A genomic analysis of 263 wild and domesticated peach varieties has revealed the molecular mechanisms behind environmental adaptations in the beloved summertime snack, opening up the possibility for easier production of hardier, tastier fruit.
Until now, agricultural scientists have largely focused on how human activity affects the genome of common fruits such as apples, tomatoes, plums and peaches. Looking to examine how environmental factors influence adaptations, the researchers who conducted this analysis chose peaches as a genomic model because they grow in a wide range of environments and display myriad genetic adaptations to suit them.
"Before this study, there's no genetic targeting information," said plant genomics professor Zhangjun Fei of the Boyce Thompson Institute at Cornell University, who is also co-lead author of the study published March 9 in Genome Research. "If I wanted to breed for dark tolerance, drought tolerance, I don't know where to begin because I don't know which genomic region or which molecular marker I should use."
To assess the genetic relationships between the diverse group of peach varieties and their underlying traits, Fei and his colleagues created a genomic variation map and proceeded to conduct genomic scans as well as genome-wide environmental association studies. These studies helped reveal over 2,700 genomic loci, or locations of genetic information, connected to 51 different environmental variables, such as soil pH, annual precipitation and latitude.
The genetic adaptations that allow peaches to survive in drought, in darkness or in high altitudes with strong UV light exposure can also govern qualities important to human taste buds. According to Fei, fruits grown in more stressful conditions tend to taste better. Peaches grown in low light, for example, are sweeter than those grown in brighter environments, though their trees yield fewer fruit.
"Kind of like in humans, for example, to live well, you have to exercise or do something better, right? The peach is the same," Fei said in an interview with The Academic Times. "They want to make themselves better. So, over a long time, millions or hundreds of thousand years, they changed their genetic element."
For roughly the past 100 to 1,000 years, peach growers have striven to breed for taste, disease resistance and yield rather than accounting for environmental adaptation. Now they might be able to, because Fei and his colleagues have identified the genes behind these adaptations, along with their molecular mechanisms that can also affect taste, yield and hardiness.
Currently based in Ithaca, New York, Fei recalls the flash freeze of 2016 that devastated peach crops in the Empire State and New Jersey. Using the adaptive relationships the researchers uncovered, they believe they can help farmers grow better peaches and protect the fruit from sudden environmental disturbances. All they need to do is use the cold-resistant genes they've identified and add them to their desired variety, or cultivar.
"I joke to them that we want to generate a super peach that tests well and tastes great and also can target all kinds of different environments, even in dark, cold and high altitude, in all kinds of weather changes — doesn't matter," Fei said.
Creating the super peach may sound easy enough, knowing the right "super" genes, but doing so will still require the same techniques peach growers have relied on for generations: crossbreeding "elite" cultivars with lesser ones. This process is slow because frost-tolerant peaches, for example, not only introduce their most desired genes when they breed with other cultivars but also bring along "background noise," Fei said, which can negatively affect the resulting crossbreeds.
According to Fei, over the next 10 years, advancements in gene-editing technology like CRISPR may be able to bring these extraordinary peaches closer to reality.
In future research, Fei and his colleagues in China want to conduct a similar study using 1,000 peach varieties, though that project is still being planned as the researchers secure funding and materials.
The dawn of the super peach will just have to come a little later.
The study, "Genomic analyses provide insights into peach local adaptation and responses to climate change," published March 9 in Genome Research, was authored by Yong Li, Chinese Academy of Agricultural Sciences and Huazhong Agricultural University; Ke Cao, Gengrui Zhu, Weichao Fang, Changwen Chen, Xinwei Wang, Qi Wang, Tiyu Ding, Jiao Wang, Liping Guan, Junxiu Wang and Lirong Wang, Chinese Academy of Agricultural Sciences; Nan Li and Sanwen Huang, Chinese Academy of Agricultural Sciences, Shenzhen; Wenwu Guo, Huazhong Agricultural University; Pere Arús, Centre de Recerca en Agrigenòmica; and Zhangjun Fei, Cornell University and Robert W. Holley Center for Agriculture and Health.