scholarly journals Biocontrol of Fusarium oxysporum f. sp. vasinfectum With Bacillus spp. Strains

2021 ◽  
Vol 13 (9) ◽  
pp. 1
Author(s):  
Sandro C. L. Montalvão ◽  
Marcelo T. de Castro ◽  
Luiz E. B. Blum ◽  
Rose Gomes Monnerat

The wilt caused by Fusarium oxysporum f.sp. vasinfectum in cotton is one of the main diseases of this crop. The pathogen is difficult to control because it produces chlamydospores, which allows it to survive in the soil for long periods without the presence of its main host. The control of this disease is based on varieties with some resistance, certified seeds, and fungicides used to treat seeds. Thus, the development of control alternatives is needed to increase the number of resources to manage this disease in the field. Bacillus are bioregulators and antagonists of several important phytopathogens. Therefore, the objective of this work was to select strains of Bacillus (Paenibacillus alvei, Bacillus thuringiensis, B. megaterium, and B. lentus), whose metabolites are toxic to F. oxysporum in laboratory and greenhouse conditions, in addition to adjusting in vitro methodologies to perform and evaluate selection tests. This work determined the best culture medium for the direct confrontation assays, proposed a grading scale to facilitate decisions about selection with the dual tests, identified among the strains selected in the confrontation assays those that produce volatile and non-volatile metabolites toxic to F. oxysporum, and tested these selected strains for disease control during seed germination in greenhouse trials. In last test, some strains of Bacillus had a potential protective effect during the germination of cotton seeds.

HortScience ◽  
2003 ◽  
Vol 38 (1) ◽  
pp. 101-104 ◽  
Author(s):  
Kimberly A. Pickens ◽  
James M. Affolter ◽  
Hazel Y. Wetzstein ◽  
Jan H.D. Wolf

Tillandsia eizii is an epiphytic bromeliad that due to over-collection, habitat destruction, and physiological constraints has declined to near threatened status. This species exhibits high mortality in the wild, and seed are characterized by low percentages of germination. As a means to conserve this species, in vitro culture protocols were developed to enhance seed germination and seedling growth. A sterilization protocol using 70% ethanol for 2 minutes followed by 2.6% NaOCl for 40 minutes disinfested seed and promoted seedling growth. Sucrose incorporated into the culture medium had no effect on germination or growth, while NAA inhibited growth, but not germination. Cultures maintained under a 16-hour photoperiod at 22 °C exhibited greater growth than those grown at 30 °C. Seed that germinated in the dark remained etiolated and failed to develop even after transfer to light conditions. Plants grown in vitro were successfully acclimatized and transferred to the greenhouse. Over 86% survival and rapid growth were obtained with either an all-pine-bark medium, or a mixture of 2 redwood bark: 2 fir bark: 2 potting mix: 1 perlite. This demonstrated that in vitro culture of seed may be used to rapidly produce large numbers of T. eizii, and thus can be used for the conservation and reintroduction of this species.


2020 ◽  
Vol 9 (11) ◽  
pp. e4079119913
Author(s):  
Thiago Anchieta de Melo ◽  
Ilka Márcia Ribeiro de Souza Serra ◽  
Ingrid Tayane Vieira da Silva do Nascimento

This work aimed to verify the effect in vitro, of Ascophyllum nodosum (AN) seaweed extract on the morphology and cellulolytic capacity of the fungus Fusarium oxysporum f. sp. vasinfectum (FOV). Thus, the fungus was placed in contact with different doses of the extract, being these: 0, 0.5, 1.0, 2.0, 4.0 and 8.0%. It was verified that the product, with increasing doses, progressively induced mycelial growth of the fungus, as measured by the diameter of the colonies and fresh mass of mycelium grown in PD (potato-dextrose) culture medium. This result was also corroborated by the progressive increase in the activity of the β-1,3-glucanase and chitinase enzymes required during the hypha elongation process. However, the AN extract progressively reduced FOV sporulation with increasing doses. Furthermore, the cellulolytic capacity of the phytopathogen was significantly reduced in the presence of the algae extract, which was measured by the activity of the enzymes endo-β-1,4-glucanase, exo-β-1,4-glucanase and β-glucosidase. Thus, these facts constitute important information for the management of fusariosis, since the inhibition of sporulation and decreasing degradation capacity of the cellulose by the pathogen, can translate into declined disease in compatible host-pathogen interactions.


