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Association of soil fungal community composition with incidence of Fusarium wilt of banana in Malaysia

Jamil FN, Hashim AM, Yusof MT, Saidi NB

Mycologia, 2023;115(2):178-186.
PMID: 36893072 DOI: 10.1080/00275514.2023.2180975

Banana (Musa spp.), an important food crop in many parts of the world, is threatened by a deadly wilt disease caused by Fusarium oxysporum f. sp. cubense Tropical Race 4 (TR4). Increasing evidence indicates that plant actively recruits beneficial microbes in the rhizosphere to suppress soil-borne pathogens. Hence, studies on the composition and diversity of the root-associated microbial communities are important for banana health. Research on beneficial microbial communities has focused on bacteria, although fungi can also influence soil-borne disease. Here, high-throughput sequencing targeting the fungal internal transcribed spacer (ITS) was employed to systematically characterize the difference in the soil fungal community associated with Fusarium wilt (FW) of banana. The community structure of fungi in the healthy and TR4-infected rhizospheres was significantly different compared with that of bulk soil within the same farm. The rhizosphere soils of infected plants exhibited higher richness and diversity compared with healthy plants, with significant abundance of Fusarium genus at 14%. In the healthy rhizosphere soil, Penicillium spp. were more abundant at 7% and positively correlated with magnesium. This study produced a detailed description of fungal community structure in healthy and TR4-infected banana soils in Malaysia and identified candidate biomarker taxa that may be associated with FW disease promotion and suppression. The findings also expand the global inventory of fungal communities associated with the components of asymptomatic and symptomatic banana plants infected by TR4.

Matched MeSH terms: Plant Diseases/microbiology
Fulltext Analysis of soil bacterial communities and physicochemical properties associated with Fusarium wilt disease of banana in Malaysia

Jamil FN, Hashim AM, Yusof MT, Saidi NB

Sci Rep, 2022 Jan 19;12(1):999.
PMID: 35046475 DOI: 10.1038/s41598-022-04886-9

Fusarium wilt (FW) caused by Fusarium oxysporum f. sp. cubense Tropical Race 4 (TR4) is a soil-borne disease that infects bananas, causing severe economic losses worldwide. To reveal the relationship between bacterial populations and FW, the bacterial communities of healthy and TR4-infected rhizosphere and bulk soils were compared using 16S rRNA gene sequencing. Soil physicochemical properties associated with FW were also analyzed. We found the community structure of bacteria in the healthy and TR4 infected rhizosphere was significantly different compared to bulk soil within the same farm. The rhizosphere soils of infected plants exhibited higher richness and diversity than healthy plant with significant abundance of Proteobacteria. In the healthy rhizosphere soil, beneficial bacteria such as Burkholderia and Streptomyces spp. were more abundant. Compared to the infected rhizosphere soil, healthy rhizosphere soil was associated with RNA metabolism and transporters pathways and a high level of magnesium and cation exchange capacity. Overall, we reported changes in the key taxa of rhizospheric bacterial communities and soil physicochemical properties of healthy and FW-infected plants, suggesting their potential role as indicators for plant health.

Matched MeSH terms: Plant Diseases/microbiology*
Phenotypic screening and molecular analysis of blast resistance in fragrant rice for marker assisted selection

Khan MA, Sen PP, Bhuiyan R, Kabir E, Chowdhury AK, Fukuta Y, et al.

