Author(s)

Charlie D. Dowling, Byron L. Burson, Jamie L. Foster, Lee Tarpley, Russell W. Jessup

Department of Soil and Crop Sciences, Texas A&M University, College Station, USA.
Department of Soil and Crop Sciences, Texas A&M University, College Station, USA;.
Texas A&M Agricultural Research and Extension Center, Texas A&M AgriLife, Beaumont, USA..
Texas A&M Agricultural Research Center, Texas A&M AgriLife, Beeville, USA.
USDA-ARS, Crop Germplasm Research Unit, Texas A&M University, College Station, USA;.

Prospects for deploying perennial grasses that are currently considered leading candidates for dedicated energy crops over large acreages are debatable because of several limitations, including vegetative propagation or small seed size, low biomass production during the first growing season, and incomplete assessments of crop invasiveness risk. Pearl Millet-Napiergrass hybrids (“PMN”; Pennisetum glaucum [L.] R. Br. × P. purpureum Schumach.), in contrast, are large-seeded, sterile feedstocks capable of high biomass production during establishment year. Novel methods are warranted for confirmation of PMN hybrids, as traditional morphological observations can be inconclusive and chromosome number determination using cytological methods is laborious and time consuming. Six putative PMN lines were produced in this study, and 10 progeny from each line were evaluated using morphological traits, seed fertility, flow cytometry, and expressed sequence tag-simple sequence repeat (EST-SSR) markers. All putative hybrid lines were sterile and failed to produce seed. The PMN hybrids could not be distinguished from either parent using flow cytometry due to highly similar nuclear genome DNA contents. A number of paternal napiergrass-specific EST-SSRs were identified for each PMN line, and four paternal-specific EST-SSRs conserved across all napiergrass accessions were selected to screen the putative PMN hybrids. These EST-SSRs confirmed that all F₁ individuals analyzed were PMN hybrids. The use of paternal-specific markers therefore provides a valuable tool in the development of both “Seeded-yet-Sterile” biofuel PMN feedstocks and additional PMN cultivar-and parental species-specific markers.

Pennisetum glaucum; Pennisetum purpureum; Bulked Segregant Analysis; Marker-Assisted Selection; Marker-Assisted Breeding; EST-SSR; Expressed Sequence Tag; Simple Sequence Repeat; Microsatellites; Biofuel; Biofuels; Pearl Millet × Napiergrass; Pearl Millet; Napiergrass; Interspecific Hybrid; PCR; Polymerase Chain Reaction; Comparative Genomics

C. Dowling, B. Burson, J. Foster, L. Tarpley and R. Jessup, "Confirmation of Pearl Millet-Napiergrass Hybrids Using EST-Derived Simple Sequence Repeat (SSR) Markers," American Journal of Plant Sciences, Vol. 4 No. 5, 2013, pp. 1004-1012. doi: 10.4236/ajps.2013.45124.