Studies on in vitro somatic embryogenesis, organogenesis and plant regeneration of sweet potato ( Ipomoea batatas L.)

• Main Authors: Hao-Hung Cheng, 鄭皓鴻
• Other Authors: Mau-Shing Yeh
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/57248730309855190803

博士 === 國立中興大學 === 農藝學系 === 89 === Studies on in vitro somatic embryogenesis, organogenesis and plant regeneration of sweet potato ( Ipomoea batatas L.) Abstract In order to studies the effects of different types and concentration of auxins and basal media for somatic embryogenesis of sweet potato, the plantlets in vitro of sweet potato of cultivars TNG67 and TNG68 were used as material source. The shoot tips of apical and lateral buds from plantlets mentioned above were cultured on MS and modified MS basal media contained with different concentration of 2,4-D and 4-FA, respectively. After culture 6~8 weeks in dark, the induced embryogenic callus were subcultured on the same fresh media or the medium supplemented with 0.5 mg/l ABA for differentiation of embryogenic callus. To understand the effects of different types and concentration of auxins, sucrose and ethylene inhibitors on organogenesis, explants leaf, petiole and root of TNG67 and TNG68 were cultured on these media contained with some agents or treatments including(1) different types of auxin were added to MS basal medium(e.g. IAA(0.1, 0.5, 1, 2 mg/l), IBA(0.05, 0.1, 0.5, 1 mg/l), NAA(0.05, 0.1, 0.5, 1 mg/l) and picolinic acid(0.1, 0.5, 1, 2 mg/l)); (2) explant from different culture time of plantlet(after cultured for 20, 30 and 60 days); (3) exlants from different media for plantlet(e.g. MS + 30 g/l sucrose, MS + 30 g/l sucrose + 1 mg/l IAA, MS + 60 g/l sucrose, LS + 30 g/l sucrose + 1 mg/l IAA, MS + 60 g/l sucrose + 1 mg/l IAA); (4) ethylene inhibitors AgNO3(5 mg/l and 10 mg/l) and CoCl2(0.65 mg/l and 1.3 mg/l) were added to media contained 0.1 mg/l NAA or 1 mg/l piciolinic acisd, respectively. The explants leaf, petiole and root of TNG68 were also cultured on the media contained with different types and concentration of sugar(15 g/l, 30 g/l, 45 g/l sucrose or fructose and 15 g/l sucrose + 15 g/l fructose added in MS basal medium), K+(adding KH2PO4 and/or KCl to MS basal medium and making N: K=1:2 or 1:3) or GA3(0.1, 0.5 and 1 mg/l). The somatic embryogenesis and organogenesis of sweet potato were observed by ways of the paraffin section and scanning electron microscope. Results were summarized as follows: 1. The induction rate of embryogenic callus from explants of TNG67 was lower than that of TNG68. For both cultivars, the induction rates of embryogenic callus from upper and middle node explants were higher than those from the lower node explants cultured on media contained with low concentration of auxins(0.1 mg/l、0.5 mg/l). The rates of embryogenic callus induction on media contained with 4-FA were better than those contained with 2,4-D. For advanced effect of embryogenic callus induction, it is not necessary to modify the composition of MS basal medium. For somatic embryo differentiation, it is better to subculture the embryogenic callus to the medium contained with 0.5 mg/l ABA. 2. The rates of shoot regeneration of TNG67 were lower than those of TNG68 generally. Among the three explants, the shoot regeneration rate of root was followed with those of leaf and petiole. The shoot regeneration rates from upper and middle leaves were higher than the other. Among different auxins, the appropriate concentration for shoot induction are different. With increasing concentration of auxins, shoot regeneration showed a tendency to decline. At early culture stage, if the leaf explant could not keep green, there was no shoot regeneration even the roots had been induced. 3. The leaf explant from plantlet after cultured 20 days was good for shoot regeneration of TNG67, but was bad for TNG68. The older the plantlet was, the lower the shoot regeneration rate was. It was only useful for shoot regeneration from leaf explant of TNG67 that the media for plantlet growth was supplemented with IAA. Media contained with different ethylene inhibitors were advantage to keep leaf green, but no advantage to induce shoot regeneration. The shoot regeneration rate declined with the concentration increase of ethylene. It was suggested that appropriate concentration of ethylene was useful for shoot regeneration. 4. The ratio of N/K attained to 1 : 2 by adding KCl into medium was noted BKC1 medium(MS + 0.1 mg/l IBA + 0.94g/l KCl). The shoot regeneration rate and shoot mean was higher than that on the control. Low sugar concentration was disadvantage to induce shoot regeneration and high sugar concentration was bad for leaf rooting. The shoot regeneration rates on the media contained with sucrose were higher than those on the media contained with fructose. The shoot regeneration rates of leaf increased with sugar concentration increase but those are opposite for root explant. Except for energy and carbon source, high concentration of sugar also had osmotic effect. GA was disadvantage for shoot regeneration but was advantage for root swelling and starch accumulation. 5. Among treatments，it was found that the regeneration rates of petiole were much lower than those of leaf. It was suggested that the exist of lameria was advantage to shoot regeneration. The shoot regeneration rates of upper and middle leaf position were higher than that of lower leaf position. Although younger explants seemed to shoot regeneration, appropriate mature of explant was more important for shoot regeneration. On different factors for shoot regeneration between TNG67 and TNG68, the differences of two cultivars became more distinguished. 6. There were two ways for shoot regeneration of sweet potato. One was from the node of leaf-derived root, and the other was from leaf base. The shoot regeneration way of the former was from the node of leaf-derived root by the observation of the paraffin section and scanner electron microscope. The factors involved shoot regeneration way included cultivar, the types and concentration of auxin, source plant age of explant, the contents of medium for source plant growth, the types and concentration of ethylene inhibitor, the types and