OsPIN2, which encodes a member of the auxin efflux carrier proteins, is involved in root elongation growth and lateral root formation patterns via the regulation of auxin distribution in rice

Abstract

Auxin flow is important for different root developmental processes such as root formation, emergence, elongation and gravitropism. However, the detailed information about the mechanisms regulating the auxin flow is less well understood in rice. We characterized the auxin transport-related mutants, Ospin-formed2-1 (Ospin2-1) and Ospin2-2, which exhibited curly root phenotypes and altered lateral root formation patterns in rice. The OsPIN2 gene encodes a member of the auxin efflux carrier proteins that possibly regulates the basipetal auxin flow from the root tip toward the root elongation zone. According to DR5-driven GUS expression, there is an asymmetric auxin distribution in the mutants that corresponded with the asymmetric cell elongation pattern in the mutant root tip. Auxin transport inhibitor, N-1-naphthylphthalamic acid and Ospin2-1 Osiaa13 double mutant rescued the curly root phenotype indicating that this phenotype results from a defect in proper auxin distribution. The typical curly root phenotype was not observed when Ospin2-1 was grown in distilled water as an alternative to tap water, although higher auxin levels were found at the root tip region of the mutant than that of the wild-type. Therefore, the lateral root formation zone in the mutant was shifted basipetally compared with the wild-type. These results reflect that an altered auxin flow in the root tip region is responsible for root elongation growth and lateral root formation patterns in rice.

Role and Regulation of Cytokinins in Plant Response to Drought Stress

“…Taken together, we suggest that the mechanisms enhancing drought tolerance by the up-or down-regulation of endogenous CK levels might involve different pathways and crosstalk with other phytohormones. For example, CK signaling was found to regulate auxin-efflux and influx carriers [134,135], which are important in controlling root developmental processes, such as root formation, emergence, elongation and gravitropism [136]. Elucidating these pathways could provide significant insights into the roles of CKs in drought stress, which could ultimately contribute to the development of CK-mediated, drought-tolerant crops.…”

Auxin EvoDevo: Conservation and Diversification of Genes Regulating Auxin Biosynthesis, Transport, and Signaling

“…In rice, functional studies have been published for OsPIN1/ OsPIN1B/OsREH1 (a rice ETHYLENE INSENSITIVE ROOT1-like gene; Xu et al, 2005;Sun et al, 2018), OsPIN2/OsLARGE ROOT ANGLE1 (OsLRA1) (Wang et al, 2009a(Wang et al, , 2018bMiyashita et al, 2010;Chen et al, 2012;Wu et al, 2014;Inahashi et al, 2018), OsPIN10A/3a/3t (Zhang et al, 2012), and OsPIN5B (Lu et al, 2015) (Supplemental Table 1). RNAi knockdown and overexpression studies show that OsPIN1/OsPIN1B/ OsREH1 plays a role in adventitious root emergence and tillering (Xu et al, 2005).…”

“…Recently characterized transfer DNA (T-DNA) insertion lines suggest an involvement of OsPIN1/ OsPIN1B/OsREH1 in the strigolactone and nitric oxidemediated elongation of seminal roots (Sun et al, 2018). Overexpression lines, as well as analysis of chemically induced mutations in OsPIN2/OsLRA1, indicate a role in tillering (Chen et al, 2012), mediation of root agravitropic responses (Wang et al, 2018b), and lateral root formation (Inahashi et al, 2018). The Ospin2/Oslra1 mutant also shows altered plant height under certain growing conditions (Wang et al, 2018b).…”

Role of Phytohormones in Piriformospora indica-Induced Growth Promotion and Stress Tolerance in Plants: More Questions Than Answers

“…Phytohormones, such as auxins (e.g., IAA, the most common auxin), CK, GAs, ABA, ET, SA, and jasmonates play important roles in growth and development of plants as well as in plant resistance/tolerance to abiotic stresses and in plant interactions with various mutualistic fungi ( Cakmak and Marschner, 1992 ; Sirrenberg et al, 2007 ; Vadassery et al, 2008 ; Schäfer et al, 2009a , b ; Camehl et al, 2010 ; Lee et al, 2011 ; Gutjahr and Parniske, 2013 ; Johnson et al, 2013 ; Miransari et al, 2014 ; Zhang Y. et al, 2015 ; Kopittke, 2016 ; Naser and Shani, 2016 ; Tian et al, 2017 ; Inahashi et al, 2018 ; Mathur et al, 2018 ). Endo- and ectomycorrhizal fungi, N 2 -fixing rhizobacteria and a large number of fungal and bacterial endophytes colonize the roots and confer benefits to the roots in addition to its effects to the leaves.…”