From growth to survival: Aux/IAA genes in plant development and stress management

Auxin, one of the earliest recognized and extensively investigated phytohormones, is crucial in plant growth and survival in adverse environmental conditions. Two gene families primarily regulate auxin signaling: auxin response factors (ARFs) and auxin/indole-3-acetic acid (Aux/IAA). Aux/IAA family proteins are recognized as essential elements of the nuclear auxin signaling system, inhibiting gene transcription in their presence and facilitating gene activation upon their degradation. Molecular investigations have demonstrated that Aux/IAA family proteins may create numerous dimers with ARFs to modulate gene expression in multiple ways. In past years, thorough research of Aux/IAA proteins confirmed their diverse roles in plant development, including primary and lateral root formation, apical dominance, gravitropism responses, and fruit and flower growth. In 1993, the first Aux/IAA proteins were identified in peas. Subsequently, genome-wide identification of Aux/IAA genes in various plants revealed the presence of 26, 84, 47, and 38 Aux/IAA genes in Solanum tuberosum, Triticum aestivum, Malus domestica, and Salix suchowensis, respectively. Aux/IAA proteins function in concert with other phytohormones, genes, and transcription factors via a complicated signaling cascade to equilibrate plant growth and development in response to biotic and abiotic stress. The current review article encapsulates the recent advancements regarding the roles and regulatory pathways of Aux/IAA in plant developmental phases. The significance of Aux/IAA is evidenced by their functions in initiating diverse physiological, biochemical, and molecular responses to withstand unfavorable environmental conditions. This information offers novel insights into the molecular mechanisms underlying the roles of Aux/IAA proteins in plant development.