The genetic and cell mechanisms that lead to the formation or absence of seeds in grapes (apireny) have just been unveiled by the team of Embrapa Grape and Wine's Laboratory of Plant Molecular Genetics, in Bento Gonçalves (RS), jointly with scientists from the Federal University of Rio Grande Do Sul (UFRGS) and the State University of Campinas (Unicamp). The discovery has the potential to accelerate and inform research to develop seedless grapes through the use of biotechnology techniques. Despite the broad appreciation of seedless table grapes, which has been growing year after year, little was known about the cell and genetic mechanisms responsible for their development. The Brazilians identified the role of the VviAGL11 gene in the development of grape seeds. The discovery was recorded in a paper published in the Journal of Experimental Botany, edited by the Oxford University Press. The group led by the Embrapa researcher Luis Fernando Revers unequivocally presented the research results that unmasked most of the biology behind seedlessness in table grapes, especially the role of the VviAGL11 gene. “The paper is quite thorough and describes the gene, its genetic structure, the regulation of its expression and effects in the formation of grapevine seeds”, informs Revers, who coordinates the Laboratory of Plant Molecular Genetics, in which important parts of the study were conducted. “Since I arrived at Embrapa Grape and Wine, in 2001, one of the missions with which I have been tasked was to help discover how seedlessness works. I am happy to write this important part of history”, celebrates Revers. The result presented in the paper comprises the knowledge that has been aggregated in the course of such 16 years, with the participation of analysts, and graduate and undergraduate scholarship holders working as a team. According to Jaiana Malabarba, one of the study authors, whose PhD thesis provided the foundation for the paper, the aim was to understand the role of the VviAGL11 gene during the seed formation. For that purpose, the gene was studied in the cultivars Chardonnay (with seeds) and Sultanine (without seeds), using allele-specific sequencing, in situ hibridization, expression analysis using RT-qPCR, and phenotype complementation in the model plant Arabidopsis thaliana. “With that purpose, we identified that VviAGL11 transcript levels significantly increased two and four weeks after fruit set for the Chardonnay seeds, specifically in the dual endotesta layer of the inner integument of the seed; as this layer is responsible for forming the seed coat, it suggests this gene is related to seed formation”, Jaiana informs. She adds that in the Sultanine cultivar, the gene is not expressed during the development of the fruit and seeds, which would result in the absence of seeds in this cultivar, a hypothesis that has been proven. “It is clear that when the gene is working correctly, this layer develops and has a decisive role in the formation of a normal seed, otherwise seeds do not grow and there are only seed traces, found in the apirenic grapes”, Jaiana details. Learn about the history of the discovery of the role of the VviAGL11 gene in the generation of grape seeds After publishing in the Journal of Experimental Botany, the team has been contacted by labs from different countries, especially from China. “I had expected good repercussion from the paper, but I am surprised about how research groups in other countries were also searching for these answers, and now our findings are helping other scientists”, Revers comments. According to him, the work represents an advance that will help genetic improvement programs plan crossings and select apirenic grapes. “Applications of the new knowledge in the long term have the potential to help the development of new cultivars, facilitating the work and reducing time. “The expectation is to transform this knowledge into a tool, so that even before producing fruit, DNA tests allow us to know whether the grapes will have seeds or not”, said the researcher. The team continues working and the next challenge is to evaluate the use of the gene in adult grapevines. “With this endeavor, the intention is to change seed size, and make them smaller, for instance, by silencing the VviAGL11 gene”, he anticipates. The general head of Embrapa Grape and Wine, Mauro Zanus, recalls that it has been nearly 20 years since Embrapa Grape and Wine started to develop new seedless grape varieties, using techniques to rescue embryos and classic plant breeding. “Now, with these studies that identify the genes responsible for the seedlessness trait, we have advanced in the scientific basis that regulates this important technology, opening doors to perfecting vine genetic improvement, reducing its costs and accelerating the development of new varieties", he assesses. Learn about the history of the discovery of the role of the VviAGL11 gene in the generation of grape seeds Challenges According to Revers, in the last decade the gene had been pinpointed as likely to be the one responsible for the seed development, but nobody had been able to gather evidence to make such statement. The researcher reports that most agronomic traits of interest, such as the presence or absence of seeds or resistance to diseases, have the influence of a very large number of genes, often dozens of them, which makes the issue so complex, as in the saying “like looking for a needle in a haystack". "Our team's greatest merit was establishing and proposing investigation strategies to gather evidence. We also counted on a fortunate coincidence of nature: the presence of a microsatellite marker positioned above the gene, which helped in its discovery”, he comments. Embrapa Grape and Wine's team relied on a partnership with important research institutions, among which are UFRGS and Unicamp, which were fundamental to conduct anatomical and morphological studies to document variations that happen with the presence or absence of the VvAGL11 gene. Professor Marcelo Carnier Dornelas, general coordinator of Unicamp's Institute of Biology's Graduate School, helped to demonstrate and record how the gene would be expressed during the seed development. The participation of UFRGS professor Jorge Ernesto de Araújo Mariath was decisive for the photographic record of seed development and its interpretation, stages that were instrumental to clearly register the differences between normal seed development and the formation of the apirenic fruit. Mariath believes that this discovery opens "a window of knowledge on gene regulation in studies on structure & function", which are extremely current for the international community. "This secured Brazil with a new international position. The work developed was magnificent and it was only possible thanks to the integrated work that congregated specialists from different institutions and in complementary areas of knowledge”, he observed. The molecular, genetic, and physiological proof of the VvAGL11 gene's action in seed development, for the professor Giancarlo Pasquali, from UFRGS, was a very relevant discovery. “This tool will be very important to manipulate and generate seedless grapevines or even to revert the process and generate plants with seeds, and it can be applied not only to grapevines, but to other plants”, he commented. Read the paper The MADS-box gene Agamous-like 11 is essential for seed morphogenesis in grapevine, written by Jaiana Malabarba, Vanessa Buffon, Jorge E.A. Mariath, Marcos L. Gaeta, Marcelo C. Dornelas, Márcia Margis-Pinheiro, Giancarlo Pasquali, and Luís F. Revers.