甜菊单倍体的离体诱导初探

A Preliminary Study on Haploid Plant Induction in vitro of Stevia rebaudiana Bertoni

对甜菊头状花序、花及小孢子的发育进行了观察,在此基础上分离了甜菊花药和未受精胚珠,并分别进行体外培养诱导单倍体。结果表明甜菊花药诱导愈伤较容易,在MS+1.5 mg/L 6-BA+0.5mg/L NAA+4%蔗糖的培养基上诱导愈伤率高达80%,由于尚未得到胚状体或再生植株,花药愈伤继续诱导分化还需进一步研究;通过培养基筛选发现未受精胚珠在MS+0.04 mg/L 6-BA+1.5 mg/L NAA+4%蔗糖的培养基上可直接诱导出胚状体,诱导率为1.2%,本试验共诱导出胚状体4个,转接生根并移栽存活2株,但经根尖细胞染色体计数发现其均为二倍体(2n=22),因为两再生植株现蕾期、株高、叶型等性状与亲本有显著差异,推测其可能是单倍体自然加倍的结果,但有待进一步研究证明。本研究作为甜菊单倍体诱导培养的初次尝试,对今后甜菊育种和遗传研究有重要意义。

The development of capitulum, flower and microspores of Stevia rebaudiana Bertoni were observed firstly in this study, and further the anthers and unfertilized ovules were isolated to obtain haploid plants via culture in vitro respectively. The result showed that the callus induction of anther was easy, the medium with MS＋ 1.5 mg/L 6-BA＋0.5 mg/L NAA＋4% sucrose was the best, and its callus initiation rate was 80%. But no regeneration plants were induced by the callus, so further studies were needed for the differentiation of anther callus and plant regeneration. In the experiment of unfertilized ovules culture, it was found that the embryoid can be induced directly on the medium with MS＋0.04 mg/L 6-BA＋ 1.5 mg/L NAA＋ 4 % sucrose. The frequency of embryo induction was 1.2%. Finally, 4 embryoids were induced and 2 survival plantlets were regenerated. But the chromosomes number in the root tip cells of two regeneration plants were all 2n =22. It may be the result of naturally doubled of haploid, further need to verify. This study, as a first attempt work of stevia haploid induction, is of great significance to the breeding and genetic research of stevia in the future.