A PIN1 Family Gene, OsPIN1, involved in Auxin-dependent Adventitious Root Emergence and Tillering in Rice

Abstract

Auxin transport affects a variety of important growth and developmental processes in plants, including the regulation of shoot and root branching. The asymmetrical localization of auxin influx and efflux carriers within the plasma membrane establishes the auxin gradient and facilitates its transport. REH1, a rice EIR1 (Arabidopsis ethylene insensitive root 1)-like gene, is a putative auxin efflux carrier. Phylogenetic analysis of 32 members of the PIN family, taken from across different species, showed that in terms of evolutionary relationship, OsPIN1 is closer to the PIN1 family than to the PIN2 family. It is, therefore, renamed as OsPIN1 in this study. OsPIN1 was expressed in the vascular tissues and root primordial in a manner similar to AtPIN1. Adventitious root emergence and development were significantly inhibited in the OsPIN1 RNA interference (RNAi) transgenic plants, which was similar to the phenotype of NPA (N-1-naphthylphalamic acid, an auxin-transport inhibitor)-treated wild-type plants. alpha-naphthylacetic acid (alpha-NAA) treatment was able to rescue the mutated phenotypes occurring in the RNAi plants. Overexpression or suppression of the OsPIN1 expression through a transgenic approach resulted in changes of tiller numbers and shoot/root ratio. Taken together, these data suggest that OsPIN1 plays an important role in auxin-dependent adventitious root emergence and tillering.

Adventitious root formation in rice requires OsGNOM1 and is mediated by the OsPINs family

“…Howev- er, the phytohormones α-naphthalene acetic acid (NAA) and penetrable 2,4-D did not restore AR development in mutants (Supplementary information, Figure S2). Suppression of OsPIN1b in WT rice resulted in reduced numbers of AR and increased sensitivity to NPA [13]. However, semi-quantitative RT-PCR analysis showed that the OsPIN1b transcript level in the basal portion of the shoots where the AR primordia are initiated was almost identical to that of the WT plants ( Figure 5A).…”

“…The hydroponic culture solution contained 1.425 mM NH 4 [13]. Rice plants were grown in growth chambers with a 12 h photoperiodic condition (200 µmol photons m -2 s −1 ) and a temperature of 30°C after germination.…”

“…It affects the number and length of LR and AR [2]. Many genes required in root development have connections with the auxin-signaling pathway [4,10], including the Aux/IAA family [11], the auxin response factor family [12] and certain hormonerelated transporters [13]. An LOB domain-containing transcription factor controlled by auxin responsive factor was known to play a critical role in the formation of AR primordia in rice and maize (Zea mays L.) [8][9]14].…”

Auxin Control in the Formation of Adventitious Roots

“…(Bellamine et al, 1998). Rice mutants affected in the expression of PINFORMEDl (OsPIN1) gene, potentially involved in auxin polar transport, are affected in adventitious root emergence and tillering confirming that the auxin concentration and distribution in the different tissues is important (Xu et al, 2005).…”

“…Auxin efflux carrier, PIN1, is a highly conserved gene family, which may play a key role in polar auxin transport (Friml and Palme, 2002).The finding that OsPIN1 is involved in auxin-dependent adventitious root emergence and tillering provides a new insight into the function of the PIN1 family in rice (Xu et al, 2005). The rice gene OsCAND1, the homolog of Arabidopsis CAND1, is involved in auxin signaling to maintain the G2/M cell cycle transition in crown root meristem and the emergence of crown root, providing new information about the molecular regulation of the emergence of crown root .…”