Plant Disease ◽  
2003 ◽  
Vol 87 (1) ◽  
pp. 63-68 ◽  
Author(s):  
M. Babadoost ◽  
S. Z. Islam

Apron XL LS (mefenoxam) and Allegiance FL (metalaxyl) were highly inhibitory to growth of mycelium of Phytophthora capsici in vitro. Effective dose (ED50) of mefenoxam and metalaxyl for 50% inhibition of mycelial growth, for all five isolates of P. capsici tested, was 0.98 and 0.99 μg a.i./ml of culture medium, respectively. For mefenoxam at 200 μg a.i./ml, sporangium and zoospore germination were reduced by 92 and 96%, respectively, and 21 and 24%, respectively, for metalaxyl. In greenhouse studies, seed treatment with mefenoxam (0.42 ml of Apron XL LS/kg of seed) and metalaxyl (0.98 ml of Allegiance FL/kg of seed) significantly reduced pre- and post-emergence damping-off of seedlings caused by P. capsici in three pumpkin cultivars (Dickinson, Hybrid-401, and Hybrid-698) tested. Thirty-one days after seeding, at inoculum levels of 0, 90, 600, 1,400, and 4,000 CFU/g of soil, the average seedling stands for mefenoxam treatment were 98.4, 93.8, 88.3, 77.8, and 64.8%; for metalaxyl, 99.1, 85.3, 85.8, 73.5, and 59.3; and for the untreated control, 97.5, 55.2, 45.7, 37.0, and 22.9%, respectively. In field trials, the average seedling stands 35 days after seeding were 76.7, 74.7, and 44.9% for mefenoxam, metalaxyl, and untreated control, respectively. Seed treatment with mefenoxam or metalaxyl did not have any significant effect on either seed germination or seedling vigor.


2021 ◽  
Vol 34 (1) ◽  
pp. 1-8
Author(s):  
SHEILA VITÓRIA RESENDE ◽  
ALONE LIMA-BRITO ◽  
GABRIELA TORRES- SILVA ◽  
JOSÉ RANIERE FERREIRA DE SANTANA

ABSTRACT The genus Melocactus (“cabeça-de-frade”) comprises 32 species in Brazil, of which M. glaucescens and M. paucispinus are threatened with extinction. The present work evaluated the effects of different concentrations of Murashige & Skoog (MS, MS/2 and MS/4) culture medium and sucrose (15 g L-1 and 30 g L-1) on in vitro seed germination and plant growth of M. glaucescens and the efficiency of sterilization with sodium hypochlorite (NaOCl) on in vitro seed germination and plant growth of M. glaucescens when using seeds and M. glaucescens and M. paucispinus when using apical segment of cladode. In M. glaucescens, the final germination at the different MS and sucrose concentrations varied between 53.5 and 68.1% and the best results for in vitro growth were observed with the lowest mineral salt (MS/2 and MS/4) and sucrose (15 g L-1) concentrations, with lengths of the aerial portion of 9.70 and 10.76 mm, respectively. There was no difference in seed germination and plant growth in chemical and autoclave medium. It is concluded that the use of chemical sterilization with NaOCl at low concentrations of salts (MS/2 and MS/4) and sucrose (15 g L-1) are quite advantageous for producing ornamental plants germinated in vitro and/or apical segment of cladode of M. glaucescens andM. paucispinus, representing a reduction of costs for in vitro cultivation of this species.


2021 ◽  
Author(s):  
Akane Shimazaki ◽  
Kana Higaki ◽  
Kento Rammitsu ◽  
Yuki Ogura-Tsujita

In vitro symbiotic culture of Gastrodia pubilabiata seeds were conducted with the fungal isolates from G. pubilabiata roots. We obtained five fungal isolates, which belonged to Mycena, Marasmiaceae and Omphalotaceae. Firstly, optimal temperature and culture medium for subculture of these fungal isolates were examined. All five isolates grew the fastest on malt extract agar medium. Mycelial growth rate was highest at 25 °C between 10 °C and 40 °C. Secondly, we evaluated suitable culture vessels and organic materials for symbiotic culture. Seeds germinated well in petri dishes with Quercus leaf disc on water agar medium, and the seed germination process was well observed without dense mycelium. The most developed seedlings were found in glass bottles filled with Japanese cedar leaves, but densely grew mycelium prevent accurate seedling counts. Leaves of Quercus, Japanese cedar and bamboo were used as organic materials for symbiotic culture. All three leaves induced seed germination with Mycena and Marasmiaceae fungi, but material types affected subsequent seedling growth. Our method will contribute to understanding the mycorrhizal association of Gastrodia species and also other mycoheterotrophic plants.


