Temporal Effects of a Begomovirus Infection and Host Plant Resistance on the Preference and Development of an Insect Vector, Bemisia tabaci, and Implications for Epidemics.

Saioa Legarrea,Stan Diffie,Apurba Barman,Rajagopalbabu Srinivasan,Wendy Marchant,Youjun Zhang

doi:10.1371/journal.pone.0142114

Abstract

Persistent plant viruses, by altering phenotypic and physiological traits of their hosts, could modulate the host preference and fitness of hemipteran vectors. A majority of such modulations increase vector preference for virus-infected plants and improve vector fitness, ultimately favouring virus spread. Nevertheless, it remains unclear how these virus-induced modulations on vectors vary temporally, and whether host resistance to the pathogen influences such effects. This study addressed the two questions using a Begomovirus-whitefly-tomato model pathosystem. Tomato yellow leaf curl virus (TYLCV) -susceptible and TYLCV-resistant tomato genotypes were evaluated by whitefly-mediated transmission assays. Quantitative PCR revealed that virus accumulation decreased after an initial spike in all genotypes. TYLCV accumulation was less in resistant than in susceptible genotypes at 3, 6, and 12 weeks post inoculation (WPI). TYLCV acquisition by whiteflies over time from resistant and susceptible genotypes was also consistent with virus accumulation in the host plant. Furthermore, preference assays indicated that non-viruliferous whiteflies preferred virus-infected plants, whereas viruliferous whiteflies preferred non-infected plants. However, this effect was prominent only with the susceptible genotype at 6 WPI. The development of whiteflies on non-infected susceptible and resistant genotypes was not significantly different. However, developmental time was reduced when a susceptible genotype was infected with TYLCV. Together, these results suggest that vector preference and development could be affected by the timing of infection and by host resistance. These effects could play a crucial role in TYLCV epidemics.

Highlights

Phytoviruses transmitted persistently often tend to alter the phenotypic and physiological traits of their host plants making them more suitable to their arthropod vectors, hemipterans [1,2,3,4,5,6,7,8,9]
Regardless of the genotype, the copy numbers were greater at 3 weeks post inoculation than at 6 and 12 weeks post inoculation
Previous research has shown that semi-dominant genes such as Ty-1 confer resistance to Tomato yellow leaf curl virus (TYLCV) by limiting symptom expression and restricting virus accumulation [38, 40, 44]

Summary

Introduction

Phytoviruses transmitted persistently often tend to alter the phenotypic and physiological traits of their host plants making them more suitable to their arthropod vectors, hemipterans [1,2,3,4,5,6,7,8,9]. Studies that documented host-mediated virus-induced effects on vector preference and/or fitness were, more often than not, conducted using expressive hosts or hosts that display flamboyant symptoms upon virus infection [8,9,10,11,13,14,18]. It is unclear if such observed effects on vector preference and/or fitness would be noticeable in not-so expressive hosts, including host genotypes that exhibit resistance to the pathogen.

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