Expressing p20 hairpin RNA of Citrus tristeza virus confers Citrus aurantium with tolerance/resistance against stem pitting and seedling yellow CTV strains

• Published in: Journal of Integrative Agriculture Vol. 14; no. 9; pp. 1767 - 1777
• Main Authors: CHENG, Chun-zhen, YANG, Jia-wei, YAN, Hu-bin, BEI, Xue-jun, ZHANG, Yong-yan, LU, Zhi-ming, ZHONG, Guang-yan
• Format: Journal Article
• Language: English
• Published: Science Press 01.09.2015; Col ege of Horticulture and landscape architecture, Southwest University, Chongqing 400715, P.R.China%Economic Crops Station, agricultural Bureau of Rongxian, Zigong 643100, P.R.China%Institute of Crop Science, Shanxi academy of agricultural Sciences, Taiyuan 030031, P.R.China%Institute of Fruit Tree Research, Guangdong academy of agricultural Sciences, Guangzhou 510640, P.R.China; Elsevier
• Subjects: aurantium; Citrus; Citrus aurantium, disease resistance; Citrus tristeza virus (CTV); Citrus tristeza virus (CTV) RNA interference transgenic plant Citrus aurantium disease resistance; CTV; disease; interference; plant; resistance; RNA; RNA interference; transgenic; transgenic plant; tristeza; virus; RNA interference; disease resistance; Citrus tristeza virus (CTV); Citrus aurantium; transgenic plant
• ISSN: 2095-3119; 2352-3425
• DOI: 10.1016/S2095-3119(14)60937-0

The Citrus tristeza virus （CTV） uses 3 silencing suppressor genes, p20, p23 and p25, to resist the attacks from its Citrus hosts. Inactivating these genes is therefore obviously a potential defensive option in addition to the current control strat- egies including aphid management and the use of mild strain cross protection. In this study, we cloned partial DNA frag- ments from the three genes, and used them to construct vectors for expressing hairpin RNAs （hpRNAs）. To facilitate the formation of hpRNAs, the constructs were introduced in a loop structure. Following transformation of sour orange （Citrus aurantium） with these constructs, 8 p20 hpRNA （hp20） and 1 p25 hpRNA （hp25） expressing lines were obtained. The 7 hp20 transgenic lines were further characterized. Their reactions to CTV were tested following inoculation with CT14A and/ or TR-L5＂I4, both of which are severe strains. Results showed that 3 lines （hp20-5, hp20-6 and hp20-8） were completely resistant to TR-L514 under greenhouse conditions for no detectable viral load was found in their leaves by PCR. However, they exhibited only partial suppression of TR-L514 under screen house conditions since the virus was detected in their leaves, though 2 months later compared to non-transgenic controls. Further tests showed that hp20-5 was tolerant also to CT14A under screen house conditions. The growth of hp20-5 was much better than others including the controls that were concurrently challenged with CT14A. These results showed that expressing p20 hpRNAwas sufficient to confer sour orange with CTV resistance/tolerance.