Malek Marian
@unitn.it
Postdoctoral researcher (Center Agriculture Food Environment C3A)
Universita degli Studi di Trento
Scopus Publications
Scopus Publications
Malek Marian, Giorgio Licciardello, Bianca Vicelli, Ilaria Pertot, and Michele Perazzolli
Oxford University Press (OUP)
ABSTRACT Complex microbial communities are associated with plants and can improve their resilience under harsh environmental conditions. In particular, plants and their associated communities have developed complex adaptation strategies against cold stress. Although changes in plant-associated microbial community structure have been analysed in different cold regions, scarce information is available on possible common taxonomic and functional features of microbial communities across cold environments. In this review, we discuss recent advances in taxonomic and functional characterization of plant-associated microbial communities in three main cold regions, such as alpine, Arctic and Antarctica environments. Culture-independent and culture-dependent approaches are analysed, in order to highlight the main factors affecting the taxonomic structure of plant-associated communities in cold environments. Moreover, biotechnological applications of plant-associated microorganisms from cold environments are proposed for agriculture, industry and medicine, according to biological functions and cold adaptation strategies of bacteria and fungi. Although further functional studies may improve our knowledge, the existing literature suggest that plants growing in cold environments harbor complex, host-specific and cold-adapted microbial communities, which may play key functional roles in plant growth and survival under cold conditions.
Malek Marian, Yusuke Takashima, Wiwiek Harsonowati, Haruhiko Murota, and Kazuhiko Narisawa
Springer Science and Business Media LLC
Malek Marian, Takashi Fujikawa, and Masafumi Shimizu
Springer Science and Business Media LLC
Mitsuaria sp. TWR114 is a biocontrol agent against tomato bacterial wilt (TBW). We aimed to gain genomic insights relevant to the biocontrol mechanisms and colonization ability of this strain. The draft genome size was found to be 5,632,523 bp, with a GC content of 69.5%, assembled into 1144 scaffolds. Genome annotation predicted a total of 4675 protein coding sequences (CDSs), 914 pseudogenes, 49 transfer RNAs, 3 noncoding RNAs, and 2 ribosomal RNAs. Genome analysis identified multiple CDSs associated with various pathways for the metabolism and transport of amino acids and carbohydrates, motility and chemotactic capacities, protection against stresses (oxidative, antibiotic, and phage), production of secondary metabolites, peptidases, quorum-quenching enzymes, and indole-3-acetic acid, as well as protein secretion systems and their related appendages. The genome resource will extend our understanding of the genomic features related to TWR114's biocontrol and colonization abilities and facilitate its development as a new biopesticide against TBW.
Nusrat Ahsan, Malek Marian, Haruhisa Suga, and Masafumi Shimizu
Japanese Society of Microbial Ecology
To identify Lysinibacillus strains with the potential to function as plant biostimulants, we screened 10 previously isolated Lysinibacillus strains from the rhizosphere and soil for their plant growth-promoting (PGP) effects. In vitro tests showed that all strains produced indole-3-acetic acid. In primary screening, the PGP effects of these strains were assessed on spinach seedlings grown on Jiffy-7 pellets; strains GIC31, GIC41, and GIC51 markedly promoted shoot growth. In secondary screening, the PGP efficacies of these three strains were examined using spinach seedlings grown in pots under controlled conditions. Only GIC41 exerted consistent and significant PGP effects; therefore, it was selected for subsequent experiments. The results of 6-week glasshouse experiments revealed that GIC41 markedly increased shoot dry weight by ca. 12-49% over that of the control. The impact of fertilization levels on the PGP efficacy of GIC41 was investigated using pot experiments. The application of a specific level of fertilizer was required for the induction of sufficient PGP effects by this strain. The phylogenetic ana-lysis based on the 16S rDNA sequence identified GIC41 as L. xylanilyticus. Collectively, these results show the potential of strain GIC41 to function as a plant biostimulant.
