Abstract
Sugar metabolism not only determines fruit sweetness and quality but also acts as signaling molecules to substantially connect with other primary metabolic processes and, therefore, modulates plant growth and development, fruit ripening, and stress response. The basic region/leucine zipper motif (bZIP) transcription factor family is ubiquitous in eukaryotes and plays a diverse array of biological functions in plants. Among the bZIP family members, the smallest bZIP subgroup, S1-bZIP, is a unique one, due to the conserved upstream open reading frames (uORFs) in the 5′ leader region of their mRNA. The translated small peptides from these uORFs are suggested to mediate Sucrose-Induced Repression of Translation (SIRT), an important mechanism to maintain sucrose homeostasis in plants. Here, we review recent research on the evolution, sequence features, and biological functions of this bZIP subgroup. S1-bZIPs play important roles in fruit quality, abiotic and biotic stress responses, plant growth and development, and other metabolite biosynthesis by acting as signaling hubs through dimerization with the subgroup C-bZIPs and other cofactors like SnRK1 to coordinate the expression of downstream genes. Direction for further research and genetic engineering of S1-bZIPs in plants is suggested for the improvement of quality and safety traits of fruit.
Highlights
Plants have developed diverse mechanisms to regulate their biological and metabolic processes via transcription factor (TF) regulatory networks (Riechmann et al, 2000)
We focus on the well-studied S1-basic leucine zipper (bZIP) subgroup, whose members contain unique conserved upstream open reading frames in the 5 region of their transcripts and play important regulatory roles in many metabolic processes relating to fruit quality and stress responses
Under highsucrose conditions, the translation of AtbZIP11 is inhibited via a upstream open reading frames (uORFs) (Hanson et al, 2008; Yamashita et al, 2017). These findings indicate that ASN1 and PROLINE DEHYDROGENASE (ProDH) are regulated in a sugar-dependent manner, with AtbZIP11 acting as the link between sugar signaling and amino acid/nitrogen metabolism (Hanson et al, 2008)
Summary
Plants have developed diverse mechanisms to regulate their biological and metabolic processes via transcription factor (TF) regulatory networks (Riechmann et al, 2000). S1bZIPs play important roles in fruit quality, abiotic and biotic stress responses, plant growth and development, and other metabolite biosynthesis by acting as signaling hubs through dimerization with the subgroup C-bZIPs and other cofactors like SnRK1 to coordinate the expression of downstream genes.
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