有髯鸢尾系间远缘杂交障碍研究

Barriers of interseries crosses in bearded iris

有髯鸢尾观赏价值高,但中国夏季雨热集中,有髯鸢尾软腐病多发,限制了有髯鸢尾的应用。为提高有髯鸢尾在高温高湿条件下的存活率,利用鸢尾属内不同系间远缘杂交有望为有髯鸢尾引入鸢尾(Iris tectorum)和西伯利亚鸢尾(Iris sibirica)抗软腐病特性。将有髯鸢尾与鸢尾、西伯利亚鸢尾人工授粉远缘杂交,观察花粉在柱头上萌发及花粉管行为,分析合子前障碍,观测杂交后子房发育动态,明确胚拯救时期。结果表明:(1)有髯鸢尾系间远缘杂交存在一定的合子前障碍,表现为花粉萌发量少、花粉管生长异常及花粉管生长停滞。除有髯鸢尾×西伯利亚鸢尾合子前障碍严重外,其余组合花粉管均能到达胚珠完成受精,合子前障碍不是有髯鸢尾系间杂交的主要障碍。(2)有髯鸢尾与西伯利亚鸢尾杂交后败育速度快于与鸢尾杂交,有髯鸢尾系间杂交与亲缘关系呈正相关。(3)有髯鸢尾×鸢尾的最佳胚拯救时期为授粉21 d后,鸢尾×有髯鸢尾为授粉24 d后,西伯利亚鸢尾×有髯鸢尾为授粉12 d后。合子后障碍是有髯鸢尾系间远缘杂交的主要障碍,通过胚拯救可获得鸢尾有髯鸢尾系间远缘杂交后代。本研究通过解析有髯鸢尾系间远缘杂交障碍及胚拯救研究,为培育适应性更高的有髯鸢尾奠定研究基础。

The ornamental value of bearded iris is high,but the frequent occurrence of bacterial soft rot in bearded iris limits the application of bearded iris due to the concentration of rain and heat in summer in China.In order to improve the survival rate of bearded iris under high temperature and high humidity conditions,it is possible to introduce the soft rot resistance characteristics of Iris tectorum and I.sibirica into bearded iris by the distant hybridization between different series within the genus Iris.The artificial pollination of bearded iris with I.tectorum and I.sibirica was carried out.The pollen germination on the stigma and pollen tube behavior were observed to determine the prezygotic barrier.The dynamics of ovary development after hybridization were monitored to determine the embryo rescue period.The results showed that:(1)There were certain prezygotic barriers in interseries crosses in bearded iris,including less pollen eruption,abnormal pollen tube growth and arrested pollen tube growth.Except the bearded iris×I.sibirica showed prezygote obstacles seriously,the rest of the combination of pollen tubes could reach ovary complete fertilization and prezygotic barrier is not the main barrier to interseries crosses in bearded iris;(2)The rate of abortion after crossing bearded iris with I.sibirica was faster than that with I.tectorum,and interseries crosses in bearded iris was positively correlated with the genetic relationship.(3)The best embryo rescue period for bearded iris×I.tectorum was 21 d after pollination,for I.tectorum×bearded iris was 24 d after pollination,and for I.sibirica×bearded iris was 12 d after pollination.In conclusion,postzygotic barrier is the main obstacle to interseries crosses in bearded iris.Embryo rescue can obtain distant hybridization progeny.This study lays the foundation for the cultivation of bearded iris with higher adaptability.