C. R. Biol., 2014 May;337(5):318-24.
PMID: 24841958 DOI: 10.1016/j.crvi.2014.02.007

Experiments were conducted to identify blast-resistant fragrant genotypes for the development of a durable blast-resistant rice variety during years 2012-2013. The results indicate that out of 140 test materials including 114 fragrant germplasms, 25 differential varieties (DVs) harbouring 23 blast-resistant genes, only 16 fragrant rice germplasms showed comparatively better performance against a virulent isolate of blast disease. The reaction pattern of single-spore isolate of Magnaporthe oryzae to differential varieties showed that Pish, Pi9, Pita-2 and Pita are the effective blast-resistant genes against the tested blast isolates in Bangladesh. The DNA markers profiles of selected 16 rice germplasms indicated that genotype Chinigura contained Pish, Pi9 and Pita genes; on the other hand, both BRRI dhan50 and Bawaibhog contained Pish and Pita genes in their genetic background. Genotypes Jirakatari, BR5, and Gopalbhog possessed Pish gene, while Uknimodhu, Deshikatari, Radhunipagol, Kalijira (3), Chinikanai each contained the Pita gene only. There are some materials that did not contain any target gene(s) in their genetic background, but proved resistant in pathogenicity tests. This information provided valuable genetic information for breeders to develop durable blast-resistant fragrant or aromatic rice varieties in Bangladesh.

Matched MeSH terms: Plant Diseases/microbiology*
Transfer of the potato plant isolates of Pectobacterium wasabiae to Pectobacterium parmentieri sp. nov

Khayi S, Cigna J, Chong TM, Quêtu-Laurent A, Chan KG, Hélias V, et al.

Int J Syst Evol Microbiol, 2016 Dec;66(12):5379-5383.
PMID: 27692046 DOI: 10.1099/ijsem.0.001524

Pectobacterium wasabiae was originally isolated from Japanese horseradish (Eutrema wasabi), but recently some Pectobacterium isolates collected from potato plants and tubers displaying blackleg and soft rot symptoms were also assigned to P. wasabiae. Here, combining genomic and phenotypical data, we re-evaluated their taxonomic position. PacBio and Illumina technologies were used to complete the genome sequences of P. wasabiae CFBP 3304T and RNS 08-42-1A. Multi-locus sequence analysis showed that the P. wasabiae strains RNS 08-42-1A, SCC3193, CFIA1002 and WPP163, which were collected from potato plant environment, constituted a separate clade from the original Japanese horseradish P. wasabiae. The taxonomic position of these strains was also supported by calculation of the in-silico DNA-DNA hybridization, genome average nucleotide indentity, alignment fraction and average nucleotide indentity values. In addition, they were phenotypically distinguished from P. wasabiae strains by producing acids from (+)-raffinose, α-d(+)-α-lactose, d(+)-galactose and (+)-melibiose but not from methyl α-d-glycopyranoside, (+)-maltose or malonic acid. The name Pectobacterium parmentieri sp. nov. is proposed for this taxon; the type strain is RNS 08-42-1AT (=CFBP 8475T=LMG 29774T).

Matched MeSH terms: Plant Diseases/microbiology*
Fulltext Population genomics reveals additive and replacing horizontal gene transfers in the emerging pathogen Dickeya solani

Khayi S, Blin P, Pédron J, Chong TM, Chan KG, Moumni M, et al.

BMC Genomics, 2015;16:788.
PMID: 26467299 DOI: 10.1186/s12864-015-1997-z

Dickeya solani is an emerging pathogen that causes soft rot and blackleg diseases in several crops including Solanum tuberosum, but little is known about its genomic diversity and evolution.

Matched MeSH terms: Plant Diseases/microbiology
Morphological and molecular characterization, sexual reproduction, and pathogenicity of Setosphaeria rostrata isolates from rice leaf spot

