User:BINGBING/sandbox

Albugo candida (white blister rust) White blister rust is a common disease caused by obligate biotroph Albugo Candida. Albugo Candida is widespread species which has over 30 host genera. Albugo candida infects broad range species including Brassicaceae, Cleomaceae and Capparaceae. Albugo candida infection will first cause the host species to develop the “green island”, where the infected the tissue looks normal and senescence is delayed. Albugo candida infection also increases susceptibility of host species to develop other diseases such as downy mildews. More importantly, Albugo candida infection is also associated with broad suppression of host plant immunity, including the effector-triggered immunity. According to the report, Albugo candida infection greatly reduced crop production and economic loss all over the world.

Recent studies also found that high degree of genetic diversity within the Albugo parasitic to Brassicaceae and 6 new specialized species have been introduced, such as Albugokoreana from Capsella bursa-pastoris, Albugo laibachii from Arabidopsis thaliana, Albugo voglmayrii from Draba nemorosa, Albugo hesleri, Albugo hohenheimia, and Albugo leimonios from species of the genus Cardamine. Albugo candida is maintained through constant genetic exchange. By performing the molecular analysis of the isolates from different host species, scientist already confirmed this hypothesis.

Albugo candida reproduces asexually via zoosporangia, which releases flagellated motile zoospores in water. Zoospores settle on the surface of leaves and extend germ tube into the substomatal chamber. Coenocytic hypae grows intracellularly inside the plant. Zoosporangia rupture the plant epidermis by force and enzymatic digestion when the Albugo candida infection is mature, which results in the “white blister rust”. Albugo candida can also be reproduced sexually, Albugo candida produces oospores which are able to survive in the tough environment. The inflorescences of Brassicaceae hosts become misshapen and forming “stagheads” during the systemic infection of Albugo candida.

At the genome level, Albugo candida has an estimated genome about 45.3 Mb. Sequencing of Albugo candida transcripts from infected host tissue and zoosporangia, and then aligned to the annotated genome, totally predicted 15824 genes. Interestingly, most of these genes have unique sequences and lack similarity with sequences from other oomycetes. The Albugo candida secretome comprised 929 proteins. According to pathway analysis, Albugo cadida have a much smaller repertoire of pathogenicity-related proteins than H. arabidopsidis, such as genes encoding for RXLR proteins, CRINKLER-like proteins, Elicitins, Necrosis and Ethylene inducing Peptides.