Location: Crop Genetics and Breeding Research2012 Annual Report
1a. Objectives (from AD-416):
To develop and evaluate bermudagrass, napiergrass, pearl millet, and rhizoma peanut for forage production and for alternative uses in the southeastern U.S.; to enhance bioenergy production from warm-season grasses; and to apply molecular genetic technology to improve grass species adapted to the southeastern U.S.
1b. Approach (from AD-416):
Develop and select improved populations and germplasms of bermudagrass for forage, bioenergy, and turf; develop and select improved populations and germplasms of napiergrass for forage and bioenergy; develop and select improved populations, inbreds, and hybrids of pearl millet for forage, bioenergy, and wildlife; and select improved rhizoma peanut germplasms for forage. Evaluate genotype and production effects on ethanol production from pearl millet; assess genotypic differences in bermudagrasses, napiergrass, and pearl millet for conversion to fermentable product or through thermochemical techniques to syngas; and improve selection efficiency for superior forage and cellulosic feedstocks. Measure genetic diversity within bermudagrass, napiergrass, and pearl millet using molecular markers; and identify associations of molecular markers in bermudagrass and pearl millet with traits important for forage or alternative uses.
3. Progress Report:
The goal is to develop improved grass and forage legume germplasm and varieties that can be more efficiently converted into livestock, bioenergy, turf, and bioproducts that can be produced in a variety of environments. Activities focused on the genetic improvement of pearl millet, napiergrass, bermudagrass, and rhizomatous peanut for forage, bioenergy, and alternative uses. Bermudagrass populations were assessed a third year for yield, selections were made to begin the next round of recurrent selection. The bermudagrass core collection continued to be evaluated for nitrogen use efficiency. Napier grass hybrids were evaluated for a fifth year for growth traits, persistence and cold tolerance from an unusually cold winter, initial selections were evaluated a third year in a replicated yield trial, and new selections were made for a new replicated evaluation. Napiergrass continued to be assessed for conversion to ethanol via different pre-treatments for biochemical conversion. Napiergrass accessions have been evaluated for differences in ethanol production with collaborators in Peoria, Illinois. Publications have been published or submitted concerning production aspects of bioenergy crops such as napiergrass and energy cane. Bermudagrass express sequence tagged simple sequence repeat (EST-SSR) markers were developed and used to create bermudagrass genetic maps (Cynodon dactylon and Cynodon transvaalensis) and work indicated that tetraploid bermudagrass is an allotetraploid. The EST-SSR markers have been published and are currently being used to differentiate many of the commercially used bermudagrass cultivars and for cultivar and pedigree identification among bermudagrass turf types. First of their kind SSR markers for measuring diversity in centipedegrass were also developed. Transferability of bermudagrass SSR and resistance analog gene (RGA) markers to zoysiagrass was assessed. The transferability of bermudagrass SSR and RGA markers to zoysiagrass cultivars was low (7-12%). Eleven markers were identified that produced a clear amplicon in both species. Each of the eight zoysiagrass cultivars was obtained from two sources. Genetic variability within the vegetatively propagated cultivar Diamond was seen.
1. Development of genetic tools for turf grass breeding and identification. The release of ‘Tifgreen’ bermudagrass in 1956, which could be mowed at 4.7 mm, spurred golf courses around the southeast to replace their common bermudagrass greens with this vegetatively propagated cultivar. Soon after its release, well-defined areas with noticeable differences in plant morphology, or off-types, appeared on ‘Tifgreen’ putting surfaces. Simple sequence repeat (SSR) markers were created to identify fragments that could distinguish among the three of the most important cultivars used today (‘TifEagle’, ‘MiniVerde’, and ‘Tifdwarf’). Furthermore, we discovered that ‘TifEagle’ and ‘Tifdwarf’ are somatic chimeras and we were the first to show that somatic chimeras exist in turfgrass. Furthermore, the five markers are the only polymerase chain reaction (PCR) markers that can distinguish between ‘Tifdwarf’, ‘MiniVerde’, and ‘TifEagle’. The markers identified are used on a weekly basis to identify stakeholder samples sent from golf courses, sod companies, landscape companies, etc. For the 2012 fiscal year alone, 126 samples have been processed for stakeholders using these markers. Furthermore, these markers were able to reveal that some of the Tifgreen-derived cultivars are somatic chimeras where the genotype of the shoot is different than the genotype of the root for a single plant.
2. The effects of minimal inputs on yields and quality of potential bioenergy crops on the Southern Coastal Plain. Warm-season perennial grasses are a promising source of biomass for energy production in the Southeast U.S., and low-input production is desirable. With only residual fertility in the soil and no irrigation, this test compared biomass yields of eight grasses under low-input production: L 79-1002 energycane (Saccharum hyb.), Merkeron and N51 napiergrass (Pennisetum purpureum Schum.), three clones of giant reed (Arundo donax L.), and two switchgrass (Panicum virgatum L.) lines. For the first two years napiergrass maintained dry matter (DM) yields over 25 Mg DM ha-1yr-1, and energycane yielded over 20 Mg DM ha-1yr-1 for three years. Switchgrass yields were lower (8.6 Mg DM ha-1yr-1 average of four years), but the biomass contained less moisture at harvest than the other, larger-stemmed grasses. Switchgrass biomass also had the lowest concentrations of nitrogen (N), potassium (K), and ash. Average yields of giant reeds were also low (6.4 Mg DM ha-1yr-1), while ash and N concentrations were relatively high compared to switchgrass and energycane. In four years of production, energycane and napiergrass removed between 269–386 kg N ha-1 and 830–1159 kg K ha-1, while the other grasses removed significantly less of these nutrients. Giant reed removed 126 kg N ha-1 and 193 kg K ha-1, and switchgrass removed 83 kg N ha-1 and 140 kg K ha-1. The results of this study provide important information to potential growers and the bioenergy industry on limitations and potential of production of biomass from perennial grasses with minimal inputs in the Southeast.
Harris-Shultz, K.R., Milla-Lewis, S.R., Zuleta, M., Schwartz, B.M., Hanna, W.W., Brady, J.A. 2012. Development of simple sequence repeat markers and the analysis of genetic diversity and ploidy level in a centipedegrass collection. Crop Science. 52:383-392.