Lateral Flow Immunoassay Detection of Ralstonia syzygii subsp. celebensis Causing Banana Blood Disease in Symptomatic and Asymptomatic Banana Plants

Banana blood disease caused by Ralstonia syzgii subsp. celebensis (Rsc) is one of the most well-known and most critical phytopathogenic bacteria which causes severe bacterial wilt in banana and considerable economic losses to the growers. Unlike common bacterial wilt caused by R. solanacearum, Rsc did not cause infection in solanaceous plant. The banana blood disease caused by the bacteria is fatal to the banana industry in Malaysia and other parts of the world. In an effort to better control the disease, a swift, sensitive, and user-friendly method for routine diagnostics is essential. This study aimed to raise polyclonal antibodies (pAb) from rabbit against whole cells of Rsc and to develop a lateral flow immunoassay (LFIA) strip utilising the purified IgG to detect the pathogen. We have developed the Rsc LFIA strips and obtained the sensitivity limit of 104 CFU/mL Rsc. The strip performance in real samples were performed using samples from symptomatic and asymptomatic banana plants consisting of samples from the pseudostems, petioles and leaves. The LFIA results were validated using polymerase chain reaction (PCR) with 100% correlation. The results showed that the strips were able to detect Rsc in all symptomatic samples. Additionally, positive result was obtained from the pseudostem of the asymptomatic samples. This study indicated the capability of the LFIA strips to detect Rsc not only in symptomatic plants but also before visible symptom appearance was observed which offered the potential for the LFIA strip to be used as a handy screening tool to detect Rsc.