Screening and Identification of Garlic Leaf Blight (Pleospora herbarum)-Resistant Mutants Induced by Ethyl Methane Sulphonate

Garlic (Allium sativum L.) is a popular condiment used as both medicine and food. Garlic production in China is severely affected by continuous cropping and is especially affected by leaf blight disease. Garlic is sterile, so it is very important to develop specialized genotypes, such as those for disease resistance, nutritional quality, and plant architecture, through genetic modification and innovation. In this experiment, we applied the induction method using EMS to mutate garlic cloves of cultivar G024. From the mutations, 5000 M(0) mutants were generated and planted in the field. Then, 199 M(1) mutant lines were screened according to growth potential and resistance to leaf blight. From M(2) to M(3), 169 generational lines were selected that grew well and were resistant to leaf blight in the field. Thereafter, their resistance to leaf blight was further analyzed in the lab; 21 lines resistant to leaf blight that had good growth potential were identified, among which 3 mutants were significantly different, and these were further screened. Also, transcriptome analysis of two mutants infected with Pleospora herbarum, A150 and G024, was performed, and the results revealed 2026 and 4678 differentially expressed genes (DEGs), respectively. These DEGs were highly enriched in hormone signaling pathway, plant–pathogen interaction, and MAPK signaling pathway. Therefore, the results provide a theoretical and technical basis for the creation of garlic germplasm resistant to leaf blight.