碳源及氮源對大豆癒傷組織碳-氮代謝之影響

Abstract

本實驗以大豆品種66-F-4-2 [Glycine max (L.) Merr.] 葉片、下胚軸及 根所產生之癒傷組織為供試材料, 探討不同碳、氮源處理, 對三種癒傷組 織生理代謝之影響情形。三種供試材料在外加碳、氮源處理下, 均以葉片 癒傷組織葉綠素含量最高 , 此現象與癒傷組織誘導來源有關, 影響趨勢 隨供試材料而異, 且碳源處理間葉綠素差異較明顯, 以3%蔗糖處理組高 於0%蔗糖處理組。光合成作用測定值均呈負值, 且碳源處理均以0%蔗糖處 理組高於3%蔗糖處理組, 氮源處理則隨材料而異。Rubisco 活性受外加碳 、氮源處理之影響結果, 亦隨供試材料而異, 且Rubisco 活性並未與光合 成作用呈正相關。三種癒傷組織在外加碳、氮源處理下之暗呼吸率, 以碳 源處理差異較明顯, 均以3%蔗糖處理組高於0%蔗糖處理組, 氮源處理則無 明顯差異。此原因為外加碳源 , 能足夠供給癒傷組織行異營作用所需之 碳素, 因此光合成作用呈負值,而癒傷組織增加之呼吸作用可利於碳源吸 收及代謝。氮源處理對三種癒傷組織之可溶性糖、非結構性碳水化合物 (TNC)及HPLC偵測之葡萄糖、果糖和蔗糖個別含量影響無明顯差異, 而外 加碳源可增加供試材料碳水化合物含量, 且可溶糖與 TNC含量間之差異, 以0%蔗糖處理 , 三種癒傷組織均以 TNC含量高於可溶糖含量, 而以3%蔗 糖處理, 則三種癒傷組織均以可溶糖含量高於 TNC含量。涉及碳素分配之 蔗糖合成酵素 sucrose phosphate synthase (SPS)活性, 在碳、氮源處 理下, 葉片癒傷組織SPS活性明顯受蔗糖含量迴饋抑制影響, 造成0%蔗糖 處理組SPS活性高於3%蔗糖處理組, 其他兩種癒傷組織 SPS活性與蔗糖含 量未有相關性亦無明顯受迴饋抑制影響之情形, 但因供試材料不同而異。 在含氮化合物含量結果分析, 推測碳素可提供合成含氮化合物之骨架, 因 此三種癒傷組織之可溶性蛋白質含量, 均以3%蔗糖處理組高於0%蔗糖處理 組。由分析三種癒傷組織氮素同化酵素活性(NR、NiR、GOGAT、GS、GDH) 結果得知, 供試材料吸收、利用銨離子及硝酸鹽離子之能力並不一致, 因 此造成各處理組之含氮量與氨基酸種類、含量趨勢不一致。

Three kinds of callus induced from soybean leaf, hypocotyl and root, were subjected to different carbon and nitrogen sources to investigate the effect on carbon-nitrogen metabolism. The results are summarized as follows: The net photosynthetic rate of the three kinds of callus were negative under all the different carbon and nitrogen sources. The net photosynthetic rate was decreased under exogenous carbon supply. The dark respiratory rate was increased under exogenous carbon supply, while it was not so obvious under exogenous nitrogen supply. It indicated that carbon source supplied the substrates for carbon matebolism and the increase of respiration contributed to the uptake and metabolism of supplied carbon. The accumulation of soluble sugar and total non-structural carbohydrate in three kinds of callus. Carbon source was more obvious under than nitrogen sources and carbohydrate content increase in accord with the amount of carbon source fertilized. Additionally, the accumulation of carbohydarte in leaf callus caused the feedback inhibition in sucrose phosphate synthase activity, but both of hypocotyl callus and root callus were not so similarly inhibited as leaf callus. The soluble protein content increased in accord with the amount of carbon source fertilized, because the carbon source supplied the carbon-skeleton for protein biosynthesizing. But the enzyme activities of nitrogen metabolism in three kinds of callus had different effects under carbon and nitrogen sources treatment. It showed that the ability of nitrate and ammonium utilization was not similar in three kinds of callus.