Rapid detection of two pathogenically important Xanthomonas in rice using a loop-mediated isothermal amplification with lateral flow dipstick (LAMP-LFD)

Bacterial leaf blight (BLB) and bacterial leaf streak (BLS) are highly destructive diseases that severely impact rice production when outbreaks occur, especially BLB. Timely identification of Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc) as the causative agents of these diseases is crucial to prevent and manage their spread. This study developed a detection method called loop-mediated isothermal amplification with lateral flow dipstick (LAMP-LFD) to facilitate the surveillance of Xoo and Xoc in rice fields. LAMP-LFD using either Xoo80 or Xoc3863 to detect Xoo and Xoc, respectively was subjected to a heat block at 63 degrees C for 50 min. The LAMP products from both reactions were then hybridized with Xoo or Xoc specific probes in a single reaction and examined using a lateral pad with two tested lines. LAMP-LFD using Xoo80 or Xoc3863 demonstrated high specificity, yielding no false positives for other bacterial species. The sensitivity of LAMP-LFD using Xoo80 (with a detection limit of 2.5 x 104 cfu/ml) was ten-fold higher than Xoc3863 (with a detection limit of 2.5 x 105 cfu/ ml). To evaluate the efficacy of this approach, 42 rice field samples were tested, resulting in the detection of nine and seven positives for Xoo and Xoc, respectively with two samples indicating the presence of both. LAMP-LFD using either Xoo80 or Xoc3863 showed significant promise as a simultaneous detection tool for Xoo and Xoc surveillance and management of rice disease outbreaks, ultimately reducing rice yield losses.