Sweet basil faces two major challenges that affect both growers and the supply chain. Downy mildew is a devastating disease that can severely damage crops, discouraging many growers from planting basil altogether. Because basil is commonly consumed fresh, chemical treatments are often not a practical solution, leaving producers with limited options for disease control. In addition, basil is highly sensitive to cold temperatures after harvest. Exposure to low temperatures causes leaf browning and quality loss, reducing shelf life and increasing handling and transportation costs.
Two BARD-supported U.S.-Israel research teams is addressing these challenges through complementary breeding and gene-editing approaches. Previous work by researchers at Rutgers University and Bar Ilan University successfully introduced resistance to downy mildew using genes from wild basil species that retain traits lost during domestication. In doing so, the researchers also tackled a longstanding breeding challenge: preserving the flavor and aroma consumers expect while incorporating beneficial resistance traits. This BARD supported research project led to the first series of downy mildew resistant sweet basils now commercialized by both Israeli and US seed companies and grown by both farmers and home gardeners in Israel, the USA and globally.
Rutgers University has been working also closely with Israel’s Agricultural Research Organization (ARO) to support the development of new and improved basil varieties for longer shelf life, reduced postharvest losses through the supply chain, benefiting growers, distributors, and consumers alike.
Building on these advances, the current project between Rutgers and the ARO investigates a genetic connection between postharvest chilling tolerance and the development of undesirable licorice or anise-like aromas. Using advanced genomic tools, including CRISPR/Cas9 gene editing, the researchers aim to develop sweet basil varieties that retain their traditional aroma while showing improved resistance to chilling damage during storage and transport.
The team combines genetic, biochemical, and gene-expression studies to better understand the mechanisms behind leaf browning and identify targets for improvement. Preliminary findings indicate that reducing the activity of polyphenol oxidase (PPO) genes, which are associated with browning, may help protect basil tissue during cold storage.
This research project was featured at the recent BARD Lab to Market reception in Washington D.C. as part of a panel of BARD projects. Robert Mattera, a graduate student of Prof. Jim Simon of Rutgers University: “Our team took the approach to identify sources of genetic resistance and then bred that into traditional sweet basil ensuring the best qualities of the traditional basil remained but now with the genes for downy mildew resistance. This was challenging yet was quite successful. With Rutgers and Bar Ilan working together but with each using different approaches, this synergy led to a series of new and popular disease resistant sweet basil varieties. The work is not over as the pathogen over time continues to change but we are developing new technologies that are being used to create the platform for newer sources to meeting the changing nature of the pathogen to retain genetic resistance growers and the basil industry.
