Response of Fibrous Roots of Sunflower and Tobacco Tissue Cultures to Plant Growth Substances

Publisher Website
Google Scholar
Abstract
Fibrous roots from tissue cultures of the sunflower (Helianthus annuus var. Russian) and tobacco (Nicotiana affinis and the hybrid N. glauca x N. langsdorffii) were grown in vitro in standard media to determine the effect of indoleacetic acid (IAA), chemical carcinogens (1,2,5,6-dibenzanthracene, 3,4-benz-pyrene, and 20-methylcholanthrene), and coconut milk, all added singly or in combination, on these organs. Growth of the fibrous roots was stimulated by the chemical carcinogens. There were linear increments with many branches formed in excess of those grown on basic media only. Root cultures grown on basic media enriched with IAA failed to increase in length but formed hyaline, jelly-like calluses which turned dark brown in the sunflower and tobacco. The hybrid tobacco roots responded much more slowly and formed fewer calluses. Secondary roots appeared from these calluses. Coconut milk induced no changes except in the hybrid tobacco roots where tawny-colored or tomentose-covered calluses were formed. Occasionally small, nodular calluses were observed on sunflower and N. affinis roots grown on media with coconut milk. Roots grown on media containing IAA combined with coconut milk produced dark brown, compact nodular calluses in the sunflower and tobacco. Calluses on these fibrous roots were excised and planted on standard media with the agents studied. The sunflower calluses consisted of large hyaline masses covered with roots. The N. affinis root cultures and those of the tobacco hybrid formed tissue masses with roots. Subsequent transplants of these cultures to media deprived of IAA produced completely differentiated plantlets. Evidently the tissue mass grown in vitro may produce organs (roots), and the organs may be induced to produce a tissue mass capable of differentiating complete plantlets.