Tests previously conducted have shown that the use of disease-free planting material increases yield by as much as 13%.

In the heart of Victorias City in Negros Occidental lies a well-equipped biotechnology laboratory where scientists doggedly look for ways to make sugar planters' lives easier.

Their latest opus: the use of molecular techniques to determine sugarcane's resistance or susceptibility to certain diseases.

Seeking ways to ensure the production of disease-free varieties of sugarcane, the Common Fund for Commodities funded the ongoing study, entitled "Molecular marker-assisted selection in identifying downy mildew and smut resistance genes in sugarcane."

"Our goal is to identify reliable molecular markers or genetic markers for two of sugarcane's most pernicious diseases in the Philippines," said Dr. Norvie Manigbas, Philippine Sugar Research Institute Foundation, Inc. crop physiologist and plant breeder, who began the study in May 2002.

Downy mildew is a fungal disease which attacks sugarcane during warm and wet conditions, and causes leaf discoloration as well as thinning of the infected plant's stalks. A fungal disease caused by Ustilago scitaminea, smut causes stunting in infected plants.

Resulting in economic losses ranging from 34% to 70%, smut and downy mildew are usually controlled through chemical and hot water treatment.

The most reliable and cost-effective approach, in Philsurin's view, is to plant high-quality, disease-resistant varieties. Tests previously conducted have shown that the use of disease-free planting material increases yield by as much as 13%.

"The problem is the conventional process of developing new varieties with resistance to pest and disease is very time-consuming and expensive," Mr. Manigbas said.

This has prompted the foundation to apply molecular techniques which provide powerful tools for screening a large number of sugarcane varieties for smut and downy and mildew resistance in a short span of time.

While traditional screening may take two years before yielding results, molecular marker-assisted selection produces outcomes in half the time, accelerating and improving the breeding process.

One of the most widely accepted modern biotechnologies, molecular markers are utilized extensively by plant breeders to identify useful agronomic traits.

Mr. Manigbas and his colleagues inoculated different varieties of sugarcane with isolates of smut and downy mildew in the glass house in 2002.

From April to October, they screened and identified the resistant and susceptible varieties to be utilized for hybridization. The hybridization process took place from October to November 2002.

Seeds from the resulting cross were then planted separately in cups, leaf samples of which were used for DNA (deoxyribonucleic) extraction.

The extracted DNAs were checked using agarose gel electrophoresis. Polymerase chain reaction was then conducted to detect polymorphism or differences in DNA sequence among the parents using various primers.

Simple sequence repeats, or microsatellites were, used for the study because they are simple, reliable, reproducible and cost-effective.

Philsurin expects to obtain the results by 2005. Once markers that are closely linked to the resistance genes are identified, sugarcane breeders may select progenies resistant to smut and downy mildew in the early stages of breeding in the convenience of their laboratories.

"The beauty of this technology is that breeders may eliminate the susceptible varieties right away, and plant only the resistant types," Philsurin Director-General Leon Arceo said.

Moreover, molecular marker-assisted selection enables breeders to do away with the tedious field trials, and eliminates the unreliability of phenotypic evaluation which is limited to screening a variety's appearance.

Adopting new technologies to sustain self-sufficiency in sugar, Philsurin has invested in scientific human capacity, as well as facilities. Its biotechnology laboratory is furnished with cutting-edge equipment which aid in sugarcane research and development.