In both, animal and plant kingdoms body size is a fundamental but still poorly understood attribute of biological systems. Here we report that the Arabidopsis NAC transcription factor RPX (REGULATOR OF PROTEASOME EXPRESSION) controls leaf size by positively modulating proteasome activity. We further show that the cis-element recognized by RPX is evolutionary conserved between higher plant species. Upon overexpression of RPX, plants exhibit reduced growth which can be reversed by low concentration of the pharmacological proteasome inhibitor MG132. These data suggest that the rate of protein turn-over during growth is a critical parameter for setting final organ size.
Via Suayib Üstün