Promoter efficiently expressing in cotton root and application thereof

The invention relates to a plant gene promoter and an application thereof, belonging to the field of biotechnology. The invention obtains a promoter pgbv-5 of a Gossypium barbadense verticillium wilt resistance-related gene Ve-5. Place analysis shows that the promoter contains a disease resistance-related regulatory element, salicylic acid, auxin, gibberellic acid, ethylene, methyl jasmonate and other hormone-induced elements. Meanwhile, the promoter sequence also contains a number of light regulatory elements. The promoter allows efficient expression of a target gene at root, especially, the expression level at root cap, growing point and partial elongation region is the highest. The expression level is very low or is nearly zero in leaves, flowers and legume tissues. After Arabidopsis thaliana plant is treated by salicylic acid, gibberellin or indoleacetic acid, GUS (beta-glucuronidase) activity is remarkably increased, which indicates that the promoter is a root hormone-induced promoter.