Genome-wide Analysis of Zinc Transporter Genes of Maize (Zea mays)

Abstract

Zinc (Zn) is an essential micronutrient for plants and animals. Zinc-regulated transporters and iron-regulated transporter-like proteins (ZIP) are important zinc transporters in plants with the characteristic ZIP domain (Pfam:PF02535). Although individual genes belonging to the ZIP family had been discovered in various plants, genome-wide analysis of the paralouges (ZmZIP) in maize and their relationships with other related genera has so far not been conducted. We performed a genome-wide analysis and identified 12 members of the ZIP gene family in maize. Chromosomal locations, motif organization, and biochemical characterizations of proteins, as well as exon–intron, trans-membrane domains of these ZmZIP genes were determined, which indicated the structural diversity of ZmZIP. Additionally, apart from the identification of the canonical form of the metal binding signature in ZIP domains of the ZmZIP proteins, we also identified a new conserved plant ZIP signature. Further, tissue-specific expressions of those genes were determined by real-time PCR in the flag leaf as well as in 10-day-old-baby kernel among the high and low kernel zinc-containing maize inbreds. We found that overall transcript abundance was higher in the flag leaf than the kernel in both the inbreds for all the members except two, namely ZmZIP5 and ZmZIP11 were expressed more in flag leaf of a high-kernel zinc-containing inbreds than a low- kernel zinc-containing inbreds. Therefore, these results provide a basis for further functional characterization of specific ZmZIP genes in the future.