改善土豆块茎的口味

By honing in on the mysterious potato genome and its tuber（块茎） – its edible¹（可食用的） portion – researchers are unveiling the secrets of the world's most-important nongrain food crop. Robin² Buell, Michigan State University plant biologist, is part of an international research team that is mapping the genome of the potato. In the current issue of Nature, the team revealed that it accomplished³ its goal, thus quickly closing the gap on improving the food source's elusive⁴ genome.

The potato is a member of the Solanaceae, an economically important family that includes tomatoes, peppers, eggplants, petunia⁵（矮牵牛花） and tobacco. Despite the importance of tubers, the evolutionary⁶ and developmental mechanisms⁷ of how they grow and reproduce remained elusive – until now, Buell said.

"This is the first plant with a tuber to be sequenced," she said. "It will still take researchers awhile to use the genome information to improve its agronomic⁸（农事的） traits, such as improved quality, yield, drought tolerance⁹ and disease resistance. But our most-recent research will accelerate efforts on improving potato varieties and help close the gap in bringing a better potato to the farmer."

Even though potatoes have flourished on every continent except Antarctica, they are susceptible¹⁰ to pests, pathogens and inbreeding depression (passing on undesirable¹¹ traits that lead to weaker offspring). Ireland's 19th century potato famine is one illustration of how the collapse¹² of such an important crop can affect a large population.

In 2009, the research team was able to identify the potato's genetic¹³ blueprint¹⁴. During the last two years, the team has worked to determine which genes¹⁵ are expressed in specific tissues, such as the tuber versus¹⁶ the flowers, to better understand the growth and development of the plants' tuber. The team focused on two types of potatoes, which provided data on a wide spectrum¹⁷ of the potato's genomic diversity.

"Since our initial release of the sequence in 2009, we have improved the quality, identified and analyzed¹⁸ the genes and analyzed the genetic basis for biology of the potato and its tuber," Buell said. "Our analysis revealed that the potato genome contains 39,000 protein coding genes, of which, 90 percent of the chromosomal¹⁹（染色体的） positions are now known."

Additionally, researchers were successful in identifying possible mechanisms by which inbreeding depression occurs. All told, the results could help potato breeders reduce the amount of time it takes to develop new varieties, which typically takes around 15 years.

Buell is looking to continue her research to address these evolutionary inadequacies as well as expand to include more varieties of potatoes as well as other members of the Solanaceae family.