Transgenic Medicago truncatula plants obtained from Agrobacterium tumefaciens -transformed roots and Agrobacterium rhizogenes-transformed hairy roots.
Medicago truncatula, barrel medic, is a forage crop that has been developed into a model legume. The development of new transformation methods is important for functional genomic studies in this species. Based on Agrobacterium tumefaciens-mediated transformation of root explants, we developed an effective system for producing M. truncatula (genotype R108) transgenic plants. Among the four A. tumefaciens strains (AGL1, C58C1, EHA105 and LBA4404) tested, EHA105 and AGL1 were most effective in regenerating transgenics. Callus induction frequency from root explants was 69.8%, and plantlet/shoot regeneration frequency was 41.3% when EHA105 was used. Transgenic nature of the regenerated plants was confirmed by PCR and Southern hybridization analyses. Progeny analysis revealed stable Mendelian meiotic transmission of transgenes. Because M. truncatula is particularly useful for the study of root endosymbiotic associations, we further developed a plant regeneration system from A. rhizogenes-transformed hairy roots of M. truncatula. Fertile true transgenic plants were regenerated from the hairy roots, thus allowing the assessment of gene functions at the whole plant level. Segregation analysis revealed that the hairy root genes could be segregated out in the progenies. By coupling A. rhizogenes-mediated hairy root transformation and the regeneration system reported here, once potential genes of interest are identified, the transformed hairy roots carrying such genes could be directly regenerated into plants for more detailed characterization of the genes.
Forage Improvement Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA.
Cynthia
C
Crane
Elane
E
Wright
Richard A
RA
Dixon
Zeng-Yu
ZY
Wang
D000123:Acetyltransferases / Q000235:genetics; D016960:Agrobacterium tumefaciens / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D020090:Chromosome Segregation; D017343:Genes, Plant; D005818:Genetic Engineering / Q000379:methods*; D018745:Genome, Plant; D040582:Inheritance Patterns; D046913:Medicago truncatula / Q000235:genetics*; D018517:Plant Roots / Q000033:anatomy & histology / Q000235:genetics; D030821:Plants, Genetically Modified / Q000033:anatomy & histology / Q000235:genetics*; D012231:Rhizobium / Q000235:genetics*; D014170:Transformation, Genetic
D001426:Bacterial Proteins; C096589:rolA protein, Agrobacterium rhizogenes; D000123:Acetyltransferases; C056243:phosphinothricin N-acetyltransferase