ABSTRACT
The soil-borne plasmodiophorid Polymyxa graminis is a vector for Barley yellow mosaic virus (BaYMV), which can severely damage barley plants. Although 22 disease resistance genes have been identified, only a few have been used for breeding virus-resistant cultivars. Recently, BaYMV strains capable of overcoming the effects of some of these genes have been detected. In this study, green fluorescent protein (GFP)-expressing BaYMV was constructed and used to examine viral dynamics in inoculated barley plants. Leaf inoculations resulted in higher infection rates than root or crown inoculations. Additionally, inoculations of some resistant cultivars produced infections that were similar to those observed in a field test. The results of this study indicate that the GFP-expressing virus is a useful tool for visualizing virus replication and dynamics, and for understanding resistance mechanisms.
ABSTRACT
The emergence of begomovirus infection is one of the most important problems affecting production of a variety of vegetable crops worldwide. Infection by begomoviruses has been detected and spread rapidly on Cucurbitaceae and Solanaceae plants in Indonesia. A rapid and simple detection assay for begomoviruses under field conditions for routine sampling of plants is needed. Primers for a loop-mediated isothermal amplification (LAMP) assay were designed based on the sequences of three Indonesian begomoviruses, namely Tomato leaf curl New Delhi virus (ToLCNDV), Pepper yellow leaf curl Indonesia virus (PepYLCIV), and Tomato yellow leaf curl Kanchanaburi virus (TYLCKaV), infecting Cucurbitaceae and Solanaceae plants. LAMP assays using a Genelyzer™ III portable fluorometer with a toothpick method successfully detected these begomoviruses in infected melon, pepper, and eggplant samples. LAMP assays conducted during a field survey for detection of the three begomoviruses on 104 fresh leaves indicated that most of the samples were positive; the findings were confirmed by PCR using universal primers of begomovirus as a common detection method. These results demonstrate that this simple and rapid LAMP assay using a fluorometer portable device may be used to achieve real-time detection of begomoviruses under field conditions.