This work aims to isolate and screen the fungicidal endophytic bacterial strains for biocontrol efficacy against Phytophthora palmivora, a soil-borne pathogenic fungus that kills durian trees worldwide. Among more than 100 isolates, 6 strains were screened as potential fungicidal strains with inhibitory efficiency of 67.4-79.8%. Based on 16S rRNA gene sequencing and phylogenetic analysis, these strains were identified as Bacillus amyloliquefaciens EB.CK9, Bacillus methylotrophicus EB.EH34, Bacillus amyloliquefaciens EB.EH18, Bacillus siamensis EB.KN10, Bacillus velezensis EB.KN15 and Paenibacillus polymyxa EB.KN35. In greenhouse tests, the two strains P. polymyxa EB.KN35 and B. velezensis EB.KN15 significantly reduced the damage to diseased roots by P. palmivora (33.3 and 35.6%, respectively), increased the rate of survival of durian trees (only 20.8 and 22.9% plant death, respectively), and showed a positive effect on promoting durian plant growth. Notably, the potential fungicidal effect of last two strains against P. palmivora was recorded for the first time in this work. HPLC analysis showed that these strains can secret several plant growth-promoting compounds, including gibberellic acid (GA3), indole-3-acetic acid (IAA), kinetin, and zeatin. Of these, GA3 and zeatin were produced with a significant amount by both strains. The volatiles bio-synthesized by these isolates were also identified using GC-MS analysis, and some major volatiles were found as fungicidal agents. This study suggested that P. polymyxa EB.KN35 and B. velezensis EB.KN15 may be potential biocontrol candidates for durian P. palmivora and bio-fertilizers for the sustainable production of durian crops.

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.

Phytophthora capsici is an infamously soil-borne pathogen that poses a serious threat to agricultural production. Curcumol is a natural plant-derived sesquiterpene lactone, whose antimicrobial effect against plant pathogens remains unclear. In this study, curcumol exhibited pronounced antifungal activity against a diverse range of plant pathogens, particularly against plant pathogenic oomycetes, which including P. capsici, Phytophthora infestans, Phytophthora parasitica, and Phytophthora sojae. The median effective concentration values of curcumol against P. capsici for spore germination and mycelial growth were 4.75 and 2.11 mu g mL- 1, respectively. After treatment with curcumol, mycelia of P. capsici exhibited morphological and ultrastructual defects, which included swelling, hyperbranching, dissolution of plasma membrane, and loss of organelles. In addition, curcumol effectively inhibited the synthesis of phosphatidylcholine (PC), a primary component of cell membrane, by downregulating the expression levels of genes participated in PC synthesis such as Phospholipid N-methyltransferase and Cholinephosphotransferase. This inhibition decreased the accumulation of PC and phospholipids within the cell, thereby increasing the cell membrane permeability and damaging its integrity. In the in vivo antifungal tests, curcumol reduced the disease incidence of P. capsici on tomato leaves as well as pepper seedlings. The systemicity tests further validated the strong phloem and xylem mobility of curcumol in both upward and downward directions. Taken together, these results indicated that curcumol could effectively combat diseases caused by P. capsici and had the potential for development into a novel fungicide for P. capsici management.

Phytophthora root and stem rot is a disease caused by the oomycete Phytophthora sojae that can lead to severe damage in soybean. Disease management involves the use of resistant soybean varieties, which can have either complete resistance through Rps genes or partial resistance. The pathogen population has rapid evolution and constant changes in pathogenicity, thus, new pathotypes of the pathogen capable of overcoming Rps genes are frequently reported. In addition to genetic resistance, other control methods of Phytophthora root and stem rot of soybean include seed treatment with oomycides/fungicides, use of biological and alternative products, and cultural practices that promote soil drainage and avoid compaction. This review provides detailed and up-to-date information on P. sojae, its interaction with soybean, the diversity of the pathogen population, and control methods of Phytophthora root and stem rot focused on host genetic resistance.