Kusai NA, Azmi MM, Zainudin NA, Yusof MT, Razak AA

Mycologia, 2016 09;108(5):905-914.
PMID: 27474518

Setosphaeria rostrata, a common plant pathogen causing leaf spot disease, affects a wide range of plant species, mainly grasses. Fungi were isolated from brown spots on rice leaves throughout Peninsular Malaysia, and 45 isolates were identified as Setosphaeria rostrata The isolates were then characterized using morphological and molecular approaches. The mating type was determined using PCR amplification of the mating type alleles, and isolates of opposite mating types were crossed to examine sexual reproduction. Based on nuclear ribosomal DNA ITS1-5.8S-ITS2 region (ITS) and beta-tubulin (BT2) sequences, two phylogenetic trees were constructed using the maximum likelihood method; S. rostrata was clustered in one well-supported clade. Pathogenicity tests showed that S. rostrata isolates are pathogenic, suggesting that it is the cause of the symptoms. Mating-type analyses indicated that three isolates carried the MAT1-1 allele, and the other 42 isolates carried MAT1-2 After isolates with opposite mating types were crossed on Sach's medium and incubated for 3 wk, six crosses produced pseudothecia that contained eight mature ascospores, and 12 other crosses produced numerous pseudothecia with no ascospores. To our knowledge, this is the first report on S. rostrata isolated from leaf spots on rice.

Matched MeSH terms: Plant Diseases/microbiology*
Cloning of nitric oxide associated 1 (NOA1) transcript from oil palm (Elaeis guineensis) and its expression during Ganoderma infection

Kwan YM, Meon S, Ho CL, Wong MY

J Plant Physiol, 2015 Feb 01;174:131-6.
PMID: 25462975 DOI: 10.1016/j.jplph.2014.10.003

Nitric oxide associated 1 (NOA1) protein is implicated in plant disease resistance and nitric oxide (NO) biosynthesis. A full-length cDNA encoding of NOA1 protein from oil palm (Elaeis guineensis) was isolated and designated as EgNOA1. Sequence analysis suggested that EgNOA1 was a circular permutated GTPase with high similarity to the bacterial YqeH protein of the YawG/YlqF family. The gene expression of EgNOA1 and NO production in oil palm root tissues treated with Ganoderma boninense, the causal agent of basal stem rot (BSR) disease were profiled to investigate the involvement of EgNOA1 during fungal infection and association with NO biosynthesis. Real-time PCR (qPCR) analysis revealed that the transcript abundance of EgNOA1 in root tissues was increased by G. boninense treatment. NO burst in Ganoderma-treated root tissue was detected using Griess reagent, in advance of the up-regulation of the EgNOA1 transcript. This indicates that NO production was independent of EgNOA1. However, the induced expression of EgNOA1 in Ganoderma-treated root tissues implies that it might be involved in plant defense responses against pathogen infection.

Matched MeSH terms: Plant Diseases/microbiology
Microsatellite and minisatellite markers based DNA fingerprinting and genetic diversity of blast and ufra resistant genotypes

Latif MA, Rafii Yusop M, Motiur Rahman M, Bashar Talukdar MR

C. R. Biol., 2011 Apr;334(4):282-9.
PMID: 21513897 DOI: 10.1016/j.crvi.2011.02.003

A total of 78 alleles and 29 loci were detected from nine microsatellite and three minisatellite markers, respectively across 26 blast and ufra disease resistant genotypes. For blast resistant genotypes, the Polymorphic Information Content (PIC) values ranged from 0.280 to 0.726 and RM21 was considered as the best marker. PIC values ranged from 0.5953 to 0.8296 for ufra resistant genotypes and RM23 was the best marker for characterization of ufra resistant genotypes. The genetic similarity analysis using UPGMA clustering generated nine clusters with coefficient of 0.66 for blast resistant genotypes while five genetic clusters with similarity coefficient of 0.42 for ufra resistant genotypes. In order to develop resistant varieties of two major diseases of rice, hybridisation should be made using the parents, BR29 and NJ70507, BR36 and NJ70507 for blast, while BR11 and Aokazi, BR3 and Aokazi, Rayda and BR3 and Rayda and BR11 for ufra.

