3种丁香属植物花粉特性及繁育系统的比较

Comparison on Pollen Characteristics and Breeding Systems of Three Syringa Species

【目的】探究3种丁香属植物花粉形态特征和花粉离体萌发方法,比较不同贮藏温度对花粉寿命的影响,明确3种丁香属植物的繁育方式,为丁香属的杂交育种提供参考。【方法】以紫丁香、白丁香和花叶丁香为试验材料,使用扫描电镜观察花粉形态,利用离体培养法测定花粉适宜的离体萌发培养条件,比较不同贮藏温度对花粉活力的影响,采用血球计数器法统计花粉/胚珠比(P/O),通过花性状检测估算杂交指数(OCI)。【结果】3种丁香属植物花粉均为中等大小,长球形,三萌发沟,具清晰的网状雕纹;极赤比(P/E)在1.45~1.83之间,体积指数在28.24~38.82之间。培养基中蔗糖、硼酸、CaCl_(2)、GA_(3)和6-BA质量浓度对花粉离体萌发均有影响。3种丁香属植物花粉萌发的适宜培养基:紫丁香为15 g·L^(-1)蔗糖+50 mg·L^(-1)硼酸+50 mg·L氯化钙+25 mg·L^(-1)6-BA,白丁香和花叶丁香为15 g·L^(-1)蔗糖+50 mg·L硼酸+50 mg·L^(-1)氯化钙+50 mg·L^(-1)GA_(3)。【结论】根据孢粉NPC系统分类,3种丁香属植物花粉均属于N3P4C5型,花粉体积、P/E、网纹纹饰可用于3种丁香属植物种间鉴别。室温下丁香花粉寿命为14天左右,–80℃下丁香花粉可持续保持较高活力。P/O统计结果显示3种丁香属植物的繁育系统属于异交型,OCI估算结果则认为其繁育系统为部分自交亲和的虫媒异交型。

【Objective】The aim of this study is to clarify the pollen morphology and pollen germination methods in vitro of three Syringa species,compare the effects of different storage temperatures on pollen viability,and estimate the pollen/ovule ratio(P/O)and out crossing index(OCI),so as to provide reference for cross breeding of Syringa.【Method】S.oblata,S.oblata var.alba and S.×persica were used as experimental materials,and the pollen morphology was observed using scanning electron microscopy.In vitro culture methods were used to study the suitable media for pollen germination,and the effect of different storage temperatures on pollen lifespan was explored.A blood cell counter method was used to calculate the P/O ratio and the out crossing index was estimated through measuring flower traits.【Result】All three Syringa species had medium sized pollens,ellipsoidal in shape,with three germination grooves and clear network carvings.The ratio of pollen polar axis length to equatorial axis length(P/E)value ranged from 1.45 to 1.83,and the volume index ranged from 28.24 to 38.82.The contents of sucrose,boric acid,CaCl_(2),GA_(3),and 6-BA in the culture medium all had effects on pollen germination in vitro.The suitable medium composition for the pollen germination of three Syringa species was as follows:15 g·L^(-1)sucrose,50 mg·L^(-1)boric acid,50 mg·L^(-1)calcium chloride,and 25 mg·L^(-1)6-BA for S.oblate,15 g·L^(-1)sucrose+50 mg·L^(-1)boric acid+50 mg·L^(-1)calcium chloride+50 mg·L^(-1)GA_(3) for S.oblata var.alba and S.×persica.【Conclusion】According to the number,position and character(NPC)system of pollen classification,the pollen of all three Syringa species belongs to the N3P4C5-type,which can be identified based on pollen volume,P/E ratio,and extine pattern of pollen.The viability of pollens stored at room temperature can only be maintained for about 14days.The pollens stored at–80℃maintains high pollen viability,making it the optimal method for preserving pollens.The P/O ratio estimation suggests that the three Syringa species have outcrossing breeding system,whereas the OCI results suggest that the breeding modes of the three Syringa species are partial self-compatible,insect-pollination outcrossing.