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UFSCar research identifies genetic signature of sugarcane resistant to orange rust

Research carried out by Scientific Initiation (CI) at the Araras Campus of the Federal University of São Carlos (UFSCar) identified a molecular marker - a kind of genetic signature - of sugarcane cultivars resistant to orange rust, an important disease in this crop, caused by fungus that spreads through the air. Thus, the study indicated that this could be an important molecular tool in the search for new cultivars resistant to the disease.

The work was carried out by Ícaro Fier, graduated in Biotechnology from UFSCar, under the guidance of Monalisa Sampaio Carneiro, professor in the Department of Biotechnology and Plant and Animal Production (DBPVA-Ar) of the Institution.

"In a first moment, we evaluated, in the field, the resistance to orange rust of these cultivars. Afterwards, we checked the frequency of the G1 marker along with the cultivars, to analyze whether this marker helps in an even greater resistance to this rust", summarizes Carneiro.

The research found that the molecular marker G1, previously tested only in sugarcane cultivars originating in the United States, is also a factor of resistance to orange rust in 10 of the 24 Brazilian cultivars tested. This is the first study in the country that analyzes the marker in Brazilian cultivars.

The results showed that the efficiency of the G1 marker in predicting resistance was 71.43%. Furthermore, on average overall, the reduction in disease severity was 35% when the G1 marker was present.

Orange rust is caused by the fungus Puccinia kuehnii and affects the leaves, which are full of orange spots. The disease impairs photosynthesis and therefore reduces sugarcane productivity. Unlike a bacterium, for example, in which it is possible to have greater control of the environment to avoid proliferation, the fungus is easily spread through the air - hence the importance of creating cultivars resistant to it.

The integration of field data with the G1 marker allowed the identification of sugarcane cultivars resistant to orange rust, and this resistance was promoted, in part, by the genes to which the G1 marker is linked. Resistant cultivars with the presence of the G1 marker can be used in the improvement process to carry out new crossings and, thus, obtain cultivars that also combine this type of resistance to orange rust, creating what scientists call durable resistance.

"This durable resistance is one of the objectives of our genetic improvement program - the largest in the country -, as it aims to release cultivars resistant to the main sugarcane diseases, thus having greater commercial durability and good conditions of productivity", says the professor at UFSCar.


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