Matched MeSH terms: Plant Diseases/microbiology
Transcriptomic analysis of pepper plants provides insights into host responses to Fusarium solani infestation

Lau ET, Khew CY, Hwang SS

J Biotechnol, 2020 May 20;314-315:53-62.
PMID: 32302654 DOI: 10.1016/j.jbiotec.2020.03.014

Black pepper is an important commodity crop in Malaysia that generates millions of annual revenue for the country. However, black pepper yield is affected by slow decline disease caused by a soil-borne fungus Fusarium solani. RNA sequencing transcriptomics approach has been employed in this study to explore the differential gene expression in susceptible Piper nigrum L. and resistant Piper colubrinum Link. Gene expression comparative analysis of the two pepper species has yielded 2,361 differentially expressed genes (DEGs). Among them, higher expression of 1,426 DEGs was detected in resistant plant. These DEGs practically demonstrated the major branches of plant-pathogen interaction pathway (Path: ko04626). We selected five groups of defence-related DEGs for downstream qRT-PCR analysis. Cf-9, the gene responsible for recognizing fungal avirulence protein activity was found inexpressible in susceptible plant. However, this gene exhibited promising expression in resistant plant. Inactivation of Cf-9 could be the factor that causes susceptible plant fail in recognition of F. solani and subsequently delay activation of adaptive response to fungal invasion. This vital study advance the understanding of pepper plant defence in response to F. solani and aid in identifying potential solution to manage slow decline disease in black pepper cultivation.

Matched MeSH terms: Plant Diseases/microbiology
Plant growth-promoting bacteria as potential bio-inoculants and biocontrol agents to promote black pepper plant cultivation

Lau ET, Tani A, Khew CY, Chua YQ, Hwang SS

Microbiol Res, 2020 Nov;240:126549.
PMID: 32688172 DOI: 10.1016/j.micres.2020.126549

Black pepper production in Malaysia was restricted by various diseases. Hazardous chemical products appear to be the best solution to control diseases in black pepper cultivation. However, persistence of chemical residues in peppercorns could affect the quality of exports and consumptions. Application of fertilizers is crucial to sustain pepper growth and high yield. But, continuous use of chemical fertilizers could affect the soil ecosystem and eventually restrict nutrient uptake by pepper roots. Therefore, we propose biological approaches as an alternative solution instead of chemical products to sustain pepper cultivation in Malaysia. In this study, we have isolated a total of seven indigenous rhizobacteria antagonistic to soil-borne Fusarium solani, the causal fungus of slow decline, the most serious debilitating disease of black pepper in Malaysia. The isolated bacteria were identified as Bacillus subtilis, Bacillus siamensis, Brevibacillus gelatini, Pseudomonas geniculata, Pseudomonas beteli, Burkholderia ubonensis and Burkholderia territorii. These bacteria were effective in production of antifungal siderophore with the amount of 53.4 %-73.5 % per 0.5 mL of cell-free supernatants. The bacteria also produced appreciable amount of chitinase with chitinolytic index was ranged from 1.19 to 1.76. The bacteria have shown phosphate solubilizing index within 1.61 to 2.01. They were also efficient in ACC deaminase (0.52 mM-0.62 mM) and ammonia (60.3 mM-75.3 mM) production. The isolated antagonists were efficacious in stimulation of black pepper plant growth and root development through IAA (10.5 μg/mL-42.6 μg/mL) secretion. In conclusion, the isolated rhizobacteria are potent to be developed not only as biocontrol agents to minimize the utilization of hazardous chemicals in black pepper disease management, but also developed as bio-fertilizers to improve black pepper plant growth due to their capabilities in plant growth-promotion.

Matched MeSH terms: Plant Diseases/microbiology
Identification of Botryosphaeriaceae associated with stem-end rot of mango (Mangifera indica L.) in Malaysia

Li L, Mohd MH, Mohamed Nor NMI, Subramaniam S, Latiffah Z

J Appl Microbiol, 2021 Apr;130(4):1273-1284.
PMID: 32813902 DOI: 10.1111/jam.14828

