Storage behavior and changes in concentrations of abscisic acid and gibberellins during dormancy break and germination in seeds of Phellodendron amurense var. wilsonii (Rutaceae)

The medicinal Asian plant genus Phellodendron is known to contain several very important compounds that have biological action. The main purpose of this study was to determine whether seeds of Phellodendron amurense var. wilsonii can be stored and to characterize their dormancy. Seeds of this taxon stored at −20 and −80 °C and in liquid nitrogen retained their high germinability, indicating that they have orthodox storage behavior. Intact seeds from freshly collected fruits were dormant and required 12 weeks of cold stratification at 4 °C for complete germination. Scarifying the seed coat was partially effective in breaking seed dormancy. Exogenous gibberellins (GA3, GA4 and GA4+7) promoted germination of scarified seeds, GA4 and GA4+7 being more effective than GA3. Fluridone, an abscisic acid (ABA) biosynthesis inhibitor, was efficient in breaking dormancy, but it was less effective than GA4 or GA4+7 alone. Paclobutrazol, a GA biosynthesis inhibitor, inhibited seed germination, and the inhibitory effect was reversed completely by GA4 and by A4+7. ABA content of seeds subjected to cold stratification or to incubation at 35/10 °C, which enhanced seed germination, was reduced about four- to sixfold compared to that of fresh seeds. Higher concentrations of GA3, GA4 and GA7 were detected in nondormant seeds and in seeds with an
emerged radicle than in fresh seeds. Present results seem to indicate that dormancy in P. amurense var. wilsonii seeds is
imposed partially by the seed coat and partially by high ABA content. ABA content decreased and GA3, GA4 and GA7
content increased during germination.

亚洲药用植物属黄檗属（Phellodendron）已知含有多种具有生物活性的重要化合物。本研究的核心目的为明确黄檗威尔逊变种（Phellodendron amurense var. wilsonii）的种子是否可耐受贮藏，并解析其休眠特性。将该变种的种子分别置于-20℃、-80℃以及液氮环境中贮藏后，仍可维持较高的萌发能力，表明其具备正常贮藏特性。从新鲜采收的果实中剥离的完整种子处于休眠状态，需经4℃低温层积处理12周方可完全萌发。划破种皮可部分破除种子休眠。外源性赤霉素（gibberellins，GA3、GA4及GA4+7）可促进划破种皮后种子的萌发，其中GA4与GA4+7的效果优于GA3。氟啶酮（fluridone）作为脱落酸（abscisic acid, ABA）生物合成抑制剂，可有效打破种子休眠，但效果不及单独使用GA4或GA4+7。多效唑（paclobutrazol）作为赤霉素生物合成抑制剂，会抑制种子萌发，该抑制效应可被GA4与GA4+7完全逆转。经低温层积处理或置于35/10℃变温环境中培养的种子，其萌发能力得到提升，与新鲜种子相比，此类种子的脱落酸含量降低了4~6倍。与新鲜种子相比，非休眠种子及已露出胚根的种子中GA3、GA4及GA7的含量更高。本研究结果表明，黄檗威尔逊变种的种子休眠部分由种皮介导，部分由高水平的脱落酸含量所引发。在萌发过程中，种子内脱落酸含量逐渐降低，而GA3、GA4及GA7的含量则逐步升高。