Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113-8657, Japan.
Laboratory of Plant Pathology, School of Agriculture, Utsunomiya University, Mine-machi 350, Utsunomiya, Tochigi, 321-8505, Japan.
Sci Rep. 2019 Apr 11;9(1):5958. doi: 10.1038/s41598-019-42400-w.
Since the propagation of plant viruses depends on various host susceptibility factors, deficiency in them can prevent viral infection in cultivated and model plants. Recently, we identified the susceptibility factor Essential for poteXvirus Accumulation 1 (EXA1) in Arabidopsis thaliana, and revealed that EXA1-mediated resistance was effective against three potexviruses. Although EXA1 homolog genes are found in tomato and rice, little is known about which viruses depend on EXA1 for their infection capability and whether the function of EXA1 homologs in viral infection is conserved across multiple plant species, including crops. To address these questions, we generated knockdown mutants using virus-induced gene silencing in two Solanaceae species, Nicotiana benthamiana and tomato. In N. benthamiana, silencing of an EXA1 homolog significantly compromised the accumulation of potexviruses and a lolavirus, a close relative of potexviruses, whereas transient expression of EXA1 homologs from tomato and rice complemented viral infection. EXA1 dependency for potexviral infection was also conserved in tomato. These results indicate that EXA1 is necessary for effective accumulation of potexviruses and a lolavirus, and that the function of EXA1 in viral infection is conserved among diverse plant species.
由于植物病毒的传播依赖于各种宿主易感性因素，因此这些因素的缺乏可以防止栽培植物和模式植物受到病毒感染。最近，我们在拟南芥中鉴定了对 poteXvirus Accumulation 1（EXA1）至关重要的易感性因子，并揭示了 EXA1 介导的抗性对三种 potexviruses 有效。尽管在番茄和水稻中发现了 EXA1 同源基因，但对于哪些病毒依赖 EXA1 进行感染能力以及 EXA1 同源物在病毒感染中的功能在包括作物在内的多种植物物种中是否保守知之甚少。为了解决这些问题，我们使用病毒诱导的基因沉默在两个茄科物种，烟草原生质体和番茄中生成了敲低突变体。在烟草原生质体中，EXA1 同源物的沉默显著削弱了 potexviruses 和 lolavirus（potexviruses 的近亲）的积累，而番茄和水稻的 EXA1 同源物的瞬时表达则补充了病毒感染。番茄中 potexviral 感染对 EXA1 的依赖性也得到了保守。这些结果表明，EXA1 是 potexviruses 和 lolavirus 有效积累所必需的，并且 EXA1 在病毒感染中的功能在不同的植物物种中是保守的。
