Sequencing the apple genome sheds light on genetic diversity and explains why no two seeds grow the same tree

Genome sequencing is a widely used and only recently developed laboratory technique which determines the complete DNA sequence of an organism’s genome. In humans, this was popularised and became a more widespread technique by the Human Genome Project. However, a lesser known use is how this is used on crops and within agriculture. 

The apple genome is a highly complex, highly heterozygous and diploid genome. The importance of its heterozygous feature is a result of apple trees requiring cross pollination with different varieties to produce its fruit, where being heterozygous simply means that it has two different alleles of genes. This cross pollination results in the apples grown inheriting two different sets of genes, just as humans would. Apple seeds start the growth of a healthy apple tree and are a result of cross pollination from different trees. Therefore, a massive amount of genetic diversity is created between trees and species, meaning that no two seeds are the same and no two seeds would grow the same tree. 

In terms of commercial production, rather than growing by their typical sexual reproduction via pollination, facilitated by bees, apples are grown asexually. The asexual reproduction gets highly specific types of apples, and this is done by grafting or budding. Whilst this method is consistent in producing high quality fruit, it carries long term biological risks due to trees and apples being genetically identical, introducing problems such as losing all the crops grown and the accumulation of mutations. This is just one example of the importance of genetics diversity within a species. 

Having now sequenced the apple genome, it is expected that this will speed up the apple breeding process, making it more accurate and efficient as well. It helps for future agricultural research, helping researchers understand apple characteristics from the sequenced genes such as flavour, texture and disease resistance. This demonstrates the importance of sequencing the apple genome to show that genome sequencing is a tool of growing importance in the agricultural world.