AIMS: To identify Botryosphaeriaceae fungal species that are associated with stem-end rot of mango, and to study their pathogenicity on mango fruit.
METHODS AND RESULTS: Based on the sequences of internal transcribed spacer (ITS), TEF1-α and β-tubulin, as well as on the phylogenetic analysis of combined sequences, four species of Lasiodiplodia (L. theobromae,L. pseudotheobromae, L. iranensis, L. mahajangana) and two species of Neofusicoccum (N. ribis, N. parvum) were identified. Pseudofusicoccum violaceum, Neoscytalidium dimidiatum and three species of Botryosphaeria (B. scharifii, B. dothidea, B. ramosa) were identified based on sequences of ITS and TEF1-α. Pathogenicity test of selected isolates were tested on Chok Anan, Waterlily and Falan mango cultivars. Generally, all species were observed to be pathogenic on the three tested mango cultivars on wounded fruits, except for N. ribis and N. parvum, which were pathogenic on both wounded and unwounded fruits. However, N. ribis was only pathogenic on cultivar Falan, whereas B. ramosa were pathogenic on cultivars Waterlily and Falan.
CONCLUSIONS: Eleven species of Botryosphaeriaceae were associated with mango stem-end rot in Malaysia. To the best of our knowledge, four species, namely L. mahajangana, B. ramosa, N. ribis and P. violaceum are the first recorded Botryosphaeriaceae fungi associated with stem end rot of mango.
SIGNIFICANCE AND IMPACT OF THE STUDY: The identification of Botryosphaeriaceae fungi is important to establish suitable control measures and quarantine requirements. Many species have a wide host range, which means that there is a possibility of cross infection from other infected plants.

Matched MeSH terms: Plant Diseases/microbiology*
Induced expression of Ganoderma boninense Lanosterol 14α-Demethylase (ERG11) during interaction with oil palm

Lim FH, Rasid OA, Idris AS, As'wad AWM, Vadamalai G, Parveez GKA, et al.

Mol Biol Rep, 2023 Mar;50(3):2367-2379.
PMID: 36580194 DOI: 10.1007/s11033-022-08131-4

BACKGROUND: The basidiomycete fungus, Ganoderma boninense is the main contributor to oil palm Basal Stem Rot (BSR) in Malaysia and Indonesia. Lanosterol 14α-Demethylase (ERG11) is a key enzyme involved in biosynthesis of ergosterol, which is an important component in the fungal cell membrane. The Azole group fungicides are effective against pathogenic fungi including G. boninense by inhibiting the ERG11 activity. However, the work on molecular characterization of G. boninense ERG11 is still unavailable today.
METHODS AND RESULTS: This study aimed to isolate and characterize the full-length cDNA encoding ERG11 from G. boninense. The G. boninense ERG11 gene expression during interaction with oil palm was also studied. A full-length 1860 bp cDNA encoding ERG11 was successfully isolated from G. boninense. The G. boninense ERG11 shared 91% similarity to ERG11 from other basidiomycete fungi. The protein structure homology modeling of GbERG11 was analyzed using the SWISS-MODEL workspace. Southern blot and genome data analyses showed that there is only a single copy of ERG11 gene in the G. boninense genome. Based on the in-vitro inoculation study, the ERG11 gene expression in G. boninense has shown almost 2-fold upregulation with the presence of oil palm.
CONCLUSION: This study provided molecular information and characterization study on the G. boninense ERG11 and this knowledge could be used to design effective control measures to tackle the BSR disease of oil palm.

Matched MeSH terms: Plant Diseases/microbiology
Research on basal stem rot (BSR) of ornamental palms caused by basidiospores from Ganoderma boninense

Lim HP, Fong YK

Mycopathologia, 2005 Jan;159(1):171-9.
PMID: 15750750

Basidiospores were isolated from the fruiting bodies of Ganoderma infecting oil palms from an estate in Johor and from ornamental palms (including oil palms) from Singapore. The spores were then germinated to obtain homokaryotic mycelia. Based on clamp connection formation in paired hyphal fusions, tester strains were identified from the homokaryons isolated. Compatibility tests were then carried out using these testers to determine the relatedness of the homokaryotic Ganoderma isolates, both from Johor and from Singapore. Results from the compatibility tests showed that Ganoderma from both locations belong to the same species, while the Ganoderma isolates from Singapore share some common alleles. The pathogenicity tests carried out on Chrysalidocarpus lutescens seedlings using inoculum growing on rubber wood blocks showed that dikaryotic mycelia can cause basal stem rot infection.

