Chinese scientists achieve new breakthrough in breeding hybrid potatoes –

Employees sort potatoes at a potato planting center in Shijie County, northwest China’s Ningxia Hui Autonomous Region, March 2, 2023 (Photo/Xinhua)

Chinese scientists have made new progress in breeding hybrid potatoes by using evolutionary genomics to identify harmful mutations, which may help shorten the breeding process and generate more and better varieties of potatoes.

This breakthrough, by a research team from the Shenzhen Agricultural Genomics Institute of the Chinese Academy of Agricultural Sciences, has been published online in the latest issue of the scientific journal Cell.

Potatoes are the most important tuberous food crop and one of the staple crops in most countries around the world, including China. Compared with other staple crops, potatoes need less water and can be grown in a wide range of areas, said Wu Yaoyao, a lead member of the research team.

“But it takes a long time to breed a new potato variety. The potato variety used in McDonald’s fries has been bred for more than 120 years,” Wu said.

The main reason is that potatoes are tetraploid, which means they have four sets of genomes, and depend on asexual reproduction through tubers, which have a long reproductive cycle and low reproductive efficiency, while the tubers are also easily infected with diseases and susceptible to pests. Wu said.

The research team launched the “Potato Everywhere Project” with the goal of shifting potato reproduction from asexual to sexual, from tuber-dependent to seed-dependent, and guiding potato breeding using genomics and synthetic biology.

Wu explained that in order to breed consistent, high-quality potato varieties, scientists need to obtain highly homozygous strains through continuous self-fertilization, so that commercial hybrid lines with consistent characteristics can be produced.

However, during the long history of asexual reproduction of potatoes, a large number of hidden harmful mutations have accumulated. Once self-fertilized, these previously ‘unseen’ mutations will reveal their detrimental effect on plants such as reduced viability, sterility, reduced disease resistance and productivity. This phenomenon, known as inbreeding depression, is a major hurdle in breeding potato hybrids.

“Overcoming harmful mutations is the most difficult task in this research,” said Huang Sanwen, head of the research team.

The researchers collected and compared genomic information from 100 Solanaceae and Convolvulaceae subjects with an accumulated evolutionary history of 1.2 billion years. Potatoes belong to the Solanaceae family, while sweet potatoes belong to the Convolvulaceae family.

“We noticed that after 1.2 billion years of evolution, if a gene or a piece of plant DNA remains unchanged, it indicates that it is particularly important. We identified the most conserved and unchanged loci in the genome,” Huang said.

“If these gene locations change, they are more likely to have adverse effects on potatoes, namely harmful mutations. We have explored the full picture of harmful mutations at the level of the entire genome, and created the first two-dimensional map of potato harmful mutations. Therefore, we can search for and eliminate harmful mutations more comprehensively and efficiently.

The research team also developed a new whole-genome prediction model that incorporates deleterious mutation information into it, which could significantly improve prediction accuracy for traits such as yield, plant height and tuber shape by 25 to 45 percent. The model can help breeders make early breeding decisions, thus reducing breeding costs and shortening the process of potato reproduction.

The research could increase the efficiency of potato breeding by about 50 percent, providing a basis for improving the variety. Huang added that this technology can also be applied in improving other crops, such as sweet potatoes, fruits and sugar cane, in addition to many tropical crops.

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