Maize Transcription Factor ZmARF4 Confers Phosphorus Tolerance by Promoting Root Morphological Development.

Jing Li,Ying Gong,Yaxi Liu,Xuanjun Feng,Bing He,Wubing Xie,Yanli Lu,Qingjun Wang,Yuxin Xie,Fengkai Wu,Baba Salifu Yahaya,Yafeng He,Jie Xu

doi:10.3390/ijms23042361

Jing Li, Ying Gong + Show 11 more

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https://doi.org/10.3390/ijms23042361

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Abstract

Plant growth and development are closely related to phosphate (Pi) and auxin. However, data regarding auxin response factors (ARFs) and their response to phosphate in maize are limited. Here, we isolated ZmARF4 in maize and dissected its biological function response to Pi stress. Overexpression of ZmARF4 in Arabidopsis confers tolerance of Pi deficiency with better root morphology than wild-type. Overexpressed ZmARF4 can partially restore the absence of lateral roots in mutant arf7 arf19. The ZmARF4 overexpression promoted Pi remobilization and up-regulated AtRNS1, under Pi limitation while it down-regulated the expression of the anthocyanin biosynthesis genes AtDFR and AtANS. A continuous detection revealed higher activity of promoter in the Pi-tolerant maize P178 line than in the sensitive 9782 line under low-Pi conditions. Meanwhile, GUS activity was specifically detected in new leaves and the stele of roots in transgenic offspring. ZmARF4 was localized to the nucleus and cytoplasm of the mesophyll protoplast and interacted with ZmILL4 and ZmChc5, which mediate lateral root initiation and defense response, respectively. ZmARF4 overexpression also conferred salinity and osmotic stress tolerance in Arabidopsis. Overall, our findings suggest that ZmARF4, a pleiotropic gene, modulates multiple stress signaling pathways, and thus, could be a candidate gene for engineering plants with multiple stress adaptation.

Highlights

Plants constantly encounter biotic and abiotic stress throughout their life cycles
Under low cellular auxin concentrations, AUXIN/INDOLE-3-ACETIC ACID (Aux/IAA) binds to auxin response factors (ARFs) through their shared PB1 domain and recruits the co-repressor TOPLESS (TPL) to inhibit auxinresponsive elements (AuxREs) [15,16,17], whereas, with the increasing of auxin levels, the auxin-mediated interaction between Aux/IAA and SCFTIR1/AFB leads to Aux/IAA proteasomal degradation, releasing ARFs from repression and inducing the transcriptional activity [14,18]
We investigated the spatiotemporal expression specificity of ZmARF4 in Pi-tolerant extreme inbred maize lines, combined promoter activity analysis, and applied GUS histochemical staining, and found that ZmARF4 was mainly induced by phosphorus starvation in roots

Summary

Introduction

Plants constantly encounter biotic and abiotic stress throughout their life cycles. Phosphorus is one of the most important macro-nutrients that plays a pivotal role in plant growth and metabolic processes. Inorganic phosphate (Pi), the readily available form in which plants obtain their phosphorus nutrition, is prominently limited in most agricultural systems due to immobilization by complex soil chemistry [2,3,4]. Under Pi-limited conditions, plants have evolved to include multiple morphological and biochemical adaptations to remobilize Pi and maintain Pi homeostasis [5]. Morphological adaptations involving root system remodeling, including inhibition of primary root extension, enhancement of lateral root, and root hair proliferation [6], enhance soil scavenging, and the Pi remobilization

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