转基因番木瓜抗病性测定和纯合系的获得

分别对转番木瓜环斑病毒（Papaya ringspot virus，PRSV）复制酶基因（Trp）的T3、T4代番木瓜（Carica papaya L．）品系在苗期进行攻毒试验和PCR分子生物学分析．结果表明，在苗期T3、T4代分子检测阳性株均高抗PRSV的Ys株系，证实Trp基因能够在后代中稳定遗传．除品系Trp-6-2外，其它所有T3、T4代自交植株仍有基因分离．Trp-6-2的自交株和其T4杂交后代，苗期攻毒试验均表现抗病，PCR检测复制酶基因均为阳性，所转基因没有发生分离，可以初步推定Trp-6-2为转基因的纯合系．大田病情调查结果表明，T3代在定植田间的前5个月内，转基因植株均高抗PRSV．但在定植5个月后发现一个转基因品系38株中有3株表现发病．

Evaluation of resistance to PRSV and selection of homogeneous line on the transgenic papaya plants

The self-pollinated and cross-pollinated seeds on transgenic T_3 and T_4 line plants containing replicase gene of papaya ringspot virus(PRSV),were separately harvested and planted in the greenhouse.The seedlings were respectively inoculated with PRSV Ys strain and the replicase gene(Trp) for each transgenic plant was detected by PCR.The results showed that Trp was still segregated on all lines from T_3 and T_4 plants except Trp-6-2(one line of T_3).All plants of Trp-6-2,no matter its self-pollinated or cross-pollinated with any susceptible cultivars,showed that no any symptom appeared after inoculation in the green house,and Trp gene could be detected.This indicated that Trp-6-2 might be one of homogenous transgenic line.T_3 plant population lines also showed high level of PRSV resistance except 3 of 38 plants of one self-pollinated line,which developed slight mosaic symptom 5 months after planting in the field.