhaps, resurrected physiological functions which maintained internal mineral status under nitrogen limitation in foxtail millet.

Feeding preference of Rhynchophorus ferrugineus (Oliver) (Coleoptera: Curculionidae) on different date palm cultivars and host biochemical responses to its infestation.

To counter the insect infestation, plants respond with wide-ranging and highly dynamic biochemical reactions. Of these, the anti-oxidative activity is poorly understood. The red palm weevil (RPW) Rhynchophorus ferrugineus (Oliver), one of the most widespread pests in Pakistan, prefers to infest date palm Phoenix dactylifera. Our present study investigated the feeding preference of RPW to 11 different date palm cultivars and the results suggested that the Hillawi cultivar was most preferred. Greater infestation rate, fecundity and hatching rate were also recorded from Hillawi and Mozawati than other cultivars. No significant decreases were observed in chlorophyll a, chlorophyll b, total chlorophylls and carotenoids of RPW-infested Hillawi cultivar over un-infested control. In contrast, the contents of enzymatic antioxidants including phenols, proline, hydrogen peroxide, anthocyanin, malondialdehyde, ascorbic acid and glycine betaine showed a drastic increase after RPW infestation, and there was enhanced superoxide dismutase, peroxidase and catalase activities. Furthermore, we recorded the increase of total protein and sugar contents in RPW-infested date palms. These findings offer valuable insight into the antioxidative molecular mechanism of date palms under RPW attack and may contribute to the breeding of insect-resistant crops.

Enumeration of citrus endophytic bacterial communities based on illumine metagenomics technique.

Citrus is a valuable crop in Pakistan. It is rich in vitamin C, other nutrients and antioxidants. Huanglongbing (HLB) caused by a bacterium "Candidatus liberibacter asiaticus" (CLas), africanus and americanus has an influence on citrus production around the world. Beside HLB there exist several other bacterial species in citrus groves in Pakistan. The structure and diversity of bacterial species in various ecosystems can be quickly examined using NGS. This approach is considerably quicker and more precise than outdated methods. Healthy or citrus greening infected leaf samples of Grapefruit (Citrus paradisi), C. aurantifolia, and C. reticulata Blanco were used for diversity analysis. In this study high throughput, NGS technique was used to access the population of both cultivable and non-cultivable bacterial endophytes from citrus leaves, by using PCR amplicons of 16S rDNA sequences (V5-V7 regions) with Illumina Hi seq. As a result, a total number of 68,722 sequences were produced from the test samples. According to the NGS-based diversity classification, the most common genera of exploited bacterial endophytes were Proteobacteria, Firmicutes, Bacteroides, Cyanobacteria, and Actinobacteria. C. aurantifolia and C. paradisi showed almost equal diversity, whereas C. reticulata Blanco had a higher proportion of Proteobacteria and Cyanobacteria in their leaves. To determine alpha diversity (AD), additional data was analyzed using statistical indices such as Shannon, Chao1, and Simpson. According to the inverse Simpson diversity index, the abundance of the microbial population in six different citrus samples was 0.48, 0.567, and 0.163, respectively. The metagenomics of microbiota in plant tissues was successfully recorded by NGS technology, which can help us learn more about the interactions between plants and microbes. This research is the first step toward a better understanding of 16SrRNA-based metagenomics from citrus in Pakistan using Illumina (Hi seq) Technology.

Triacontanol regulates morphological traits and enzymatic activities of salinity affected hot pepper plants.

Potential role of triacontanol applied as a foliar treatment to ameliorate the adverse effects of salinity on hot pepper plants was evaluated. In this pot experiment, hot pepper plants under 75 mM NaCl stress environment were subjected to foliar application of 25, 50, and 75 µM triacontanol treatments; whereas, untreated plants were taken as control. Salt stress had a significant impact on morphological characteristics, photosynthetic pigments, gas exchange attributes, MDA content, antioxidants activities, electrolytes leakage, vitamin C, soluble protein, and proline contents. All triacontanol treatments significantly mitigated the adversative effects of salinity on hot pepper plants; however, foliar application triacontanol at 75 µM had considerably improved the growth of hot pepper plants in terms of plant height, shoot length, leaf area, plant fresh/dry biomasses by modulating above mentioned physio-biochemical traits. While, improvement in gas exchange properties, chlorophyll, carotenoid contents, increased proline contents coupled with higher SOD and CAT activities were observed in response to 75 µM triacontanol followed by 50 µM triacontanol treatment. MDA and H2O2 contents were decreased significantly in hot pepper plants sprayed with 75 µM triacontanol followed by 50 µM triacontanol foliar treatment. Meanwhile, root and shoot lengths were maximum in 50 µM triacontanol sprayed hot pepper plants along with enhanced APX activity on exposure to salt stress. In crux, exogenous application triacontanol treatments improved hot pepper performance under salinity, however,75 µM triacontanol treatment evidently was more effective in mitigating the lethal impact of saline stress via controlling the ROS generation and increment in antioxidant enzyme activities.

