Physical and biochemical differences in Agrobacterium rhizogenes-mediated transgenic hairy root lines of Echinacea purpurea

Previous efforts to transform lentil have been considerably hampered by the crop’s recalcitrant nature, giving rise to particularly low transformation and regeneration frequencies. This study aimed at optimizing an Agrobacterium rhizogenes-mediated transformation protocol for the generation of composite lentil plantlets, comprised of transgenic hairy roots and wild-type shoots. Transformation was performed by inoculating the cut hypocotyl of young lentil seedlings, while optimization involved the use of different bacterial strains, namely R1000, K599 and Arqua, and protocols differing in media composition with respect to the presence of acetosyringone and MES. Composite plantlets had a transgenic hairy root system characterized by an increased number of hairy roots at the hypocotyl proximal region, occasionally showing plagiotropic growth. Overall findings underline that transformation frequencies are subject to the bacterial strain, media composition as well as their combined effect. Among strains tested, R1000 proved to be the most capable of hairy root formation, while the presence of both acetosyringone and MES in inoculation and culture media yielded considerably higher transformation rates. The transgenic nature of hairy roots was demonstrated by the Ri T-DNA-mediated transfer of the rolB2 gene and the simultaneous absence of the virCD sequence of A. rhizogenes. Our findings provide strong evidence that A. rhizogenes-mediated transformation may be employed as a suitable approach for generating composite seedlings in lentil, a species whose recalcitrance severely hampers all efforts addressed to transformation and whole plant regeneration procedures. To the best of our knowledge, this is the first report on the development of a non-laborious and time-efficient protocol for the generation of transgenic hairy roots in lentil, thus providing an amenable platform for root biology and gene expression studies in the context of improving traits related to biotic and abiotic stress tolerance.

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A reliable and efficient protocol for induction of hairy roots in Agastache foeniculum

Biologia ◽

10.2478/s11756-014-0382-8 ◽

2014 ◽

Vol 69 (7) ◽

Cited By ~ 16

Author(s):

Elnaz Nourozi ◽

Bahman Hosseini ◽

Abbas Hassani

Keyword(s):

Salicylic Acid ◽

Agrobacterium Rhizogenes ◽

Hairy Root ◽

Hairy Roots ◽

High Performance ◽

Root Culture ◽

Hairy Root Culture ◽

Biochemical Properties ◽

Separate Experiment ◽

Transformed Roots

AbstractHairy root culture system is a valuable tool to study the characteristics of gene expression, gene function, root biology, biochemical properties and biosynthesis pathways of secondary metabolites. In the present study, hairy roots were established in Anise hyssop (Agastache foeniculum) via Agrobacterium rhizogenes. Three strains of Agrobacterium rhizogenes (A4, A7 and 9435), were used for induction of hairy roots in four various explants (hypocotyl, cotyledon, one-month-old leaf and five-month-old leaf) of Anise hyssop. The highest frequency of transformation was achieved using A4 strain in one-month-old leaves (51.1%). The transgenic states of hairy root lines were confirmed by PCR (Polymerase chain reaction) method. High performance liquid chromatography analysis revealed that the production of rosmarinic acid (RA) in transformed roots of A. foeniculum was almost 4-fold higher than that of the non-transformed roots. In a separate experiment, hairy roots obtained from one-month-old leaves inoculated with A4 strain, were grown in liquid medium and the effects of different concentrations of salicylic acid (0.0, 0.01, 0.1 and 1 mM) and chitosan (0, 50, 100 and 150 mg L−1) (as elicitor) and sucrose (20, 30, 40 and 50 g L−1) on the growth of hairy roots were evaluated. The results showed that, 30 g L−1 sucrose and 100 mg L−1 chitosan increased the biomass of hairy root cultures and application of salicylic acid reduced the growth of hairy roots compared with control roots.

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