Triticeae Genomics and Genetics, 2025, Vol.16, No.2, 79-91 http://cropscipublisher.com/index.php/tgg 88 induced systemic resistance. Essentially, the transgenic plant might be not only directly attacking the pathogen with Mtk but also turning on a bunch of its native defenses more strongly. That’s a double benefit: Mtk kills fungi and also signals the plant to gear up its overall defenses. ICRISAT’s studies demonstrate that using AMPs from non-plant sources is a viable strategy to boost plant disease resistance. It opens the door to a wide range of AMPs (from insects, animals, microbes, etc.) as potential genetic resources for engineering disease-resistant crops. They do note, however, the need to evaluate each AMP’s expression stability and safety. We have to ensure that an AMP doesn’t, for example, end up harming beneficial microbes or affecting plant processes negatively. For Mtk in barley, they observed no adverse effect on plant growth. They even checked if it would affect brewing - since brewing involves yeast fermentation, one might worry an antimicrobial peptide could inhibit brewing yeast. They reported that overexpressing Mtk did not significantly interfere with the microorganisms used in brewing, which is a relief. Going forward, ICRISAT plans to stack AMPs with other resistance genes to create crops with multi-faceted resistance. For example, adding an AMP gene to a plant that already has some traditional resistance genes could give an even more robust disease resistance profile. Their work so far suggests that AMPs are a promising tool in the toolbox. And importantly, their transgenic barley lines did not show unusual phenotypes or yields - meaning the trait is agricultural viable. For barley, which can be susceptible to numerous fungal diseases at once (leaf, stem, and head diseases), having a broad-spectrum approach like AMPs could be extremely valuable. It’s somewhat akin to giving barley an immune system upgrade with components from other organisms. As long as these components are safe and don’t compromise the plant’s normal function, this approach may become an important part of future disease-resistant crop breeding. 7.3 University of Copenhagen: barley overexpressing BDAI (α-amylase inhibitor) The University of Copenhagen has developed a specialized barley strain that overexpresses barley's own dimeric α-amylase inhibitor (BDAI-1). BDAI is a protein native to barley grains that prevents pests and certain fungi from breaking down starch for nutrients. It works by "blocking" the enzymes used to break down starch, starving the pathogens or pests. They cloned the BDAI gene from barley and used cis-transgenic methods to express it in large quantities. Because the gene is native to the barley plant, no foreign genes are introduced, making it easier to pass biosafety and regulatory reviews (Iimure et al., 2015). Experiments have shown that this transgenic barley significantly improves resistance to stored-grain pests, such as the grain borer. Pests that ingest this seed have fewer survivors and slower growth. In vitro experiments also show that BDAI inhibits the growth and toxin production of fungi such as Fusarium verticillioides (Mendes et al., 2015). After inoculation in a greenhouse, these barley kernels showed a lower incidence of fungal infection and lower levels of fungal DNA. This is believed to be because BDAI prevents the fungus from utilizing starch in the kernels. BDAI is already a protein in barley seeds, so increasing its expression did not affect plant growth. Agronomic traits such as plant height and 1000-kernel weight remained similar to those of normal barley. Furthermore, this method provides long-term protection during barley seed storage or sowing, reducing pesticide use. This type of "cis-transgenic" barley has great potential for development of disease- and insect-resistant beer or feed barley, and also better meets biosafety requirements. 8 Concluding Remarks This research demonstrates that antifungal protein genes from plants or even insect sources can be stably inherited and effectively expressed in barley. We achieved high levels of foreign chitinase and antimicrobial peptide accumulation in the transgenic barley at both the RNA and protein levels. Functional tests revealed that barley plants expressing these antifungal proteins have significantly improved resistance to several major fungal diseases - notably powdery mildew, leaf rust, and Fusarium head blight - compared to normal barley. Under controlled greenhouse infections, disease indices in the transgenic barley were reduced by more than half, and some transgenic lines were virtually immune to powdery mildew and other fungal challenges. In field conditions with natural disease pressure, the transgenic lines also showed much lower infection rates and suffered far less disease damage than the control plants.
RkJQdWJsaXNoZXIy MjQ4ODYzNA==