Studies on Hairy Root and Cultured Cells Transformed by Ri Plasmid in Relation to Disease Resistance or Susceptibility

利用发根农杆菌介导的T-DNA插入法诱导甜瓜毛状根，研究其抗病或感病机理，并通过转基因技术诱导抗病性。根际侵染。毛状根在无菌培养基上生长旺盛。毛状根在生长调节剂的存在下培养时分化成愈伤组织，并且当愈伤组织在50 μ g/l的2，4-D和BAP中继代时，经常从愈伤组织再分化芽。将pBI 121通过A. NPT Ⅱ和GUS基因在发达的毛状根中表达。GUS阳性毛状根系DNA的Southern印迹分析证实了载体DNA整合到植物染色体上。用卡那霉素处理愈伤组织、芽发育的叶片和再生体的次生毛状根，然后进行b-古鲁糖醛酸酶活性的组织化学检测。结果表明，NPT载体和GUS基因均能稳定地整合到毛状根中，并在毛状根再分化的各个阶段表达。通过农杆菌介导法将黄瓜花叶病毒外壳蛋白基因导入甜瓜细胞，对转化愈伤组织DNA进行Southern杂交分析，证明CP基因已整合到甜瓜细胞中。发根菌。T-DNA诱导的根转化率在50%以上。毛状根对番茄枯萎病的抗性筛选不成功。

Utilization of hairy root induced by T-DNA insertion with Agrobacterium rhizogenes was studied to elucidate resistance or susceptibility mechanisms in plant disease and to induce resistance by gene-transfer.Hairy roots of melon were induced by A. Rhizogenes-infection. The hairy roots could grow vigorously on hormone-free medium. Hairy roots were differentiated into callus tissues when cultured in the presence of growth regulator, and shoots were frequently redifferentiated from the callus when the callus tissues were subcultured in the 50 ug/l of 2, 4-D and BAP. pBI121 was introduced into leaf cell by A. Rhizogenes, and both NPT II and GUS gene were expressed in developed hairy roots. Southern blot analysis of DNA from GUS-positive hairy root lines confirmed the integration of vector DNA to the plant chromosome. Callus tissues, leaves developed from shoots, and secondary hairy roots of regenerants were treated with kanamycin, and then subjected to histochemical detection of b-guluculonidase activity. The results clearly indicated that both the NPT vector and GUS genes transferred to the primry hairy roots were stably integrated and expressed at all stages of redifferentiation. Coat protein gene of Cucumber mosaic virus was introduced in melon cells through agroinfection, and the integration of CP gene was demonstrated by Southern blot analysis of DNA from transformed callus.Hairy roots of tomato were also induced by A. Rhizogenes. Transformed rate of the roots by T-DNA were over 50% of the induced. Screening of hairy roots resistant to Fusarium oxysporum lycopercisi was not successful.