Induction of somatic embryogensis and plant regeneration system in cassava seed

ObjectiveSomatic embryogensis induction of cassava hybrid seed and seedling regeneration system were constructed to provide technology reference for cassava breeding and germplasm innovation.MethodHybrid seeds of cassava variety Southern China 5(SC5)at various maturity degrees were used as explant materials,including cotyledons (a1)and germs(b1)of immature seed,cotyledon(a2)and germ(b2)of mature seed,cotyledon(a3),germ(b3)and hy-pocotyl(c3)of germinated seed.Different exogenous hormones were used to induce the somatic embryogenesis,forma-tion of cotyledon organ,development and rooting of adventitious bud(stem and leaf organ).And the induction effects of these exogenous hormones were compared.ResultPre-culture with basic culture medium(M1)could control the pollu-tion rate(<5.00%)of explants,maintain their biological activities(>90.00%).The browning rate of pretreated materials decreased 30.00%-40.00% than control(not pretreated,CK),and swelling rates of cotyledon(a),germ(b)and hypocotyl (c)increased 6.67%-13.33%,6.67%-50.00% and 20.00% respectively.Inducing somatic embryogenesis with 4.00 mg/L 2,4-D and 12.00 mg/L Picloram,somatic embryogenesis induction rate of germ was the highest,hypocotyl was the se-cond and cotyledons was the lowest.Somatic embryogenesis induction rate of mature seed material was higher than imma-ture seed material,and the effects of 4.00 mg/L 2,4-D was better than that of 12.00 mg/L Picloram.0.10 mg/L BAP and 1.00 mg/L NAA could induce differentiation and proliferation of somatic embryogenesis.But the induction rates of soma-tic embryogenesis in a,b and c induced by 0.05 mg/L BAP+0.50 mg/L NAA were significantly(P<0.05,the same below) increased compared with those adding single 0.10 mg/L BAP or 1.00 mg/L NAA.The adventitious buds induction rate were 30.00%(a2),40.00%(a3),40.00%(b1),53.33%(b2),70.00%(b3)and 13.33%(c3)respectively,which showed that for the same tissue,somatic embryogenesis induction rate of mature seed materials were better than immature seed materials.Among all the seed materials with various maturities,the effects of b were the best. The rooting rates were 23.33%(a2),23.33%(a3),16.67%(b1),30.00%(b2),56.67%(b3)and 0(c3)respectively;the rooting rate of b3 was significantly higher than other materials,and there was no significant difference between a2,a3,b1 and b2.It showed that for the same tissue,rooting induction of mature seed materials was easier than immature seed materials,and their de-velopment was also better.Out of seven hybrid seed materials with various maturities,regeneration plants of a2,a3,b1, b2 and b3 were obtained through somatic embryogenesis induction with success rate of 71.43%.ConclusionPre-culture can inhibit browning of cassava hybrid seed tissues and increase the swelling induction effects. In cassava planting, adding 4.00 mg/L 2,4-D in medium can induce somatic embryogenesis,and adding 0.05 mg/L BAP and 0.50 mg/L NAA misture in medium can proliferate somatic embryogenesis.In addition,seed materials with high maturity level(e.g.em-bryo of germinated seed)should be selected as explant materials.