Wiwiek Harsonowati, Malek Marian, Surono, and Kazuhiko Narisawa
Frontiers Media SA
Strawberry Fusarium wilt, caused by the virulent fungus Fusarium oxysporum formae speciales fragariae (Fof) is a devastating soil-borne disease that causes severe production losses worldwide, including Japan. Fof is one of the top 10 fungal pathogens that threaten global crop security, and a method to effectively control this pathogen has yet to be found. This study aimed to investigate the effectiveness of dark septate endophytic (DSE) fungi against Fof to develop an efficient, effective, and environmentally friendly approach to improve plant health and fitness. A total of 19 fungal isolates were assessed, out of which three (SK47, SK48, and SK51) were selected based on their effectiveness in disease suppression in controlled growth chamber conditions using a soil system. Isolates SK47, SK48, and SK51 suppressed disease severity by 85.71, 61.90, and 90.48%, respectively. Molecular identification based on highly conserved small subunit (SSU), internal transcribed spacer (ITS), and large subunit (LSU) nrRNA regions identified these isolates as DSE Exophiala sp., Exophiala pisciphila, and Cladophialophora chaetospira, respectively. The sequences were deposited under accession numbers MN811693–MN811695 in the GenBank database. Notably, our results revealed that isolate C. chaetospira SK51 possessed superior growth promotion activities as well as disease suppression by significantly increased plant growth parameters (shoot and root dry mass, chlorophyll content, flower bud initiation, and number of fruit) in comparison to control plants and other two fungal candidates. Root colonization by C. chaetospira SK51 was visualized, and it was confirmed that the symbiosis with strawberry plants occurred successfully. Our results provide new insights in the application of DSE fungus C. chaetospira SK51 as a biocontrol agent on strawberry plants could promote plant growth, flower bud initiation, and fruit formation. C. chaetospira SK51 exhibited remarkable beneficial traits for the host plant, and it can potentially be applied in the development of new, safe, and effective treatments as an alternative to chemical fertilizers and fungicides for sustainable crop protection.
Malek Marian, Teppei Ohno, Hirofumi Suzuki, Hatsuyoshi Kitamura, Katsutoshi Kuroda, and Masafumi Shimizu
Elsevier BV
Anthracnose caused by Glomerella cingulata is one of the most devastating diseases of strawberry in Japan, particularly during its nursery period in the summer. In this study, we aimed to isolate and screen endophytic actinobacteria, to identify potential biocontrol agents capable of suppressing strawberry anthracnose. A total of 226 actinobacteria were successfully isolated from surface-sterilized strawberry tissues. In the first screening, 217 out of 226 actinobacteria isolates were studied for their suppression effect on strawberry anthracnose using a detached leaflet assay. It was discovered that isolates MBFA-172 and MBFA-227 markedly suppressed the development of anthracnose lesions. The efficacy of both isolates was then tested on two-month-old strawberry plug seedlings in a controlled environmental chamber. It was found that isolate MBFA-172 provided consistent disease suppression and was thus selected as a final candidate for further evaluation in a glasshouse experiment. Results showed that the severity as well as incidence rate of strawberry anthracnose was significantly reduced by treatment with isolate MBFA-172 compared with that of untreated control. Accordingly, the disease control efficacy provided by MBFA-172 was statistically comparable to the chemical fungicide propineb. A re-isolation experiment using a spontaneous thiostrepton-resistant mutated strain of isolate MBFA-172 revealed that it efficiently colonized the above-ground tissues of strawberry plants for at least three weeks after spray treatment. Using cultural, morphological, and physiological tests combined with 16S rRNA-based molecular analysis, MBFA-172 was identified as a moderately thermophilic Streptomyces thermocarboxydus-related species. Upon review, our results strongly indicated that MBFA-172 is a promising biocontrol agent for strawberry anthracnose.