Interaction between bacterial endophytes and host plants.

Endophytic bacteria are mainly present in the plant's root systems. Endophytic bacteria improve plant health and are sometimes necessary to fight against adverse conditions. There is an increasing trend for the use of bacterial endophytes as bio-fertilizers. However, new challenges are also arising regarding the management of these newly discovered bacterial endophytes. Plant growth-promoting bacterial endophytes exist in a wide host range as part of their microbiome, and are proven to exhibit positive effects on plant growth. Endophytic bacterial communities within plant hosts are dynamic and affected by abiotic/biotic factors such as soil conditions, geographical distribution, climate, plant species, and plant-microbe interaction at a large scale. Therefore, there is a need to evaluate the mechanism of bacterial endophytes' interaction with plants under field conditions before their application. Bacterial endophytes have both beneficial and harmful impacts on plants but the exact mechanism of interaction is poorly understood. A basic approach to exploit the potential genetic elements involved in an endophytic lifestyle is to compare the genomes of rhizospheric plant growth-promoting bacteria with endophytic bacteria. In this mini-review, we will be focused to characterize the genetic diversity and dynamics of endophyte interaction in different host plants.

Triacontanol modulates salt stress tolerance in cucumber by altering the physiological and biochemical status of plant cells.

Cucumber is an important vegetable but highly sensitive to salt stress. The present study was designed to investigate the comparative performance of cucumber genotypes under salt stress (50 mmol L-1) and stress alleviation through an optimized level of triacontanol @ 0.8 mg L-1. Four cucumber genotypes were subjected to foliar application of triacontanol under stress. Different physiological, biochemical, water relations and ionic traits were observed to determine the role of triacontanol in salt stress alleviation. Triacontanol ameliorated the lethal impact of salt stress in all genotypes, but Green long and Marketmore were more responsive than Summer green and 20252 in almost all the attributes that define the genetic potential of genotypes. Triacontanol performs as a good scavenger of ROS by accelerating the activity of antioxidant enzymes (SOD, POD, CAT) and compatible solutes (proline, glycinebetaine, phenolic contents), which lead to improved gas exchange attributes and water relations and in that way enhance the calcium and potassium contents or decline the sodium and chloride contents in cucumber leaves. Furthermore, triacontanol feeding also shows the answer to yield traits of cucumber. It was concluded from the results that the salinity tolerance efficacy of triacontanol is valid in enhancing the productivity of cucumber plants under salt stress. Triacontanol was more pronounced in green long and marketer green than in summer green and 20252. Hence, the findings of this study pave the way towards the usage of triacontanol @ 0.8 mg L-1, and green long and marketer genotypes may be recommended for saline soil.

Role of biochar, compost and plant growth promoting rhizobacteria in the management of tomato early blight disease.

The individual role of biochar, compost and PGPR has been widely studied in increasing the productivity of plants by inducing resistance against phyto-pathogens. However, the knowledge on combined effect of biochar and PGPR on plant health and management of foliar pathogens is still at juvenile stage. The effect of green waste biochar (GWB) and wood biochar (WB), together with compost (Comp) and plant growth promoting rhizobacteria (PGPR; Bacillus subtilis) was examined on tomato (Solanum lycopersicum L.) physiology and Alternaria solani development both in vivo and in vitro. Tomato plants were raised in potting mixture modified with only compost (Comp) at application rate of 20% (v/v), and along with WB and GWB at application rate of 3 and 6% (v/v), each separately, in combination with or without B. subtilis. In comparison with WB amended soil substrate, percentage disease index was significantly reduced in GWB amended treatments (Comp + 6%GWB and Comp + 3%GWB; 48.21 and 35.6%, respectively). Whereas, in the presence of B. subtilis disease suppression was also maximum (up to 80%) in the substrate containing GWB. Tomato plant growth and physiological parameters were significantly higher in treatment containing GWB (6%) alone as well as in combination with PGPR. Alternaria solani mycelial growth inhibition was less than 50% in comp, WB and GWB amended growth media, whereas B. subtilis induced maximum inhibition (55.75%). Conclusively, the variable impact of WB, GWB and subsequently their concentrations in the soil substrate was evident on early blight development and plant physiology. To our knowledge, this is the first report implying biochar in synergism with PGPR to hinder the early blight development in tomatoes.

Genetic variability, community structure, and horizontal transfer of endosymbionts among three Asia II-Bemisia tabaci mitotypes in Pakistan.

