A genetic improvement program for sugarcane

Advances in knowledge regarding this plant genome will allow an increase in crop productivity through genetic manipulation, says scientist.

By Elton Alisson, Recife

Agência FAPESP – Brazil’s efforts in recent years to better understand the sugarcane genome could lead to a genetic improvement program in the near future, which may be modeled after the programs for wheat and corn.

This is opinion of Marie-Anne Van Sluys, a professor at the Biosciences Institute (USP) of the Universidade de São Paulo and a member of the FAPESP Bioenergy Research Program (BIOEN) coordination team, who made the affirmation during a roundtable on “Recent developments and research challenges in bioenergy in Brazil”. The roundtable was held during the 65th meeting of the Brazilian Society for Progress in Science (SCPC) in Recife (PE).

Heitor Cantarella, a researcher at the Agronomy Institute of Campinas (IAC), and Antonio José de Almeida Meirelles, a professor at the School of Food Engineering of the Universidade Estadual de Campinas (Unicamp) also participated. Glaucia Mendes de Souza, a professor at the USP Chemistry Institute and a member of the BIOEN coordination team, organized the event.

According to data presented by Van Sluys, wheat and corn, which are considered as “first cousins” to sugarcane, showed much more significant increases in their production yield per hectare compared with sugarcane between 1961 and 2010.

One of the possible reasons for the difference, according to Van Sluys, is that improvement programs are in place for wheat and corn that are assisted by genomics. Such programs do not exist for sugarcane, which is likely because we still know very little about the genome of this perennial grass.

“Building a database containing sugarcane genomic information will allow us to utilize a more integrated approach, similar to that which is utilized in corn and wheat, for the genetic improvement of this crop. In the case of sugarcane, we are assembling this database from scratch,” she affirmed.

Research programs

According to Van Sluys, to develop biotechnology focused on improving crops, one must thoroughly understand the biological structure of the plant. In the case of sugarcane, this challenge is even greater.

Sugarcane grown today is a hybrid variety, derived from crossing Saccharum officinarum with Saccharum spontaneum. Of these two species, the first contributes to the production of sugar, and the second provides vigor and resistance to a series of agricultural plagues.

Unlike in humans, where genetic contributions are equivalent (50/50) from each parent, in sugarcane, the genetic makeup can be unbalanced. Saccharum officinarum contributes approximately 75% of the plant’s genome, whereas Saccharum spontaneum accounts for 25%.

Furthermore, whereas humans have 23 pairs of chromosomes, the plant has many more, in addition to having many more repetitive genetic sequences. “Human beings have approximately 50% repetitive genomic sequence; sugarcane is capable of having much more, albeit perhaps not as much as some corn varieties, in which this percentage could reach 80%,” said Van Sluys.

“The fact that this is a hybrid organism with a very large genome and a significant amount of repetitive sequence makes the genetic improvement of sugarcane very challenging,” stressed the researcher.

“In the last ten years or so, Brazil has taken steps toward making biotechnology more efficient to increase the productivity of sugarcane”, said Van Sluys.

Among these steps are the establishment of FAPESP’s BIOEN Program and the National Institute of Science and Technology (INCT) on Bioethanol, the latter of which is one of the INCTs funded by FAPESP and the National Council of Scientific Development (CNPq) in São Paulo State.

“We want to identify new ways to genetically manipulate energy metabolism in plants, similar to what we have seen with corn”, said Van Sluys.

In the last few years, the program’s participating researchers have begun to develop a database with information on the sugarcane genome.

When completed, the genetic database will pave the way for the eventual inclusion of transgenics (i.e., genetically manipulated sugarcane plants) in the improvement programs for the plant.

“Based on the genomic tools that are being constructed due to our partnerships with improvement programs and our increased comprehension of sugarcane physiology, we are beginning to better understand genetic networks and distinguish, for example, Saccharum officinarum genes from Saccharum spontaneum genes in the varieties grown,” said Van Sluys.