Mechanical transmission of maize rayado fino marafivirus (MRFV) to maize and barley by means of the vascular puncture technique

Abstract

Maize rayado fino marafivirus (MRFV) was mechanically transmitted to kernels of three Costa Rican maize cultivars by the vascular puncture technique. A transmission rate of up to 43·2% was obtained for cultivar HC-57. The rate of MRFV transmission to maize was possibly affected by the morphology of the kernel, which may influence physical access to the vascular tissue after water imbibition. Transmission to maize was confirmed by western blot and immunosorbent electron microscopy. By slight modifications of the procedure, MRFV was also transmitted to barley. This is the first report of MRFV infecting a species outside the supertribe Andropogonodae. Virus infection and replication in barley were confirmed by RT-PCR detection of MRFV RNA and by detection of the virus by ELISA.

Infectious Maize rayado fino virus from Cloned cDNA

“…The range of transmissibility observed (8-25%) is not unusual for leafhopper-borne viruses, which are typically quite variable in their transmissibility (20). Furthermore, transmission of both wild-type and cloned viruses by both vector species at the earliest tested interval of seven days after first exposure to infected plants indicates that the latent periods for each virus are similar.Consistent with previous reports characterizing MRFV(13,18,28,31) and similar to OBDV (8,10), two forms of capsid protein were present in infected plants and protoplasts. Investigations on both OBDV (11) and MRFV(18) indicated that the two proteins are carboxy-coterminal with the larger protein possessing an amino-terminal extension of the smaller.…”

“…Marafiviruses infect both plants and insects and therefore comprise a unique system for investigations comparing infection strategies across biological kingdoms. Although vector specificity (2,20,29,36) and a lack of mechanical transmissibility impose a significant constraint on investigations in this group of viruses, this impediment has been partially overcome in maize and small grains by the development of the vascular puncture inoculation (VPI) technique, which abrogates the need for the insect vector in virus inoculation (30,31,43).…”

Insect Vector Interactions with Persistently Transmitted Viruses

“…Based on genomic structure and other similarities, Martelli et al (110) suggested that the genus Marafivirus be included in family Tymoviridae, which does not include any leafhopper-or even hemipteran-borne viruses. The marafiviruses are not seed-borne and cannot be mechanically transmitted except by VPI (105,107).…”

Linear-motion tattoo machine and prefabricated needle sets for the delivery of plant viruses by vascular puncture inoculation

“…Additionally, although the VPI technique has been used successfully for transmission of several viruses (Louie 1995;Madriz-Ordeñana et al 2000;Redinbaugh et al 2001;Redinbaugh 2003;Seifers et al 2004;Louie et al 2006), the engraving tool is noisy and somewhat cumbersome to use. Moreover, laboratory fabrication of needle arrays can be time-consuming and a source of experimental variability.…”

“…Many of the viruses transmitted in that study cannot be transmitted by rub inoculation; for these viruses, therefore, the technique experimentally circumvented the need for the natural insect vector in virus transmission. Subsequent reports confirmed the efficacy of the "vascular puncture inoculation" (VPI) technique, which has been used to initiate plant virus infections from pure and crude preparations of plant viruses (Madriz-Ordeñana et al 2000;Redinbaugh et al 2001;Louie et al 2006) as well as from natural and synthetic viral DNA and RNA (Redinbaugh et al 2001;Redinbaugh 2003). Drawbacks of VPI as it has been described to date are the excessive noise associated with the recommended engraving tool and the need to fabricate needle arrays, which are fragile, may exhibit considerable between-array variability, and are time-consuming to produce.…”