Temporal host responses of rice (Oryza sativa L.) to single and mixed infection of Rice Tungro Bacilliform Virus (RTBV) and Rice Tungro Spherical Virus (RTSV)

Date

4-2014

Degree

Bachelor of Science in Agricultural Biotechnology

College

College of Agriculture and Food Science (CAFS)

Adviser/Committee Chair

Johnny F. Balidion

Abstract

The effect of single and mixed infection of Rice tungro bacilliform virus (RTBV) and Rice tungro spherical virus (RTSV) on host responses and virus population dynamics was examined in a susceptible line, Taichung Native 1 (TN1) and an Utri Merah-derived resistant line, TW16 (BC5F8). Plant height, leaf chlorosis, biomass, gene expression and virus accumulation were assessed up to 35 days post inoculation (dpi). Mix-infected TN1 plants were severely stunted and chlorotic while mix-infected TW16 plants exhibited mild symptoms and recovered at 35 dpi. Virus accumulation in mix-infected TN1 peaked at 12 dpi for RTBV and 18 dpi for RTSV. At 12 dpi, there is a 32-fold synergistic increase in RTBV load and 5-fold antagonistic decrease in RTSV load in mix-infected TN1 plants compared to single infections. Expression analysis of virus-responsive genes show high repression of cell wall and photosynthesis related genes in mixed infection at 18 dpi with stronger and prolonged repression in TN1. Enhanced repression of these genes during mixed infection is consistent with higher biomass reduction of 25% in TN1 compared to TW16. Early induction of gene silencing related genes was observed at 6 dpi with stronger induction in TW16 than in TN1. This could have led to the decrease in the accumulation levels of RTBV after 18 dpi and the evident suppression of RTSV. The xi reduction ratio for plant height and biomass in mixed and single infection indicates a synergistic effect in TN1 (ER >1.0) but only an additive effect for TW16 (ER <1.0). These results suggest that temporal dynamics of RTSV and RTBV in single and mixed infection directly impacts the severity of symptom expression and eventually yield loss.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2014 A127 /R57

Document Type

Thesis

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