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Carnation (Dianthus caryophyllus L.) is a cut flower with greater stipulation in the world cut flower
market. In India, carnations are cultivated under polyhouses in Nilgiris and Kodaikanal districts in the
state of Tamil Nadu. Carnations cultivation is impeded by various diseases, among them stem rot
caused by Sclerotinia sclerotiorum (Lib.) de Ba...
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... Since complete reliability on chemical protection is yet to become a reality for managing Fusarium wilt in banana, and taking into account the adverse effects of fungicidal formulations on the soil and environment, it is imperative to find alternative and sustainable approaches to manage this fungal pathogen to safeguard the global banana industry. Biocontrol measures involving selection of endophytes have been a part of integrated disease management in several agricultural and horticultural crops (Vinodkumar et al. 2015;Dheepa et al. 2016). Identification and exploitation of bacterial endophytes associated with resistance and susceptibility could be a possible and viable strategy to complement existing management strategies. ...
Banana (Musa spp.), a major cash and staple fruit crop in many parts of the world, is infected by Fusarium wilt, which contributes up to 100% yield loss and causes social consequences. Race 1 and race 2 of Panama wilt caused by Fusarium oxysporum f. sp. cubense (Foc) are prevalent worldwide and seriously affect many traditional varieties. The threat of Foc tropical race 4 (Foc TR4) is looming large in African counties. However, its incidence in India has been confined to Bihar (Katihar and Purnea), Uttar Pradesh (Faizabad), Madhya Pradesh (Burhanpur) and Gujarat (Surat). Management of Foc races by employing fungicides is often not a sustainable option as the disease spread is rapid and they negatively alter the biodiversity of beneficial ectophytes and endophytes. Besides, soil drenching with carbendazim/trifloxystrobin + tebuconazole is also not effective in suppressing the Fusarium wilt of banana. Improvement of resistance to Fusarium wilt in susceptible cultivars is being addressed through both conventional and advanced breeding approaches. However, engineering of banana endosphere with bacterial endophytes from resistant genotypes like Pisang lilly and YKM5 will induce the immune response against Foc, irrespective of races. The composition of the bacterial endomicrobiome in different banana cultivars is dominated by the phyla Proteobacteria, Bacteroidetes and Actinobacteria. The major bacterial endophytic genera antagonistic to Foc are Bacillus, Brevibacillus, Paenibacillus, Virgibacillus, Staphylococcus, Cellulomonas, Micrococcus, Corynebacterium, Kocuria spp., Paracoccus sp., Acinetobacter spp. Agrobacterium, Aneurinibacillus, Enterobacter, Klebsiella, Lysinibacillus, Micrococcus, Rhizobium, Sporolactobacillus, Pantoea, Pseudomonas, Serratia, Microbacterium, Rhodococcus, Stenotrophomonas, Pseudoxanthomonas, Luteimonas, Dokdonella, Rhodanobacter, Luteibacter, Steroidobacter, Nevskia, Aquicella, Rickettsiella, Legionella, Tatlockia and Streptomyces. These bacterial endophytes promote the growth of banana plantlets by solubilising phosphate, producing indole acetic acid and siderophores. Application of banana endophytes during the hardening phase of tissue-cultured clones serves as a shield against Foc. Hitherto, MAMP molecules of endophytes including flagellin, liposaccharides, peptidoglycans, elongation factor, cold shock proteins and hairpins induce microbe-associated molecular pattern (MAMP)-triggered immunity to suppress plant pathogens. The cascade of events associated with ISR and SAR is induced through MAPK and transcription factors including WRKY and MYC. Studies are underway to exploit the potential of antagonistic bacterial endophytes against Foc isolates and to develop an understanding of the MAMP-triggered immunity and metabolomics cross talk modulating resistance. This review explores the possibility of harnessing the potential bacterial endomicrobiome against Foc and developing nanoformulations with bacterial endophytes for increased efficacy against lethal pathogenic races of Foc infecting banana.
Supplementary information:
The online version contains supplementary material available at 10.1007/s13205-021-02833-5.
