ORIGINAL RESEARCH published: 14 May 2021 doi: 10.3389/fpls.2021.646736

PIP2, An Induced Plant Peptide Regulates and Hypocotyl Elongation in Arabidopsis

Saddam Hussain 1,2†, Wei Wang 2†, Sajjad Ahmed 2, Xutong Wang 2, Adnan 2, Yuxin Cheng 2, Chen Wang 2, Yating Wang 2, Na Zhang 2, Hainan Tian 2, Siyu Chen 2, Xiaojun Hu 1, Tianya Wang 2 and Shucai Wang 1,2*

1 Laboratory of Plant Molecular Genetics & Crop Editing, School of Life Sciences, Linyi University, Linyi, China, 2 Key Laboratory of Molecular Epigenetics of MOE, Northeast Normal University, Changchun, China

Auxin is one of the traditional plant , whereas peptide hormones are peptides with hormone activities. Both auxin and plant peptide hormones regulate multiple aspects Edited by: of plant growth and development, and there are cross-talks between auxin and plant Ling Huang, peptide hormones. PAMP-INDUCED SECRETED PEPTIDES (PIPs) and PIP-LIKEs (PIPLs) Salk Institute for Biological Studies, United States are a new family of , and PIPL3/TARGET OF LBD SIXTEEN 2 Reviewed by: (TOLS2) has been shown to regulate lateral root formation in Arabidopsis. We report here Dior Rose Kelley, the identification ofPIP2 as an auxin response gene, and we found it plays a role in Iowa State University, United States Wei Zhang, regulating root and hypocotyl development in Arabidopsis. By using quantitative RT-PCR, Shandong University, China we found that the expression of PIP2 but not PIP1 and PIP3 was induced by auxin, and *Correspondence: auxin induced expression of PIP2 was reduced in nph4-1 and arf19-4, the lost-of-function Shucai Wang mutants of Auxin Response Factor 7 (ARF7) and ARF19, respectively. By generating and [email protected] characterizing overexpressing transgenic lines and gene edited mutants for PIP2, we found †These authors have contributed equally to this work that root length in the PIP2 overexpression plant seedlings was slightly shorter when compared with that in the Col wild type plants, but root length of the pip2 mutant seedlings Specialty section: remained largely unchanged. For comparison, we also generated overexpressing This article was submitted to Plant Development and EvoDevo, transgenic lines and gene edited mutants for PIP3, as well as pip2 pip3 double mutants. a section of the journal Surprisingly, we found that root length in the PIP3 overexpression plant seedlings is shorter Frontiers in Plant Science than that of the PIP2 overexpression plant seedlings, and the pip3 mutant seedlings also Received: 28 December 2020 Accepted: 29 March 2021 produced short . However, root length in the pip2 pip3 double mutant seedlings is Published: 14 May 2021 largely similar to that in the pip3 single mutant seedlings. On the other hand, hypocotyl Citation: elongation assays indicate that only the 35S:PIP2 transgenic plant seedlings produced Hussain S, Wang W, Ahmed S, longer hypocotyls when compared with the Col wild type seedlings. Further analysis Wang X, Adnan, Cheng Y, Wang C, Wang Y, Zhang N, Tian H, Chen S, indicates that PIP2 promotes cell division as well as cell elongation in hypocotyls. Taken Hu X, Wang T and Wang S (2021) together, our results suggest that PIP2 is an auxin response gene, and PIP2 plays a role PIP2, An Auxin Induced Plant Peptide Hormone Regulates Root and in regulating root and hypocotyl elongation in Arabidopsis likely via regulating cell division Hypocotyl Elongation in Arabidopsis. and cell elongation. Front. Plant Sci. 12:646736. doi: 10.3389/fpls.2021.646736 Keywords: auxin, peptide hormone, PIP2, PIP3, root elongation, Arabidopsis

Frontiers in Plant Science | www.frontiersin.org 1 May 2021 | Volume 12 | Article 646736 Hussain et al. PIP2 Regulates Root Elongation<