Worldwide Genetic Diversity for Mineral Element Concentrations in Rice Grain

Abstract

With the aim of identifying rice (Oryza spp.) germplasm having enhanced grain nutritional value, the mineral nutrient and trace element concentrations (or ionome) of whole (unmilled) grains from a set of 1763 rice accessions of diverse geographic and genetic origin were evaluated. Seed for analysis of p, Mg, K, S, Ca, As, Cd, Co, Cu, Fe, Mn, Mo, Ni, rb, Sr, and Zn concentrations by inductively coupled plasma mass spectrometry was produced over 2 yr in Beaumont, TX, under both flooded and unflooded watering regimes. The distributions of all element concentrations analyzed were skewed toward higher concentration. A significant portion of this ionomic variation has a genetic basis (broad sense heritabilities 0.14-0.75), indicating an ability to breed for improved grain concentration of all elements except possibly Ni. Variation in grain elemental concentrations was not strongly associated with plant height, heading time, or grain shape, suggesting these physiological factors are not of primary importance in controlling ionomic variation in rice grain. Accessions high in specific elements were sometimes found to have similar genetic or geographic origins, suggesting they share a heritable mechanism underlying their enhanced ionomes. For example, accessions with high Ca, Mg, or K were more common in the indica than in the japonica subgroup; low As was most common among temperate japonica accessions; and several lines high in Mo originated in Malaysia or adjacent Brunei.

Contamination: The toxic side of rice

“…Pinson and her colleagues studied more than 1,700 strains of rice from around the world 3 . They found that some varieties from the United States contained significantly less arsenic than other rice varieties grown using the same soil and water.…”

Diversity of Maize Kernels from a Breeding Program for Protein Quality III: Ionome Profiling

“…Unlike small grains, where variation in [nutrient] density was not closely associated with grain shape [47], most physical attributes of the maize kernel had reasonably significant effects on densities of most nutrients ( Figure 2; Table 2). Evidence of K-weight dilution effect on nutrient densities (e.g., Fe and Zn) has not been shown to be conclusive [48].…”

“…However, our results indicated that divalent cations were the most interactive, while K and Cu, contrary to other findings [46], were the least interactive. This may be interpreted as evidence of no common genetic control of such nutrients [47]. However, several genetic, physiological, and (bio)chemical factors within the complex kernel composition may influence these relationships [53].…”

Biofortification in Cereals:Progress and Prospects

“…However, 90% of Fe and 40% of Zn are lost during polishing 12,13 . Several QTL for grain Zn concentration and genes associated with Zn metabolism have been reported in rice 14 .…”