... Sanogo and Puppala (2007) reported that sclerotia of S. sclerotiorum produced tan to beige coloured apothecial structures with varying sizes. Selvaraj et al. (2015) artificially induced carpogenic germination of apothecia in Fig. 7 Un-weighted pair group method with arithmetic mean (UPGMA) dendrogram showing the genetic relationships between the 25 isolates of S. sclerotiorum based on Jacccard's similarity matrix data using 10 URPs Page 13 of 15 177 S. sclerotiorum and reported that 10-15 apothecium were produced by a single sclerotia and also suggested that cool white fluorescent light and optimum temperature are important in the development of apothecium. Moreover, in the field, germination of apothecia is stimulated by an extended period i.e., 10 days of high soil moisture content, low temperature (4-20 °C) and a dense plant canopy (Abawi and Grogan 1979;Morrall and Dueck 1982). ...
White mould or stem rot, caused by Sclerotinia sclerotiorum (Lib.) de Bary, is a devastating fungal disease found in major potato cultivation areas worldwide. The aim of this study was to characterize genetic diversity in the S. sclerotiorum population from the main potato producing regions of India by means of morphological (mycelial growth, colony colour, number and distribution pattern of sclerotia) and molecular characteristics, as well as to evaluate the virulence of S. sclerotiorum isolates in potato for the first time. Among the S. sclerotiorum population analyzed, high phenotypic and genotypic diversity were observed. Using all the morphological characteristics, a dendrogram was constructed based on Gower’s similarity coefficient that distributed all the isolates into three clusters at the 0.62 similarity coefficient. Carpogenic germination of apothecia revealed that larger sclerotia produced a greater number of apothecia while smaller sclerotia produced fewer apothecia. Pathogenicity test results revealed that out of 25 isolates, seven were highly aggressive, 14 were moderate and four had low aggressiveness, whilst isolates from Punjab were more pathogenic than those of Uttar Pradesh. Phylogenetic analysis of universal rice primer polymorphism showed high genetic variability within the isolates that grouped all the isolates in three evolutionary lineages in the resulting dendrogram and showed partial relationship with geographical locations of the isolates. Further, the findings suggest the occurrence of higher heterogeneity and genetic diversity among the S. sclerotiorum isolates that indicates the existence of both clonal and sexual reproduction in the pathogen population of potato producing areas in India.
... A previous survey in two Egyptian governorates, El-Sharkiya (New El-Salhia region) and Ismailia (El-Shabab region), showed variation in disease resistance among planted cultivars. The highest infection for black scurf symptoms was recorded in Lady Rosetta cultivar during the growing seasons of -2015(Hassan, 2016. This due to the high susceptibility of Lady Rosetta to the infection caused by R. Solani. ...
... Sequence-based identification has become an essential tool in plant pathology. The official sequence used for barcoding of fungi is the ITS (Selvaraj et al., 2015). In this study, two primers (ITS1 and ITS4) were used to amplify the ribosomal RNA gene in the Egyptian R. solani isolates. ...
... Stem rot, caused by Sclerotinia sclerotiorum (Lib.) de Bary, causes a major impact for carnation productivity worldwide. In India, carnation was reported as a new host crop for S. sclerotiorum by Vinodkumar et al. (2015a). Sclerotinia causes stem rot in carnation leading to death of the entire plant which reflects severe yield loss. ...
In the present investigative study, fifty Trichoderma spp. (Persoon) were isolated from the rhizosphere of various crop plants. Their potential, as an antagonist was assessed against S. sclerotiorum (Lib.) de Bary, causing stem rot of carnation (Dianthus caryophyllus L.). T. asperellum (NVTA2) was superior in inhibiting the growth and development of stem rot pathogen up to 53.7 per cent in vitro. Seven Trichoderma species with greatest antagonistic potential were identified up to species level through molecular characterization. They were identified as T. asperellum (NVTA1, NVTA2), T. harzianum (NVTH1, NVTH2), T. citrinoviride (NVTC1, NVTC2), and T. erinaceum (NVTE1). Effective strains were screened for the presence of cellobiohydrolase (cbh1) and endochitinase (ech42) genes through PCR. Among the seven strains, T. asperellum (NVTA2) alone had both genes. Crude metabolite extracted from T. asperellum (NVTA2), effectively inhibited the mycelial growth of S. sclerotiorum up to 374.4 mm². GC/MS profiling of crude extract revealed the presence of antifungal compounds including aliphatic hydrocarbons, terpenes and fatty acids. Root dipping and soil application of talc formulations of the seven Trichoderma spp. revealed that T. asperellum (NVTA2) effectively suppressed disease incidence up to 11.8 (PDI-Percent Disease Incidence) compared to the control (37.9 PDI), resulting in approximately 69% reduction. More over NVTA2 also promoted plant growth that resulted in increase in shoot numbers (6.60/plant), stalk length (72.7 cm) and flower yield (205.9 numbers/m²), which was comparatively greater than control.
