Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/7/2012
Publication Date: 2/1/2013
Citation: Ratnaprabha, R., Pinson, S.R., Tarpley, L. 2012. Can rice grain mineral concentrations be predicted at seedling stage? 35TH Rice Technical Working Group Meeting Proceedings, February 27, - March 1, 2012, Hot Springs, Arkansas. CDROM Interpretive Summary:
Technical Abstract: The study investigated the possibility of using the mineral (ionomic) concentrations of rice (Oryza sativa L.) seedling leaves to predict genotypes that accumulate large amounts of certain minerals in their grains. This information will be used for genetically improving the nutritional value of rice grain and for improving our understanding of mineral uptake, transport, and accumulation in rice. In 2007 and 2008, preliminary field trials were conducted on a core subset of 1640 rice accessions from the USDA National Small Grains Collection. These flooded and unflooded trials identified germplasm with varying levels of grain mineral concentrations. The present study investigated association between seedling-leaf and grain mineral concentrations of 16 minerals within this diverse set of germplasm to determine if seedling leaf data could be used to predict grain concentrations. Such association could greatly accelerate breeding efforts aimed at developing rice genotypes with improved grain mineral composition (nutritional value). The 40 rice genotypes selected for their extreme grain mineral concentrations were grown in an outdoor potted plant study in 2010. All 40 genotypes were planted in 7-10 day intervals to provide, on a single sampling date, 70 days after planting of the first set, plants of a wide range of developmental stages. Leaf tips (5cm) for ionomic analysis were collected from the most recently fully emerged leaf per plant. For molybdenum (Mo), several genotypes selected for their high grain-Mo concentrations, were found to consistently exhibit high leaf-Mo concentrations, implying that seedling leaf tips can be used to a) select among F2s, and b) select among diverse germplasm sets. For calcium (Ca), some genotypes selected for high grain-Ca concentrations exhibited high leaf-Ca concentrations. For Arsenic (As) and Cadmium (Cd), some genotypes selected for high grain-As or Cd concentration exhibited high seedling-leaf As or Cd concentrations. Enhanced seedling-leaf sodium (Na) concentrations seemed a better predictor of high grain potassium (K) than did seedling leaf K content. It is possible that different genotypes have different physiological mechanisms underlying their high-grain concentrations of particular minerals, some of which may be reflected in seedling leaves, others not. Observations of F2 progeny leaf and grain mineral concentrations will be used to further investigate the relationship between grain and leaf concentrations of Mo, Ca, As & Cd. For the remaining eight elements (Fe, Sr, Cu, Mg, Mn, Ni, P, Rb, S, Zn) seedling leaf concentration did not appear predictive of grain element content, neither in the high nor low directions.