Low-temperature storage of monosporidial cultures of the wheat bunt fungi

摘要

Collections ofTilletiaspecies are commonly maintained in the form of sori harvested from smutted heads. This has been a convenient and effective storage method because teliospores enclosed in a sorus remain viable for over 20 years. However, mycelial cultures derived from germinated teliospores are genetically mixed because of meiotic segregation among sporidia. For the purposes of genetic analysis and establishing strain identity, it is necessary to maintain haploid sporidial cultures that can be readily retrieved for manipulations. We found that sporidial cultures ofTilletia triticiandTilletia controversacan be preserved for at least 1 year by suspending a mixture of mycelia and sporidia in 15 glycerol and storing at minus;70 deg;C. Approximately 80 of the stored cultures were viable after 12 months in storage. Five out of nine monosporidial cultures ofT.triticiandT.controversatested retained their sexual fertility in interspecific crosses. The glycerol storage method has advantages over serial transfer in the maintenance of monosporidial cultures by reducing the accumulation of somatic mutations; however, the technique should be used cautiously until greater infectivity of stored cultures is demonstrated.Key words: common and dwarf bunt fungi,Tilletia controversa,Tilletia tritici.