Phytophthora infestans-induced potato late blight is considered the cancer of the potato crop. In this work, mesoporous silica nanoparticles (MSNs) with ultrahigh specific surface area (786.28 m(2)/g) were synthesized, which significantly inhibited P. infestans compared with some commercial fungicides. Moreover, MSNs inhibited the growth and reproductive of P. infestans processes, including germination, sporangia infection, and zoospore release. MSNs targeted key biological pathways and induced a stress response in the P. infestans, leading to reactive oxygen species (center dot O2-, center dot OH, and O-1(2)) production and structural damage of sporangia. Pot experiments showed that MSNs are translocated from leaves to roots of potato plants, enhancing physiological and biochemical processes, alleviating drought stress, improving resistance to pathogens, and exhibiting soil microbe-friendly. This study systematically reveals the mechanism of MSNs to weaken the reproduction process of P. infestans and confirm the safety and feasibility of MSNs as a green and sustainable fungicide.

Arbuscular mycorrhizal fungi (AMF) and Chitooligosaccharide (COS) can increase the resistance of plants to disease. COS can also promote the symbiosis between AMF and plants. However, the effects of AMF & COS combined application on the rhizosphere soil microbial community of tobacco and the improvement of tobacco's resistance to black shank disease are poorly understood.& sdot;We treated tobacco with AMF, COS, and combined application of AMF & COS (AC), respectively. Then studied the incidence, physio-biochemical changes, root exudates, and soil microbial diversity of tobacco seedling that was inoculated with Phytophthora nicotianae. The antioxidant enzyme activity and root vigor of tobacco showed a regular of AC > AMF > COS > CK, while the severity of tobacco disease showed the opposite regular. AMF and COS enhance the resistance to black shank disease by enhancing root vigor, and antioxidant capacity, and inducing changes in the rhizosphere microecology of tobacco. We have identified key root exudates and critical soil microorganisms that can inhibit the growth of P. nicotianae. The presence of caprylic acid in root exudates and Bacillus (WdhR-2) in rhizosphere soil microorganisms is the key factor that inhibits P. nicotianae growth. AC can significantly increase the content of caprylic acid in tobacco root exudates compared to AMF and COS. Both AMF and COS can significantly increase the abundance of Bacillus in tobacco rhizosphere soil, but the abundance of Bacillus in AC is significantly higher than that in AMF and COS. This indicates that the combined application of AMF and COS is more effective than their individual use. These findings suggest that exogenous stimuli can induce changes in plant root exudates, regulate plant rhizosphere microbial community, and then inhibit the growth of pathogens, thereby improving plant resistance to diseases.

The biocontrol potential of three native soil cyanobacteria from biological soil crusts (Nostoc commune, Scytonema hyalinum, and Tolypothrix distorta) was tested by means of in vitro mycelial growth inhibition assays for eighteen cyanobacteria-based products against three phytopathogenic soilborne fungi (Phytophthora capsici, Pythium aphanidermatum, and Fusarium oxysporum f. sp. radicis-cucumerinum). Three cyanobacteria-based production factors were considered: (i) cyanobacterium strain, (ii) cyanobacterial culture growth phase, and (iii) different post-harvest treatments: raw cultures, cyanobacterial filtrates, and cyanobacterial extracts. Results showed that any of the factors considered are key points for successfully inhibiting fungal growth. N. commune showed the highest growth inhibition rates for the three phytopathogens; stationary phase treatments produced higher inhibition percentages than logarithmic ones; and all the post-harvest treatments of N. commune at the stationary phase inhibited the growth of P. capsici, up to 77.7%. Thus, N. commune products were tested in planta against P. capsici, but none of the products showed efficacy in delaying the onset nor reducing the damage due to P. capsici, demonstrating the complexity of the in planta assay's success and encouraging further research to design an appropriate scaling up methodology.

