Plant genetic engineering has become one of the most important molecular tools in the modern molecular breeding of crops. Over the last decade, significant progress has been made in the development of new and efficient transformation methods in plants. Despite a variety of available DNA delivery methods, Agrobacterium- and biolistic-mediated transformation remain the two predominantly employed approaches. In particular, progress in Agrobacterium-mediated transformation of cereals and other recalcitrant dicot species has been quite remarkable. In the meantime, other transgenic-enabling technologies have emerged, including generation of marker-free transgenics, gene targeting, and chromosomal engineering. Although transformation of some plant species or elite germplasm remains a challenge, further advancement in transformation technology is expected because the mechanisms of governing the regeneration and transformation processes are now better understood and are being creatively applied to designing improved transformation methods or to developing new enabling technologies.

The present study demonstrates the establishment of embryogenic tissue from seeds and (seedling-derived hypocotyls) shoot base explants derived from seedlings of Eremochloa ophiuroides. The highest percentage of callus induction obtained from seed and young shoot base explants was 52.0% and 66.6% on Murashige and Skoog (MS) basal media supplemented with 9.0 μM and 18.1 µM 2,4-dichlorophenoxyacetic acid (2,4-D), respectively. The type of callus obtained from both types of explants was offwhite to yellow in color and non-friable and shiny in texture. Excised callus from the explants was subcultured onto fresh media of the same recipe for further proliferation. After 10-12 d of subculture, a yellow, globular, friable embryogenic callus was obtained from the initial callus. The highest percentage of embryogenic calli obtained at 40.0% was observed on media containing 2.2 µM 2,4-D. The highest regeneration rate of 46.6% was observed on MS media supplemented with 0.4 μM 2,4-D and 2.2 µM benzylaminopurine (BA). Regenerated shoots were rooted in MS basal medium. Plants with well-developed roots were transferred to pots containing a soil mix and acclimatized in greenhouse conditions. Four weeks post-transfer, acclimatized plants showed 100% survival and remained healthy and green. This is the first report of a successful method for induction of somatic embryogenesis with subsequent plant regeneration in centipede grass and demonstrates the establishment of embryogenic callus and efficient plant regeneration with potential application in the development of genetic transformation systems for centipede grass.

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Cinnamate-4-hydroxylase (C4H) is a key enzyme in the phenylpropanoid pathway, which synthesizes a variety of secondary metabolites to participate in differentiation and protection of plant tissues against environmental stresses. We isolated a full-length cDNA of the C4H gene from a Korean native bramble (Rubus coreanus Mique), using a reverse transcriptase-PCR and a rapid amplification of the cDNA ends (RACE)-PCR. The full-length cDNA of the RcoC4H gene contained a 1,515 bp open reading frame (ORF) encoding a 504 amino acid protein with a calculated molecular weight of about 57.9 kDa and an isoelectric point (pI) value of 9.1. The genomic DNA analysis revealed that the RcoC4H gene had three exons and two introns. The comparison of the deduced amino acid sequence of RcoC4H with other C4Hs was highly conserved among widely divergent plant species. Also, the P450-featured motifs such as the heme-binding domain, the Tcontaining binding pocket motif (AAIETT), the ERR triad and the tetrapeptide (PPGP) hinge motif necessary for an optimal orientation of the enzyme were highly conserved. Southern blot analysis indicated that RcoC4H exists as a single copy in R. coreanus. Reverse transcriptase PCR analysis showed that the gene is expressed at similar levels in the stem, leaf and flower.