PROJECT STUDIES HOW POLLEN INFLUENCES THE QUALITY OF WINES

SCIENTISTS ARE STUDYING IN MOLECULAR GENETICS A FORMULA TO CORRECT THE DEFECTS OF THE VINE BEFORE THE FAULTY FRUIT, THAT WOULD AFFECT WINE PRODUCTION, GERMINATES.



April 8, 2016

One of the purposes of the Fondecyt Regular study developed by academics from the Institute of Biological Sciences, belonging to the Department of Agricultural Sciences of our University, is to contribute to optimize the quality of the wines from the molecular genetics improvement of the vines.

It is about the “Reproductive Development in vines. The Regulation of Pollen Formation and Its Effect on the Production of Parthenocarpic Fruits” project, whose main researcher is Professor Enrique Gonzalez, together with co-researchers Professors Simon Ruiz and Fernando Guerra.

This scientific work is the result of successive past projects since 2002. It focuses on the study of fruit development in the more representative vines of the country, such as Carmenere. In this sense, one of the difficulties generated in production are the seedless grapes, identified as “parthenocarpic fruit”.

When the percentage of grains in this condition is high, it is well known that the quality of the wine is affected by the effect of the lower quality of the fruit, which had an abnormal development.

As explained by professor González, this parthenocarpic phenomenon—to some extent—is associated to the lack of micronutrients in the plants, which are required in very low amounts. It is zinc and boron, two essential minerals for these fruits to grow properly.

However, he remarked that, despite the fact that the levels of these nutrients are controlled at the vineyards, there anyways arise defective bunches that lack seeds in varying percentages.

“Then we saw that one cannot explain the whole phenomenon of fruit production by the simple fact that there is missing a micronutrient. Therefore, we conducted molecular genetic studies to identify genes associated with the phenomenon, and we discovered a lot by using such techniques as trasnscriptome analysis (genomic analysis). And we examined a list of genes that could be linked to the problem,” said the academic.

Then, the genetic material that encodes proteins and which is responsible for the transport of zinc and boron, and that makes it easier for these micronutrients to be absorbed from the soil, was identified. In this way it was determined the importance of this biological process.

Pollen

The next stage was the correlation established between the magnitude of the fruits and the quality of the pollen produced by the vines. “Then we discovered, for example, that these varieties having a greater tendency to produce seedless fruit tend to generate a high proportion of anomalous pollen, which, when examined in the microscope, is structurally irregular. And if you see it and it is made to germinate, it is also functionally anomalous. Then, what we have been proposing as a hypothesis these times is that the cause of the phenomenon of parthenocarpic fruit production is linked to the quality of the pollen from the plant in a particular season”, he explained.

On the basis of the foregoing, the current Fondecyt project tries to solve a new problem. How is the development of the vine pollen controlled? What factors are associated with all of the events that occur during the development of the pollen?

Enrique González points out that there is another variety of vine that has no quality difficulties when producing seedless grapes. It is the case of the Cabernet Sauvignon vine variety, where virtually 100% of the pollen is normal. “But if you see a Carmenere or Merlot variety, with a lot of seedless fruit, the amount of pollen structurally aberrant (faulty) is also very high, and the correlation here is almost perfect. Then, the more abnormal pollen is produced, the more seedless grapes will be produced”, said the academic.

Proteins

Along this, the team of scientists analyzed how pollen is generated. “And we have managed to identify a group of proteins that control its development, and in the case of a protein in particular, which is the core of this project, we have established that it is effectively linked with the generation of the seeds. This was achieved using relatively indirect methods and the model plant used was Arabidopsis thaliana (which facilitates experimentation, since its genome is completely deciphered),” said the professor.

Therefore, the project postulates that seed formation in grapes has its origin in an abnormal pollen development process. He ensured that before, the causes were identified long after the fruit began to grow. “But we now say that the cause is prior to it, it happens even before the pollination and fertilization of the vine plant occurs. It occurs at the pollen development stage, which precedes fruit growth,” he said.

He sated that, if they manage to reduce the rates of structurally abnormal pollen, they will be able to minimize the phenomenon of seedless fruit. “And, as a result, the quality of the grapes to be produced will be a lot better for the wine-making process,” explained the scientist.



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