Matched MeSH terms: Plant Diseases/microbiology*
Expression of rice thaumatin-like protein gene in transgenic banana plants enhances resistance to fusarium wilt

Mahdavi F, Sariah M, Maziah M

Appl Biochem Biotechnol, 2012 Feb;166(4):1008-19.
PMID: 22183565 DOI: 10.1007/s12010-011-9489-3

The possibility of controlling Fusarium wilt--caused by Fusarium oxysporum sp. cubensec (race 4)--was investigated by genetic engineering of banana plants for constitutive expression of rice thaumatin-like protein (tlp) gene. Transgene was introduced to cauliflower-like bodies' cluster, induced from meristemic parts of male inflorescences, using particle bombardment with plasmid carrying a rice tlp gene driving by the CaMV 35S promoter. Hygromycin B was used as the selection reagent. The presence and integration of rice tlp gene in genomic DNA confirmed by PCR and Southern blot analyses. RT-PCR revealed the expression of transgene in leaf and root tissues in transformants. Bioassay of transgenic banana plants challenged with Fusarium wilt pathogen showed that expression of TLP enhanced resistance to F. oxysporum sp. cubensec (race 4) compared to control plants.

Matched MeSH terms: Plant Diseases/microbiology
Molecular characterization of Phytophthora palmivora responsible for bud rot disease of oil palm in Colombia

Maizatul-Suriza M, Dickinson M, Idris AS

World J Microbiol Biotechnol, 2019 Feb 27;35(3):44.
PMID: 30810828 DOI: 10.1007/s11274-019-2618-9

Bud rot disease is a damaging disease of oil palm in Colombia. The pathogen responsible for this disease is a species of oomyctes, Phytophthora palmivora which is also the causal pathogen of several tropical crop diseases such as fruit rot and stem canker of cocoa, rubber, durian and jackfruit. No outbreaks of bud rot have been reported in oil palm in Malaysia or other Southeast Asian countries, despite this particular species being present in the region. Analysis of the genomic sequences of several genetic markers; the internal transcribe spacer regions (ITS) of the ribosomal RNA gene cluster, beta-tubulin gene, translation elongation factor 1 alpha gene (EF-1α), cytochrome c oxidase subunit I & II (COXI and COXII) gene cluster along with amplified fragment length polymorphism (AFLP) analyses have been carried out to investigate the genetic diversity and variation of P. palmivora isolates from around the world and from different hosts in comparison to Colombian oil palm isolates, as one of the steps in understanding why this species of oomycetes causes devastating damage to oil palm in Latin America but not in other regions. Phylogenetic analyses of these regions showed that the Colombian oil palm isolates were not separated from Malaysian isolates. AFLP analysis and a new marker PPHPAV, targeting an unclassified hypothetical protein, was found to be able to differentiate Malaysian and Colombian isolates and showed a clear clade separations. Despite this, pathogenicity studies did not show any significant differences in the level of aggressiveness of different isolates against oil palm in glasshouse tests.

Matched MeSH terms: Plant Diseases/microbiology*
Fulltext Preparation of Chitosan-Hexaconazole Nanoparticles as Fungicide Nanodelivery System for Combating Ganoderma Disease in Oil Palm

Maluin FN, Hussein MZ, Yusof NA, Fakurazi S, Idris AS, Zainol Hilmi NH, et al.

