精胺和亚精胺影响水稻种子萌发与温度的关系(简报)

在25℃下以0．01～1．0mmol·L-1精胺和0．01～0．1mmol·L-1亚精胺预处理水稻种子48h，可以提高16℃下萌发指数和活力指数，但对28℃下的种子萌发无影响。种子萌发时胚芽中α-淀粉酶活性和胚芽、胚根的呼吸速率的变化规律基本上与活力指数相似。     

Metabolism of [H]Gibberellin A(5) by Immature Seeds of Apricot (Prunus armeniaca L.)

Immature seeds of apricot (Prunus armeniaca L.) were fed the native gibberellin A₅ (GA₅) as 1- and 1,2-[³H]GA₅ (5.3 Curies per millimole to 16 milliCuries per millimole) at doses (42 nanograms to 10.6 micrograms per seed) 2 to 530 times the expected endogenous level. After 4 days of incubation, seeds were extracted and free [³H]GA-like metabolites were separated from the highly H₂O-soluble [³H]metabolites. For high specific activity feeds the retention times (Rts) of radioactive peaks were compared with Rts of authentic GAs on sequential gradient-eluted → isocratic eluted reversed-phase C₁₈ high performance liquid chromatography (HPLC) -radiocounting (RC). From high substrate feeds (530 and 230 × expected endogenous levels) HPLC-RC peak groupings were subjected to capillary gas chromatography-selected ion monitoring (GC-SIM), usually six characteristic ions. The major free GA metabolites of [³H] GA₅ were identified as GA₁, GA₃, and GA₆ by GC-SIM. The major highly water soluble metabolite of [³H]GA₅ at all levels of substrate GA₅ had chromatographic characteristics similar to authentic GA₁-glucosyl ester. Expressed as a percentage of recovered radioactivity, low substrate [³H]GA₅ feeds (2 × expected endogenous level) yielded a broad spectrum of metabolites eluting at the Rts where GA₁, GA₃, GA₅ methyl ester, GA₆, GA₂₂, GA₂₉ (17, 14, 1.6, 7, 1.1, 0.5%, respectively) and GA glucosyl conjugates of GA₁, GA₃, GA₅, and GA₈ (33, 11, 1, 0.1%, respectively) elute. Metabolites were also present at Rts where GA glucosyl conjugates of GA₆ and GA₂₉ would be expected to elute (8 and 0.1%, respectively). Only 5% of the radioactivity remained as GA₅. Increasing substrate GA₅ levels increased the proportion of metabolites with HPLC Rts similar to GA₁, GA₆, and especially GA₁ glucosyl ester, primarily at the expense of metabolites with HPLC Rts similar to GA₃, GA₃-glucosyl ester, and a postulated conjugate of GA₆. There was evidence that high doses of substrate GA₅ induced new metabolites which often, but not always, differed from GA₁, GA₃, and GA₆ in HPLC Rt. These same metabolites, when analyzed by GC-SIM yielded m/e ions the same as the M⁺ and other characteristic m/e ions of the above GAs, albeit at differing GC Rt and relative intensities.