Researchers from Duke University in North Carolina produced pathogen-resistant crops without compromising the plant’s yield and fitness.
Plants are commonly attacked by microbial, viral or fungal pathogens. Improving crop production involves the applications of pesticides. In recent years, genetically modified pathogen-resistant crops that express a high level of immune proteins have been produced. One of the key regulators of a plant’s immune response is the gene NPR1. However, disease-resistant strains overexpressing NPR1, display weaker fitness, making them undesirable agriculture products. Much like the human condition of elevated immunity is problematic, NPR1 overexpression results in a resistant but less healthy plant. In other words, a gain in resistance was balanced by a penalty in fitness. To resolve this problem researchers attempted to create strains able to transiently activate immune responses only at the time of infection.
Two back-to-back papers published last month in Nature by Xinnian Dong and colleagues from Duke University in North Caroline report a successful implementation of the transient immune response. It is well understood that infection with pathogens triggers activation of the plant immune response at the transcriptional level, providing a pool of messengers that would be translated into immune-defense related proteins. Interestingly, in a recent study, Dong and colleagues identify that alongside with changes in gene expression, there are modifications in the translation efficacy. Alterations of translational machinery allows priority translation for messengers encoding protein products crucial for immune response. Researchers identified the sequence responsible for the induction of rapid translation, and found that when it was transferred to the gene of interest translational efficiency was accelerated. Then, the translation-enhancing element was fused to NPR1 gene to enable rapid translation of the NPR1 transcript. In order to create a gene which would be transcribed only at the time of infection, researchers also added pathogen-responsive elements to the sequence.
The researchers created genetically modified pathogen-resistant plants, able to elicit immune defense at the time of infection and fight the pathogen, but short enough to keep plants healthy. The immune-boost approach was demonstrated on genetically-modified strains of rice and Arabidopsis and provided protection against bacterial and fungal infections.
Pathogen-resistant strains of rice is of major importance in agriculture, where farmers frequently lose fields with crops due to infections. Especially, it’s important for developing countries, where farmers can always afford application of pesticides.
Research experts are optimistic about the possible applications of these findings. A next step is to test more pathogens on various crops with the boosted-immunity system. Hopefully, in 50 years, the use of chemicals in agriculture will be history and genetics will be used to control disease in plants.
Written By: Bella Groisman, PhD