几种生长素对木薯体细胞胚发生和植株再生的作用

木薯（ＭａｎｉｈｏｔｅｓｃｕｌｅｎｔａＣｒａｎｔｚ）嫩叶外植体在含２，４－Ｄ（１－１６ｍｇＬ－１）或ＮＡＡ（４０ｍｇＬ－１）的诱导培养基上能直接诱导初生体细胞胚胎发生，而低活性的生长素ＩＢＡ或ＩＡＡ（４０ｍｇＬ－１）或低浓度的２，４－Ｄ（０．１ｍｇＬ－１）则不能。而以木薯初生体细胞胚切段为外植体时，次生体细胞胚的诱导对生长素的活性或浓度的要求降低。降低生长素浓度或活性能缩短体细胞胚诱导时间并促进根的形成，有利于提高体细胞胚的再生频率。体细胞胚外植体在诱导培养基上的培养时间对下一步体细胞胚胎发生的诱导产生影响。通过石腊切片观察，在含２，４－Ｄ诱导培养基上，木薯体细胞胚不能形成芽分生组织。结果表明，２，４－Ｄ等生长素类物质对诱导木薯体细胞胚胎发生是关键因子，但对体细胞胚的进一步发育和植株再生起抑制作用。

EFFECTS OF SEVERAL AUXINS ON SOMATICEMBRYOGENESIS AND PLANT REGENERATION IN CASSAVA

Primary somatic embryogenesis could be directly induced from immature leaves ofcassava (Manihot esculenta Crantz) on the MS solidified medium supplemented with higherconcentration of 2,4-D (1 - 16 mg L-1) or NAA (40 mg L-1), but IBA and IAA (40 mg L-1)could not induce it. When the somatic embryo fragments were used as explants, the needof auxin activity and concentration for the induction of secondary somatic embryogenesisdecreased. The decrease of the concentration or activity of the auxins in the induction mediacould enhance somatic embryogenesis and root formation, and result in the increase ofplant regeneration frequency. It was observed that somatic embryos could not developshoot meristem on the induction medium containing 4 mg L-1 2,4-D. The experimentsshowed that the auxins stimulated the induction of cassava somatic embryogenesis butinhibited the development of somatic embryos and decrease plant regeneration in cassava.