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大花蕙兰原球茎的诱导、增殖及植株再生研究

2012-04-29季华吴伟剑吴华

湖北农业科学 2012年15期
关键词:原球茎组织培养

季华 吴伟剑 吴华 等

摘要:从大花蕙兰(Cymbidium hybridum)试管苗取材,诱导原球茎,建立植株再生体系,分析了不同激素及其浓度对原球茎诱导、增殖和植株生根的影响。结果表明,不定芽比叶片更容易诱导出原球茎;生长素NAA对原球茎的诱导效果好于2,4-D,最适合原球茎诱导的激素组合为1.0 mg/L BA+1.0 mg/L NAA;原球茎增殖培养基中添加1.0 mg/L BA+0.5 mg/L NAA增殖效果较好,增殖系数可达7.90;最适生根培养基为1/2 MS+0.5 mg/L NAA+30 g/L蔗糖。

关键词:大花蕙兰(Cymbidium hybridum);原球茎;组织培养;植株再生

中图分类号:S682.31;S603.6文献标识码:A文章编号:0439-8114(2012)15-3369-03

Study on Protocorm Induction, Proliferation and Plantlet Formation of

Cymbidium hybridum

JI Hua1,WU Wei-jian2,WU Hua1,CHEN Long-qing1

(1.Key Laboratory of Hoticultural Plant Biology, Ministry of Education/ College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan 430070,China; 2.Wuhu Farm, Huangpi District, Wuhan 430345,China)

Abstract: Explants were drawing from Cymbidium hybridum plantlet for protocorm induction and plantlet regeneration. Effects of the kind and concentration of plant growth regulators on protocorms induction, proliferation and root formation were analyzed. The results showed that introducing protocorm from adventitious bud was more easily than from leaf primordial. NAA was more effective for protocorm induction than 2,4-D. The optimum hormone combination for protocorm induction was 1.0 mg/L BA+1.0 mg/L NAA. The multiplication coefficient of protocorm was the highest (7.90) in medium adding 1.0 mg/L BA+0.5 mg/L NAA. The optimal medium for root formation was 1/2 MS+0.5 mg/L NAA+ 30 g/L sucrose.

Key words: Cymbidium hybridum; protocorm; tissue culture; plant regeneration

大花蕙兰(Cymbidium hybridum)是兰科兰属中大花型附生种类的杂交种,具有花大色艳、花多且花期长的特点,深受大众喜爱[1]。大花蕙兰的繁殖方式主要以分株为主,由于长期无性繁殖,造成带病毒植株日益增多,使兰花的品质下降;同时新品种的培育也对繁殖方式和快繁技术提出了需求。目前,兰属植物的组织快繁主要是以原球茎(Protocorm-like body,PLB)为外植体诱导出愈伤组织或胚性愈伤组织,进而获得小植株[2-8]。国内对大花蕙兰组织培养[9-16]多数是采用茎尖、侧芽为外植体,通过诱导原球茎获得小植株。本实验以大花蕙兰试管苗的不定芽和叶片为外植体,诱导和增殖原球茎,建立大花蕙兰的快速繁殖体系,以达到加大试管苗繁殖系数、简化繁殖步骤的目的。

1材料与方法

1.1材料

供试材料为华中农业大学园艺林学学院种质资源实验室的大花蕙兰试管苗。

1.2方法

1.2.1原球茎的诱导从长势良好的大花蕙兰试管苗上取大小一致、高2~3 mm的不定芽及叶片作为外植体,将叶片切割成0.5~1.0 cm2的小块。外植体接种在MS+30 g/L蔗糖+6 g/L琼脂培养基上。培养基中添加不同浓度的BA、NAA或2,4-D,激素浓度组合见表1。每处理接种6个外植体,重复3次。在培养室中培养,培养温度(25±2) ℃,光照14 h/d,光照度2 000 lx,30 d后统计各处理原球茎的诱导率。

1.2.2原球茎的增殖以MS为基本培养基,附加30 g/L蔗糖和6 g/L琼脂,pH 5.5~5.8,添加不同浓度的BA和NAA(表2)。每处理接种15个不定芽,重复3次,培养条件同1.2.1,培养40 d后统计外植体增殖系数。

