烟草花序苞叶的离体花芽分化

IN VITRO FLORAL BUD FORMATION ON BRACTLETS OF NICOTIANA TABACUM

烟草(Nicotiana tabacum,Ge Xing No 1)花序上的苞叶在MS(附加2.0mg/l6—BA,0.2mg/1IBA)培养基上培养,能直接分化出营养芽、花芽和愈伤组织,组织切片表明花芽起源于亚表皮细胞。分化花芽的潜力和母体植株的发育状态有关。进入生殖生长阶段的植株其花序苞叶培养后能直接形成花芽。从抽苔期、现蕾期、始花期、盛花期、结果期到成熟期成花百分率由上升到下降,在盛花期达到最大值。分化花芽能力还和外植体在母体植株上的着生位置有关,从花序上端到基部递减,不同基因型的烟草品种其花序小叶具有不同的分化花芽的潜力。

The bractlets in a inflorescence of Nicoliana tabacum, which were cultured in MS medium containing 2. 0mg /1 6-BA, 0.2mg /1 TBA directly formed vegetative buds, floral buds, or / and callus. The histological aspect of flower bud development in vitro were studied. It was found that the floral buds may originated from sub-epidemic layers. The physiological state of mother plant strongly effected the flowering of bractlets in inflorescence of N. tabacum in vitro. Only when the mother plants entered the stage of reproductive growth, the floral bud might form in vitro. From the stage of bolting, bud raising, corolla elongating, first flowering to the stage of blooming of mother plants, from which the bractlets were excised and cultured respectively, the potential of initiation of floral bud on bractlets gradually increased. However on the stages of fruiting, fruit maturing, it may be decreased. We discovered that the greatest potential was in the stage of blooming. Floral bud formation also depends on the position of bractlets on the mother plants. We noted a basipetally decreasing gradient of the capacity of floral bud formation along the stem. The capacity of floral bud formation of four genotypies invitro were different and the percentage of bractlets with floral buds was maxium in N. tabacum 'Ge Xing Nol'.