• 作者： 朱德民; 李成章
• 作者服務機構： 國立中興大學農藝學系
• 中文摘要： 水稻幼苗移植後三十天，遭受缺水，其葉片中氨基酸含量發生顯著變化，特別是脯氨酸大量增加呈現累積現象。此種累積現象，在水稻中甚為普遍，不僅在栽培稻中發生，野生稻中亦有發生。脯氨酸累積以葉片中最多，葉鞘次之，根部無此能力。同一植株中，以葉齡較小的葉片具有較高累積能力。不僅完整植株遭受缺水時發生脯氨酸的累積，切離葉片浸漬在滲透溶液中亦有此能力。 切離葉片脯氨酸累積能力與其品種抗旱性有密切關係。三十天株齡之葉片在 -20 barspolyethylene glycol溶液中浸漬48小時（20℃，無光照），葉片中脯氨酸含量增加為原有含量1～5倍者可劃分為敏感型品種，如Sintiane Diofor，臺中在來－號。增加5～10倍者為中度敏感型品種，如IR20。10～15倍為中間型，如Tapol，IR8。15～20倍為中度抗旱型，如RikutoNorin-21。20倍以上為抗旱型品種，如OS4, Dular。惟葉片之葉齡大小，採取部位不同其結果亦不同。 四個遺傳集團中，高脯氨酸含量之基因作用為不相等之累加性作用所致，且遺傳率頗高，有效基因對數為2～3對，此種信息將裨益育種家從事選育抗旱性之品種。
• 英文摘要： After 30 days transplanting when plant wassubjected to water stress, the amino acids con-tent of rice leaves was greatly changed, especiallyincreased in proline content. This proline ac-cumulation following water stress was positivelyrelated to drought resistance in rice cultivarsand wild rice species. All the varieties ac-cumulated higher amount of proline in leavesthan leaf sheath, and no proline accumulated atthe root of rice plant. Within a plant of dif-ferent leaves under water stress, younger leafshowed top accumulation of proline. Althoughproline accumulation under water stress wasapparent in intact plant, it was also shown higheraccumulation in the excised leaves floating atosmotic solution leading to water stress. It was evident that the level of proline ac-cumulation in excised leaves was closely relatedto the degree of drought resistance. Therefore,excised leaves of 30-day-old rice seedlings whentreated at -20 bars polyethylene glycol solutionfor 48 hr (20℃ with dark condition), the ac-cumulated proline content can serve as a usefulcriterion in testing rices for drought resistance.From this method, eight rice varieties can beclassified into five categories based on the foldof increased proline accumulation: (1) susc-eptibility (increased 1-5 times)-TN1, SintianeDiofor, (2) moderately susceptable (increased 5-10 times)-IR20, (3) intermediate (increased 10-15times)-IR8, and Tapol, (4) moderately droughtresistance（increased 15-20 times)-Rikuto Norin-21, (5) drought resistance (increased more than20 times)-OS4 and Dular. Proline accumulation was controlled at leastby two to three gene pairs which showed noneor partial dominance (low over high prolinecontent). It was assumed that the gene effectin partial dominance was additive and moder-ately unequal while it was polygenic additive innone dominance. In the latter case, modifiersmight be also involved. Heritability estimateswere moderately high. These results indicatedsignificant potential for improving drought re-sistance based on proline accumulation throughselection.
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