珍稀濒危植物珙桐种子休眠萌发过程中内源激素的变化

Changes on the edogenous phytohormone content of the Davidia involucrate seed during dormancy and germination process

关键词:  珙桐  内源激素  休眠  萌发

Key words:  Davidia involucrate  phytohormones  dormancy  germination

摘要:

珙桐是我国特有珍稀濒危植物,休眠期长且具二次休眠现象。将处于休眠萌发过程中的珙桐种子依据胚根长度划分为4个阶段,利用高效液相色谱(HPLC)测定各阶段种子及其内果皮中ABA(脱落酸)、GA(赤霉素)、KT(细胞分裂素)、IAA(3-吲哚乙酸)4种内源激素含量,分析其比值动态变化,并与幼苗阶段进行比较。结果显示:未破壳种子的内果皮中内源激素含量以ABA最高,其次是GA、IAA、KT,随着种子破壳后四种激素含量显著降低。除ABA外,种子中GA、IAA和KT含量随着胚根的伸长逐渐升高,但仍低于幼苗阶段。此外,随着胚根伸长,种子中GA/ABA、IAA/ABA、KT/ABA比值逐渐增大,其中以GA/ABA的变化最显著。因此,珙桐种子的休眠和萌发可能主要受ABA和GA的平衡和拮抗来调控。

Abstract:

Davidia involucrate is an ornamental tree native to China and one of the very rare and endangered plants,which has double dormancy as well as a long dormant period. In the study,dormancy and germination process of Davidia involucrate seeds was divided into four stages according to radicle length. The changes of ABA(Abscisic acid),IAA(Indole-3-acetic acid),GA(Gibberellin)and KT(Kinetin)content in seeds and endocarp were determined by using HPLC among four stages. In addition,the dynamics on GA/ABA,IAA/ABA,KT/ABA and KT/IAA ratio were analysed among four stages. Finally,above-mentioned data were compared with those in seedlings stage. The results showed that:(1)the endogenous hormones content order is ABA>GA>IAA>KT in endocarp of uncracked seeds,the four endogenous hormones content decreased significantly after seeds were cracked;(2)except ABA,GA,IAA and KT contents in seeds increased gradually with radicle elongation. However,the GA,IAA and KT contents were less compared to those in seedlings;(3)in addition,GA/ABA,IAA/ABA and KT/ABA ratio in seed increased gradually with radicle elongation. The change in GA/ABA ratio was greatest than the other two ones. So it is suggested that the trade-off between ABA and GA contents could control the dormancy and germination process in Davidia involucrate seed.