Expression of Nodule Cysteine-Rich (NCR) Defensin-Like (DEFL) genes among four different accessions of Medicago truncatula inoculated with two different rhizobial strains.

We have undertaken a detailed study to identify expression polymorphism of NCRs. We used a custom Affymetrix oligonucleotide microarray to examine the expression changes of 566 NCRs in four different accessions of Medicago truncatula. Each accession was inoculated with two different rhizobial strains to assess the NCR expression differences caused by host-symbiont specificity. The NCRs displayed significant expression differences among the ecotypes but had subtle differences in gene expression because of strain difference. We used a custom Affymetrix chip containing 684 probe sequences of Medicago DEFLs to explore the expression polymorphism of NCRs in nodules inoculated with Sinorhizobium meliloti 1021(Sm1021) and Sinorhizobium medicae (SmA321) totalling 8 different treatments. Each treatment was supported by three biological replicates giving a grand total of 24 samples.