Molecular characterization and expression analysis of membrane transporters involved in iron and zinc homeostasis in hexaploid wheat

Abstract

Micronutrient deficiencies affecting human health and performance globally are a serious concern. Hexaploid wheat (Triticum aestivum L.) is an important cereal crop that has been targeted to enhance grain micronutrients (Zn/Fe). In this direction, modulating the expression of plant transporters involved in Fe and Zn homeostasis could be one priority that still remained unaddressed. Therefore, my work is centric towards genome wide identification, In-silico characterization and expression analysis of two gene families Zinc Induced Facilitator-Like (ZIFL) and Vacoular Iron Transporter-Like (VTL). In-silico analysis identified 15 putative ZIFL genes. ZIFL genes were characterized for their transcriptional expression response during micronutrient and heavy metal stress. ZIFL genes of wheat show overlapping expression response during Fe deficiency and Zn excess condition. ZIFLs also encode for transporters of mugineic acid (TOM), which are involved in efflux of phytosiderophores during micronutrient stress. Three wheat TOM genes TaZIFL4.1/TaZIFL4.2 referred as TOM1. TaZIFL5 as TOM2 and TaZIFL7.1/ TaZIFL7.2 referred as TOM3 were identified. Differential expression of TOMs under heavy metal stress clearly indicates that the heavy metals are acting as a stimulus for release of PS. Vacuolar Iron transporter like genes (VTLs) is another set of gene family which is reported in this work. It is involved in sequestration of Fe in vacuoles when cells encounter high amounts of Fe. 23VTL genes were identified including homoeologs representing four genes TaVTL1, TaVTL2, TaVTL4 and TaVTL5. Most of all TaVTL genes are induced under Fe surplus conditions, thus depicting their role in Fe homeostasis. Expression analysis revealed that VTL are substrate specific and presence and absence of micronutrients can fluctuate their expression. This study will act as a foundation for prioritizing the genes involved in enhancing the micronutrient content in the cereal crops. newline