Location: Children's Nutrition Research CenterTitle: Overexpression of Arabidopsis VIT1 increases accumulation of iron in cassava roots and stems
|NARAYANAN, NARAYANAN - Danforth Plant Science Center|
|BEYENE, GETU - Danforth Plant Science Center|
|CHAUHAN, RAJ DEEPIKA - Danforth Plant Science Center|
|GAITAN-SOLIS, ELIANA - Danforth Plant Science Center|
|TAYLOR, NIGEL - Danforth Plant Science Center|
|ANDERSON, PAUL - Danforth Plant Science Center|
Submitted to: Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/6/2015
Publication Date: 11/1/2015
Citation: Narayanan, N., Beyene, G., Chauhan, R., Gaitan-Solis, E., Grusak, M.A., Taylor, N., Anderson, P. 2015. Overexpression of Arabidopsis VIT1 increases accumulation of iron in cassava roots and stems. Plant Science. 240: 170-181.
Interpretive Summary: Inadequate iron nutrition affects more than one-half of the world's population and especially impairs health and wellbeing in women and preschool children. A reason for the low intake of iron is that several of the world's staple food crops contain low concentrations of iron. One of these crops which is consumed by millions of people worldwide, is the starchy root crop cassava. To help fortify the storage roots of this plant with more iron, we used a biotech approach that involved inserting a gene that helped cassava absorb and store more iron in its tissues. When functioning in these plants, more total iron came into the cassava plant and a large proportion of this iron was accumulated in the edible portions of the roots. This biotech strategy could help to alleviate iron deficiency conditions in at-risk human populations that rely on cassava as a daily source of calories.
Technical Abstract: Iron is extremely abundant in the soil, but its uptake in plants is limited due to low solubility in neutral or alkaline soils. Plants can rely on rhizosphere acidification to increase iron solubility. AtVIT1 was previously found to be involved in mediating vacuolar sequestration of iron, which indicates a potential application for iron biofortification in crop plants. Here, we have overexpressed AtVIT1 in the starchy root crop cassava using a patatin promoter. Under greenhouse conditions, iron levels in mature cassava storage roots showed 3-4 times higher values when compared with wild-type plants. Significantly, the expression of AtVIT1 showed a positive correlation with the increase in iron concentration of storage roots. Conversely, young leaves of AtVIT1 transgenic plants exhibit characteristics of iron deficiency such as interveinal chlorosis of leaves (yellowing) and lower iron concentration when compared with the wild type plants. Interestingly, the AtVIT1 transgenic plants showed 4 and 16 times higher values of iron concentration in the young stem and stem base tissues, respectively. AtVIT1 transgenic plants also showed 2-4 times higher values of iron content when compared with wild-type plants, with altered partitioning of iron between source and sink tissues. These results demonstrate vacuolar iron sequestration as a viable transgenic strategy to biofortify crops and to help eliminate micronutrient malnutrition in at-risk human populations.