imported>Lcovelli at 11:44, 15 March 2010

2010-03-15T11:44:25Z

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{{Element
|genbank=[http://www.ncbi.nlm.nih.gov/entrez/viewer.fcgi?db=nucleotide&val=40457268 40457268]
|type=
|genus= Badnavirus
|subfamily= Class 2
|family= Caulimoviridae
|group= LTR retroelements
|description= ''Banana streak virus'' (BSV), the causal agent of viral "leaf streak disease" of banana and plantain (''Musa'' spp.) ([[Literature:100630|Lockhart, 1986]]), is a member of the plant pararetrovirus genus ''Badnavirus'' of family ''Caulimoviridae'' (''International Committee on the Taxonomy of Viruses'' -ICTV- [[Literature:100589|Fauquet ''et al''. 2005]]). Several isolated have been studied, one of which is BSGFV infecting the tetraploid plantain hybrid cultivar "Goldfinger" ([http://www.ncbi.nlm.nih.gov/nuccore/40457268 Zhang ''et al.'' 2003], unpublished). According to [[Literature:100596|Llorens ''et al''. 2009]], BSGFV belongs to ''Badnavirus'' genus within Class 2 of the [[Caulimoviridae|''Caulimoviridae'']] family.

The bacilliform virions of BSGFV contain a circular dsDNA genome of about 7.3 kb in size (7263 bp long) which three Open reading frames (ORFs I, II, III) encode for proteins with a molecular weight of 19, 12.2 and 199.2 kDa, respectively. ORF I product shows sequence similarity with the virion associated protein (VAP) encoded by the correspondent ORF I of other ''Badnavirus'' species. ORF II encodes a small protein of unknown function, whereas ORF III contains a large polyprotein consisting of the putative movement protein, the coat protein, the aspartic protease, the reverse transcriptase and the RNase H ([http://www.ncbi.nlm.nih.gov/nuccore/40457268 Zhang ''et al.'' 2003], unpublished). The COAT ''gag''-like region includes a large region (only observed in Badna- and Tungroviruses), which is rich in zinc finger (CCHC) array duplications similarly to those of several LTR retroelement nucleocapsids ([[Literature:100605|Hull 1996]]; [[Literature:8054|Bouhida ''et al.'' 1993]]; [[Literature:100596|Llorens ''et al''. 2009]]).

First described in the Ivory Coast, Africa in 1968 ([[Literature:100631|Lassoudiere 1974]]), "leaf streak disease" has been identified in almost every producing area of banana and plantain (''Musa'' spp.) worldwide. The symptoms are associated with variations in virus concentration and may vary from pale broken chlorotic lines to necrosis of young leaves, internal necrosis of the pseudostem and plant death. The bunch size and fruit quality are also compromised ([[Literature:100630|Lockhart, 1986]]). The virus is transmitted naturally by the two mealybug vectors (''Pseudococcidae'') ''Planococcus citri'' and ''Saccharicoccus sacchari'' (both of which colonize banana), as well as by seed, even if the vegetative propagation is the principal method of virus spread.

Unlike the petuvirus ''Petunia vein clearing virus'' (PVCV, [[Literature:63308|Richert-Pöggeler and Shepherd 1997]]), no obvious integrase motif could be identified in the BSV sequences ([[Literature:100632|Harper and Hull 1998]]). However, multiple DNA sequences (Endogenous pararetrovirus, EPRV) related to the virus are found integrated into the nuclear genome of different ''Musa'' cvv. ([[Literature:100635|Harper ''et al.'' 1999]]; [[Literature:100608|Ndowora ''et al.'' 1999]]; [[Literature:100633| Geering ''et al.'' 2005]] [[Literature:89696|Gayral and Iskra-Caruana 2009]]). Two types of BSV-EPRV sequences have been described in ''Musa'' genome. The first type sequences, defined as noninfectious (with nonfunctional viral ORFs and/or incomplete viral genomes), are present in the two most common ''Musa'' species ''Musa acuminata'' (denoted A) and ''Musa balbisiana'' (denoted B) that, together to ''Musa schizocarpa'' (denoted S) are the wild progenitors of the domesticated banana ([[Literature:100633|Geering ''et al.'' 2005]]). The second EPRV sequences, so-called infectious type, contain the complete functional viral genome and have been detected in some ''Musa'' genotypes (i.e AAB and BB groups, [[Literature:100633| Geering ''et al.'' 2005]]; [[Literature:89695|Gayral ''et al.'' 2008]]).
The presence of two entire BSGFV-EPRVs (EPRV-7 and EPRV-9) in the nuclear genome of the wild diploid ''M. balbisiana'' cv. "PKW" (BB genotype) has been demonstrated ([[Literature:89695|Gayral ''et al.'' 2008]]). These integrated sequences are much longer than a single BSGFV genome and exhibit a complex rearrangement consisting in a succession of several fragmented, inversed, and partially repeated BSGFV genomes. Although the complete BSGFV genome (the ORFs and intergenic region) is present at least once in each EPRV, only EPRV-7 has demonstrated to be infectious and able to cause systemic infection ([[Literature:89695|Gayral ''et al.'' 2008]]). Surprisingly, [[Literature:89695|Gayral ''et al.'']] (2008) discovered that both BSGFV-EPRVs integrated in the middle of a ''Ty3/Gypsy''-like retrotransposon itself integrated in the fifth intron of the ''mom'' gene and hypothesized that their integration in Musa genome might occur as a chimeric ''Ty3/Gypsy''-BSGFV transposable element.
|structure=BSGFV.png
|host=Musa sp
|hostpic=Musa_sp.gif
|literature=
|picowner=[http://www.biotechvana.com Image, Carlos Llorens, <br>Copyright, GyDB, Biotech Vana]
}}
[[Category:Element]]

Element:BSGFV - Revision history

imported>Lcovelli at 11:44, 15 March 2010