OsAUX1 controls lateral root initiation in rice (Oryza sativa L.)

Abstract

Polar auxin transport, mediated by influx and efflux transporters, controls many aspects of plant growth and development. The auxin influx carriers in Arabidopsis have been shown to control lateral root development and gravitropism, but little is known about these proteins in rice. This paper reports on the functional characterization of OsAUX1. Three OsAUX1 T-DNA insertion mutants and RNAi knockdown transgenic plants reduced lateral root initiation compared with wild-type (WT) plants. OsAUX1 overexpression plants exhibited increased lateral root initiation and OsAUX1 was highly expressed in lateral roots and lateral root primordia. Similarly, the auxin reporter, DR5-GUS, was expressed at lower levels in osaux1 than in the WT plants, which indicated that the auxin levels in the mutant roots had decreased. Exogenous 1-naphthylacetic acid (NAA) treatment rescued the defective phenotype in osaux1-1 plants, whereas indole-3-acetic acid (IAA) and 2,4-D could not, which suggested that OsAUX1 was a putative auxin influx carrier. The transcript levels of several auxin signalling genes and cell cycle genes significantly declined in osaux1, hinting that the regulatory role of OsAUX1 may be mediated by auxin signalling and cell cycle genes. Overall, our results indicated that OsAUX1 was involved in polar auxin transport and functioned to control auxin-mediated lateral root initiation in rice.

Abscisic Acid Regulates Auxin Homeostasis in Rice Root Tips to Promote Root Hair Elongation

“…Auxin redistribution is mainly controlled by auxin transporters, which include the influx transporters of the AUXIN1/LIKE AUX1 (AUX1/LAX) family (Kerr and Bennett, 2007; Swarup et al, 2008; Zhao et al, 2015), and efflux transporters of the PIN-FORMED (PIN) families (Petrasek et al, 2006; Wang et al, 2009). To test how ABA signaling regulates auxin transport, we investigated the ABA-regulated expression of the major genes involved in auxin transport.…”

The auxin influx carrier, OsAUX3, regulates rice root development and responses to aluminium stress

“…In Arabidopsis , the AUX1 and LIKE‐AUXIN3 (LAX3) auxin influx carriers are required for auxin signalling activating LBD16 and LBD18 (lateral organ boundaries domain [LBD]) to control LR development (Lee, Cho, & Kim, ). In rice, the osaux1 mutant has a reduced number of LR primordia (Zhao et al, ). In osaux3‐2 , all these feature including delayed LR initiation, decreased LR primordia, reduced LR density, and decreased expression of genes related to LR initiation suggest that OsAUX3 plays an important role during LR initiation, which would be consistent with a conserved function to its homologues/analogues, AtAUX1, AtLAX3, or OsAUX1 (Figure ).…”

“…In rice, there are five members of the AUX1/LAX family (Shen et al, ). OsAUX1 was reported to function in regulation of LR development (Zhao et al, ). Previously, we have shown that OsAUX1 , besides negatively regulating primary root (PR) elongation, positively regulates root hair (RH) development and responds to Cd stress (Yu et al, ).…”

Genome-wide identification and expression analysis of ClLAX, ClPIN and ClABCB genes families in Citrullus lanatus under various abiotic stresses and grafting

“…PaLAX1 , from wild cherry ( Prunus avium ), promotes the absorption rate of auxin in cells and affects the distribution of free endogenous auxin [20]. OsAUX1 controls the lateral root initiation, primary root and root hair elongation in rice [21, 22]. In sorghum , maize ( Zea mays ) and soybean (Glycine max), some AUX/LAX genes are in response to hormonal and abiotic stress at transcriptional level [23–25].…”