利用花药培养系统选育烟草抗赤星病品系

在接种有烟草赤星病菌的双层培养基上及含赤星病菌毒素的选择培养基上，获得了烟草推广品种ＮＣ８９的花药培养苗。温室内采用离体叶片法对这些花培苗进行了赤星病抗性鉴定，结果约１８％－４２．９％的植株抗性较对照ＮＣ８９有所提高。选其中４株抗性较高且农艺性状与对照ＮＣ８９相近的单株经秋水仙素加倍后收获了种子，然后于１９９２、１９９３年分别在赤星病病圃及大田条件下对其Ｒ—１代、Ｒ—２代植株进行了赤星病抗性及农艺性状测试。两年试验结果一致表明：在染色体加倍以后，所选植株的后代在基因型上已完全纯合，赤星病抗性较对照ＮＣ８９有较大提高，农艺性状也有所改善，而且均稳定遗传，是不同于原ＮＣ８９的烟草新品系。其中两个品系对赤星病的田间相对防效分别达５７．８％和５３．４％，且农艺性状优异，在生产上具有广泛应用前景。

Cell Selection of Tobacco Lines Resistant to Alternaria Alternata

Using culture filtrates of Alternaria Alternata as in vitro selective agent in either a toxin-containing culture medium or a double-layers medium, anther-derived mutated plants of a commercial tobacco cultivar NC89 were obtained. Resistance to Alternaria Alternata of these mutated plants was screened by 11 in vitro leaf method n and 18% 42. 9% of them had higher resistance than control NC89 plants, among which 4 plants were selected to be diploidized by 0. 4% cochicine and then self-pollinated. The resistance of the progenies of the 4 plants was retested in the following two generations under mechanically inoculated and natural conditions respectively, and all of them showed consistant, stable and heritable resistance to Alternaria Alternata, suggesting that the resistance genes were already homozygous. The agronomic characters of the mutated resistant lines were also evaluated in the field trial of 1993 and most of them averaged better than control NC89 plants and stablely maintained. Therefore,we could conclude that we have selected 4 resistance tobacco lines from highly susceptible cultivar NC89 and 2 of them would be popularly applied in the field.