Plant regeneration from callus and protoplasts in Medicago polymorpha

Abstract

Seventeen ecotypes of the wild species Medicago polymorpha adapted to a Sardinian (Italy) environment have been evaluated for their response to tissue culture. The accession Samughero-Albi was the more respondent for callus induction and, together with Usassai, showed the highest regeneration capacity on media containing i mg 1-1 2iP and 0.1 mg 1-1 IAA. The morphogenetic response was also affected by the explant source. The hypocotyl-derived-calli were the best regenerating tissues. Regenerated plantlets were difficult to root and it was possible to obtain plants with a well developed root system only after 5-7 weeks of culture on media containing 2iP and IAA both at 0.2 mg 1-1. Mesophyll cells were the best protoplast yielding source but only those isolated from roots were able to divide and to regenerate plants. Results are discussed in relation to the genotype specificity for the morphogenetic response and the feasibility of using M. polymorpha in the somatic hybridization with M. sativa.

Plant regeneration from explant and protoplast derived calluses of Medicago littoralis

“…In M. littoralis morphogenetic calluses, rooting of shoots and embryo germination were all achieved easily when compared to M. polymorpha (Scarpa et al 1993), and M. truncatula (Nolan et al 1989), two other annual self-pollinated legume species. In M. littoralis, explant origin affects the morphogenetic response in the order: leaves > hypocotyls _> roots > cotyledons.…”

Characterization of factors affecting plant regeneration frequency of Medicago lupulina L.

“…Cytokinin hormones also appear to be essential for the induction of somatic embryogenesis of three other autogamous species: M. truncatula Garn. (Li, 1988;Nolan et al, 1989), M. polymorpha L. (Scarpa et al, 1993) and M. suffruticosa Romond (Li & Demarly, unpublished). However, it is not possible at present to conclude if there is a general difference between the two groups of Medicago species in the phytohormone requirements for the induction of regeneration.…”

“…In contrast, plant regeneration and somatic embryogenesis from autogamous Medicago species appear to be more difficult and have only been reported in M. lupulina L. (Li et al, 1986), M. truncatula Garn. (Nolan et al, 1989) and M. polymorpha L. (Scarpa et al, 1993). We have previously reported that plant regeneration was induced in immature inflorescence explants of M. lupulina L., pretreated for only 10 min with a solution containing 10 mg/1 BA and 1 mg/l 2,4-D before transfer onto hormonefree agar medium.…”

Investigation of the Potential of two WildMedicagoSpecies -Medicago OrbicularisandMedicago Arabicaforin VitroCallusogenesis and Direct Organogenesis

“…The first regeneration protocol for annual M. truncatula via indirect somatic embryogenesis is achieved (6) and a lot of protocols for this species have been reported (7,8,9). Protocols for regeneration of other annual also have been created -M. polymorpha (10), M. littoralis (11), M. suffruticosa (12), M.lupulina (13), M. orbicularis (14). Regeneration via direct somatic embryogenesis in liquid and solid media for M. truncatula (15,16) and for M. littoralis, M.murex and M. polymorpha also has been established (17).…”