A fundamental principle in the field of genetics is that phenotypes are the output of interactions between genotypes and the environment. Changes in phenotype caused by differing environmental conditions are classified as phenotypic plasticity. Quite how environmental signals are perceived by multicellular organisms to regulate phenotypes is, however, far from clear. In a study published in the Genome Biology special issue on plant genomics, Mario Pezzotti from the University of Verona, Italy and colleagues demonstrate that the yearly climate in which grapevines (Vitis vinifera) grow plays a far greater role in affecting grape berry gene expression and metabolism than the specific vineyard environment. These findings advance our understanding of how wine vintages are produced.
In stark contrast with animals, plants are sessile organisms, and as such, cannot move to avoid stressful environmental conditions. This means phenotypic plasticity can have particularly striking consequences in plants. In the economically important and extensively cultivated fruit crop grapevine, it is essential that all grape berries mature at the same rate to generate high quality wine products. However, changing environmental conditions can lead to phenotypic plasticity and berries maturing at different rates, thereby detrimentally affecting the end quality of the wines produced.
To elucidate how grapevine berries perceive changes in the environment, in terms of transcriptomic and metabolomic responses, the authors grew Vitis vinifera cultivar Corvina in several different vineyards scattered across Italy. They collected berries at different developmental stages over three consecutive years and detected transcriptional changes occurring at a genome-wide level through microarray analysis. They also interrogated metabolic changes by performing mass spectrometry. In doing so, they found that the expression of genes encoding enzymes that regulate the biosynthesis of secondary metabolites, phenylpropanoid derivatives, are affected by different seasonal climates (on a year-by-year basis). This was matched with a concomitant change in the levels of phenylpropanoid derivatives.
They also showed that early stages of berry development are most responsive to environmental changes. Intriguingly, they found that growing grapevines in different vineyard environments does not cause significant differences in transcription and metabolism. This may help towards understanding how different terroirs – described as the collection of characteristics specific to a region, such as geography, geology and climate, that influence the cultivation of agricultural crops – affect the quality of wine produced.
Since climate change is predicted to impact plant growth, as well as crop yields and quality, it will be imperative to understand how plants perceive changes in the environment. The results gained in this study will, therefore, aid breeding programs and agricultural practices to optimize grape berry yields, and decrease the detrimental effects that phenotypic plasticity can have on berry uniformity.