The genes that a moss species contains, which are acquired from microorganisms, might have facilitated the primitive plant’s adaptation to life on land, reports a study published in Nature Communications this week.

Horizontal gene transfer - the direct acquirement of genes from other species - is prevalent in microorganisms, but is thought to be rare in land plants. Through bioinformatic analyses on the sequenced moss species, Physcomitrella patens, Jinling Huang and colleagues identify 57 families of moss genes that are closest to genes in bacteria, fungi or viruses, instead of more related species such as algae. These genes are known to function in plant metabolism, development, and mostly notably in defence against photo-oxidative stress. The authors hypothesize that intense UV radiation on land challenged early plants as they first emerged from the sea, and the plants thrived by obtaining useful genes from microorganisms.

This work suggests that horizontal gene transfer may not be uncommon in land plants, however it remains unclear how the reported horizontal gene transfers might have taken place, and whether vascular plants that produce seeds instead of spores are resistant to such mechanisms.