by Ricardo Muniz, FAPESP
A study conducted at the State University of Campinas (UNICAMP) in Brazil has identified orphan genes in wild sugarcane (Saccharum spontaneum), a species with exceptional resistance to biotic stresses such as nematodes, fungi, bacteria and other pests and diseases, and abiotic stresses such as cold, drought, salinity and nutritionally deficient soil.
According to an article on the study published in the journal Frontiers in Plant Science, the scientists responsible had set out to see if the orphan genes in S. spontaneum played a significant role in its stress resistance properties.
All living beings have genes that closely resemble those of other organisms' genomes. Plants, for example, share the genes involved in photosynthesis. On the other hand, most organisms also have orphan or lineage-specific genes.
Orphan genes are found in a particular taxonomic group with no significant sequence similarity to genes from other lineages. They are sometimes called taxonomically restricted genes for this reason.
Birds, for example, have some genes that differ a great deal from those of mammals. Recent research has shown that even organisms in closely related species belonging to the same genus can have genes not shared by other species.
The researchers were interested in S. spontaneum because of characteristics such as past whole-genome duplication events that resulted in several copies of the same gene. Scientific evidence suggests orphan genes can originate in copies of pre-existing genes whose sequences change over time owing to mutations and eventually differ entirely from the original sequences.