A novel indicator plant to test the hypersensitivity of phytopathogenic bacteria

Hypersensitive response is an important, definitive test to separate plant pathogenic bacteria from saprophytes. The current standard protocol uses tobacco and four o'clock plants as indicators for Gram negative and Gram positive phytopathogenic bacteria, respectively, and inoculation is accomplished by infiltrating bacterial suspensions into intact leaves. Both plants, especially the four o'clock, have thin leaves which make inoculation difficult, sometimes leading to inaccurate tests. Here we propose the use of Sedum hybridum as an alternative indicator plant. Sedum plants are readily available, easy to propagate and fast growing. Their leaves are much thicker, thus infiltration of a bacterial suspension is easier compared to tobacco and four o'clock. Additionally, sedum plants can be used universally to test both Gram negative and Gram positive phytopathogenic bacteria.