Candidate Genes In The Iron-Efficiency Response Of Soybean

Iron Deficiency Chlorosis (IDC) is an global problem for crops grown on calcareous soil, leading to yield loss.  We have conducted transcriptomic studies of leaf and root tissue from the iron efficient soybean cultivar, Clark, at 30, 60 and 120 minutes after reduction of iron from hydroponic media.  We see an increase in the number of differentially expressed genes (DEGs) over time in leaves, and a decrease over time in roots. Both leaves and roots regulate the expression of DEGs involved in hormone signaling, cell wall biogenesis, regulation of DNA replication and iron uptake utilization, which are key aspects of the soybean iron-efficiency response.  Despite the similarity in pathways identified in leaves and roots, there is very little overlap in individual DEGs between the tissues and time points. This data suggests the involvement of many transcription factors in eliciting rapid changes in gene expression.  

We have performed RNAseq on GmNAC3-silenced Clark and Isoclark plants. NAC3 is a transcription factor that has been shown to be involved in both biotic and abiotic stresses, and its transcript is reduced in Clark leaves in response to iron stress.  Silencing the gene affected leaf development and chlorophyll content.  These results should provide more insight into the mechanism of iron tolerance.

To further characterize iron deficiency responsive genes, we are using Virus-induced gene silencing (VIGS) to elucidate the function of several candidate genes. We are currently targeting members of the SnRK/TOR signaling pathway and Casparian strip formation genes that were significant in our dataset.