环境因子对蕨类植物孢子萌发的影响

Effect of environmental factors on fern spore germination

蕨类植物通过孢子萌发形成独立生活的配子体,配子体能够形成精子器和颈卵器,进而通过受精作用形成新的孢子体。孢子萌发是蕨类植物生活史过程中配子体世代向孢子体世代转变的关键步骤。同时,此过程不仅受到多种环境因子的影响,也是研究细胞核极性移动、细胞不对称分裂、假根极性生长等独特的细胞学事件的良好模型。迄今为止,人们已经研究发现多种环境因子对约200余种蕨类植物孢子萌发有影响。总结了环境因子对蕨类植物孢子萌发影响的规律如下:(1)孢子萌发除了受到光照强度影响外,主要受光质的影响,光质的影响主要表现为4种方式:①孢子萌发受红光刺激与远红光抑制像开关一样调控;②孢子萌发不受远红光抑制;③孢子萌发受蓝光抑制;④孢子只能在黑暗条件下萌发。(2)重力作用会影响孢子细胞核移动,进而影响孢子细胞发育的极性。(3)赤霉素(GA)能增加孢子萌发率或帮助孢子打破休眠。成精子囊素与GA作用相似,启动或促进孢子萌发。而脱落酸(ABA)、茉莉酸(JA)和乙烯等其它激素对孢子萌发的影响相对较小。(4)不同植物孢子有着各自最适的萌发培养基条件,如不同种类孢子对MS培养基中无机盐含量、蔗糖含量、pH值的要求不同。孢子外被中的Ca2+、Mn2+和Mg2+,培养基中的Cd2+和La3+,以及孢子接种密度、萌发空间CO2含量也会对孢子萌发造成影响。(5)多数蕨类植物孢子在15-30℃可以萌发,最适萌发温度为25℃。(6)4℃和液氮储藏可以延长孢子寿命并保持较高萌发率。

Ferns produce spores that germinate to form gametophytes which live independently.The gametophytes later develop antheridia and archegonia and produce new sporophytes upon fertilization.Spore germination is a key step for ferns to switch from the gametophytic phase to the sporophytic phase.Spore germination also is a good single-cell model for exploration of cell nuclear polar movement,asymmetrical cell division,tip-growth of rhizoids and other unique cellular differentiation events.Furthermore,fern spore germination is affected by various environmental factors.So far,fern spore germination features in response to environmental factors have been investigated in about 200 species.The present paper gives an overview of this research progress and summarizes the common responses to environmental factors for germination of fern spores as follows：（1）Fern spore germination is affected by light intensity,and the action spectrum for germination is diverse among species.The four representative influence modes include a）red light-stimulated and far red light-inhibited spore germination which operates as a switch,b）far red-uninhibited spore germination,c）blue light-inhibited spore germination,and d）spore germination in the dark.（2）Gravity directs the early nuclear polar movement in spores of Ceratopteris richardii,which irreversibly determines the axis of spore cell development.（3）Gibberellins（GA）can function to increase the germination rate of spores or break spore dormancy.Antheridiogen has a similar role as GA,which is to initiate and promote spore germination from many species.Abscisic acid,jasmonic acid and ethylene have only minor effects on spore germination.（4）The spores of diverse species have different optimal culture medium compositions for germination and growth.Spores can obtain the maximum germination rate in their favorable mineral and sugar content in MS medium.Moreover,spores from different species may need an optimized pH to obtain the highest germination rate.Furthermore,the metal ions including Ca2＋,Mn2＋ and Mg2＋ in spore coat,Cd2＋ or La3＋ in culture medium,and CO2 content in environment also have effects on spore germination.（5）Many fern spores can germinate under 15-30℃,and 25℃ is suitable for most spores.（6）Storage at 4℃ or in liquid nitrogen can increase spore longevity and maintain germination rate.