Hui-Zhen Fu, Malek Marian, Takuo Enomoto, Haruhisa Suga, and Masafumi Shimizu
Japanese Society of Microbial Ecology
The present study aimed to investigate the potential of simple sugars for use as protection agents in the control of tomato bacterial wilt caused by Ralstonia pseudosolanacearum. Based on the sugar assimilation patterns of the pathogen, four unassimilable sugars (L-arabinose, maltose, D-raffinose, and D-ribose) were selected from 10 representative sugars present in tomato root exudates. These sugars were evaluated for their effects on bacterial wilt using a tomato seedling bioassay. The application of 0.25% L-arabinose significantly reduced disease severity and was, thus, selected as a candidate for further evaluations in a pot experiment under glasshouse conditions. The results obtained showed that the disease suppressive effects of L-arabinose slightly increased at higher concentrations; drench treatments at 0.1, 0.25, and 0.5% reduced disease severity by ca. 48, 70, and 87%, respectively. The drench treatment with 0.5% L-arabinose significantly reduced the pathogen population in the rhizosphere and stem tissues of tomato plants without any antibacterial activity. Real-time reverse-transcription PCR revealed that the expression of salicylic acid-dependent and ethylene-dependent defense genes was significantly enhanced in the stem tissues of L-arabinose-treated tomato plants following the pathogen inoculation. These results suggest that soil drenching with L-arabinose effectively suppresses tomato bacterial wilt by preventing pathogen proliferation in the rhizosphere and stem tissues of tomato plants. This is the first study to report the potential of L-arabinose as a safe, eco-friendly, and cost-effective plant protection agent for the control of tomato bacterial wilt.
Hui-Zhen Fu, Malek Marian, Takuo Enomoto, Ayaka Hieno, Hidemasa Ina, Haruhisa Suga, and Masafumi Shimizu
Japanese Society of Microbial Ecology
The aim of the present study was to identify a strain of endophytic Bacillus species that control tomato bacterial wilt by foliar spray application. Fifty heat-tolerant endophytic bacteria were isolated from the surface-sterilized foliar tissues of symptomless tomato plants that had been pre-inoculated with the pathogen Ralstonia pseudosolanacearum. In the primary screening, we assessed the suppressive effects of a shoot-dipping treatment with bacterial strains against bacterial wilt on tomato seedlings grown on peat pellets. Bacillus sp. strains G1S3 and G4L1 significantly suppressed the incidence of tomato bacterial wilt. In subsequent pot experiments, the biocontrol efficacy of foliar spray application was examined under glasshouse conditions. G4L1 displayed consistent and significant disease suppression, and, thus, was selected as a biocontrol candidate. Moreover, the pathogen population in the stem of G4L1-treated plants was markedly smaller than that in control plants. A quantitative real-time PCR analysis revealed that the foliar spraying of tomato plants with G4L1 up-regulated the expression of PR-1a and LoxD in stem and GluB in roots upon the pathogen inoculation, implying that the induction of salicylic acid-, jasmonic acid-, and ethylene-dependent defenses was involved in the protective effects of this strain. In the re-isolation experiment, G4L1 efficiently colonized foliar tissues for at least 4 weeks after spray application. Collectively, the present results indicate that G4L1 is a promising biocontrol agent for tomato bacterial wilt. Furthermore, to the best of our knowledge, this is the first study to report the biocontrol of bacterial wilt by the foliar spraying with an endophytic Bacillus species.
Tomoki Nishioka, Malek Marian, Issei Kobayashi, Yuhko Kobayashi, Kyosuke Yamamoto, Hideyuki Tamaki, Haruhisa Suga, and Masafumi Shimizu
Springer Science and Business Media LLC
Crop rotation and intercropping with Allium plants suppresses Fusarium wilt in various crops. However, the mechanisms underlying this phenomenon have not been fully elucidated. This study was designed to assess the role of microorganisms inhabiting Allium rhizospheres and antifungal compounds produced by Allium roots in Fusarium wilt suppression by Allium cultivation. Suppression of cucumber Fusarium wilt and the pathogen multiplication by Allium (Welsh onion and/or onion)-cultivated soils were eliminated by heat treatment at 60 °C, whereas those by Welsh onion-root extract were lost at 40 °C. The addition of antibacterial antibiotics eliminated the suppressive effect of Welsh onion-cultivated soil on pathogen multiplication, suggesting the contribution of antagonistic gram-negative bacteria to the soil suppressiveness. The Illumina MiSeq sequencing of 16S rRNA gene amplicons revealed that genus Flavobacterium was the predominant group that preferentially accumulated in Allium rhizospheres. Flavobacterium species recovered from the rhizosphere soils of these Allium plants suppressed Fusarium wilt on cucumber seedlings. Furthermore, confocal laser scanning microscopy revealed that Flavobacterium isolates inhibited the multiplication of the pathogen in soil. Taken together, we infer that the accumulation of antagonistic Flavobacterium species plays a key role in Fusarium wilt suppression by Allium cultivation.
