常规授粉下不同植物激素处理对烟草种间杂交花粉管生长和结实率的影响OA

Interspecific hybridization is an effective means to broaden the diversity of genetic resources in Nicotiana.To find methods for improving seed setting rate of interspecific hybridization,four treatments were established in this study including conventional pollination(CK)and individual or combined application of plant hormones GA3,IAA and 6-BA before and after conventional pollination.The effects of these treatments on seed setting rate were investigated in the crosses between N.tabacum cv.K326(as the female parent)and N.rustica var.brasilia,N.glutinosa,or N.longiflora(as the male parents).The results showed that the T3 treatment(250 mg/L GA3 applied to the stigma+conventional pollination+200 mg/L IAA sprayed onto the stigma at 24 h of pollination+20 mg/L 6-BA sprayed onto the stigma at 72 h of pollination)significantly in-creased the seed setting rate in all the three hybrid combinations.Fluorescence microscopy of pollen tubes in the crosses with K326 as the female parent and N.glutinosa or N.rustica var.brasilia as the male parents showed that the pollen viability was inhibited during 4 to 12 h after pollination but recovered at 24 h,and the pollen tube germinated at 48 h and entered the stylar tissues at 72 h.The incompatibility reaction was observed between the paternal pollen and the maternal stigma:the pollen tubes stopped growing upon reaching about one-quarter of the style length,numerous branches produced,and their tips exhibited swelling,bending and callose plug deposition.Compared with the control(CK),the T1 treatment(250 mg/L GA3 applied to the stigma+conventional pollination)promoted pollen germination but had a negligible effect on pollen tube growth.Compared with T1,the T2 treatment(250 mg/L GA3 applied to the stigma+conventional pollination+200 mg/L IAA sprayed onto the stigma at 24 h of pollination)showed no significant improvement in pollen tube growth.In contrast,the T3 treatment markedly enhanced pollen tube growth within the pistils compared with the T2 treatment.The results of this study could provide a theoretical foundation for improving the seed setting rate of Nicotiana interspecific hybridization and improving the tobacco quality in future.