A peanut plant genetically infused with the RUBY gene reporter. Credit: Dr. Vijay Sheri, Texas Tech University
The answer came in the form of betalains. These naturally occurring pigments are responsible for the bright colors we see in beets, dragon fruit, Swiss chard and other plants. Zhao and his colleagues saw betalains as a natural marker that could be used to track the activities of specific genes. They created RUBY as a synthetic gene that converts the amino acid tyrosine into red betalain. This “cassette” is then inserted into the plant’s genome at the targeted genes of interest. If those genes are expressed, say in the florets of cauliflower or leaves, then the area of focus will bloom with a clear red hue.
When RUBY was first announced to the scientific community, plants were the main focus. But the initial description of the tool in the landmark paper published by Zhao and his colleagues teased the future potential of such a novel technology: “We envision that RUBY can be adapted for applications in some microbes and animals,” they noted, “because the substrate tyrosine exists in all cells.” In one demonstration in live animals, RUBY was used to generate pink silk from silkworms.
As the research applications of RUBY continue to multiply, another use has emerged. Educators are finding that RUBY can be implemented as a powerful teaching aid. In classrooms and teaching laboratories, educators are now using RUBY’s inexpensive and easy-to-use features to teach biological concepts and tools such as genome editing.
RUBY is also spreading into the business sector. In the name of open science, RUBY is complimentary for use in academic labs and classrooms. However, industry users pay a fee to license the technology in commercial business applications. UC San Diego’s Office of Innovation and Commercialization reports that 10 commercial licenses have been issued for RUBY in the past two years, spanning from giant multinational Scotts Company (now known as Scotts Miracle-Gro), the producer of consumer lawn and garden products, to tiny spinoffs and startup firms.
Cquesta, a recently launched San Diego-based company spun out of the Salk Institute, is developing new technologies to help plants sequester carbon in soil and make crops more resilient in the face of rising temperatures. RUBY is helping the company visualize genetic changes in crops, including corn, soy, canola and sorghum, focusing on the plant’s root systems.