As for why smaller genomes can result in smaller cells, the scientists said that there is not necessarily any link between plant size and either genome or cell size.
"However," Roddy said, "there is a strong link between genome size and cell size because the minimum size of a cell is defined by the size of the nucleus, where the genome resides. So, genome size acts as a hard, lower boundary on the minimum size of the cells."
The same phenomenon occurs in animals and all other eukaryotes, prior research suggests. The human genome contains about 3 billion chemical units of DNA, or base pairs. In contrast, the seemingly simple small creature Amoeba dubia has 670 billion base pairs, according to the organization Genome News Network.
Numerous factors aside from genome size can affect cell size, though, such as environmental conditions and biological factors. Having small cells is not even always beneficial because plenty of functions may require large cells.
"For example," Roddy said, "desert plants frequently store water inside their cells to tolerate prolonged drought conditions, and this means they have large cells."
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Nevertheless, smaller genomes — and therefore smaller cells — have proven to be very beneficial to flowering plants. Their emergence irrevocably altered global climate and all life on Earth.
The scientists explained that because of their high metabolic rates, flowering plants promote faster rates of cycling of water, carbon, and nutrients. Many angiosperms are also annual plants, which rely on short life cycles and fast physiological rates. Flowering plants may help to maintain wetter, less seasonal tropical forests, due to their higher transpiration rates.
"Furthermore, the angiosperms are the basis of our global food supply," Roddy said. "Humanity would not survive without them."