TDZ和6-BA对芜菁离体再生过程中内源激素水平的不同影响(英文)

为研究外源TDZ和6-BA对芜菁离体再生过程中内源激素的影响来阐明TDZ在促进芜菁离体再生方面比6-BA更为有效的原因,采用不同浓度的TDZ和6-BA分别配合不同浓度NAA诱导芜菁带柄子叶离体再生.结果表明:适合芜菁带柄子叶离体再生的外源激素浓度组合分别是TDZ 4·0 mg·L-1+ NAA1·0 mg·L-1和6-BA5·0 mg·L-1+ NAA1·0 mg·L-1;在这2种组合诱导下的不定芽再生率分别是80·4 %和30·2 %.分别测定在这2种外源激素组合诱导下带柄子叶外植体内源生长素(IAA)、玉米素(Z)、赤霉素(GAs)和脱落酸( ABA)的绝对含量,并计算IAA/ABA和IAA/Z之间的相对含量.结果表明:TDZ 4·0 mg·L-1+ NAA1·0 mg·L-1的激素组合诱导带柄子叶外植体产生内源IAA和Z的水平峰值显著高于6-BA5·0 mg·L-1+ NAA1·0 mg·L-1的激素组合;而在2种外源激素组合诱导条件下,内源GAs和ABA的含量差异不显著;IAA的绝对含量左右了IAA/ABA和IAA/Z的变化趋势.综合内源激素的绝对含量和相对含量,TDZ比6-BA更好地诱导芜菁分化效果的关键因素是由于TDZ诱导外植体产生了更高水平的IAA含量和IAA/ABA比值.TDZ和6-BA诱导产生不同水平的内源Z和IAA/Z的作用还不明确.

Effects of thidiazuron and N6-benzylaminopurine on endogenous hormone levels during regeneration of Brassica campestris ssp.Rapifera

To investigate the reason that thidiazuron (TDZ) is more effective than N6-benzylaminopurine (6-BA) in regeneration of Brassica campestris L. ssp. rapifera (Matzg.) Sinsk (syn. B. rapa ssp. rapifera), shoot regeneration was achieved from cotyledonary petiole of in vitro cultures using Murashige and Skoog (MS) medium supplemented with 1-naphthalene-acetic acid (NAA) and TDZ or 6-BA. The regeneration results suggested that the optimal combination was TDZ 4.0 mg·L-1+NAA 1.0 mg·L-1 or 6-BA 5.0 mg·L-1+NAA 1.0 mg·L-1, respectively, and the shoot frequency was 80.4% and 30.2%, respectively. The different effects of the two combinations on the endogenous indole-3-acetic acid (IAA), zeatin (Z), gibberellic acids (GAs) and abscisic acid (ABA) contents in cotyledonary petiole explants were studied. Higher endogenous IAA and Z levels induced by TDZ 4.0 mg·L-1+NAA 1.0 mg·L-1 than 6-BA 5.0 mg·L-1+NAA 1.0 mg·L-1 were observed. The endogenous GAs and ABA contents induced by the two combinations were similar, respectively. The ratio of IAA/ABA and IAA/Z both shifted towards IAA. The ratio of IAA/ABA induced by TDZ was higher than 6-BA, and no visible different effect on IAA/Z between TDZ and 6-BA. The results revealed that higher levels of IAA, and ratio of IAA/ABA were two critical factors, but ABA and GAs had no effect on more effective regeneration induced by TDZ than 6-BA. The roles of Z and IAA/Z were uncertain and should be investigated in further works.