The “art” of plant breeding is ancient. For ages, humankind has sown seeds collected from favored plants, slowly but surely evolving more nutritious, higher-yielding crops. Breeders, such as Luther Burbank, were quite effective in operating within this intuitive world of breeding.
Genetic “science” and the understanding of the transmission of traits is relatively new. Gregor Mendel’s work with pea plants and the transmission of traits from parent to progeny dates to the 1860s but was not widely recognized until 19001.
Today, the world of potato breeding is evolving in new and very productive ways that enhance the likelihood of genetic improvement. The research department at Potatoes USA has a front-row seat to view these exciting changes. The following is an overview of just a few seismic shifts in breeding, per interviews with important U.S. breeders and scientists2.
Diploid Breeding (an SCRI project, often referred to as Potato 2.0)
This Specialty Crop Research Initiative (SCRI) funded project team is dedicated to simplifying the potato genome. Commercial potato varieties are polyploids with four sets of chromosomes. However, it is easier to impart desirable traits into breeding stock with two sets of chromosomes (diploid) versus four. For example, we now know of genes that contribute strong, multi-strain resistance to late blight. These genes could be added to inbred lines through crossing and stacking them over time, resulting in greater potential for durable late blight resistance.
Marker Assisted Selection
James Watson and Francis Crick described the double helix structure and molecular composition of DNA in 1953. Decades later, genetic sequencing technology became available, with costs dropping steeply in recent years. High throughput genetic analyses using tens of thousands of molecular markers is becoming routine and accessible to most labs. These developments open the door for marker assisted selection. For example, sequence DNA in offspring from two breeding lines, one with PVY resistance, and the other lacking that resistance. You can identify short DNA sequences (“chromosome regions”) that appear only in PVY-resistant plants. These sequences are used to design genetic “markers” for PVY resistance. Now you have a fast, inexpensive way to eliminate candidates early in the selection process (that lack PVY resistance – an attribute hard to see or measure in traditional ways). Note that efforts are underway to use this technique for several common potato diseases.
Polyploid Breeding (a second SCRI project recently initiated)
Marker Assisted Selection is just one example of new technologies to enhance the toolset of breeders and predict the value of breeding candidates. The polyploid breeding project takes this a step further, looking at the efficient evaluation of the potato candidate’s entire genome to predict breeding success.
Specific steps include:
- Build the Breeder Tool Set– Look at predictive software used for other crops with an eye to modification for polyploids. Develop a new computational tool for predicting candidate success.
- Test the Tools– Validate predictions using over 1000 clones in six potato breeding programs; and utilizing the historical results in the National Chip Program (NCP) trial and National Fry Processors Trial (NFPT) databases.
- Train the Breeders– Socialize the use of the most effective new breeding tools, broadening the toolset of polyploid breeders.
Trial Information Sharing (NCP chip trials and NFPT fry trials)
Lastly, building a shared dataset (Medius.Re) of trial results conducted in multiple locations has enhanced the evaluation of potential new potato varieties. These trials also provide valuable information to the breeder about processing characteristics and taste evaluations, which is critical information for assessing whether the candidate will succeed in the market.
All these efforts combine the art and science of breeding with the latest technologies to create, enhance, and improve, a whole new ecosystem of potato varieties. Software, genetic sequencing, and simplified diploid breeding stock enhance candidates’ ability to carry desirable traits. It is a whole new world of breeding.