Durum wheat cultivation is increasingly threatened by viral diseases worldwide. Soil-borne cereal mosaic virus (SBCMV) and wheat spindle streak mosaic virus (WSSMV) cause significant crop losses in Europe. These viruses are transmitted through a soil-inhabiting vector, the plasmodiophoromycota Polymyxa graminis Led. There are very few methods available to eradicate P. graminis, whose resting spores survive in infested soil for decades, but they are either too expensive or not environmentally friendly. Therefore, it is crucial to develop resistant wheat varieties to mitigate the damage. For this purpose, more than 200 durum wheat genotypes, mostly landraces, were selected from the Global Durum Wheat Panel germplasm collection. Then, an experiment was conducted in a semi-controlled environment: the genotypes were sown in pots containing soil infested by P. graminis carrying SBCMV and WSSMV and maintained through the winter period. In early spring, visual assessment of viral symptomatology was performed. Subsequently, the viral loads of the two viruses in leaf tissues were determined through qRT-PCR analysis. The tested genotypes exhibited different responses to the two viruses: SBCMV showed very diversified viral loads among genotypes, whereas WSSMV infected all genotypes. We identified 23 genotypes, with low viral loads of both viruses and reduced symptoms, that could be of particular interest for breeders aiming at new resistant durum wheat varieties. A pilot GWAS allowed to identify genomic regions putatively associated to resistance to SBCMV or WSSMV, as well as possible candidate genes involved in these traits.

Bacterial wilt disease caused by Trinickia (Burkholderia) caryophylli poses a significant threat to carnation cultivation in many regions around the world, often leading to severe damage once established. In this study, we developed a BIO-PCR method with high sensitivity and accuracy to detect and quantify T. caryophylli in soil, enabling precise evaluation of pathogen contamination levels. Single PCR (using a touchdown PCR program) was performed using the bacterial cells pre-incubated in a selective liquid medium as a template. The detection limit for this assay was 3 colony-forming-units (cfu) per g dry mass soil. By combining the most probable number (MPN) method and touchdown BIO-PCR, T. caryophylli can be quantified simultaneously. We validated this method in carnation cultivation fields and found a correlation between the degree of disease in each field and the measured density of the bacteria. This method will help develop and establish effective pest control techniques because it targets only live T. caryophylli in soil and can measure the density with high sensitivity and accuracy.

PurposeThe study focused on developing a rapid PCR-based detection method and employing gamma irradiation techniques to manage Ralstonia solanacearum, aiming to produce brown rot-free export-quality potatoes. This initiative seeks to enhance potato exports from Bangladesh.Materials and MethodsSamples of potato tubers and soil were collected from various commercially significant potato-growing areas, resulting in a total of 168 Ralstonia solanacearum isolates from potato tubers and soil across 12 regions. The detection of R. solanacearum in the enriched tuber extract and soil were conducted using the primer pairs (PS-1, PS-2) and (759, 760). For the gamma irradiation experiment, petri dishes containing R. solanacearum cultures were subjected to different doses of gamma rays at the Bangladesh Institute of Nuclear Agriculture using a 60Co source. The irradiation doses applied to the samples were 0-6.0KGy.ResultsMorphological identification based on pink/light red colonies on TTC medium was confirmed R. solanacearum in 148 isolates. PCR using species-specific primers (PS-1/PS-2) and (759, 760) verified 26 isolates (14 tubers, 12 soil), producing 553 bp and 281 bp fragments in latently infected tubers and soil samples respectively. Gamma irradiation at 2.5 kGy damaged R. solanacearum's DNA and cells, preventing brown rot, while higher doses eliminated it entirely. This offers a promising strategy to enhance safety of stored potatoes, potentially mitigating economic losses from this quarantine pathogen.ConclusionThe study developed a PCR detection method and gamma irradiation techniques to manage R. solanacearum, enhancing the export quality of potatoes.

