Establishing a portable diagnostic method for identifying plant pathogens is essential to prevent the spread of plant disease, especially in field and customs inspections. Leptosphaeria maculans (L. maculans) is an aggressive fungus, which causes severe phoma stem canker of Brassica napus, responsible for major yield losses of oilseed rape worldwide. In this study, CRISPR/Cas12a-based detection system and recombinase polymerase amplification (RPA) technique were employed to develop a rapid and sensitive detection method for identifying L. maculans. The involved RPA pre-amplification and CRISPR/Cas12a cleavage confer considerable sensitivity and selectivity, which can be finished within 45 min with a LOD of 4.7 genomic DNA copies. This detection system was further developed to two portable platforms, i.e., one-pot lateral flow detection and all-in-one chip lateral flow assay (AOCLFA), which integrates the lyophilized recombinase polymerase amplification (RPA) reagents and lyophilized Cas12a cleavage reagents in one tube or chip. The developed portable platforms have flexible portability and simple operation for the detection of L. maculans from plant tissues in the field. The proposed portable suitcase containing the minimum equipment, regents, and AOCLFA meets the practical needs of rapid on-site disease screening of plant fungi, port quarantine, or pathogen spreading control.

Plenodomus lindquistii (basionym: Leptosphaeria lindquistii) is the most prevalent fungus pathogen causing the black stem disease in sunflower. To date, only one whole-genome sequence is reported in NCBI, but no complete gene annotation has been submitted. Herein, we sequenced a Leptosphaeria lindquistii isolate from sunflower seeds imported from the United States using Oxford Nanopore long-read sequencing and Illumina short-read sequencing. We generated a 38.6-Mb genome assembly consisting of 29 contigs with an N50 of 1.689 Mb and a maximum length of 5.316 Mb. In the genome assembly, we identified 13,481 protein-coding genes, of which 12,531 were annotated. The high-quality assembly and annotation of the Leptosphaeria lindquistii genome will allow us to conduct further studies for the specific identification of pathogens causing sunflower black stem disease and provide a better understanding of the infection mechanisms of Leptosphaeria lindquistii.