Endosymbionts associated with the whitefly Bemisia tabaci cryptic species are known to contribute to host fitness and environmental adaptation. The genetic diversity and population complexity were investigated for endosymbiont communities of B. tabaci occupying different micro-environments in Pakistan. Mitotypes of B. tabaci were identified by comparative sequence analysis of the mitochondria cytochrome oxidase I (mtCOI) gene sequence. Whitefly mitotypes belonged to the Asia II-1, -5, and -7 mitotypes of the Asia II major clade. The whitefly-endosymbiont communities were characterized based on 16S ribosomal RNA operational taxonomic unit (OTU) assignments, resulting in 43 OTUs. Most of the OTUs occurred in the Asia II-1 and II-7 mitotypes (r 2 = .9, p < .005), while the Asia II-5 microbiome was less complex. The microbiome OTU groups were mitotype-specific, clustering with a basis in phylogeographical distribution and the corresponding ecological niche of their whitefly host, suggesting mitotype-microbiome co-adaptation. The primary endosymbiont Portiera was represented by a single, highly homologous OTU (0%-0.67% divergence). Two of six Arsenophonus OTUs were uniquely associated with Asia II-5 and -7, and one occurred exclusively in Asia II-1, two only in Asia II-5, and one in both Asia II-1 and -7. Four other secondary endosymbionts, Cardinium, Hemipteriphilus, Rickettsia, and Wolbachia OTUs, were found at ≤29% frequencies. The most prevalent Arsenophonus OTU was found in all three Asia II mitotypes (55% frequency), whereas the same strain of Cardinium and Wolbachia was found in both Asia II-1 and -5, and a single Hemipteriphilus OTU occurred in Asia II-1 and -7. This pattern is indicative of horizontal transfer, suggestive of a proximity between mitotypes sufficient for gene flow at overlapping mitotype ecological niches.

Chitinase genes from Metarhizium anisopliae for the control of whitefly in cotton.

Entomopathogenic fungi produces endochitianses, involved in the degradation of insect chitin to facilitate the infection process. Endochitinases (Chit1) gene of family 18 glycosyl hydrolyses were amplified, cloned and characterized from genomic DNA of two isolates of Metarhizium anisopliae. Catalytic motif of family 18 glycosyl hydrolyses was found in Chit1 of M. anisopliae, while no signal peptide was found in any isolate, whereas substrate-binding motif was found in Chit1 of both isolates. Phylogenetic analysis revealed the evolutionary relationship among the fungal chitinases of Metarhizium. The Chit1 amplified were closely related to the family 18 glycosyl hydrolyses. Transient expressions of Chit1 in cotton plants using Geminivirus-mediated gene silencing vector of Cotton Leaf Crumple Virus (CLCrV) revealed the chitinase activity of Chit1 genes amplified from both of the isolates of M. anisopliae when compared with the control. Transformed cotton plants were virulent against fourth instar nymphal and adult stages of Bemisia tabaci which resulted in the mortality of both fourth instar nymphal and adult B. tabaci. Thus, the fungal chitinases expressed in cotton plants played a vital role in plant defence against B. tabaci. However, further studies are required to explore the comparative effectiveness of chitinases from different fungal strains against economically important insect pests.

Infectivity of okra enation leaf curl virus and the role of its V2 protein in pathogenicity.

Cotton crop has been severely affected by multiple begomoviruses in Pakistan and India. In our previous study, we found okra enation leaf curl virus (OELCuV), cotton leaf curl Multan betasatellite (CLCuMuB) and cotton leaf curl Multan alphasatellite (CLCuMuA) infecting cotton in Pakistan. The current study was designed to investigate the infectivity of OELCuV and its ability to trans-replicate non-cognate CLCuMuB. Agro-infectious clones containing the partial tandem repeats of OELCuV and CLCuMuB were constructed and the infectivity assays were carried out through Agrobacterium mediated transformation in the model host species Nicotiana benthamiana under controlled conditions. The results showed that in the inoculated plants OELCuV alone can cause downward curling and yellowing of leaves with thickened veins. However, when co-inoculated with the non-cognate CLCuMuB it could functionally trans-replicate CLCuMuB resulting in a more severe phenotype. The expression of Pre-coat/V2 protein in the N. benthamiana plants through the potato virus X (PVX) system caused localized cell death after severe leaf curling in the infiltrated leaves. The tissue tropism of the virus was associated with the systemic development of a hypersensitive response (HR), which ultimately lead to the plant death. The results indicated the involvement of V2 protein in the pathogenicity of OELCuV and its ability to trigger the host defense machinery. This study also demonstrated the ability of OELCuV to trans-replicate CLCuMuB resulting in typical leaf curl disease symptoms in N. benthamiana.