Somatic embryogenesis and plant regeneration of tropical maize genotypes

• Published in: Plant cell, tissue and organ culture Vol. 102; no. 3; pp. 285 - 295
• Main Authors: Anami, Sylvester Elikana, Mgutu, Allan Jalemba, Taracha, Catherine, Coussens, Griet, Karimi, Mansour, Hilson, Pierre, Van Lijsebettens, Mieke, Machuka, Jesse
• Format: Journal Article
• Language: English
• Published: Dordrecht Dordrecht : Springer Netherlands 01.09.2010; Springer Netherlands; Springer; Springer Nature B.V; Springer Verlag
• Subjects: 2,4-D; Acclimation; Acclimatization; Agrobacterium; Biological and medical sciences; Biomedical and Life Sciences; Biotechnology; Callus; Changing environments; Corn; Cultivation; Culture media; Deoxyribonucleic acid; Dichlorophenoxyacetic acid; DNA; dose response; Embryonic growth stage; Embryos; Fundamental and applied biological sciences. Psychology; gene transfer; genetic transformation; Genotypes; Germplasm; Growth regulators; in vitro regeneration; Inbreeding; Life Sciences; micropropagation; Original Paper; plant age; Plant Genetics and Genomics; plant growth substances; Plant Pathology; Plant Physiology; plant propagation; Plant Sciences; Population growth; Regeneration; Shoots; Somatic embryogenesis; somatic embryos; T-DNA; tropical and subtropical crops; Virulence; Zea mays; Callus induction; Tropical maize; Somatic embryogenesis; Embryonic development; Monocotyledones; Vegetals; Zea mays; Tissue culture; Tropical crop; Genotype; Callogenesis; Somatic embryo; Regeneration; Gramineae; Angiospermae; Spermatophyta
• ISSN: 0167-6857; 1573-5044
• DOI: 10.1007/s11240-010-9731-7

In Latin America and sub-Saharan Africa, tropical maize (Zea mays L.) is a major crop for human consumption. To cope with the increasing population and changing environment, there is a need for improving tropical maize germplasm. As part of a biotechnological approach, efficient in vitro regeneration of two tropical maize inbred lines (CML216 and CML244) was established. A number of parameters were optimized, such as age of the immature embryos, plant media and growth regulator concentration. After 6 weeks of culture, somatic embryos that had already reached the coleoptilar stage produced shoots after light induction and developed into fertile plants after acclimation in the soil. The callus induction frequencies and somatic embryo-derived plantlet formation were higher when cultured with the Linsmaier and Skoog medium than those with the Chu's N6 basal medium. Regeneration of tropical maize shoots depended on the 2,4-dichlorophenoxyacetic acid (2,4-D) concentration at the callus initiation stage from immature embryos. The recalcitrance of the tropical maize inbred line TL26 to in vitro regeneration was overcome in a single-cross hybrid with the CML216 and CML244 genotypes. Remarkably, tropical maize somatic embryos were formed at the abaxial side of the scutellum facing the medium, probably from the axis of the immature embryos, as shown by histological sections. Upon co-cultivation, agrobacteria transiently expressed their intronless β-glucuronidase-encoding gene at the embryogenic tissue, but not with an intron-containing gene, suggesting that virulence genes are induced in Agrobacterium, but that subsequent steps in the T-DNA transfer are inhibited.