Submitted to: Chinese Journal of Tropical Crops
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/23/2010
Publication Date: 8/22/2010
Citation: Gao, S., Pan, Y.-B., Chen, R.-K. 2010. Detection of sugarcane yellow leaf virus by direct antigen coated enzyme-linked immunosorbent assay. Chinese Journal of Tropical Crops. 31(8):1356-1361. Interpretive Summary: Symptoms of sugarcane yellow leaf syndrome, a viral disease affecting sugarcane productivity worldwide, is often shown at late growth stage or in stressed plants when yellowing of the upper leaves throughout the midribs spreads gradually throughout the leaf tissue followed by necrosis from the leaf tip to the base. Detection of sugarcane yellow leaf virus (SCYLV) can be performed either by a nucleic acid-based RT-PCR procedure or by immunological methods. In this study, a direct antigen coated enzyme-linked immunosorbent assay (DAC-ELISA) method was optimized and used to determine the best sample location and sample volume for SCYLV detection. Juice from the top, middle, and bottom internodes and four leaves (top-visible dewlap, -1, +3 and +5) were used in the testing. The results indicated that there was significantly more SCYLV in the upper internodes than in the medium and lower internodes. In addition, there were also significantly more SCYLV in the top-visible dewlap (TVD) and -1 and +1 leaves than in the older +3 and +5 leaves. This finding suggests that younger tissue samples, either internodes or leaves, be collected for SCYLV detection during quarantine or germplasm evaluation for SCYLV resistance.
Technical Abstract: The L9 (34) orthogonal diagram was applied to optimize detection conditions of direct antigen coated enzyme-linked immunosorbent assay (DAC-ELISA) for Sugarcane yellow leaf virus (SCYLV) in sugarcane. Statistic analyses indicated that 150 µL of SCYLV in juice and leaf crude extract antigens was the optimal volume based on 1:1500 dilution of SCYLV-IgG and 1:20000 or 1:30000 dilution of alkaline phosphatase labeled goat anti-rabbit IgG. The reaction time was recommended for 1 hr or 2 hrs for the substrate coloring. Different SCYLV titer in different parts of cane and leaf were investigated using the optimized DAC-ELISA system. The titer of SCYLV was significantly higher in the upper internodes than in medium and lower internodes. In addition, SCYLV titer was significantly higher in the top-visible dewlap (TVD) leaf (+1 leaf) and the younger leaf (-1 leaf) than that in the older leaf (+3 leaf and +5 leaf). It is concluded that younger tissue (both internodes and leaves) was better samples for SCYLV detection due to a higher viral titer.