Phytophthora, one among the most devastating phytopathogenic genus representing the oomycetes inflicts substantial damage to a broad spectrum of economically important horticultural crops worldwide. The rapid dissemination of Phytophthora in agro-ecosystems is mediated through bi-flagellated zoospores and their homing response towards the host is profoundly influenced by chemo-electrotactic mechanisms leading to encystment and subsequent colonization. Though different procedures are reported to isolate Phytophthora from infested rhizospheric soils, studies addressing zoospore encystment-based method using different baits for isolation and subsequent retrieval of cultures (in case of bacterial contamination) are meagre in Phytophthora-black pepper host-pathosystem. In the present study, Phytophthora was isolated from infested rhizospheric soils of black pepper using different baits viz., thermocol, impregnated paper discs, leaves of Albizzia falcataria and green gram roots. Modified cabin-sequestering methods were subsequently adopted to salvage the cultures in case of bacterial contamination, if any. The zoospore encystment-based method is cost effective and consumes lesser time for isolation of Phytophthora from infested rhizospheric soils of black pepper. Further, the two approaches of cabin sequestering method which were found promising in obtaining pure cultures of Phytophthora devoid of bacterial contamination, can also be employed to retrieve bacterial contaminated cultures of research significance.

A retrospective examination of early pest and disease outbreaks, such as ink disease, offers new insights into their impact on ecosystems and landscapes. Ink disease, caused by Phytophthora spp., is one of the most destructive diseases affecting Castanea sativa Mill. It first appeared in Europe in the early 18th century, with the initial recorded case in Italy (Piedmont) dating back to 1845. However, its spread instilled significant concerns in several chestnut-growing regions primarily devoted to fruit production. In 1938, a comprehensive assessment of Phytophthora xcambivora outbreaks was conducted in the Bolognese Apennines (Italy), providing a detailed overview of chestnut cultivation status. Thirty-six disease foci were documented, and laboratory tests confirmed the presence of ink disease. To understand the disease's impact on chestnut ecosystem and landscape over the past 85 years, the 1938 sites were revisited to assess chestnut persistence and phytosanitary status, with Phytophthora species detected using isolation and molecular techniques. Monitoring data revealed that C. sativa still thrives in all but one site, with its wood seemingly able to coexist in dynamic equilibrium with the disease. While P. xcambivora was still detected in several foci, the extent of damage appeared limited. The potential for natural control, likely influenced by the complexity of soil biota, along with the natural spread of hypovirulence in chestnut blight and biological control of the Asian chestnut gall wasp, could explain the continued presence of chestnut in the investigated area and potentially throughout the Italian chestnut range, despite nearly two centuries of ink disease prevalence. Nevertheless, ongoing monitoring is essential to dynamically comprehend the factors at play and their efficacy, particularly in the context of climate change and the possible spread of other Phytophthora species. The survival of chestnut ecosystems amidst ink disease underscores the preservation of the economic, ecological, and landscape values associated with these woodlands.

Christmas trees are an economically and culturally important ornamental plant in North America. Many microorganisms are pathogens of firs cultivated as Christmas trees. Among those, Phytophthora causes millions of dollars in damage to plantations annually. In Canada, it is unknown which species are responsible for Phytophthora root rot (PRR) of cultivated Abies species. Between 2019 and 2021, soil and root samples were collected from 40 Christmas tree plantations in Qu & eacute;bec province. We used soil baiting and direct isolation from unidentified root fragments to assess the diversity of culturable Phytophthora spp. The obtained isolates were identified using a multilocus sequencing and phylogenetic approach. A total of 44 isolates were identified, including eight P. chlamydospora, eight P. abietivora, seven P. gonapodyides, three P. gregata, six P. megasperma, and two P. kelmanii isolates, plus 10 isolates belonging to a previously unknown taxon that is phylogenetically close to P. chlamydospora and P. gonapodyides. Among the known species, P. abietivora was the most prevalent isolated species associated with trees showing aboveground PRR-like symptoms. Pathogenicity trials confirmed the pathogenicity potential of P. abietivora on both Fraser fir and balsam fir seedlings. Our study provides a first snapshot of the Phytophthora diversity in Qu & eacute;bec's Christmas tree productions and describes multiple potential first associations between Phytophthora species and Abies balsamea and A. fraseri.