Historical lessons in crop breeding

There will be seven billion people on this planet before the year is out, a fact noted by United Nations Secretary General Ban-Ki Moon in a statement marking July 11 as World Population Day. That number is expected to rise to eight billion in 2030, and to nine billion halfway through the century.

To meet the needs of this growing population, scientists around the world are working on improving breeding strategies to produce more food from crops faster. As part of this approach, on July 10, an international team of researchers announced that they’d determined the complete genetic code of the potato, one of the most important staple food crops besides rice and corn, and a challenge to crop breeders. Researchers will apply the genetic information gathered over the past five years to the study of traits such as pest and disease resistance in order to produce new varieties of potatoes that are more tolerant of plant stressors such as disease, and also have more nutrients.

The potato wasn’t the only important food crop to appear in the headlines recently, but researchers working with bananas and coconuts weren’t content to just look at DNA code. Instead these two teams took a slightly different approach to improving crop breeding techniques, combining studies of historical records and genetics to trace these crops back to their birthplaces, which turn out to be quite close to home.

More than 100 million tons of bananas are produced every year in many different varieties, but the problem is the plants on which these fruit grow all stem from just a few ancestral plants, making the crop extremely vulnerable to disease. For this reason, noted the team of researchers in a study first published online, the week in July 4 in the journal Proceedings of the National Academy of Sciences USA, “a prerequisite for banana improvement is to reconstruct as precisely as possible the domestication pathways of the major [cultivar] groups.”

Tracking the banana plants’ across the world allows the researchers to identify the genetic changes associated with changing habitats and with ancient breeding strategies. For example, the team compared records of what various banana varieties are called and applied genetics to show that some banana plants found in Africa and in the Philippines have similar characteristics and likely came from the same place in the vicinity of the Celebes Sea.

Staple source

A similar approach was employed by plant biologist Kenneth Olsen of Washington University and his colleagues, who reported on how coconuts spread out from two main points of origin to become a staple source of food, fuel and building materials in several countries.

“Within the Pacific basin, human influence on coconut population is most readily detectable in the prehistoric introduction of southeast Asian coconuts to the New World coast,” Olsen and his colleagues wrote in the study, adding that this introduction took place more than two thousand years ago.

In the June 22 issue of the journal Plos One, the researchers analyzed more than 1,300 coconut samples from around the world to determine that there are two main types of coconuts, one which originated in south Asia and another which came from southeast Asia, specifically the Philippines.

One anecdote shared by Olsen and his colleagues combines genetics and trade route historical records to explain the origin of the coconut trees found along the coasts of Mexico. These trees turn out to share the same genetic characteristics as the coconut trees in the Philippines, suggesting, the researchers said, that Spaniards brought the coconut to North America during the period a few centuries ago when Spain controlled both nations.

“The big surprise was that there was so much genetic differentiation clearly correlated with geography, even though humans have been moving coconuts around for so long,” said Olsen in a statement.

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