Abstract
Switchgrass (Panicum virgatum L.; family Poaceae) is a warm-season C4 perennial grass. Tillering plays an important role in determining the morphology of aboveground parts and the final biomass yield of switchgrass. Auxin distribution in plants can affect a variety of important growth and developmental processes, including the regulation of shoot and root branching, plant resistance and biological yield. Auxin transport and gradients in plants are mediated by influx and efflux carriers. PvPIN1, a switchgrass PIN1-like gene that is involved in regulating polar transport, is a putative auxin efflux carrier. Neighbor-joining analysis using sequences deposited in NCBI databases showed that the PvPIN1gene belongs to the PIN1 family and is evolutionarily closer to the Oryza sativa japonica group. Tiller emergence and development was significantly promoted in plants subjected toPvPIN1 RNA interference (RNAi), which yielded a phenotype similar to that of wild-type plants treated with the auxin transport inhibitor TIBA (2,3,5-triiodobenzoic acid). A transgenic approach that inducedPvPIN1 gene overexpression or suppression altered tiller number and the shoot/root ratio. These data suggest that PvPIN1plays an important role in auxin-dependent adventitious root emergence and tillering.
Highlights
Switchgrass (Panicum virgatum L.; family Poaceae) is a perennial warm-season C4 grass
Analysis of the transcriptome results for switchgrass tillering mutants indicated that the PIN1 gene was differentially expressed
Based on the sequence in the transcriptome database, the PvPIN1 gene was amplified from the cDNA of switchgrass young tillers with the primer pairs F and R (Table 1)
Summary
Switchgrass (Panicum virgatum L.; family Poaceae) is a perennial warm-season C4 grass. Switchgrass has received increasing attention as a highly versatile feedstock used for soil and water conservation, livestock feeding and bioethanol production (Casler, 2012; Parrish et al, 2012). The competition between switchgrass and crops for water and arable lands may exacerbate current food security challenges (Varvel et al, 2008). Maximizing the use of various nonirrigated marginal croplands and improving the resistance of switchgrass may be plausible approaches to address the above concern. One of the practical strategies to enhance plant production and anti-stress abilities is to use molecules involved in various stages of plant growth. The plant phytohormone auxin regulates numerous developmental processes during plant growth, including growth direction, shoot and root branching, and differentiation of vascular tissue (Xu et al, 2005).
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