山桃种子内源激素在休眠萌发期间的变化 (Ⅰ)ABA和IAA(英文)

为了比较全面地了解需低温种子休眠和萌发的激素控制机理,我们以室温贮藏为对照,系统研究了低温和外源植物生长调节物对山桃种子萌发的影响,并用气相色谱和气相色谱—质谱联用仪分别测定了内源ABA和IAA在不同贮藏条件下的变化。研究发现:山桃种子去除种皮、子叶后的离体胚轴是不休眠的,在整个室温贮藏期间,种皮对萌发均有显著的抑制作用。去除种皮即可使贮前山桃种子的萌发率由0提高到40％。如果不去除种皮而仅在胚根处划破种皮,可使萌发率提高到26％左右。所以,种皮的抑制作用肯定有一部分是抑制物质引起的。分析证明,种皮ABA含量在贮藏前高达690.07ng/g·FW。干藏16周后仅下降到616.47ng/g·FW。对萌发的抑制作用仍保持原有水平。低温层积6周,种皮ABA含量下降到374.08ng/g·FW,对萌发的抑制作用未见明显减小。到第10周下降为183.74ng/g·FW,种皮对萌发的抑制作用完全解除。去除种皮后,仍有60％的种子不能萌发,而离体胚轴是完全能够迅速萌发的。所以,贮前来自子叶的抑制作用是相当强的。胚的ABA含量在贮前为303.82ng/g·FW,由于子叶比种皮重得多,所以ABA的总含量相当可观。加之子叶与胚之间的直接解剖结构联系,子叶的抑制作用要大于种皮。无论在室温或低温条件下,种子ABA含量均有下降。低温层积6周时,?

Changes in Endogenous Phytohormones of Prunusdavidiana Seed during Dormancy andGermination (Ⅰ) ABA and IAA

The germination rates of seed,embryo and embryonic axis of Prur.ua davi-diana in relation to endogenous ABA,IAA and exogenously applied GAs and BA during the processes of cold stratification and dry storage at room temperature have been studied.Sixteen weeks of dry storage resulted in only a slight reduction of ABA levels in the seed coat,but reduced that in the embryo from 303.82ng/g.FW to 92.15ng/g.FW.At the same time the IAA level in both seed coat and embryo decreased slightly.These seeds germinated readily but appeared dwarf thereby implying inhibition of epicotyl growth.However,10 weeks of cold stratification apparently was enough to reduce the ABA level to 183.70μg/g·FW in coat and 9.03 μg/g-FW in embryo,and drastically increase the IAA level in embrvonic axis from 40.24μg/g-FW to 8007.80μg/g·FW.The cold-stratified seeds gave a 100% germination rate and normal seedlings,implying that the IAA might be necessary for normal growth of peach epicotyl.The experiments also showed that GA3 and GA3+BA could partly replace chilling in breaking dormancy of epicotyl and hypicotyl.A tentative mechanism for phytohormone control of dormancy and germination of peach seeds has been discussed.