... The pathogen was isolated from an infected stem of carnation plant by following standard procedure (Tutte, 1969). Then the plates were incubated at 20 ± 2 • C. The pathogen was identified through morphological and molecular characterization by sequencing 18S-28S rRNA genes (Vinod Kumar et al., 2015b). ...
Bacillus species are widely exploited as biocontrol agents because of their efficiency in impeding various plant pathogens with multifaceted approach. In this study, Bacillus species were isolated from rhizosphere of various plants viz., carnations, cotton, turmeric, and bananas in Tamil Nadu state of India. Their potential to control the mycelial growth of Sclerotinia sclerotiorum was assessed in vitro by dual plate and partition plate techniques. B. amyloliquefaciens strain VB7 was much effective in inhibiting mycelial growth (45% inhibition of over control) and sclerotial production (100%). PCR detection of AMP genes revealed that B. amyloliquefaciens (VB7) had a maximum of 10 diverse antibiotic biosynthesis genes, namely, ituD, ipa14, bacA, bacD, bamC, sfP, spaC, spaS, alba, and albF, that resulted in production of the antibiotics iturin, bacilysin, bacillomycin, surfactin, subtilin, and subtilosin. Further, metabolites from B. amyloliquefaciens strains VB2 and VB7, associated with inhibition of S. sclerotiorum, were identified as phenols and fatty acids by gas chromatography mass spectrometry (GC-MS). Delivery of bacterial suspension of the effective strains of Bacillus spp. as root dip was found promising for the management of stem rot of cultivated carnations. Minimal percent disease incidence (4.6%) and maximum plant growth promotion was observed in the plants treated with B. amyloliquefaciens (VB7).
FEATURES OF THE FORMATION OF MICROCONIDIA BY THE FUNGUS SCLEROTINIA SCLEROTIORUM (LIB.) DE BARY
M. Y. Pikovskyi, M. M. Kyryk, V. V. Bоrodai, O. V. Kolesnichenko, V. I. Melnyk
Abstract. The fungus Sclerotinia sclerotiorum (Lib.) de Bary belongs to dangerous pathogens that cause significant economic losses of crops. Its populations are polymorphic in morphological, physiological and biochemical characteristics. In the biological cycle of development, the pathogen reproduces sexually and asexually, producing various structures. At the same time, the features of the formation of the conidial stage are not well understood.
The purpose of the study was to establish the features of the formation of microconidia by S. sclerotiorum fungus and study their morphology. The objects of research were samples of soybean, rapeseed, sunflower, pea, and dahlia plants affected by the stem form of white mold, taken in various soil and climatic conditions of Ukraine.
The ability of S. sclerotiorum fungus to produce microconidia in vitro in various ways was established: on individual elongated, septated conidiophores, 100–250 μm long and on the short conidiophores located in groups, on hyphae, 8–12 μm thick. Spores formed in the form of chains on conidiogenic cells – phialids, the thickness of which was 6–8 microns and a length of 15–25 microns. The size of the microconidia was 4–5 microns, they had a spherical shape, with a pronounced membrane and interspersed in the center, were hyaline the revealed regularity of the formation of this sporulation was obtained only during the cultivation of incompatible isolates. This type of asexual spores formed in the zone of interaction of the mycelium, regardless of the host plant from which they were isolated. Further studies are aimed at establishing the role of microconidia in the biological and infectious cycles of the pathogen.
Key words: microconidia, Sclerotinia sclerotiorum, mycelium, sporulation, incompatibility of isolates
Diseases of carnation and integrated management practices.
