|Tian, Yang - PURDUE UNIVERSITY|
Submitted to: Fungal Genetics Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: January 17, 2002
Publication Date: N/A
Technical Abstract: Previous analyses of DNA fingerprint probe pSTL70 from the Loculoascomycete Mycosphaerella graminicola revealed the 3' end of a reverse transcriptase (RT) gene and three 29 base-pair direct repeats characteristic of a transposable element. Further research on this transposable element showed movement during the sexual cycle. Most isolates had stable DNA fingerprint patterns during asexual transfers. However, one isolate gained a band during asexual transfers, presumably due to movement of an active copy of the transposable element. The active copy and two inactive copies of the RT gene were cloned and sequenced. A high frequency of G:C to A:T transitions characteristic of RIP were found in the RT sequences of the two inactive copies compared with the active copy. The active copy contained a long open reading frame with no stop codons. In contrast, the two inactive copies contained one or more stop codons within the coding region. Most of the stop codon mutations were G:C to A:T, most likely due to RIP. By comparison, a single-copy gene from M. graminicola showed no evidence of RIP. This provides the first evidence for RIP in a Loculoascomycete and indicates RIP may be very important for inactivating transposable elements in the genus Mycosphaerella.