2013 ◽  
Vol 53 (2) ◽  
pp. 177-183 ◽  
Author(s):  
Souad Zaim ◽  
Lakhdar Belabid ◽  
Miloud Bellahcene

Abstract Among 131 rhizobacteria isolates, 29 potentially antagonistic strains were screened in in vitro assays. The five antagonistic Bacillus spp. Rb29, Rb6, Rb12, Rb4, and Rb15 showed the most inhibitory effect against FOC1 (from 25.63 to 71.11%), mycelial growth, and FOC2 (from 28.43 to 60.65%) in vitro. Results also revealed that production of volatile metabolite, components and inhibition of the test pathogen by volatile metabolites varied among different antagonistic rhizobacteria. Isolates Rb29, Rb6, Rb12, Rb4, and Rb15 produced more volatile metabolites which inhibited mycelial FOC growth by 40%. Chickpea Fusarium wilt severity caused by FOC1 was reduced from 60 to 99% in the susceptible cultivar ILC 482 treated with antagonistic Bacillus spp. (Rb29, Rb6, Rb12, Rb4, and Rb15) in pot assays and by 98, 81, 68, 64, 57.20%, respectively, in the field trials. As for their beneficial effects on disease control, the results revealed that Bacillus spp. may improve plant growth and disease control.


2017 ◽  
Vol 66 (4) ◽  
pp. 544-548 ◽  
Author(s):  
Seir Antonio Salazar Mercado ◽  
Nelson Alfonso Vega Contreras

Cattleya trianae (Linden & Reichb.f., 1860), Colombian national flower, is in danger of extinction due to the destruction of its natural habitats and excessive collection for horticultural purposes. Therefore, in vitro culture is a tool for the conservation of threatened species. In this study we determined the most suitable culture medium for asimbytic seed germination and in vitro propagation of C. trianae. Initially, mature capsules were collected, the seeds were subsequently disinfected and seeded with the syringe method (Vendrame et al., 2007), to evaluate the effect of five media on the development of C. trianae after 20 weeks. The seedlings were transplanted and acclimated using different substrates. The best percentage (54.2%) of seedling formation after 20 weeks was found in MS + JP medium with significant differences (P <0.05: Tukey HSD). In this research, it is reported that the addition of organic additives to the MS medium improves the efficacy of this, and therefore, allows a greater growth and development of C. trianae under in vitro conditions.


2019 ◽  
Vol 26 (3) ◽  
pp. 133
Author(s):  
Julius Dwi Nugroho ◽  
Agustina Yohana Setyarini Arobaya ◽  
Evelyn Anggelina Tanur

A New Guinea Orchid, Dendrobium antennatum Lindl urgently needs to conserve. The availability of in vitro germination technique for this orchids is significantly important to present the useful tool for conservation effort. This study aimed to find a simple media that consists of Growmore 10-55-10, a foliar fertilizer and complex organic i.e. coconut water, banana pulp, onion spring extract, and carrot juice. Five in vitro medium for seed germination and four in vitro sub-culture medium for planlet growth were formulated and used in this study. Our findings revealed that seed germination in vitro of Dendrobium antennatum well occured on the medium of Growmore 10-55-10 supplemented with 10% coconut water (GCw) and of Growmore 10-55-10 supplemented with 50 g/l extract spring onion. The seed germination process from sowing the seed to plantlet production ready to transfer to sub-culture medium for further growth took time 140 days. The embryo became pale green at the day 11 on the germination media. It could be used as a tool for detection of viability of the seeds. Both seed germination medium could be used also as sub-culture medium for enhancing the growth of the plantlets but not for multiplication of shoots.


HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1052D-1052
Author(s):  
Guochen Yang ◽  
Carl Niedziela ◽  
Zhongge (Cindy) Lu

The goal of this study was to expedite galax seed germination in vitro. Galax seeds were collected from Yancey County, N.C., at an elevation of about 1100 m. Aseptic cultures were established using the tiny rust-colored seeds. In vitro seed germination was achieved under different pH conditions (4.2, 5.0, and 5.8). Seeds cultured in the medium with pH 4.2 tended to germinate early with a better rate than those cultured with a higher pH of 5.0 or 5.8 at the very beginning. Gradually, seeds from media with pH 5.0 and 5.8 caught up in germination. Eventually, seeds from all pH treatments produced a very similar germination rate. Attempts to use the matted and scaly rhizomes and very tender new growth as explant materials to establish aseptic cultures were not successful, due to severe contamination. However, our observations suggested that the very tender new growth could be a good source of explants once the optimum sterilization time is established.


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