Patterns of virulence diversity in Puccinia recondita on wheat in Morocco in 2005 and 2006

A total of 105 isolates of Puccinia recondita from durum wheat and common wheat were collected from the four main agro-ecological areas of Morocco, Abda-Doukkala, Chaouia-Tadla, Gharb-Saïss and Tangérois. The isolates were tested for virulence phenotypes on seedling plants of 21 near-isogenic lines of Thatcher wheat. Eightynine virulence phenotypes were identified and the resistance genes Lr2a, Lr2b, Lr2c, Lr3bg, Lr3ka, Lr9, Lr21, and Lr24 were found to confer a good resistance on isolates of all four collections. In the set of differentials used in this study, no significant difference was found between virulence frequencies of isolates from durum and from common wheat. Principal coordinates analysis and the Kosman distance between virulence phenotypes showed that the collections from Gharb-Saïss and Tangérois were closely related to each other, while Abda-Doukkala was closely related to Chaouia-Tadla

Antagonistic Activity of Trichoderma ISolates against Sclerotium rolfsii : Screening of Efficient Isolates from Morocco Soils for Biological Control

Seventy Trichoderma spp. isolates collected from different regions of Morocco were tested for their capacity to inhibit in vitro mycelial growth of Sclerotium rolfsii, and for their effect on the viability of S. rolfsii sclerotia in the soil. The Trichoderma spp. isolates inhibited mycelial growth of S. rolfsii to various degrees, with 52% of isolates expressing an average inhibition, varying between 45 and 55%. The effect on the viability of sclerotia in the soil also varied between isolates of Trichoderma, with the majority (84%) having a slight effect. A group of twenty isolates identified as Trichoderma harzianum when tested in sterilized soil, significantly reduced sclerotial viability though not in natural soil. Four of these isolates (Nz, Kb2, Kb3 and Kf1) showed good antagonistic activity against S. rolfsii and were also highly competitive in natural soil. These isolates would therefore be candidates for development in biological control program

Survey of Barley and Wheat Diseases in the Central Highlands of Eritrea

Annual surveys of barley and wheat diseases were conducted in Eritrea from 2000 to 2002. The surveys covered six zones of the central highlands where barley and wheat are grown. The main diseases of barley were netform net blotch, spot-form net blotch, leaf rust and scald. Other, less important diseases were loose smut, covered smut, barley stripe and septoria leaf blotch. Wheat was mainly affected by yellow rust and leaf rust. Loose smut, septoria leaf spot and tan spot diseases were less prevalent. The average incidence of these diseases varied according to the zone. Among barley diseases, net blotch incidence was high in four of the six zones surveyed. Leaf rust occurred at medium incidence in five zones. Loose smut was more severe in the southern highland plains, while covered smut was more common in the south-eastern highland terraces. For wheat, yellow rust incidence was high in two zones. Areas with a high incidence of yellow rust were not necessarily those with a high incidence of leaf rust. Leaf rust was important in the south-eastern and western highland terraces and in the western highland plains. The number of diseases found in the same field varied from 2 to 5. The south eastern highland terraces, the western highland terraces and the northern highland terraces had the highest proportions of individual barley fields with three or more diseases

Detection of amyloid beta aggregates in the brain of BALB/c mice after Chlamydia pneumoniae infection

Neuroinflammation, initiated by cerebral infection, is increasingly postulated as an aetiological factor in neurodegenerative diseases such as Alzheimer’s disease (AD). We investigated whether Chlamydia pneumoniae (Cpn) infection results in extracellular aggregation of amyloid beta (Aβ) in BALB/c mice. At 1 week post intranasal infection (p.i.), Cpn DNA was detected predominantly in the olfactory bulbs by PCR, whereas brains at 1 and 3 months p.i. were Cpn negative. At 1 and 3 months p.i., extracellular Aβ immunoreactivity was detected in the brain of Cpn-infected mice but also in the brain of mock-infected mice and mice that were neither Cpn infected nor mock infected. However, these extracellular Aβ aggregates showed morphological differences compared to extracellular Aβ aggregates detected in the brain of transgenic APP751SL/PS1M146L mice. These data do not unequivocally support the hypothesis that Cpn infection induces the formation of AD-like Aβ plaques in the brain of BALB/c mice, as suggested before. However, future studies are required to resolve these differences and to investigate whether Cpn is indeed an etiological factor in AD pathogenesis

Patterns of virulence diversity in Puccinia recondita on wheat in Morocco in 2005 and 2006

A total of 105 isolates of Puccinia recondita from durum wheat and common wheat were collected from the four main agro-ecological areas of Morocco, Abda-Doukkala, Chaouia-Tadla, Gharb-Saïss and Tangérois. The isolates were tested for virulence phenotypes on seedling plants of 21 near-isogenic lines of Thatcher wheat. Eightynine virulence phenotypes were identified and the resistance genes Lr2a, Lr2b, Lr2c, Lr3bg, Lr3ka, Lr9, Lr21, and Lr24 were found to confer a good resistance on isolates of all four collections. In the set of differentials used in this study, no significant difference was found between virulence frequencies of isolates from durum and from common wheat. Principal coordinates analysis and the Kosman distance between virulence phenotypes showed that the collections from Gharb-Saïss and Tangérois were closely related to each other, while Abda-Doukkala was closely related to Chaouia-Tadla