Heterologous expression of ISU1 gene from Fragaria vesca enhances plant tolerance to Fe depletion in Arabidopsis.

Iron-sulfur (Fe-S) cluster assembly genes play important roles in plant growth and development. However, their biological function in fruit crops is still unknown, especially in strawberry. In this study, Fe depletion significantly inhibited the growth, photosynthesis, Fe accumulation level and the enzyme activity of Fe-S proteins of aconitase (ACO), nitrate reductase (NiR) and succinate dehydrogenase (SDH) in strawberry seedlings. In addition, 40 Fe-S cluster assembly genes were isolated from strawberry, which were significantly varied among different tissues/organs and were differentially responded to Fe depletion in different tissue parts. In total, 79% of the responsive genes were up-regulated in shoots, while 65% of the responsive genes were down-regulated in roots under Fe depletion. Moreover, the expression level of ISU1 was the highest in strawberry tissues, especially in young fruits, and over-expression of ISU1 gene in Arabidopsis significantly enhanced the Fe accumulation, leaf total chlorophyll, ACO and SDH activities in transgenic lines, and strengthened plant tolerance to Fe depletion. This study provides gene resources to elucidate the molecular mechanisms of Fe-S cluster assembly in strawberry, and lays a theoretical foundation to reveal Fe nutrition and metabolism in Rosaceae fruits.