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An analysis of the effect of gibberellic acid on adventitious shoot formation and development from tuber discs of potato
436
.~BSTRACTS OF CONTRIBUTED MANUSCRIPTS
when individual bulbils were separated and transferred to a medium containing the basal constituents with 0.1 rag/1 NAA.
Asexual embryogenesis in callus derived from palm inflorescences. J o a n F. REYNOLDS, Experimental Agricultural Sciences, The Upjohn Company, Kalamazoo, MI 49001. This study was initiated to determine conditions for growth and regeneration of adult palm tissue in vitro. Complete panicles from immature inflorescences of Chamaedorea costaricana Oerst. were utilized as explant source. Flower buds from emerging inflorescences or whole rachillae from immature inflorescences were used as explant source in Phoenix dactylifera L. Explants were cultured on a medium containing MS salts plus 100rag/1 2,4-D and 1.0mg/l 2iP(N 6isopentenyladenine). After three months in culture the initial explants formed a nodular, grainy callus. Transfer of C. costaricana callus to medium without growth regulators resulted in the tbrmation of a root and shoot, in a manner resembling the germination of a zygoticatlyderived embryo. Similar observations were made in callus cultures from P. dactylifera, however, the embryo-like structures which developed did not form shoots or roots. Inflorescence explants from C. costaricana were also cultured on medium containing MS salts and 1.0 mg/1 2,4-D. After eight months in culture shoots appeared directly from the flower bud meristem and continued to multiply via axillary branching. Charcoal, in a concentration of 0 3% was included in all media formulations in an effort to remove inhibiting substances from the tissue. The charcoal also reduced medium hormone levels, consequently requiring a high auxin concentration (100 rag/l) to induce callus formation. These results show that regeneration of adult palm tissues is possible and signifies a potential for rapid clonal propagation of palms.
An analysis of the effect of gibbereUic acid on adventitious shoot formation and development from tuber discs of potato. ROSF.RT L. JARR~.T and PAUL M. HASEOAWA, Purdue University, Department of Horticulture, West Lafayette, IN 47907. This investigation was conducted to determine
why inclusion of gibberellic acid (GA) into the nutrient medium is required for adventitious shoot formation from cultured tuber discs of potato (Solanum tuberosum L.). Seventy percent of the cultured tuber discs initiated adventitious shoots seven weeks after implantation onto a modified Murashige and Skoog (MS) medium containing Nt-benzyladenine (BA) (3.0mg/l), • -naphthaleneacetic acid (NAA) (0.01rag/I), and GA (3 x 10 -7 M). Concentration of GA greater than this (3 x 10 -7 M) increasingly delayed and inhibited shoot formation. However, no shoots developed on discs cultured in the absence of GA. Microscopic examination of the callus protuberances from which shoots arose revealed that GA inhibited the formation of 'meristemoids' and to some extent the formation of the callus protuberances themselves. However, if the tuber discs were cultured for six weeks on MS medium containing BA and NAA without GA and subsequently transferred to MS medium containing GA as the only growth regulator, 100% of the tuber discs initiated adventitious shoots. Tuber discs recultured in this manner to MS medium lacking GA did not form adventitious shoots although microscopic examination revealed the presence of nu0aerous 'meristemoids' in the callus protuberances. Thus, for shoot formation from potato tuber discs it appears that although GA inhibits 'meristemoid' initiation, it is required for shoot development once 'meristemoids' are formed. This procedure has enabled successful recovery of whole plants from discs excised from tubers of 18 different potato genotypes.
Somatic embryogenesis of carrot callus: modification of competence parameters by vernalization of parent roots. WILLXAM R. KRUr., Department of Plant and Soil Science, University of Rhode Island, Kingston, RI 02881. Roots of nine commercial cultivars of carrot were vernalized for 0, 1, 2 or 3 months. Explants from vernalized and control roots were assayed for (a) length of the precompetent phase, (b) duration of the competent phase, (c) intensity of embryoid production, (d) capacity of embryoid production, and (e) growth. The effects of vernalization on the above parameters varied with genotype of parent material and
.~BSTRACTS OF CONTRIBUTED MANUSCRIPTS
when individual bulbils were separated and transferred to a medium containing the basal constituents with 0.1 rag/1 NAA.
