芥菜型多室与二室油菜花芽分化过程的比较分析

Comparative analysis on flower bud differentiation of multilocular and bilocular traits in Brassica juncea

芥菜型油菜中存在天然的多室性状。与普通二室油菜相比,多室油菜因多果室(3～5个腔室)、多粒特征,具有高产潜力,为了揭示多室性状的形成过程,本研究以青海芥菜型多室油菜和塔油2号(芥菜型二室油菜)双亲、BC3F5群体中纯合的二室和多室单株为材料,通过石蜡切片结合扫描电镜观察,比较分析表明,青海芥菜型多室油菜自出苗开始,约22 d左右,平均叶片数为5时,开始花芽分化且经历5个时期;多室茎顶端分生组织(SAM)和花顶端分生组织(FM)伸长膨大,直径较二室大;随心皮分化,多室花顶端向内凹陷成"X"状的四心皮区域,而二室花芽中心生长锥向内凹陷成"I"状,形成二心皮的对半区域,该凹陷分裂影响心皮数目,并决定了子房中籽粒的排列数目;柱头顶端也形成"I"及"X"状凹陷,可作为一种指标用以早期区分多室及二室性状。

Brassica juncea,possessing natural multilocular traits compared with bilocular rapeseed(two-chambered),has high yielding potential due to multiple locules(3–5 locules)and multi-grains.To disclose the formation process of multilocular traits,we constructed a BC3F5 population from a cross between Qinghai multilocular rapeseed and Tayou 2(two locules)to analyse the whole process of flower bud differentiation of homozygous bilocular plants and multilocular plants through paraffin section along with scanning electron-microscopy observation.The flower bud differentiation in multilocular rapeseed took place at about 22 days after seedling emergence,with an average leaf number of 5,and whole differentiation was divided into five stages.The diameters of shoot apical meristem(SAM)and floral meristem(FM)in multilocular plants were significantly larger than these in bilocular plants.The center of growing cone of the multilocular was deeply recessed into an“X”shaped region with four carpels,while that of the bilocular into an“I”shape,forming half and half regions with two carpels,such differentiation could affect the number of carpels and seeds rows.The tip of the stigma also formed“I”and“X”shapes,which could be used as an indicator,to distinguish between multilocular plants and bilocular plants in the early stage.