Halophytic endophytes potentially contribute to the host’s adaptation to adverse environments, improving its tolerance against various biotic and abiotic stresses. Here, we identified the culturable endophytic bacteria of three crop wild relative (CWR) halophytes: Cakile maritima, Matthiola tricuspidata, and Crithmum maritimum. In the present study, the potential of these isolates to improve crop adaptations to various stresses was investigated, using both in vitro and in-planta approaches. Endophytic isolates were identified by their 16S rRNA gene sequence and evaluated for their ability to: grow in vitro in high levels of NaCl; inhibit the growth of the economically important phytopathogens Verticillium dahliae, Ralstonia solanacearum, and Clavibacter michiganensis and the human pathogen Aspergillus fumigatus; provide salt tolerance in-planta; and provide growth promoting effect in-planta. Genomes of selected isolates were sequenced. In total, 115 endophytic isolates were identified. At least 16 isolates demonstrated growth under increased salinity, plant growth promotion and phytopathogen antagonistic activity. Three showed in-planta suppression of Verticillium growth. Furthermore, representatives of three novel species were identified: two Pseudomonas species and one Arthrobacter. This study provides proof-of-concept that the endophytes from CWR halophytes can be used as “bio-inoculants,” for the enhancement of growth and stress tolerance in crops, including the high-salinity stress.

The efficacy of various chemicals as alternatives to antibiotics for the control of fireblight (Erwinia amylovora) on pear trees was tested. The chemicals were applied in two ways. In 1999 and 2000, preselected pear twigs (80-90% bloom stage) were sprayed once either preventively 1 day before inoculation or curatively one or three days after artificial inoculation with pathogen concentrations of 10 5 and 10 7 cfu ml -1 . In 2000 and 2001, whole trees were sprayed 2 and 4 days before artificial inoculation of the flowers. From the incidence of diseased flowers it appeared that Bion (50% benzothiadiazole) at 0.2 g litre -1 H 2 O and Aliette (80% fosetyl-Al) at 2.5 g litre -1 H 2 O showed considerable preventive action by eliciting systemic acquired resistance mostly when they were applied in the whole trees. However the best control was achieved with the antibiotic Agrept (20% streptomycin) at 0.5 g litre -1 H 2 O. This showed both preventive and curative action. Kocide (77% copper hydroxide) at 0.9 g litre -1 H 2 O, Dentamet (citric acid in chelate) at 1.5 ml litre -1 H 2 O, Bactosan (an extract from the plant Pongamia pinnata) at 3.0 g litre -1 H 2 O and Bion at 0.1 g litre -1 H 2 O, showed preventive action, but only when the inoculum concentration was low.

In November 2019, a severe outbreak of fruit rot was observed in olive orchards in Crete, southern Greece. Symptoms appeared primarily on fruits and stalks, resembling those caused by anthracnose. Typical symptoms were fruit rot, shrinkage and mummification, associated commonly with stalk discoloration and fruit drop. Disease incidence was estimated up to 100% in some cases and an unprecedented increase in olive oil acidity reaching up to 8% (percentage of oleic acid) in severely affected olive groves was recorded. Thirty-two olive groves were then surveyed, and samples of fruit, stalk, leaf and shoot were collected. Visual, stereoscopic and microscopic observations revealed several fungi belonging to the genera Alternaria, Botryosphaeria, Capnodium, Colletotrichum, Fusarium and Pseudocercospora. Fungal infection in fruits was commonly associated with concomitant infestation by the olive fruit fly Bactrocera oleae along with increased air temperature and relative humidity conditions that prevailed in October-November 2019. Twenty representative fungal strains isolated from symptomatic fruits and stalks were characterized by morphological, physiological and molecular analyses. By rDNA-ITS region and EF1-α gene sequencing analysis, these isolates were identified as Alternaria spp., A. infectoria, Botryosphaeria dothidea, Colletotrichum boninense sensu lato, Fusarium lateritium, F. solani species complex and Stemphylium amaranthi. Pathogenicity tests on punctured fruits revealed that all isolates were pathogenic; however F. solani isolates along with B. dothidea were the most virulent and wounds were necessary for efficient fungal infection. Moreover, as little as 10 spores of F. solani were sufficient of causing significant infection in punctured fruits. Fusarium solani was also capable of infecting olive fruits in the presence of B. oleae, with no additional wounding, in artificial inoculation experiments. Moreover, it was capable of colonizing and affecting olive blossoms. Further analyses in olive oil extracted from fruits artificially inoculated with F. solani indicated a significant increase in oil acidity, K232, K270 and peroxide value, whereas total phenols content was significantly decreased. To the best of our knowledge, this is the first report of Fusarium solani associated with olive fruit rot and olive oil degradation worldwide.

No abstract

No abstract