Asexual embryogenesis in callus derived from palm inflorescences. J o a n F. REYNOLDS, Experimental Agricultural Sciences, The Upjohn Company, Kalamazoo, MI 49001. This study was initiated to determine conditions for growth and regeneration of adult palm tissue in vitro. Complete panicles from immature inflorescences of Chamaedorea costaricana Oerst. were utilized as explant source. Flower buds from emerging inflorescences or whole rachillae from immature inflorescences were used as explant source in Phoenix dactylifera L. Explants were cultured on a medium containing MS salts plus 100rag/1 2,4-D and 1.0mg/l 2iP(N 6isopentenyladenine). After three months in culture the initial explants formed a nodular, grainy callus. Transfer of C. costaricana callus to medium without growth regulators resulted in the tbrmation of a root and shoot, in a manner resembling the germination of a zygoticatlyderived embryo. Similar observations were made in callus cultures from P. dactylifera, however, the embryo-like structures which developed did not form shoots or roots. Inflorescence explants from C. costaricana were also cultured on medium containing MS salts and 1.0 mg/1 2,4-D. After eight months in culture shoots appeared directly from the flower bud meristem and continued to multiply via axillary branching. Charcoal, in a concentration of 0 3% was included in all media formulations in an effort to remove inhibiting substances from the tissue. The charcoal also reduced medium hormone levels, consequently requiring a high auxin concentration (100 rag/l) to induce callus formation. These results show that regeneration of adult palm tissues is possible and signifies a potential for rapid clonal propagation of palms.
An analysis of the effect of gibbereUic acid on adventitious shoot formation and development from tuber discs of potato. ROSF.RT L. JARR~.T and PAUL M. HASEOAWA, Purdue University, Department of Horticulture, West Lafayette, IN 47907. This investigation was conducted to determine
why inclusion of gibberellic acid (GA) into the nutrient medium is required for adventitious shoot formation from cultured tuber discs of potato (Solanum tuberosum L.). Seventy percent of the cultured tuber discs initiated adventitious shoots seven weeks after implantation onto a modified Murashige and Skoog (MS) medium containing Nt-benzyladenine (BA) (3.0mg/l), • -naphthaleneacetic acid (NAA) (0.01rag/I), and GA (3 x 10 -7 M). Concentration of GA greater than this (3 x 10 -7 M) increasingly delayed and inhibited shoot formation. However, no shoots developed on discs cultured in the absence of GA. Microscopic examination of the callus protuberances from which shoots arose revealed that GA inhibited the formation of 'meristemoids' and to some extent the formation of the callus protuberances themselves. However, if the tuber discs were cultured for six weeks on MS medium containing BA and NAA without GA and subsequently transferred to MS medium containing GA as the only growth regulator, 100% of the tuber discs initiated adventitious shoots. Tuber discs recultured in this manner to MS medium lacking GA did not form adventitious shoots although microscopic examination revealed the presence of nu0aerous 'meristemoids' in the callus protuberances. Thus, for shoot formation from potato tuber discs it appears that although GA inhibits 'meristemoid' initiation, it is required for shoot development once 'meristemoids' are formed. This procedure has enabled successful recovery of whole plants from discs excised from tubers of 18 different potato genotypes.
Somatic embryogenesis of carrot callus: modification of competence parameters by vernalization of parent roots. WILLXAM R. KRUr., Department of Plant and Soil Science, University of Rhode Island, Kingston, RI 02881. Roots of nine commercial cultivars of carrot were vernalized for 0, 1, 2 or 3 months. Explants from vernalized and control roots were assayed for (a) length of the precompetent phase, (b) duration of the competent phase, (c) intensity of embryoid production, (d) capacity of embryoid production, and (e) growth. The effects of vernalization on the above parameters varied with genotype of parent material and