登熟期の気象条件が小麦子実のα-アミラーゼ活性に及ぼす影響 Effect of Weather Conditions on α-Amylase of Ripening Wheat (Triticum aestivum L.) Grain

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Abstract

人工気象室を用いて,秋播小麦3品種(チホクコムギ:穂発芽耐性弱,北系1354,Lancer:穂発芽耐性強)について,登熟期の気象条件が成熟期のα-アミラーゼ活性およびそのアイソザイムに及ぼす影響を解析した.その結果,1)チホクコムギにおいては登熟期の早・中期の低温高湿処理(昼間20℃,・夜間10℃,相対湿度80-100%)により発芽は認められなかったが,登熟中に発現している低p1のα-アミラーゼアイソザイム(Amy-2)が成熟期まで残存し,比較的高活性を示した(Retentionofpericarpα-amylase:RPA).登熟の晩期に低温かつ穂が濡れる程度まで加湿されると,穂発芽耐性の弱いチホクコムギでは成熟期前で穂発芽が発生し,高plのα-アミラーゼアイソザイム(Amy-1)が大きく活性化した(Pre-maturitysproutingα-amylase:PrMS). 2)北系1354はチホクコムギやLancerと比較して登熟期の気象条件の影響を受けにくく,低温高湿下においても発芽せず,成熟期のα-アミラーゼ活性も全般に低かった. 3)Lancerは低温高湿および高温低湿の両気象条件において,発芽が認められなかったが高いAmy-1の活性が認められた(Pre-maturity α-amylase:PMAA). 4)このように,北海道における成熟期の高α-アミラーゼ活性現象について,三つの要因(RPA,PrMA,PMAA)が観察された.また,Lancerのように穂発芽耐性が強いにもかかわらず,成熟期のα-アミラーゼ活性が高まることが示されたことから,成熟期におけるα-アミラーゼ活性は休眠性と同様に重要な指標と考えられる.しかし,PMAAを誘導する気象条件については不明な点が多く,今後さらに検討する必要がある.

The effects of weather conditions on a-amylase activity and its isozymes at maturity were investigat-ed in the three winter wheat (Triticum aestivum L.) varieties of Chihokukomugi (susceptible to pre-harvest sprouting), Kitakei-1354 (tolerant) and Lancer (tolerant) using environment cabinets. The results were: 1) In Chihokukomugi, wheat grains which were exposed to cool and wet conditions (20°C/10°C and from 80 to 100% relative humidity) at the early and middle stages of ripening exhibited relatively high α-amylase activity, due to Amy-2 isozymes, in the absence of germination (RPA: retention of pericarp α-amylase). Under cool and wet conditions in the late stage of ripening, grains germinated at maturity and with high p1 isozymes of Amy-1 were activated (PrMS: pre-maturity sprouting α-amylase). 2) Since Kitakei-1354 showed a dull response to weather conditions during the ripening stage, low α-amylase activity and little germination were observed consistently. 3) In Lancer, Amy-1 was activated in the absence of germination (PMAA: pre-maturity α-amylase) under not only cool and wet conditions but also under hot and dry conditions. 4) Accordingly, three pathways (RPA, PrMS and PMAA) of α-amylase formation at maturity were observed in Hokkaido. Since certain varieties like Lancer often exhibited high α-amylase activity at maturity in spite of high tolerance to pre-harvest sprouting, α-amylase activity at maturity as well as dormancy of wheat grain was an important criteria. Further investigations are needed to clarify the precise environmental factors which induce PMAA formation.

Journal

  • Journal of Applied Glycoscience

    Journal of Applied Glycoscience 46(3), 291-298, 1999-08-31

    The Japanese Society of Applied Glycoscience

References:  18

Cited by:  2

Codes

  • NII Article ID (NAID)
    10008259276
  • NII NACSIS-CAT ID (NCID)
    AN10453916
  • Text Lang
    ENG
  • Article Type
    Journal Article
  • ISSN
    13403494
  • NDL Article ID
    4846272
  • NDL Source Classification
    ZP24(科学技術--化学・化学工業--糖・澱粉)
  • NDL Call No.
    Z17-15
  • Data Source
    CJP  CJPref  NDL  J-STAGE  JASI 
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