Molecules, 2019 Jul 08;24(13).
PMID: 31288497 DOI: 10.3390/molecules24132498

Fungicide is used to control fungal disease by destroying and inhibiting the fungus or fungal spores that cause the disease. However, failure to deliver fungicide to the disease region leads to ineffectiveness in the disease control. Hence, in the present study, nanotechnology has enabled the fungicide active agents (hexaconazole) to be encapsulated into chitosan nanoparticles with the aim of developing a fungicide nanodelivery system that can transport them more effectively to the target cells (Ganoderma fungus). A pathogenic fungus, Ganoderma boninense (G. boninense), is destructive to oil palm whereby it can cause significant loss to oil palm plantations located in the Southeast Asian countries, especially Malaysia and Indonesia. In regard to this matter, a series of chitosan nanoparticles loaded with the fungicide, hexaconazole, was prepared using various concentrations of crosslinking agent sodium tripolyphosphate (TPP). The resulting particle size revealed that the increase of the TPP concentration produced smaller particles. In addition, the in vitro fungicide released at pH 5.5 demonstrated that the fungicide from the nanoparticles was released in a sustainable manner with a prolonged release time up to 86 h. On another note, the in vitro antifungal studies established that smaller particle size leads to lower half maximum effective concentration (EC50) value, which indicates higher antifungal activity against G. boninense.

Matched MeSH terms: Plant Diseases/microbiology*
Chitosan-Based Agronanofungicides as a Sustainable Alternative in the Basal Stem Rot Disease Management

Maluin FN, Hussein MZ, Azah Yusof N, Fakurazi S, Idris AS, Zainol Hilmi NH, et al.

J Agric Food Chem, 2020 Apr 15;68(15):4305-4314.
PMID: 32227887 DOI: 10.1021/acs.jafc.9b08060

The rise of environmental and health concerns due to the excessive use of the conventional fungicide urges the search for sustainable alternatives of agronanofungicides where the latter is aimed to enhance plant uptake and minimize the volatilization, leaching, and runoff of fungicides. With this in mind, fungicides of hexaconazole and/or dazomet were encapsulated into chitosan nanoparticles for the formulation of chitosan-based agronanofungicides. In the present study, chitosan nanoparticles (2 nm), chitosan-hexaconazole nanoparticles (18 and 168 nm), chitosan-dazomet nanoparticles (7 and 32 nm), and chitosan-hexaconazole-dazomet nanoparticles (5 and 58 nm) were synthesized and used as potent antifungal agents in combating the basal stem rot (BSR) disease caused by Ganoderma boninense in which they were evaluated via an artificial inoculation of oil palm seedlings with the rubber woodblock, which was fully colonized with the fungal Ganoderma boninense mycelium. The results revealed that chitosan nanoparticles could act as dual modes of action, which are themselves as a biocide or as a nanocarrier for the existing fungicides. In addition, the particle size of the chitosan-based agronanofungicides plays a crucial role in suppressing and controlling the disease. The synergistic effect of the double-fungicide system of 5 nm chitosan-hexaconazole-dazomet nanoparticles can be observed as the system showed the highest disease reduction with 74.5%, compared to the untreated infected seedlings.

Matched MeSH terms: Plant Diseases/microbiology
Fulltext Chitosan-Based Agronanochemicals as a Sustainable Alternative in Crop Protection

Maluin FN, Hussein MZ

Molecules, 2020 Apr 01;25(7).
PMID: 32244664 DOI: 10.3390/molecules25071611

The rise in the World's food demand in line with the increase of the global population has resulted in calls for more research on the production of sustainable food and sustainable agriculture. A natural biopolymer, chitosan, coupled with nanotechnology could offer a sustainable alternative to the use of conventional agrochemicals towards a safer agriculture industry. Here, we review the potential of chitosan-based agronanochemicals as a sustainable alternative in crop protection against pests, diseases as well as plant growth promoters. Such effort offers better alternatives: (1) the existing agricultural active ingredients can be encapsulated into chitosan nanocarriers for the formation of potent biocides against plant pathogens and pests; (2) the controlled release properties and high bioavailability of the nanoformulations help in minimizing the wastage and leaching of the agrochemicals' active ingredients; (3) the small size, in the nanometer regime, enhances the penetration on the plant cell wall and cuticle, which in turn increases the argochemical uptake; (4) the encapsulation of agrochemicals in chitosan nanocarriers shields the toxic effect of the free agrochemicals on the plant, cells and DNA, thus, minimizing the negative impacts of agrochemical active ingredients on human health and environmental wellness. In addition, this article also briefly reviews the mechanism of action of chitosan against pathogens and the elicitations of plant immunity and defense response activities of chitosan-treated plants.

