The AtPIN-like family of proteins (AtPILS) was identified based on predicted topological similarities with AtPIN proteins. In Arabidopsis, 4 amino acid permease-like family members (AtAUX1/LAX1–3) regulate auxin uptake from the apoplast, whereas 8 PIN proteins (AtPIN1-PIN8) and 7 PILS members (AtPILS1–7) are responsible for the polar pump-off of auxin and determine the direction of auxin flow through tissues. The IAA-H form of auxin freely enters the cell via diffusion, and the transport of its anionic form (IAA -) is mediated mainly by auxin influx transporters (AUX1/LAX proteins) and efflux transporters (ATP binding cassette B and PIN/PILS proteins). IAA mainly exists in the protonated form (IAA-H) in the apoplast, whereas the deprotonated form (IAA -) becomes dominant inside the plant cell due to the pH changes. In Arabidopsis, 11 YUC family proteins act redundantly and cooperatively at various growth and developmental stages. YUC proteins that encode flavin monooxygenases catalyze a rate-limiting step of the IPA pathway. Īlthough auxin biosynthesis is not fully understood in plants, genetic and biochemical studies have demonstrated that the endogenous plant auxin indole-3-acetic acid (IAA) is mainly synthesized by a two-step reaction: Trp is first converted to indole-3-pyruvate (IPA) by TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS (TAA) and then IAA is produced by YUC flavin-containing monooxygenase family proteins. Auxin action can be achieved through different levels, mainly auxin concentration pathways including auxin biosynthesis and directional auxin transport, and auxin signaling pathways including auxin perception and signal transduction. In summary, we generated an overview of the auxin pathway in bamboo, which provides information for uncovering the precise roles of auxin pathway in this important species in the future.Īuxin acts as a central organization hub in controlling plant growth and development. A comprehensive study of auxin-responsive genes using RNA sequencing technology was performed, and the results also supported that moso bamboo shared a conserved regulatory mechanism for the expression of auxin pathway genes meanwhile it harbors its own specific properties. Phylogenetic analysis of these genes from Arabidopsis, Oryza sativa and bamboo revealed that auxin biosynthesis, transport, and signaling pathways are conserved in these species. Genes involved in auxin action, including 13 YUCCA (YUC) genes involved in auxin synthesis, 14 PIN-FORMED/PIN-like ( PIN/PILS) and 7 AUXIN1/LIKE-AUX1 ( AUX1/LAX) members involved in auxin transport, 10 auxin receptors ( AFB) involved in auxin perception, 43 auxin/indole-3-aceticacid ( AUX/IAA) genes, and 41 auxin response factors ( ARF) involved in auxin signaling were identified through genome-wide analysis. Here we showed that exogenous auxin has strong effects on crown and primary roots. Although substantial progress has been made in understanding auxin pathways in model plants such as Arabidopsis and rice, little is known in moso bamboo which is famous for its fast growth resulting from the rapid cell elongation and division. Auxin is essential for plant growth and development.
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