Aux/IAA Gene Family in Plants: Molecular Structure, Regulation, and Function

Abstract

Auxin plays a crucial role in the diverse cellular and developmental responses of plants across their lifespan. Plants can quickly sense and respond to changes in auxin levels, and these responses involve several major classes of auxin-responsive genes, including the Auxin/Indole-3-Acetic Acid (Aux/IAA) family, the auxin response factor (ARF) family, small auxin upregulated RNA (SAUR), and the auxin-responsive Gretchen Hagen3 (GH3) family. Aux/IAA proteins are short-lived nuclear proteins comprising several highly conserved domains that are encoded by the auxin early response gene family. These proteins have specific domains that interact with ARFs and inhibit the transcription of genes activated by ARFs. Molecular studies have revealed that Aux/IAA family members can form diverse dimers with ARFs to regulate genes in various ways. Functional analyses of Aux/IAA family members have indicated that they have various roles in plant development, such as root development, shoot growth, and fruit ripening. In this review, recently discovered details regarding the molecular characteristics, regulation, and protein–protein interactions of the Aux/IAA proteins are discussed. These details provide new insights into the molecular basis of the Aux/IAA protein functions in plant developmental processes.

Translating auxin responses into ovules, seeds and yield: Insight from Arabidopsis and the cereals

“…The Aux/IAA proteins contain four key domains (Paul et al ; Wu et al ; Luo et al ); domain I recruits TPL/TPR co‐repressors to enhance repression of ARF target genes, domain II facilitates interaction with the TIR1/AFB proteins (Worley et al ; Ramos et al ; Lee et al ), and domains III and IV facilitate interaction with ARF activator proteins and dimerization between Aux/IAA proteins (Ulmasov et al ; Guilfoyle et al ). These domains are sometimes absent, depending on the gene and species (Luo et al ).…”

Rice siR109944 suppresses plant immunity to sheath blight and impacts multiple agronomic traits by affecting auxin homeostasis

“…Gretchen Hagen 3 (GH3) proteins modulate auxin homeostasis through conjugating excess auxins to various amino acids and sugar, therefore contributing to the biological activity of auxin (Domingo et al , ; Fu et al , ), such as in rice IAA‐amido synthetase via GH3‐8 (Ding et al , ). Aux/IAA‐mediated auxin signalling also affects plant developmental processes (Zenser et al , ; Luo et al , ). For example, IAA14/SLR is the auxin response gene that acts as a key regulator in auxin‐regulated lateral root formation (Muto et al , ).…”

The Roles of Auxin Biosynthesis YUCCA Gene Family in Plants

“…), they were named after the yucca plant and the gene identified was named YUCCA (YUC) [15]. YUC enzymes are encoded by a relatively small gene family compared to genes involved in auxin transport [6] or signaling [8,30]. By genome-wide phylogenetic analysis, the YUC gene family has been identified in over 20 plant species (Table 1), including 11 genes in Arabidopsis thaliana [31], 9 in Cucumis melo [32], 10 in Cucumis sativus [33], 8 in Fragaria vesca [23], 14 in Medicago truncatula [34], 22 in Glycine max [35], 13 in Phyllostachys heterocycla [36], 12 in Populus trichocarpa [37], 14 in Oryza sativa [38], and 14 in Zea mays [39].…”

“…Amongst all the discovered naturally occurring endogenous auxins in plants, IAA has been well and widely characterized so far, and auxin refers to IAA in plants by strict definition [2]. The auxin functions in diverse cellular and developmental responses during plant lifespan, such as adventitious root initiation, apical dominance, vascular tissue formation, tropic responses, and flower and fruit development [6,7], which need the coordination of several complex processes, such as auxin metabolism, auxin transport, and auxin signaling pathway [6,[8][9][10].…”