Shoot propagation, regeneration, and callus induction and differentiation, of Axonopus compressus (Swartz) Beauv

Abstract

Axonopus compressus (Swartz) Beauv., a perennial herb in the Poaceae that has been introduced to a number of tropical and subtropical countries and regions, can serve as a lawn ground cover while its leaves can be developed as a bioenergy resource. It also displays some resistance to heavy metals, allowing it to be planted in areas and urban green spaces polluted by heavy metals. A. compressus is also used as a traditional Chinese medicine. This study is the first report on tissue culture of A. compressus. Stem explants induced shoot clusters on 6-benzyladenine (BA)-containing Murashige and Skoog (MS) medium, with 2.0 mg L^–1 BA inducing a shoot proliferation coefficient (SPC) of 10.89 within 30 d, while MS medium containing 2.0 mg L^–1 BA and 0.1 mg L^–1 α-naphthaleneacetic acid (NAA) amplified SPC to 12.88 within 30 d. SPC on MS medium supplemented with kinetin (KIN) or thidiazuron (TDZ) was not as high as on medium with BA and never exceeded 3.57 within 30 d. A. compressus formed adventitious roots easily, within 15 d, most efficiently on ½MS medium supplemented with 0.1 to 0.5 mg L^–1 IAA, NAA, or IBA, or even on auxin-free medium. Resulting plantlets displayed a high survival rate (> 98%) when transplanted to a substrate containing humus, or humus mixed with vermiculite or sand. Callus was also successfully induced from leaf sheaths on MS medium containing 1.0 mg L^–1 2,4-dichlorophenoxyacetic acid, even more so when 1.15 g L^–1 l-proline was added. Induced callus was able to differentiate into adventitious shoots on MS medium with 0.1 to 0.5 mg L^–1 KIN or BA. An efficient system of shoot proliferation, callus induction, and regeneration in A. compressus has been established.