Laboratory of Biological and Agronomic Sciences for Development (LaSBAD), Life Science Department, University of Bangui, BP, 908, Bangui, Central African Republic.
Institute of Environment and Agricultural Research (INERA), Ouagadougou, 01 BP 476, Burkina Faso.
Virol J. 2018 Jan 8;15(1):6. doi: 10.1186/s12985-017-0912-4.
Rice yellow mottle virus (RYMV) of the genus Sobemovirus is the most important viral pathogen of rice causing more damage to rice crop in Sub Saharan Africa. The aim of this study was to conduct pathogenic characterization of RYMV isolates from the Central African Republic (CAR) and to screen commonly cultivated rice accessions in the country for resistance/tolerance to the virus.
The pathogenicity of RYMV isolates was studied by mechanical inoculation with comparison to differential rice lines highly resistant to RYMV available at the Institute of Environment and Agricultural Research (INERA) in Burkina Faso. To screen commonly cultivated rice accessions in CAR, characterized RYMV isolates from the country were used as inoculum sources. Resistant breaking (RB) isolates were used to prepare RB-inoculum, whereas non-resistant breaking isolates (nRB) were used for nRB-inoculum.
Overall 102 isolates used in this study, 29.4% were able to overcome the high resistance genes in the rice cultivars Gigante and Tog7291. All isolates were distributed within three distinct pathogenic profiles. The first profile constituted of 6.9% of the isolates was able to break down the resistance in rice cultivar Gigante only. The second pathogenic profile made of 19.6% of isolates was able to infect Tog7291 only. The third profile, 2.9% of isolates overcame simultaneously resistance genes in both rice cultivars Gigante and Tog7291. Out of isolates able to break down the resistance gene in cultivar Gigante, a single isolate was found to be non-infectious to the susceptible control IR64. Data from screening showed that all accessions were susceptible to RYMV, although IRAT213 was found to be partially resistant to both nRB-inoculum and RB-inoculum.
The present study can be considered as the first in the Central African Republic, it gives a caution on the high risk of RYMV damage to rice production in the country. Beside, skills of pathogenic profiles of RYMV isolates will contribute to better disease management.
呼肠孤病毒科斐济病毒属的水稻黄斑驳病毒（RYMV）是引起水稻最重要的病毒病原体，在撒哈拉以南非洲对水稻作物造成的损害最大。本研究的目的是对来自中非共和国（CAR）的 RYMV 分离株进行致病性特征分析，并筛选该国常种植的水稻品种对该病毒的抗性/耐受性。
通过与布基纳法索环境与农业研究所（INERA）提供的对 RYMV 高度抗性的差异水稻品系进行机械接种比较，研究 RYMV 分离株的致病性。为了筛选 CAR 中常种植的水稻品种，使用该国的特征性 RYMV 分离株作为接种源。抗性突破（RB）分离株用于制备 RB 接种物，而非抗性突破（nRB）分离株用于制备 nRB 接种物。
在本研究中使用的 102 个分离株中，29.4%能够克服水稻品种 Gigante 和 Tog7291 中的高抗性基因。所有分离株均分布在三个不同的致病性谱中。第一个致病性谱由 6.9%的分离株组成，仅能破坏水稻品种 Gigante 的抗性。第二个致病性谱由 19.6%的分离株组成，仅能感染 Tog7291。第三个致病性谱由 2.9%的分离株同时克服了 Gigante 和 Tog7291 两个水稻品种中的抗性基因。在能够破坏 Gigante 品种抗性基因的分离株中，发现单个分离株对易感对照 IR64 无传染性。筛选数据显示，所有品种均对 RYMV 敏感，尽管发现 IRAT213 对 nRB 接种物和 RB 接种物均具有部分抗性。
本研究可以被认为是中非共和国的首例研究，它对 RYMV 对该国水稻生产造成的高风险发出了警告。此外，RYMV 分离株的致病性谱技能将有助于更好地进行疾病管理。
