Molecular mechanisms underlying heat or tetracycline treatments for citrus HLB control

Abstract

Citrus disease: Fighting one infection with another Heat treatment to cure citrus plants of Huanglongbing (HLB) works not by killing the HLB bacteria directly but by triggering a virus to attack them. HLB, also known as citrus greening because it causes plants to produce green, bitter fruit, threatens citrus production worldwide. No commercial-scale treatments are available, but thermotherapy, growing plants at 40 °C or higher, has recently been shown to reduce symptoms. YongPing Duan and Fang Ding at the USDA Horticultural Research Laboratory in Florida investigated how the thermotherapy works. They found that heat treatment triggered a stress response in a virus asymptomatically infecting the bacteria, causing it to multiply rapidly and killing the HLB bacteria. Heat treatment eliminated both the bacteria and HLB symptoms; application of the antibiotic tetracycline produced the same effect. These results may help in identifying potential treatments for HLB.