阿拉伯芥毛狀根形成相關之轉錄因子 NAC13 的功能性分析

Abstract

Hairy root is a specialized, fast-growing tissue that is induced by the infection of Agrobacterium rhizogenes. Root locus genes (rol genes) which encoded in root-inducing plasmid (Ri plasmid) of A. rhizogenes play key roles in hairy root formation. Among the rol genes, researches showed that fast and branched root growth required the presence of rolC gene. Our previous data showed that the viability of rolC-deficient hairy roots decreased significantly compared to wild-type hairy roots, hairy root formation and its fast growth were regulated by rolC with unknown mechanism. Previous researches also indicated that many transcription factors were thought to have large impacts on tissue characteristics in Arabidopsis. Took the things together, we focused on revealing the transcription factors which under the regulation of rolC, attempting to elucidate the mechanism of hairy root formation. Based on the previous microarray results, a putative transcription factor, NAC13, was identified according to its capacity for regulating the main root length in Arabidopsis mutants. The activation ability of NAC13 was demonstrated by using transactivation assay in yeast. By confocal microscopy observation, fusion proteins of NAC13 and yellow fluorescence protein (NAC13-YFP) were visualized in and around the nucleus. Moreover, comparing the morphology, induction efficiency and the mitochondria of nac13-deficient hairy roots and wild-type hairy roots showed that rolC might involve in the mitochondria stress signaling pathway through nac13 gene and its downstream genes, aox1a and hre2, to eliminate the excess reactive oxygen species for maintaining fast growth and preventing mitochondrial apoptosis in hairy roots.