OsPIN9, an auxin efflux carrier, is required for the regulation of rice tiller bud outgrowth by ammonium

Abstract

The degree of rice tillering is an important agronomic trait that can be markedly affected by nitrogen supply. However, less is known about how nitrogen-regulated rice tillering is related to polar auxin transport. Compared with nitrate, ammonium induced tiller development and was paralleled with increased 3 H-indole-acetic acid (IAA) transport and greater auxin into the junctions. OsPIN9, an auxin efflux carrier, was selected as the candidate gene involved in ammonium-regulated tillering based on GeneChip data. Compared with wild-type plants, ospin9 mutants had fewer tillers, and OsPIN9 overexpression increased the tiller number. Additionally, OsPIN9 was mainly expressed in vascular tissue of the junction and tiller buds, and encoded a membrane-localised protein. Heterologous expression in Xenopus oocytes and yeast demonstrated that OsPIN9 is a functional auxin efflux transporter. More importantly, its RNA and protein levels were induced by ammonium but not by nitrate, and tiller numbers in mutants did not respond to nitrogen forms. Further advantages, including increased tiller number and grain yield, were observed in overexpression lines grown in the paddy field at a low-nitrogen rate compared with at a high-nitrogen rate. Our data revealed that ammonium supply and an auxin efflux transporter co-ordinately control tiller bud elongation in rice.

SPL14/17 act downstream of strigolactone signalling to modulate rice root elongation in response to nitrate supply

“…Roots are crucial organs for N uptake in crops (Mounier et al ., 2014; Xuan et al ., 2017). Nitrate functions as a signal to trigger several molecular and physiological processes, including root elongation, resulting in the crop’s response to its availability (Hou et al ., 2020; Liu et al ., 2013; Sun et al ., 2018). However, the mechanisms underlying NO 3 − signalling pathways in modulating root elongation remain mostly unknown.…”

Molecular Regulatory Networks for Improving Nitrogen Use Efficiency in Rice

“…An auxin efflux carrier OsPIN9 was induced by ammonium, compared to single nitrate, and involved in ammonium induced rice tillering in rice. The overexpression of OsPIN9 increased yield under low nitrogen condition [124]. Therefore, appropriate modulation of auxin response is also a promising strategy for achieving NUE in rice.…”

Pertumbuhan, Hasil dan Efisiensi Pemakaian Air Padi Inpari 33 pada Perlakuan Pupuk Anorganik dan Organik

“…Hal ini karena regulasi jumlah anakan padi terkait dengan transport auxin polar yang diatur oleh nitrogen (Hou et al, 2021). Aplikasi pupuk organik yang bersumber dari pupuk kandang (pukan) sapi dan kompos jerami memberikan pengaruh yang sangat nyata pada jumlah anakan padi umur 35 HST dan terjadi interaksi antara pupuk anorganik dan organik terhadap jumlah anakan (Tabel 3).…”