A research conducted at the State University of Campinas (Unicamp) identified "orphan genes" – exclusive to a certain group of organisms – in a species of sugarcane, Saccharum spontaneum. The species is known for its tolerance to biotic stresses, such as attack of pests and diseases caused by insects, nematodes, fungi and bacteria; such as cold tolerance, water deficit, high salinity and soil nutritional deficiency.

The article, published in Frontiers in Plant Science on June 30, was based on the assumption that some of the genes in this species could play a significant role in the face of stress.

Every living being has genes very similar to those present in genomes of other organisms. Plants, for example, share similarities in genes involved in the photosynthesis process. On the other hand, an organism also has genes that are not similar to those found in other species. This is the case of birds, which have some genes without similarity level with any other found in the mammalian genome. Recent research has shown that even organisms of very close species (of the same genus) may have genes that are not shared.

Sugarcane aroused interest from the group because of some peculiar characteristics. Among them are the genome duplication events that occurred in the past and resulted in multiple copies of the same gene. There is scientific evidence that orphangenes can arise from copying a preexisting gene. The copy, over time, has its sequence modified due to mutations to the point of having almost no resemblance to the gene that originated it.

It would also be possible for orphan genes, also taxonomically restricted genes, to have arisen from the reorganization of regions of the genome that do not encode genes, a very common phenomenon in organisms with complex genomes, such as sugarcane.

"In the article, we identified genes in the sugarcane genome that have no similarity to any found in other organisms. We believe that they can be responsible for specific physiological characteristics or patterns of the species," says Cláudio Benício Cardoso-Silva, who developed the project during his postdoctoral studies at unicamp's Center for Molecular Biology and Genetic Engineering (CBMEG), supported by Fapesp.

"A relevant fact is that some have increased or decreased their expression levels in sugarcane plants in response to various types of abiotic stresses, especially cold," explains Cardoso-Silva. "It may be an indication that they are being regulated as a result of these stresses," adds the scientist, who, in his work, was mentored by Anete Pereira de Souza, full professor in the department of plant biology at the Institute of Biology at Unicamp.

With the results reported in the article it is still not possible to affirm that the orphangenes identified make the plant more tolerant to stresses. "But the fact that they are being regulated in stress conditions alerts to the possibility of having an important role in these processes," says the researcher.

The next step will be to verify how these genes behave in terms of expression in experiments with plants subjected to various stresses and compare them to those of plants not subjected to stress. With the confirmation of the best candidate genes, the possibility of biotechnological application opens up, with its insertion in plants of commercial interest. This would enable the development of sugarcane varieties more tolerant to various types of environmental pressures in the future.

"We put a spotlight on this possibility for those who want to resume the data in the article and continue the research, or work with transformation or gene editing, which is another area of research, choose one or two genes as candidates and perform validations," says Cardoso-Silva, who continues to work with genomics at the State University of Norte Fluminense (UENF)."My current research focuses on an evolutionary context, the study of the expansion of gene families."

The researcher spent a year at the University of British Columbia in Vancouver, Canada, on a Fapesp scholarship. "Today we have CRISPR [technique for genetic editing], and this work offers for those who work with biotechnology the selection of specific genes for tolerance to water deficit, high salinity, cold or excessive heat at a time when we seek greater resilience of cultivated plants, with fewer insums", comments Anete Pereira de Souza.

Source: RPA news