First Report of Botryosphaeria iberica Associated with Dieback and Tree Mortality of Monterey Cypress (Cupressus macrocarpa) in Algeria.

Stem cankers and branches showing bark discoloration, fissuring, resin exudation leading to dieback, crown wilting, and tree mortality have been observed since late spring 2008 on 40-year-old Cupressus macrocarpa (Hartw.) trees planted in forests mixed with Juniperus oxycedrus L. and Acer monspessulanum L. in Taffet, near Ain Abbessa, in the district of Bougaa, Algeria (36°18'57″N; 05°06'33″E; 1,400 m elevation). In 2010, approximately 60% of the C. macrocarpa trees were diseased. For fungal isolations, cankered branches were surface sterilized with ethanol. After removal of the outer bark, fragments of necrotic inner bark taken from the margin of cankers were plated on potato dextrose agar (PDA). Most of the colonies were identified as Botryosphaeria iberica (Phillips, Luque & Alves) based on comparison of morphological traits and DNA sequences with known isolates of the fungus (1). Pestalotiopsis funerea colonies were also obtained, although with less frequency. B. iberica colonies on PDA were dark green with aerial mycelium and optimum growth at 25°C. Pycnidia were produced after 3 weeks of incubation at 20°C under a 12-h near UV light photoperiod on water agar amended with autoclaved cypress seeds. Conidia were brown, one-septate, oval to oblong, and 24.2 (20.1 to 27.4) × 11.2 µm (8.8 to 14.1) (n= 50). An isolate was deposited at the Centralbureau voor Schimmelculture as CBS 130984. DNA was extracted from freeze-dried mycelium and amplified using primers ITS1 and ITS4. The amplified DNA sequence of B. iberica isolate CBS 130984 from Algeria (GenBank Accession No. JN836991) showed 100% homology with sequences of B. iberica isolates obtained from dead and cankered bark of oaks from Spain and Italy (GenBank Accession Nos. AY573216, AY573214, AY573213, AY573210, AY573202, and AY573201). Stem inoculations were performed in the greenhouse on 10 4-year-old, grafted plants of C. macrocarpa growing in 5-liter pots using isolate CBS 130984. A 3-mm plug taken from the margin of a colony grown on PDA for 1 week was inserted in a circular wound of the same size made in the bark with a cork borer where the stem diameter was approximately 1 cm. Inoculations were repeated in June 2010 and June 2011. Five months after inoculations, small rounded to elongated lesions (1.0 to 2.5 cm long), sometimes with resin exuding cracks, were visible on all inoculated stems. Control trees, inoculated with sterile PDA plugs, showed no canker development. B. iberica was successfully reisolated from the necrotic bark surrounding the inoculation sites. No significant differences in canker size were observed between the two replicated experiments. Some Botryosphaeria species that are found on a variety of hosts are also known to cause cankers and dieback of cypress; among these are B. stewensii, B. obtusa, B. dothidea, and B. ribis, often acting as weak pathogens (2,3). Considered weakly virulent in causing dieback of grapevine (4) and, to our knowledge, reported here for the first time on Cupressaceae, B. iberica caused cankers and dieback of C. macrocarpa trees that had probably been weakened by repeated drought events occurring in Algeria during the last 10 years. References: (1) A. Phillips et al. Mycologia 97:513, 2005. (2) E. Punithalingam and J. M. Waller. IMI Descriptions of Fungi and Bacteria 40, Sheet 394, 1973; (3) E. Punithalingam and P. Holliday. IMI Descriptions of Fungi and Bacteria. 40, Sheet 395, 1973; (4) R. Úrbez-Torres et al. Plant Dis. 93:584, 2009.

Results of screening greenhouse and int vitro behaviour to evaluate some durum wiieat varieties and their F5 descendents selected in algeria for resistance to Septoria tritici.

15 genotypes of durum wheat, composed of 5 parental varities and 10 F5 lines selected in Algeria, were studied for evaluating thein behaviour to Septoria tritici Two trials were realised: one under green house conditions, where seedlings were inoculated artificially with Septoria tritici suspension, and another under in vitro conditions where detached leaves where also inoculated. Among this range of varieties, some genotypes were tolerant, others susceptible and others showed rather reactions between tolerant and susceptible. Tolerant genotypes presented a low number of necrosis in the green house trial and a reduced lesion size on the in vitro infected tissu. On the contrary. sucseptible genotypes showed a high necrosis number and an important lesion size on their detached leaves. Some observations, during the experimentation, permitted to underline the important limiting effect that could impose some biotic and abiotic factors (temperature, relative humidity and age of plant tissue) to the pathogen development, reported by other studies before, In comparision with other investigations, varieties which were reported to be resistant or susceptible had confirmed their reactions in our study, it will be interesting to include them into a primary range of varieties for use to study the fungus Septoria tritici.

The effect of solanapyrone a produced by Ascochyta rabiei on seed germination and the elongation of radicles and hypocotyls of chickpea (Cicer areitinum L.).

Three Algerian isolates of A. rabiei (72, Mat 1.2 and 9216) were grown on Czapek Dox medium supplemented with cations and incubated for 14 days. After incubation, the mycelium of the fungus was removed by filtration through four layers of muslin cloth and spores were removed from the filtrate by centrifugation at 10,000 g for 20 min. Solanapyrone A was partially purified by liquid phase extraction into ethyl acetate and, after removal of the ethyl acetate, the toxin samples were dissolved in methanol and quantified by analytical High Performance Liquid Chromatography (HPLC). Solanapyrone A was identified by superimposition of its UV spectrum, obtained from the diode array detector of the HPLC, on the spectrum of an authentic sample. The action of solanapyrone A solution on seed germination and elongation of radicles and hypocotyls was tested using a concentration of 18.2 microg/ml and a two-fold dilution series of this solution in distilled water. The three Isolates, 72, Mat1.2 and 9216 produced solanapyrone A at concentrations of 37.2, 14.2 and 11.09 microg/ml, respectively. When probit % inhibition of seed germination was plotted against log2 of solanapyrone A concentration, there was a linear relationship and the EC50 concentration was determined as 7.2 microg/ml. Similarly, when radicle and hypocotyl elongation was plotted against log2 of solanapyrone A concentration, both gave linear relationships and the EC50 concentrations were determined as 5.37 and 6.02 microg/ml, respectively. It was concluded that solanapyrone A has a considerable inhibition of chickpea. However radicles and hypocotyls were susceptible than seed germination.