Changes in endogenous levels of IAA and PAA in rice seed during development, prediction of auxin signaling proteins and docking for its binding efficiency with auxin molecules

Abstract

Indole-3-acetic acid (IAA) and phenyl acetic acid (PAA) are two major physiologically active auxins, found in higher plants. The objective of this study was to evaluate changes in the endogenous levels of IAA and PAA in rice (Oryza sativa) seed and predict probable transporter and efflux (signaling) proteins for docking with auxins from the available rice genome data. IAA and PAA were estimated during rice seed development using sensitive and specific antibodies against each hormone. The levels of IAA and PAA were higher when sink size development was at its peak, suggesting an important role played by the auxin in sink size development of rice seed. Furthermore, auxin binding transporters proteins of rice were confirmed for docking purpose and compared with Arabidopsis and maize proteins. In this context, PAA docked with known IAA proteins; although, docking score of IAA was higher than that of PAA in rice seed. Twelve genes of the auxin efflux carrier (PIN family) of rice were also analysed for phylogeny relatedness with Arabidopsis and maize, to further understanding auxin concentrations and efflux within rice seeds. The predicted PIN proteins for IAA efflux of rice showed docking affinities with PAA, revealed its role in maintaining physiological concentrations of auxins in rice seeds.