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Cacao is considered to be the food of gods and is one of the most sought-after food. According to an article on the website Willie's Cacao, Theobroma cacao has three main varieties. These are criollo, forastero, and trinitario, although there are multiple hybrids that exist from each strain.

Each strain of cacao has their own unique characteristics, and so does their hybrid variants. Now, a team of molecular geneticists is studying the genomes of multiple strains of cacao to further understand plant diversity.

They published their study, titled "Genomic Structural Variants Constrain and Facilitate Adaptation in Natural Populations of, The Chocolate Tree," in the Proceedings of the National Academy of Sciences.

 Comparisons of Multiple Strains of Cacao Trees Provide Insights on Genomic Structural Variants Responsible for Plant Diversity
(Photo: Pixabay)
Comparisons of Multiple Strains of Cacao Trees Provide Insights on Genomic Structural Variants Responsible for Plant Diversity

Genetic Structural Variants Play a Significant Role in Adapting to the Environment

According to Penn State News, a group of scientists studied the multiple strains of cacao trees to understand the role of genomic structural variants in regulating gene expression and chromosome evolution that gives rise to plant diversity.

"The genomes of different populations of cacao trees are 99.9% identical, but it's the structural variants in that one-tenth of 1% of their genomes that accounts for the plant's diversity in different regions and its adaptation to climate and various diseases," Professor Mark Guiltinan said in the news release.

He added that their study creates the link between structural variation and the plant's ability to adapt to a local environment. They compared chromosome-scale genome assemblies of 31 naturally occurring populations of Theobroma cacao to investigate the fitness consequences of genomic structural variants in natural populations. They found 160,000 structural variants out of 31 cacao strains.

Although scientists have long known that genomic structural variants play important roles in the adaptation and speciation of animals and plants, their overall influence on the fitness of plant populations is not yet well-understood.

Penn News reported that researchers found that most structural variants are deleterious, which means they constrain the adaptation of the cacao plant. Researchers think this might have been caused by impaired gene function and an indirect result of gene recombination.

Nevertheless, researchers were able to identify individual structural variants that have similar local adaptation, and many of them are linked to genes differently expressed between cacao populations. This includes the genes resistant to pathogens, which is an important local adaptation trait.

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Role of Structural Variants in Genetics

A paper in NCBI defines structural variation as a region of DNA that is approximately 1 kb and larger in size. It could include copy number variants, which often overlap more than once in the genome with segmental duplications or regions of DNA less than 1 kb.

According to a study titled "Structural Variant Calling: The Long and the Short of It" published in BMC: Genome Biology, recent studies in structural variants have established that they play an important role in medicine and molecular biology.

They give insights into their role in various diseases, gene expression regulation, ethnic diversity, and large-scale chromosome evolution, which determines the diversity among species within populations.

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