Arabidopsis NAC Transcription Factors, NARS1 and NARS2, Regulate the Mucilage Accumulation in Seed Coats

Abstract

The Arabidopsis integument is separated into two integuments (the outer and inner integuments). The cells of outermost cell layer of integument accumulate a large amount of mucilage, pectic polysaccharides, during seed development. We identified that two NAC transcription factors, NARS1 and NARS2, regulated seed morphogenesis redundantly (1). Both NARS1 and NARS2 were specifically expressed in outer integument, and the mucilage was not accumulated in a double knock-out mutant nars1 nars2. To clarify the molecular mechanism underlying the mucilage accumulation, we searched factors whose expressions were regulated by NARS1 and NARS2. DNA microarray analysis revealed that more than 300 genes were down-regulated in nars1 nars2. Furthermore, 15 of 300 genes were down-regulated in the ttg1-1 mutant, which had a deficiency of the mucilage accumulation as nars1 nars2 did. This result suggests that these genes are involved in the mucilage accumulation.
(1) Kunieda et al., Plant Cell, 2008. doi: 10.1105/tpc.108.060160.