A team of Spanish researchers have made the first complete analysis of the genome of seven varieties of melon, providing important new knowledge to understand the phenotypic variability of the fruit and to help increase the plant's yields and quality through selective breeding. Among the key findings, the researchers highlighted the great plasticity of the melon genome.
The researchers, from the Institute of Food Research and Technology and the Center for Genomic Research Agriculture in Barcelona, tried to close the gap between the expansion of genetic knowledge of melons and the understanding of important features, such as taste, size, and use of water.
The study is the first comprehensive analysis of the genetic diversity in melon and describes more than 4.3 million individual DNA sequence variants (SNP), along with a number of structural variants that include deletions, inversions, duplications, and movements of mobile elements.
The team demonstrated that highly cultivated and reproduced lines have a lower diversity, and wild melons had a bigger diversity. Similar studies on corn, rice and soybeans have also found that the most cultivated and domesticated varieties show lower genetic variability.
This new research reveals in great detail the genomic architecture of the melon genome. Overall, the research found 902 genes that may be affected by structural changes in DNA, 53 genes supposedly involved in disease resistance (29), the metabolism of the cell wall (10), the metabolism of aroma volatiles (9), sugar metabolism (4) and the biosynthesis of carotenoids (1).
The mobile elements, called transposons, have been very active during the recent evolution of melon and, according to the study, a number of transposon insertions may be linked to the variability of important agronomic traits, even between two closely related elite lines. The melon genome as a whole has evolved under the selective pressure of negative performance, eliminating harmful traits over time to improve its physical condition and adaptation.
"This study reveals the great plasticity of the melon genome, paving the way for future analysis regarding melon improvement, such as increasing the quality of the fruit or its resistance against pests and diseases. In a broader perspective, more studies like this will be needed to obtain new varieties of plants that can respond to the challenges in agriculture, including an increase in human population, scarcity of land and water, and the future impact of climate change," stated Josep Casacuberta, co-author of the study.