Malek Marian and Masafumi Shimizu
Springer Science and Business Media LLC
Reducing dependence on chemical pesticides is considered as an essential challenge for sustainable crop production. The use of microbial biocontrol agents (MBCAs) is a key component of sustainable pest management. Numerous antagonistic microorganisms are known to suppress plant diseases, but their practical application and commercialization are still limited in part due to poor reliability of their efficacy in the field. Although promising MBCAs achieve remarkable disease control in the laboratory or greenhouse, field control is often unsatisfactory. Thus, for MBCAs to be integrated into crop production, their field performance must be improved to provide the cost-effectiveness and efficacy required by growers. In this review, we highlight recent approaches to enhance the field performance of MBCAs.
Malek Marian, Akio Morita, Hiroyuki Koyama, Haruhisa Suga, and Masafumi Shimizu
Springer Science and Business Media LLC
We previously identified Mitsuaria sp. TWR114 and nonpathogenic Ralstonia sp. TCR112 as potential biocontrol agents to suppress tomato bacterial wilt caused by Ralstonia pseudosolanacearum. Because commercial biocontrol products require a practical cost-effective application method that maximizes their performance, we investigated whether the combined application of TWR114 and TCR112 enhances the biocontrol of bacterial wilt. In pot experiments, all the tested inoculum ratios (i.e., 1:1, 1:2, and 2:1) of the TWR114 + TCR112 treatment significantly suppressed the incidence of bacterial wilt, even at 28 days post-challenge inoculation (dpi) (13–47% wilt incidence), while 60% of plants treated with the individual isolates developed bacterial wilt within 10–12 dpi. The pathogen population in the rhizosphere and aboveground regions decreased considerably after the TWR114 + TCR112 treatment compared with that in the individual treatments. Moreover, the pathogen population in the aboveground parts of TWR114 + TCR112-treated plants had decreased to an undetectable level by 28 dpi. After inoculation with the pathogen, the expression of several tomato defense-related genes was higher in the TWR114 + TCR112-treated plants than in those treated with the individual isolates. Altogether, the results indicate that TWR114 and TCR112 applied together have a synergistic suppressive effect and that stronger defense priming might contribute to the improved biocontrol. The combination of both isolates may be a very promising approach for controlling tomato bacterial wilt in the future.
Malek Marian, Tomoki Nishioka, Hiroyuki Koyama, Haruhisa Suga, and Masafumi Shimizu
Elsevier BV
Abstract In this study, we aimed to identify potential biocontrol agents capable of suppressing tomato bacterial wilt caused by Ralstonia pseudosolanacearum. In total, 441 bacteria were isolated from the rhizosphere soil of tomato, Chinese chive, and Welsh onion. Based on the results of the in vitro antibacterial activity assay, 275 isolates were selected and further evaluated using a tomato seedling bioassay. Eighteen isolates that belonged to that the genera Ralstonia and Mitsuaria exhibited a relatively higher disease suppression (>50% reduction in disease severity) than the other isolates. The isolate TCR112 of Ralstonia and 10 isolates of Mitsuaria were assessed for their biocontrol effect in a series of pot experiments. Among the isolates, TCR112 (identified as Ralstonia sp.) and TWR114 (identified as Mitsuaria sp.), which showed a consistent disease suppression in pot experiments, were selected as final candidates for further evaluation under field conditions. The results showed that soil drenching at weekly intervals with isolates TCR112 and TWR114 reduced the wilt incidence in the first year by 57.2% and 85.8%, and in the second year by 57.2% and 35.3%, respectively, indicating that these isolates were promising biocontrol agents of tomato bacterial wilt. The isolates effectively reduced the pathogen population in the rhizosphere and crown of pot grown tomatoes. Monitoring the population dynamics of biocontrol isolates revealed that both isolates have stable rhizosphere and endophytic colonization capacities. Furthermore, the in vitro assay for siderophore, indole-3-acetic acid, protease, and polygalacturonase production revealed that TCR112 produces the former three substances and TWR114 produces the latter three substances. Altogether, the results suggest that both isolates suppress tomato bacterial wilt by preventing pathogen multiplication and infection via direct antagonism and/or indirect effects such as competing for nutrients and inducing resistance in tomato plants. Furthermore, this is the first study reporting the potential of Mitsuaria as a biocontrol agent against tomato bacterial wilt.