Nuclear facility sites built on soft deposits often adopt a combined piled cushion raft foundation (CPCRF) to enhance bearing capacity. However, separation and slip at the raft-bottom interface is inevitable in refined seismic simulations of weakly anchored nuclear island buildings (NIBs). Multiple factors related to both the structure and foundation influence the interface behavior. To address this, a structure-interface-soil nonlinear interaction model was developed, incorporating interfacial discontinuity characteristics, tri-directional wave inputs, and a stable semi-unbounded condition. The validity of the wave-field simulation method and the interface model were confirmed through theoretical comparisons. Using the AP1000 NIB at a specific CPCRF site as an example, the practicability of the model was validated, and key behavioral patterns were identified. In the static-seismic process, correlations between interface behavior, pile damage, and structural vibration were quantitatively elucidated. When seismic intensity exceeded design limits, the minimum instantaneous grounding ratio decreased rapidly. Structural vertical acceleration nearly doubled, and the frequency band of peak horizontal vibration shifted to higher frequencies. Interface behavior strongly correlated with slip stability and pile body damage. These findings indicate that interfacial discontinuities at the raft's bottom pose safety risks warranting further investigation.

The horticultural crops, including spices and plantation crops, are known for their enormous benefits, contributing to the country's economy. However, Phytophthora, a genus of Oomycetes class, poses a threat to spice and plantation crops by infecting and damaging them, resulting in yield losses, economic hardship for farmers, and food security concerns, thereby threatening the sustainability of spice and plantation crops. Moreover, Phytophthora has greater adaptation sys tems in varying environmental conditions. Therefore, eradicating or controlling Phytophthora is a highly challenging process due to the longevity of its infective propagules in soil. Early detection and curative measures would be more effective in managing this destructive pathogen. Additionally, molecular detection using innovative methods such as polymerase chain reaction, reverse transcription polymerase chain reaction, recombinase polymerase amplification, and loop-mediated isothermal amplification would offer reliable and rapid detection. Furthermore, integrated disease management strategies, combining cultural, physical, chemical, and biological methods, would prove highly beneficial in managing Phytophthora infections in spices and plantation crops. This review provides a comprehensive overview of the diversity, symptomatology, pathogenicity, and impact of Phytophthora diseases on prominent spice and plantation crops. Finally, our review explores the current disease reduction strategies and suggests future research directions to address the threat posed by Phytophthora to spices and plantation crops.

BACKGROUNDRoot-knot nematodes (RKN, Meloidogyne spp.) are economically significant pests that cause immense damage to a wide range of crops. Among them, M. incognita and M. enterolobii are of particular concern, as their high virulence and broad host range. RKN are challenging for detection due to their subterranean lifestyle underground. Also, the mixed infection of nematodes in field crops complicates the need for more accurate diagnostic and quantification technologies.RESULTSTo address this challenge, we developed and optimized a novel duplex droplet digital PCR (ddPCR) method, using primer/probe sets targeting M. incognita and M. enterolobii, to simultaneously identify and quantify both species within a single assay. The innovative ddPCR diagnostic demonstrated excellent performance in terms of sensitivity, precision and reproductivity when quantifying the eggs and soil samples containing juveniles of both species. Moreover, the application of the duplex ddPCR method enables the monitoring of population dynamics of M. incognita and M. enterolobii under competitive environmental conditions. Our results indicated that the reproduction factor of M. incognita possibly inhibited when in mixed populations of M. enterolobii.ConclusionIn this study, we first applied duplex ddPCR technique for differentiating mixed infections of M. incognita and M. enterolobii, offering a valuable tool for species detection and quantification. It enables the monitoring of population dynamics for both species, which is crucial for providing theoretical guidance for the implementation of timely and effective control measures. (c) 2024 Society of Chemical Industry.

Key messageMelatonin increases Pb tolerance in P. ovata seedlings via the regulation of growth and stress-related phytohormones, ROS scavenging and genes responsible for melatonin synthesis, metal chelation, and stress defense.AbstractLead (Pb) is a highly toxic heavy metal that accumulates in plants through soil and air contamination and impairs its plant growth and development. Because of its pharmaceutical importance, improvements in Plantago ovata yield against abiotic stresses are necessary. Melatonin (MEL) is a stress-alleviating biostimulator and our results showed a reduction in Pb induced phytotoxicity by enhancing plant growth attributes and balancing protective osmolytes. Pb-induced reactive oxygen species accumulation, including superoxide and peroxide free radicals and their mitigation through enzymatic antioxidants, was demonstrated in presence of MEL. Cell viability and Pb bioaccumulation were determined to understand the extent of cellular damage. Moreover, MEL increased secondary metabolite (flavonoids and anthocyanins) contents by 2-3-fold at the lowest Pb concentrations. Similar increases in the relative expression of genes (PoPAL and PoPPO), which are responsible for the production of non-enzymatic antioxidants, were observed. Notably, the upregulation of the PoCOMT gene up to 4-fold indicates increased melatonin production, as manifested in the phytomelatonin level. MEL supplementation also increased the auxin (IAA) level by 3-fold in the 100 mu M Pb treatment group, while the abscisic acid (ABA) level decreased (1.4-fold) and the expression of PoMYB (a stress-related transcription factor) increased (up to 2.66-fold). Additionally, we found extreme downregulation (up to 18-fold) in the relative expression of PoMT 2 (a metal binding thiol compound) with melatonin treatment, which is otherwise upregulated (by 6-fold) during Pb stress. In the current study, these effects collectively revealed that MEL contribute to enhanced plant growth and Pb stress tolerance.