Matched MeSH terms: Plant Diseases/microbiology
Fulltext Transposable Elements Adaptive Role in Genome Plasticity, Pathogenicity and Evolution in Fungal Phytopathogens

Mat Razali N, Cheah BH, Nadarajah K

Int J Mol Sci, 2019 Jul 23;20(14).
PMID: 31340492 DOI: 10.3390/ijms20143597

Transposable elements (TEs) are agents of genetic variability in phytopathogens as they are a source of adaptive evolution through genome diversification. Although many studies have uncovered information on TEs, the exact mechanism behind TE-induced changes within the genome remains poorly understood. Furthermore, convergent trends towards bigger genomes, emergence of novel genes and gain or loss of genes implicate a TE-regulated genome plasticity of fungal phytopathogens. TEs are able to alter gene expression by revamping the cis-regulatory elements or recruiting epigenetic control. Recent findings show that TEs recruit epigenetic control on the expression of effector genes as part of the coordinated infection strategy. In addition to genome plasticity and diversity, fungal pathogenicity is an area of economic concern. A survey of TE distribution suggests that their proximity to pathogenicity genes TEs may act as sites for emergence of novel pathogenicity factors via nucleotide changes and expansion or reduction of the gene family. Through a systematic survey of literature, we were able to conclude that the role of TEs in fungi is wide: ranging from genome plasticity, pathogenicity to adaptive behavior in evolution. This review also identifies the gaps in knowledge that requires further elucidation for a better understanding of TEs' contribution to genome architecture and versatility.

Matched MeSH terms: Plant Diseases/microbiology*
Fulltext Comparative Genomics: Insights on the Pathogenicity and Lifestyle of Rhizoctonia solani

Mat Razali N, Hisham SN, Kumar IS, Shukla RN, Lee M, Abu Bakar MF, et al.

Int J Mol Sci, 2021 Feb 22;22(4).
PMID: 33671736 DOI: 10.3390/ijms22042183

Proper management of agricultural disease is important to ensure sustainable food security. Staple food crops like rice, wheat, cereals, and other cash crops hold great export value for countries. Ensuring proper supply is critical; hence any biotic or abiotic factors contributing to the shortfall in yield of these crops should be alleviated. Rhizoctonia solani is a major biotic factor that results in yield losses in many agriculturally important crops. This paper focuses on genome informatics of our Malaysian Draft R. solani AG1-IA, and the comparative genomics (inter- and intra- AG) with four AGs including China AG1-IA (AG1-IA_KB317705.1), AG1-IB, AG3, and AG8. The genomic content of repeat elements, transposable elements (TEs), syntenic genomic blocks, functions of protein-coding genes as well as core orthologous genic information that underlies R. solani's pathogenicity strategy were investigated. Our analyses show that all studied AGs have low content and varying profiles of TEs. All AGs were dominant for Class I TE, much like other basidiomycete pathogens. All AGs demonstrate dominance in Glycoside Hydrolase protein-coding gene assignments suggesting its importance in infiltration and infection of host. Our profiling also provides a basis for further investigation on lack of correlation observed between number of pathogenicity and enzyme-related genes with host range. Despite being grouped within the same AG with China AG1-IA, our Draft AG1-IA exhibits differences in terms of protein-coding gene proportions and classifications. This implies that strains from similar AG do not necessarily have to retain similar proportions and classification of TE but must have the necessary arsenal to enable successful infiltration and colonization of host. In a larger perspective, all the studied AGs essentially share core genes that are generally involved in adhesion, penetration, and host colonization. However, the different infiltration strategies will depend on the level of host resilience where this is clearly exhibited by the gene sets encoded for the process of infiltration, infection, and protection from host.

Matched MeSH terms: Plant Diseases/microbiology

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