Broad-spectrum resistance to different geographic strains of Papaya ringspot virus in coat protein gene transgenic papaya
Broad-spectrum resistance to different geographic strains of Papaya ringspot virus in coat protein gene transgenic papaya
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DOI：
10.1094/phyto.2003.93.1.112
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发表时间：
2003-01-01
期刊：
影响因子：
3.2
通讯作者：
Yeh, SD
中科院分区：
文献类型：
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作者：
Bau, HJ;Cheng, YIH;Yeh, SD
番木瓜环斑病毒(PRSV)是世界热带、亚热带地区番木瓜栽培的主要限制因子。虽然PRSV外壳蛋白(CP)基因已通过基因枪法导入番木瓜，获得了对夏威夷株系具有高抗性的转基因株系，但它们对夏威夷以外的分离物很敏感。这种特定菌株的抗药性限制了转基因品系在世界其他地区的应用。本研究通过农杆菌介导法将我国台湾地区分离株PRSV YK的CP基因导入番木瓜。共获得45个转基因株系，经聚合酶链式反应扩增，证实了转基因番木瓜的存在。转基因植株机械接种PRSV YK后，表现出从症状延缓到完全免疫的不同程度的抗性。对筛选出的9个表现不同抗性水平的品系的分子分析表明，转基因表达水平与抗性程度呈负相关，表明抗性是通过RNA介导的机制表现出来的。分离分析表明，免疫品系18-0-9的转基因具有2个显性遗传位点，其余4个高抗品系为1个显性遗传座位。对来自夏威夷、泰国和墨西哥的三个PRSV异源毒株进行了进一步的抗性测试。7个品系中有6个品系对异源菌株表现出不同程度的抗性，其中1个品系19-0-1不仅对同源YK菌株免疫，而且对3个异源菌株免疫。因此，这些具有广谱抗性的转CP基因番木瓜品系在台湾和其他地理区域防治PRSV方面具有很大的潜力。
Papaya ringspot virus (PRSV) is a major limiting factor for cultivation of papaya (Carica papaya) in tropical and subtropical areas throughout the world. Although the coat protein (CP) gene of PRSV has been transferred into papaya by particle bombardment and transgenic lines with high resistance to Hawaii strains have been obtained, they are susceptible to PRSV isolates outside of Hawaii. This strain-specific resistance limits the application of the transgenic lines in other areas of the world. In this investigation, the CP gene of a local strain isolated from Taiwan, designated PRSV YK, was transferred into papaya via Agro-bacterium-mediated transformation. A total of 45 putative transgenic lines were obtained and the presence of the transgene in papaya was confirmed by polymerase chain reaction amplification. When the plants of transgenic lines were challenged with PRSV YK by mechanical inoculation, they showed different levels of resistance ranging from delay of symptom development to complete immunity. Molecular analysis of nine selected lines that exhibited different levels of resistance revealed that the expression level of the transgene is negatively correlated with the degree of resistance, suggesting that the resistance is manifested by a RNA-mediated mechanism. The segregation analysis showed that the transgene in the immune line 18-0-9 has an inheritance of two dominant loci and the other four highly resistant lines have a single dominant locus. Seven selected lines were tested further for resistance to three PRSV heterologous strains that originated in Hawaii, Thailand, and Mexico. Six of the seven lines showed varying degrees of resistance to the heterologous strains, and one line, 19-0-1, was immune not only to the homologous YK strain but also to the three heterologous strains. Thus, these CP-transgenic papaya lines with broad-spectrum resistance have great potential for use in Taiwan and other geographic areas to control PRSV.