A substantial fraction of barley (Hordeum vulgare L.) low phytic acid mutations have little or no effect on yield across diverse production environments

Authors: Raboy, Victor; Peterson, Kevin; JACKSON, CHAD - University Of Idaho; MARSHALL, JULIET - University Of Idaho; Hu, Gongshe; SANEOKA, HIROFUMI - University Of Hiroshima; Bregitzer, Paul

Submitted to: Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/21/2015
Publication Date: 4/29/2015
Citation: Raboy, V., Peterson, K.L., Jackson, C., Marshall, J., Hu, G., Saneoka, H., Bregitzer, P.P. 2015. A substantial fraction of barley (Hordeum vulgare L.) low phytic acid mutations have little or no effect on yield across diverse production environments. PLANTS. 4(2):225-239. doi: 10.3390/plants4020225.

Interpretive Summary: Breeding staple food crops such as cereals and legumes for improved nutritional quality is a major yet challenging objective. A key target for improved nutritional quality is elevated levels of nutritionally available micronutrients including mineral micronutrients such as iron and zinc. Iron and zinc deficiency are world-wide problems that even impact the health of many U.S. citizens including those in the middle class. One approach to enhancing mineral micronutrient nutritional quality is to reduce the level of a compound called “phytic acid”, which is found in high levels in seeds and consumption of which has a negative impact on retention and utilization or iron and zinc in people. Phytic acid is the main storage form of phosphorus in seeds, and in poultry and swine production seed phytic acid results in greatly reduced availability of phosphorus. This creates both production and environmental problems. The USDA-ARS has developed “low-phytate” crops varieties that help to solve these problems; however, the challenge has been to develop “low phytic acid” crops that have good yields. Here we report studies that used a powerful approach to provide a stringent test of yields of six barley low phytic acid lines. We found that one of these lines yielded just as well as did a normal line in a variety of production environments. Therefore there is no “yield penalty” for a farmer if they produced this type of barley. In addition, we found that many of the barley low phytic acid lines have good yields as compared with normal lines.

Technical Abstract: The potential benefits of the low phytic acid (lpa) seed trait for human and animal nutrition, and for phosphorus management in non-ruminant animal production, are well documented. However, in many cases the lpa trait is associated with impaired seed or plant performance, resulting in reduced yield. This has given rise to the perception that the lpa trait is tightly correlated with reduced yield in diverse crop species. Here we report a powerful test of this correlation. We measured grain yield in lines homozygous for each of six barley (Hordeum vulgare L.) lpa mutations that greatly differ in their seed phytic acid levels. Performance comparisons were between sibling wild-type and mutant lines obtained following backcrossing and across two years in five Idaho (USA) locations that greatly differ in crop yield potential. We found that one lpa mutation (Hvlpa1-1) had no detectable effect on yield and a second (Hvlpa4-1) resulted in yield loses of only 3.5%, across all locations. When comparing yields in three relatively non-stressful production environments, at least three lpa mutations (Hvlpa1-1, Hvlpa3-1, and Hvlpa4-1) typically had yields similar to or within 5% of the wild-type sibling isoline. Therefore in the case of barley, lpa mutations can be readily identified that when simply incorporated into a cultivar result in adequately performing lines, even with no additional breeding for performance within the lpa line. In conclusion, while some lpa mutations do greatly or consistently impact field performance, a substantial fraction of all possible mutations appear to have little or no effect on yield.