Studies on Plant Growth Characteristics and Leaf Protoplasts of Several Ipomoea Species

• Main Authors: Yong, Kim-Chong, 楊金昌
• Other Authors: Kwan-Long Lai
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/09643381025142570385

博士 === 國立臺灣大學 === 農藝學系 === 85 === Sweet potato (Ipomoea batatas (L.) Lam.) is one of the most important root crops in Taiwan. It''s area harvested and total production in Asia is top of the world. Since sweet potato is a crop which is always propagated by asexual propagation method , it would be appropriate to carry out those update research methods. In this research first of all the plant characteristics of sweet potato cultivar Tainung No.66 (TNG66), two closely related wild species of sweet potato I. triloba and I. trifida 〔containing diploid (2n=2x)，tetraploid(2n=4x) and hexaploid(2 n=6x)〕were investigated, then established the methods of isolation and culture of their leaf mesophyll protoplast. The condition of electrofusion between their protoplasts and culture were also studied. The characteristics of fusant were examined with isozyme zymograms and chromosome numbers respectively.Seeds of closely related wild species were firstly disinfected and sown on the aseptic solidified MS medium containing 3% sucrose and 0.7% agar-agar with pH5.7. After the plant were established in vitro, their stem segment which contained one to two axillary buds were subcultured to fresh medium containing different concentration of NAA. The results showed that I. triloba , I. trifida 2x ,4x and 6x grew better in medium containing 0.1 mg/l, 0.1 mg/l, 0.3 mg/l and 0 mg/l NAA respectively.Plants of sweet potato cultivar TNG66 and three different ploidy plants of I. trifida were transplanted to natural light phytotrone with different day/night temperatures. Plants characteristics and growth habitat were investigated, there are several plant characteristics and growth habitat such as self-incompatibility, starch containing in roots and perennial growth, which are similar in cultivar TNG66 and three different ploidy plants of I. trifida. Width and length of leaf ,length and diameter of petiole, diameter of stem and length of 5 th internode of cultivar TNG66 and those I. trifida increased when the growing day/night temperature were increased. Variation of leaf shape, periderm cell on leaf and thickness of stem were increased with the increment of ploidy among those I. trifida. Protoplast isolation of leaf mesophyll of sweet potato cultivar TNG66 were found to be improved greatly if the leaf mesophyll were presoaked in mannitol or sorbitol solution before enzyme solution treatment. Leaf mesophyll protoplasts of the three different ploidy plants of I. trifida could be isolated successfully by treatment of enzyme solution containing 4﹪ cellulase RS, 0.5﹪pectolyase Y-23, 0.5﹪hemicellulase, 0.4 M mannitol, 1/4 MS inorganic salts, 1 mg/l thiamine-HCl, 1 mg/l pyridoxine-HCl , 10 mg/l nicotinic acid及100 mg/l myo-inositol without pretreatment. Colonies were induced respectively from the three ploidy I. trifida protoplasts when they were cultured in MS liquid medium with 0.1 mg/l 2,4-D and 0.5 mg/l KIN. Protoplasts yield per gram leaf fresh weight of I. trifida 2x,4x and 6x were 1.45x107±0.32x107, 3.95x106±1.22x106 and 3.5x106 ±1.65x106 respectively, and callus were formed after the colonies were plated and transfered to solid medium.The electrofield strength of protoplast electrofusion condition were studied. The result showed that adequate ac-field and dc-field for protoplast inducing electrofusion of sweet potato cultivar TNG66 and I. triloba were 600 V/cm and 1800 V/cm. Callus could be induced from the electrofused protoplasts of sweet potato cultivar TNG66 and I. triloba after cultured. Root organs were regenerated when they were transferred to 1/2 modified MS medium containing NAA and BA. The peroxidase isozyme zymogram and chromosome number of those callus similar to that of sweet potato cultivar TNG66. Callus induced from electrofused protoplasts of I. trifida 2x and 4x did show different zymogram of peroxidase isozyme from both protoplast donors. Their chromosome number showed 2n=90 or more.