Genome-wide identification and expression analysis of the ferritin family in sweetpotato and its two diploid relatives.

Ferritin (FER), a type of iron-storing proteins, play an essential role in iron storage and in protection against oxidative stress. However, there is limited detailed information regarding FERs in sweetpotato. In this study, a total of 17 putative FER genes, 7, 5 and 5 FERs in sweetpotato (I. batatas, 2n = 6x = 90) and its two diploid relatives I. trifida (2n = 2x = 30) and I. triloba (2n = 2x = 30), located on chromosomes were identified. Phylogenetic analysis revealed that these genes are divided into two different groups. Promoter analysis revealed that IbFER promoters contained a number of abiotic/biotic stress-responsive elements, hormone-responsive element, and iron-dependent regulatory sequence. The structural motif analysis of FER proteins showed that Euk_Ferritin domain was identified near the C-terminus and the structures were relatively conserved in sweetpotato and its two diploid relatives. Transcriptome and RT-qPCR analysis demonstrated that the expression of FERs were detected in different tissues and showed tissue specificity, and they responded to abiotic stresses, such as drought, salt and Fe deficiency. Our results provide a theoretical basis for future genetic research, development of breeding strategies against abiotic stresses and food enrichment with iron in sweetpotato.