1.2.3生根培养生根培养以1/2MS为基本培养基,附加6 g/L琼脂和质量分数0.5%的活性炭,添加不同浓度的NAA与蔗糖(表3),pH 5.5~5.8。每处理接种15个不定芽,重复3次,培养条件同1.2.1。60 d后统计外植体的苗高、根长大于1 cm的根数目、根长和生根率。

1.2.4炼苗移栽将生根培养得到的大花蕙兰试管苗炼苗移栽,以水苔为栽培基质,移栽前用无菌水将植株根部的培养基冲洗干净,再植入穴盘,移入遮阴棚中培养。每天向叶片喷水数次,每周浇施1~2次稀释的营养液。

2结果与分析

2.1原球茎的诱导

将大花蕙兰叶片和不定芽接种到含不同激素配比的培养基,30 d后原球茎的诱导结果见表1。诱导30 d后,处理A1~A4的叶片有肿胀膨大的现象,但没有诱导出原球茎;而处理A5~A8的腋芽周围有绿色半透明颗粒状组织产生并逐渐长大,即诱导产生的原球茎(图1),说明不定芽较叶片易发生再分化产生原球茎。其中A6处理的原球茎诱导效果最好,诱导率达76.9%。培养基中BA浓度相同时,1.0 mg/L NAA的诱导效果要好于0.5 mg/L 2,4-D;随着BA浓度的增高,两种生长素的诱导率都有所增加。可见实验范围内原球茎诱导的最佳激素浓度组合为1.0 mg/L BA+1.0 mg/L NAA。

2.2原球茎的增殖培养

增殖培养40 d后,不定芽周边长出新的原球茎(图2),一般产生5~8个,最多达到15个(表2)。激素BA和NAA的浓度不同,增殖系数也会发生变化。B5处理,即BA和NAA的浓度分别为1.0 mg/L和0.5 mg/L时增殖系数最高,为7.90。BA和NAA浓度过高或过低均不利于原球茎的增殖。

2.3生根培养

将增殖培养获得的大花蕙兰原球茎转移到含不同浓度NAA和蔗糖的生根培养基上,20 d后各处理陆续有根形成,并有新的叶片展开。培养60 d后各处理生根及苗生长情况见表3和图3。

由表3可知,大花蕙兰原球茎的生根情况较好,除C1处理外,其他处理的生根率均达到100.0%。在相同的蔗糖浓度条件下,NAA浓度对各处理之间苗高、叶片数和根长的影响不显著。而NAA为0.5 mg/L时,较高的蔗糖浓度对植株苗高有显著的促进作用。各处理中,C4(0.5 mg/L NAA+30 g/L蔗糖)处理的幼苗生长情况最好,试管苗苗高、叶片数、根长均大于其他处理,其中苗高和根长显著大于其他处理。

2.4炼苗移栽

移栽培养7 d后,幼苗未出现死亡现象,但部分移栽苗叶尖变黄,且大多发生于较小的植株,较大的植株则生长良好。说明试管苗个体越大、越健壮,移栽后的生长状况越好,移栽越易成活。一般适于移栽的植株要求苗高5 cm以上、具有展开叶3~5片,以及2条以上长度大于1 cm的根。

3讨论

在以叶片为外植体诱导原球茎时,叶片虽有膨大的现象,但生长30 d左右后叶片逐渐死亡,没有原球茎产生,与Teixeira da silva等[17]的报道一致,叶片诱导原球茎不成功可能与激素的种类有关[18]。本实验发现2,4-D的诱导效果没有NAA好,与Huan等[5,6]的报道是一致的,实验浓度范围内1.0 mg/L NAA+1.0 mg/L BA对原球茎的诱导效果好,这与徐宏英等[11]的结果略有差异,可能与试管苗体内的激素浓度变化有关。传统的增殖方式主要是由原球茎直接获得生根的小植株;也有的以初次诱导的原球茎或原球茎薄层细胞为外植体诱导出愈伤组织或胚性愈伤组织,获得增殖的原球茎后再获得小植株[19,20]。本实验中以不定芽为外植体,有原球茎的形成,但未见愈伤组织形成。增殖培养40 d后增殖系数均在4.67以上,1.0 mg/L BA+0.5 mg/L NAA的增殖效果最好,增殖系数达7.90,高于以往的报道[21]。在生根实验中,较高浓度的NAA和蔗糖有利于根的生长和植株伸长,可适当缩短生根时间,对移栽后植株的生长有利。

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