Many differentiated plant organs have the ability to regenerate into a new plant after detachment via de novo organogenesis. During de novo root organogenesis from Arabidopsis thaliana leaf explants, wounding first induces endogenous auxin production in mesophyll cells. Auxin is then polar transported to, and accumulates in, regeneration-competent cells near the wound to trigger the cell-fate transition. The TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS (TAA) family proteins and the YUCCA (YUC) family proteins catalyze two successive biochemical steps in auxin biogenesis, and YUCs have been shown to be involved in auxin production in mesophyll cells during de novo root organogenesis. In this study, we show that the TAA family is also required for adventitious rooting. Inhibition of TAA blocked adventitious root formation from leaf explants. Intriguingly, whereas YUC1 and YUC4 have been shown to be highly induced by wounding, TAA genes retained consistent expression levels before and after leaf detachment. Therefore, we suggest that TAAs and YUCs are both required for auxin biogenesis in leaf explants, but they play different roles in regeneration. While YUC1 and YUC4 function in response to wounding to catalyze the rate-limiting step in auxin biosynthesis, TAAs probably serve as abiding and basal enzymes during de novo root organogenesis from leaf explants.
De novo root organogenesis TAA1TAR2Plant regeneration Auxin biogenesis Arabidopsis
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We thank T. J. Guilfoyle and ABRC for Arabidopsis seeds used in this work. This work was supported by the National Basic Research Program of China (973 Program, 2014CB943500/2012CB910503), the National Natural Science Foundation of China (91419302/31422005) and Youth Innovation Promotion Association CAS.
Conflict of interest
The authors declare that they have no conflict of interest.
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1.National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological SciencesChinese Academy of SciencesShanghaiChina
2.College of Life and Environment SciencesShanghai Normal UniversityShanghaiChina
3.University of Chinese Academy of SciencesBeijingChina
4.Department of Plant and Microbial Biology, Zürich-Basel Plant Science CenterUniversity of ZürichZurichSwitzerland