Location: Grain, Forage, and Bioenergy ResearchTitle: Global changes in mineral transporters in tetraploid switchgrasses (Panicum virgatum L.)) Author
|Palmer, Nathan - Nate|
Submitted to: Frontiers in Plant Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/18/2013
Publication Date: 1/2/2014
Publication URL: http://handle.nal.usda.gov/10113/58977
Citation: Palmer, N.A., Saathoff, A., Donze-Reiner, T., Waters, B., Heng-Moss, T., Twigg, P., Tobias, C.M., Sarath, G. 2014. Global changes in mineral transporters in tetraploid switchgrasses (Panicum virgatum L.). Frontiers in Plant Science. 4:1-12. Interpretive Summary: Switchgrass is a native perennial prairie grass that has been targeted for use as a bioenergy crop. Mineral nutrition is an important aspect of plant growth. Lowering levels of minerals required to produce a unit of biomass is an important factor in long term sustainable production from perennial bioenergy crops, and biomass with lower mineral content can improve conversion into fuels. Although, plants absorb minerals from the soil to sustain growth, some of these minerals can be returned to the perennial structures at the end of the growing season. In general, early in the growing season minerals are absorbed from the soil and transit via the roots to the above-ground shoots and leaves. At the end of the growing season some minerals are remobilized from the senescing above-ground tissues and transported to the below-ground tissues for storage. Improving this seasonal movement of mineral nutrients can have a positive impact on the economics of biomass production from switchgrass. Proteins called transporters are responsible for this regulated movement of minerals in plants. The tissue specific and growth-stage specific expression of mineral transporters is poorly understood in switchgrass. In this study, a combination of tools in bioinformatics and molecular biology were used to identify genes involved in the mineral nutrition of the switchgrass plants. Results indicate that a majority of the genes controlling switchgrass mineral nutrition were discovered and their expression patterns in different tissues were documented. Mineral analysis of below ground structures suggested that some minerals were more likely to be transported from the shoots to the rhizomes at the end of the growing season. This initial study will now enable a detailed analysis of the roles of specific mineral transporters in the flux of individual minerals in switchgrass.
Technical Abstract: Switchgrass (Panicum virgatum L) is perennial, C4 grass with great potential as a biofuel crop. An in-depth understanding of the mechanisms that control mineral uptake, distribution and remobilization will benefit sustainable production. Nutrients are mobilized from aerial portions to below-ground crowns and rhizomes as a natural accompaniment to above-ground senescence post seed-set. Mineral uptake and remobilization is dependent on transporters, however, little if any information is available about the specific transporters that are needed and how their relative expression changes over a growing season. Using well-defined classes of mineral transporters, we identified 520 genes belonging to 40 different transporter classes in the tetraploid switchgrass genome. Expression patterns were determined for many of these genes using publically available transcriptomic datasets obtained from both greenhouse and field grown plants. Certain transporters showed strong temporal patterns of expression in distinct developmental stages of the plant. Gene-expression was verified for selected transporters using qRT-PCR. By and large these analyses confirmed the developmental stage-specific expression of these genes. Mineral analyses indicated that K, Fe, Mg, Co and As had a similar pattern of accumulation with apparent limited remobilization at the end of the growing season. These initial analyses will serve as a foundation for more detailed examination of the nutrient biology of switchgrass.