| Pogonatherum paniceum (Lam.) Hack. is an indigenous rock plant with good potential for eco-recovery and construction of eco-landscape. However, low survival seedling resulted by poor anti-adversity in infant stage, hampers the practical application of this species in eco-engineering. This study showed that young seedling of P. paniceum could be greatly propagated by tissue culture and subsequent artifical seeds production ways. And the hormonal regulation of in vitro morphogenic pathways was studied. And then the effects of PEG stress and culture conditions on the callus regeneration of P. paniceum were analyzed.A high frequency in vitro regeneration system was developed for P. paniceum. Calli were induced from explants of mature seeds, seedlings, young leaves, and stem segments on Murashige and Skoog (MS) medium supplemented with 1.0 mg·L-1 2,4-dichlorophenoxyacetic acid (2,4-D), 2 mg·L-1α-naphthalene acetic acid (NAA) and 0.2mg·L-1 6-benzylaminopurine (BAP). High induction rates (59.57ï¼…) and regeneration rates (100ï¼…) were obtained from mature seed explants; calli were sub-cultured for over two years and still retained a high regenerative capacity. One seed explant resulted in 69,997 plants in one year. Shoot-buds derived from calli were used for encapsulation in liquid MS medium containing 3ï¼…sucrose and two different alginate matrices (3ï¼…sodium alginate (w/v)+MS medium containing 3ï¼…sucrose and 3ï¼…sodium alginate + 1ï¼…activated carbon (w/v) + MS medium containing 3ï¼…sucrose) with a 20-rain exposure to 2ï¼…CaCl2 and 0.3ï¼…bavistin (w/v). The capsule with 3.0ï¼…sodium alginate (w/v) and 1ï¼…activated carbon (w/v) showed a higher conversion rate (61.58ï¼…) and stronger plantlets under non-aseptic conditions. These systems are useful for the rapid clonal propagation and dissemination of artificial seed material of P. paniceum for eco-recovery.Four types of calli were induced by different concentrations of 2,4-D. High levels of 2,4-D (more than 2 mg·L-1) induced typeâ… callus characterized bipolar somatic embryogenesis and typeâ…¡callus (non-morphogenesis callus), whereas low concentrations of 2,4-D (less than 0.1 mg·L-1) only induced typeâ…£callus characterized shoot-genesis, The 2,4-D concentrations between 0.1tol mg·L-1induced typeâ… callus, typeâ…¡callus and typeâ…¢callus characterized both types of callusâ…£andâ… . Another auxin, NAA only induced typeâ…£callus. These results indicated that different 2,4-D concentrations might trigger different gene expression profiles corresponding for different developmental patterns and NAA might have negative effect on functions of 2,4-D. The combinations of 2,4-D and NAA induced both callus typeâ…¢andâ…¡. The cytokinin BAP, if replaced 2,4-D in callus induction medium, induced direct organogenesis from the seedling and inhibited shoot elongation after normal germinationWe compared the effect of polyethylene glycol (PEG) on regeneration and free proline accumulation of callus of P. paniceum under motionless liquid culture condition and shake liquid culture condition: Callus of P. paniceum had the ability to resist the stress of PEG. The effects of PEG stress and culture conditions on the callus of P. paniceum appeared mainly in two aspects, delaying regeneration time and debasing regeneration rates. The shake liquid culture mainly delayed the regeneration time and PEG stress mainly debased the regeneration rates. Free proline accumulated in the two cultures conditions, and the contents of proline were positively correlated with PEG concentrations and culture time. After stress removal, most of the callus could recover the ability of regeneration, and the free proline might pay an important part in the inhibition and recovery. So it must be chosen a more than 300 g·L-1 PEG concentration and long than 3 weeks culture time in the selection of drought-resistant mutants of P. paniceum. The motionless liquid culture was more suitable for selection of drought-resistant mutants.
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