The genus Genlisea (corkscrew plants) belongs to the bladderwort family (Lentubulariaceae), a family of carnivorous plants. Some of the 29 species of Genlisea that have been described possess tiny genome sizes. Indeed, the smallest genome yet discovered among flowering plants belongs to a member of the group.
The LMU researchers also discovered a new record-holder. Genlisea tuberosa, a species that was discovered only recently from Brazil, and was first described by Andreas Fleischmann in collaboration with Brazilian botanists, turns out to have a genome that encompasses only 61 million base pairs (= Mbp; the genome size is expressed as the total number of nucleotide bases found on each of the paired strands of the DNA double helix) Thus G. tuberosa possesses now the smallest plant genome known, beating the previous record by 3 Mbp. Moreover, genome sizes vary widely between different Genlisea species, spanning the range from ~60 to 1700 Mbp.
The reasons for the wide range of genome size found in different species remain largely enigmatic. “Interestingly, the size of an organism’s genome does not correlate with its complexity or evolutionary level. Although unicellular organisms like brewer’s yeast, as well as some plant species, have far less DNA in their cells than humans do, many plants have much larger genomes than ours,” Fleischmann explains. The genus Genlisea, with its broad range of variation in genome size between different species, therefore offers a perfect group of model organisms to study the evolutionary pressures that determine genome size. “Genlisea is an ideal model system for understanding the molecular basis for genome reduction and the mechanisms that drive it, especially since the complete genome of G. aurea has already been sequenced and published,” says Günther Heubl. – “Evolution of genome size and chromosome number in the carnivorous plant genus Genlisea (Lentibulariaceae), with a new estimate of the minimum genome size in angiosperms.” Ann Bot (2014) 114 (8): 1651-1663 first published online October 1, 2014 DOI: 10.1093/aob/mcu189
Photos here. (The one accompanying the press release is not of the actual plant, but of a close relative. )
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