Fecha de publicación: -- Fuente: WIPO "tomato" The present disclosure discloses a citrus genus gene fragment related to Huanglongbing resistance of plants and application thereof. The gene promoter fragment has a nucleotide sequence as shown in SEQ ID NO. 1, and includes a plurality of characteristic motifs that bind to a disease-resistant transcription factor MYC2. The transcription factor MYC2 can bind to the characteristic motifs and exert transcription factor activities to transcriptively activate expression of a plant Huanglongbing susceptibility gene PUB21. The present disclosure clarifies a tight gene feedback loop formed by the susceptibility gene PUB21 and a ubiquitinated substrate thereof, i.e. the transcription factor MYC2, and provides a breeding strategy for enhancing disease resistance of plants by reducing and/or eliminating an expression level of the susceptibility gene PUB21. The resistance breeding strategy can effectively resist replication and spread of a Huanglongbing pathogen and is of great significance to prevention and control of Huanglongbing in plants.