Root-lesion nematodes (Pratylenchus spp.) are significant plant parasites, causing substantial crop damage worldwide. This study aimed to characterize Pratylenchus spp. in New Zealand maize fields using molecular techniques and map their prevalence. Soil sampling from 24 maize fields across the North and South Islands provided 381 composite samples. Root-lesion nematodes were extracted using the sieving-centrifugal-sugar flotation method and differentiated into five morphospecies. Molecular characterization involved direct partial sequencing of the D2/D3 28S rDNA, ITS rDNA, and COX1 mtDNA regions using Sanger technology from a single nematode. Five Pratylenchus species were identified: P. neglectus, P. crenatus, P. thornei, P. penetrans, and P. pratensis, confirmed by phylogenetic analysis. Prevalence mapping showed P. neglectus and P. crenatus in all sampled fields, while P. thornei, P. penetrans, and P. pratensis were more localized. This study is the first to report these Pratylenchus species on maize in New Zealand and provides the first partial sequences of the D2/D3, COX1, and ITS regions for these species on maize in New Zealand. The findings highlight the diversity of Pratylenchus populations in New Zealand maize fields and emphasize the need for region-specific management strategies to mitigate crop damage.

Soil remediation for cadmium (Cd) toxicity is essential for successful tobacco cultivation and production. Melatonin application can relieve heavy metal stress and promote plant growth; however, it remains somewhat unclear whether melatonin supplementation can remediate the effects of Cd toxicity on the growth and development of tobacco seedlings. Herein, we evaluated the effect of soil-applied melatonin on Cd accumulation in tobacco seedlings, as well as the responses in growth, physiological and biochemical parameters, and the expression of stress-responsive genes. Our results demonstrate that melatonin application mitigated Cd stress in tobacco, and thus promoted plant growth. It increased root fresh weight, dry weight, shoot fresh weight and dry weight by 58.40%, 163.80%, 34.70% and 84.09%, respectively, compared to the control. Physiological analyses also showed significant differences in photosynthetic rate and pigment formation among the treatments, with the highest improvements recorded for melatonin application. In addition, melatonin application alleviated Cd-induced oxidative damage by reducing MDA content and enhancing the activities of enzymatic antioxidants (CAT, SOD, POD and APX) as well as non-enzymatic antioxidants (GSH and AsA). Moreover, confocal microscopic imaging confirmed the effectiveness of melatonin application in sustaining cell integrity under Cd stress. Scanning Electron Microscopy (SEM) observations illustrated the alleviative role of melatonin on stomata and ultrastructural features under Cd toxicity. The qRT-PCR analysis revealed that melatonin application upregulated the expression of photosynthetic and antioxidant-related genes, including SNtChl, q-NtCSD1, NtPsy2 and QntFSD1, in tobacco leaves. Together, our results suggest that soil-applied melatonin can promote tobacco tolerance to Cd stress by modulating morpho-physiological and biochemical changes, as well as the expression of relevant genes.

Mercury (Hg) is a notorious toxic heavy metal, causing neurotoxicity and liver damage, posing grave threats to human health and environmental safety. There is an urgent imperative for developing novel Hg2+ detection methods. In this work, we developed a CRISPR-based method for Hg2+ detection named CRISPR-Hg. A CRISPR/ Cas12a system was employed and could be activated by the PCR product, generating fluorescence signals based on the trans-cleavage activity. CRISPR-Hg exhibited remarkable selectivity and specificity, achieving a detection limit of 10 pM and minimal interference with background signals. This approach has been successfully applied to detect Hg2+ in real samples, including water, soil, and mushroom. Ulteriorly, a portable device was devised to streamline the readout of fluorescence signals by a smartphone within 30 min. We offer an affordable, highly selective and visually interpretable method for Hg2+ detection, with the potential for broad application in Hg2+ monitoring for food safety and public health.