Potential Effect of Antagonistic Bacteria in the Management of Olive Knot Disease Caused by Pseudomonas Savastanoi Pv. Savastanoi

Abstract

Keywords: Pseudomonas savastanoi pv. savastanoi, olive knot disease, biological control, antagonistic bacteria, Bacillus subtilis 1240, Shimadzu) at 600 nm (El-kinany et al., 2017). Antagonistic strainsAll antagonistic strains belong to the collection of laboratory of plant bacteriology and Biological Control at the National Institute of Agronomic Research (Meknes, Morocco). Theirs origins, isolation dates, and references are described in Tab 1.Olive knot disease caused by Pseudomonas savastanoi pv. savastanoi (PSS) is considered as the main bacterial disease of olive tree in Morocco. However, sole prophylactic measures are available. The main aim of this work was to evaluate the effects of eighteen antagonistic bacteria, as an alternative approach, to control in vitro and in planta the pathogens strains previously isolated from olive trees in Morocco. In vitro experiments revealed that many bacterial strains such as Rahnella aquatilis, Enterobacter ludwiqii, Paenibacillus brasiliensis, and Bacillus subtilis selected from collection of Regional Center of Agronomic Research, were efficient on solid media against pathogen strains. Their inhibition zones ranged from 8 to 23 mm with a higher inhibition rates found by B. subtilis strains. Enzymatic activities of antagonistic strains were assessed (cellulase, protease and amylase) as well as some plant growth promotion traits (phosphorus solubilisation and indole acetic acid production) for performance screening. B. subtilis 2515-1 was selected for pots experiment using olive trees (cv. Arbequina). This bacterium significantly reduced number and weight of knots against two pathogens strains (PSS 2064-8 and PSS 2102-4). The most reduction rates of weight and knot number were respectively 95.60% and 50%. This study suggested an alternative approach to assess the efficiency of selected bacterium in field conditions. ARTICLE INFO

The Role of Microbial Inoculants on Plant Protection, Growth Stimulation, and Crop Productivity of the Olive Tree (Olea europea L.)

“…B. subtilis 2515-1 strain decreased the tumors in olive's stems caused by Pseudomonas savastanoi pv. Savastanoi 2064-8 strain [54]. B. subtilis QST 713 strain significantly reduced the percentage of latent infections of anthracnose on olive fruits, caused by Colletotrichum acutatum and Colletotrichum gloeosporioides [17].…”

“…Over the last decade, PGPR (10 studies), endophytes (nine), and PGPF (six) have been the center of attention for their biocontrol potential against major olive plant diseases, whereas only two studies with AMF were conducted for this purpose (Table 3). Many strains of Bacillus and Pseudomonas have been used in agriculture as biocontrol agents against several diseases caused either by fungi or bacteria [54]. Sanei [55] reported that eight isolates of Pseudomonas fluorescens inhibited Verticillium's microsclerotia germination.…”

“…Strains of Bacillus subtilis were very effective against Verticillium wilt, root rot, olive knot, and anthracnose [17,54,57]. B. subtilis Y1336 strain significantly reduced the disease incidence of V. dahliae and other soil-borne diseases like Fusarium oxysporum, Fusarium solani, Rhizoctonia solani, and Pythium sp.…”

“…The effectiveness of these strains relies on the ability of Bacillus species to promote growth by increasing nutrient availability [57] and on their high, antibacterial specificity with Pseudomonas savastanoi pv. savastanoi strains [54]. They can also be used as an alternative to chemical or other Cu-based products that are mainly used to treat the symptoms of anthracnose [17].…”

Proteolytic, Lipolytic and Amylolytic Bacteria Reservoir of Turkey; Cold-Adaptive Bacteria in Detergent Industry

“…R. aquatilis could survive at washing room of a minimally proceed plant with a temperature of 5°C and was not able to produce protease 29 . Also R. aquatilis, which had antagonistic activity against olive knot disease was not able to produce protease 30 , amylase and lipase. However, R. aquatilis in this study, was determined with protease, lipase and strong amylase activities, so until now, this is the first report of lipase production from cold-adaptive R. aquatilis.…”