Hormonal Requirements Induced Different Regeneration Pathways in Alhagi graecorum

Hormonal requirements inducing different regeneration pathways with particular emphasis on somatic embryo-genesis in Alhagi graecorum were studied. While combination of 0.5 $\mu{M}$ 2,4-dichlorophenoxyacetic acid (2,4-D), 2.5 $\mu{M}$ 6-benzylaminopurine (BAP) and 5 $\mu{M}$ 1-naphthaleneacetic acid (NAA) in MS medium induced callus formation and callus maintenance from internodal explants, each alone or in combination with other induced distinct regeneration pathway. Adventitious bud formation was induced on MS medium supplemented with 2.5 $\mu{M}$ BAP. It was improved when 2.5 $\mu{M}$ BAP was used in combination with 5 $\mu{M}$ NAA. MS medium containing 0.5 $\mu{M}$ 2,4-D or 5 $\mu{M}$ NAA induced the formation of abnormal direct somatic embryos. While increase of 2,4-D concentration (1.125-9) resulted in the formation of viable embryogenic mass, increase of NAA did not change its effect. NAA should be used in combination with 2,4-D even at low concentration (0.5 $\mu{M}$) to form embryogenic mass. In A. gaecorum, the role of 2,4-D as trigger of somatic embryogenesis and BAP as trigger of adventitious bud formation was deduced, but for maximum yield certain auxin-cytokinin ratio should be applied. Embryogenic masses characterized by high water content, low peroxidase activity, and low number of peroxidase and glutamate oxaloacetate transaminase bands in comparison with calli obtained under conditions stimulating adventitious bud formation. The resulted differential gene expression, which could be detected by native-PAGE patterns, could be used as marker for organogenic pathway in A. graecorum.