OsJAZ11 regulates phosphate starvation responses in rice

Abstract

Main conclusion OsJAZ11 regulates phosphate homeostasis by suppressing jasmonic acid signaling and biosynthesis in rice roots. Abstract Jasmonic Acid (JA) is a key plant signaling molecule which negatively regulates growth processes including root elongation. JAZ (JASMONATE ZIM-DOMAIN) proteins function as transcriptional repressors of JA signaling. Therefore, targeting JA signaling by deploying JAZ repressors may enhance root length in crops. In this study, we overexpressed JAZ repressor OsJAZ11 in rice to alleviate the root growth inhibitory action of JA. OsJAZ11 is a low phosphate (Pi) responsive gene which is transcriptionally regulated by OsPHR2. We report that OsJAZ11 overexpression promoted primary and seminal root elongation which enhanced Pi foraging. Expression studies revealed that overexpression of OsJAZ11 also reduced Pi starvation response (PSR) under Pi limiting conditions. Moreover, OsJAZ11 overexpression also suppressed JA signaling and biosynthesis as compared to wild type (WT). We further demonstrated that the C-terminal region of OsJAZ11 was crucial for stimulating root elongation in overexpression lines. Rice transgenics overexpressing truncated OsJAZ11ΔC transgene (i.e., missing C-terminal region) exhibited reduced root length and Pi uptake. Interestingly, OsJAZ11 also regulates Pi homeostasis via physical interaction with a key Pi sensing protein, OsSPX1. Our study highlights the functional connections between JA and Pi signaling and reveals JAZ repressors as a promising candidate for improving low Pi tolerance of elite rice genotypes.

OsJAZ11 regulates spikelet and seed development in rice

“…On the other hand, silencing of OsJAZ11 did not produce any spikelet defects. Analogous to OsJAZ1, OsJAZ11 was found to form protein complexes with common components of JA machinery including OsMYC2 transcription factor (master regulator of JA‐response) and OsNINJA1 (Novel INteractor of JAZ) (Pandey et al, 2021 ). OsJAZ11 also heterodimerizes with other rice JAZ repressors including OsJAZ1.…”

“…WT and transgenics rice, generated earlier (Pandey et al, 2021 ), were grown in soil pots in containment greenhouse conditions at 28°C, ~70% relative humidity, and 12/12 h (light/dark) photoperiod. Seed length and width traits were estimated in mature seeds using WinSEEDLE Pro (Regent Instruments Inc., Canada).…”

“…RT‐qPCR was performed using QuantStudio 3 Real‐Time PCR system (Thermo Scientific, USA) as described earlier (Pandey et al, 2021 ; Singh et al, 2015 ). Ubiquitin5 was used as internal reference.…”

“…All vector constructs were independently transformed and induced into Escherichia coli strain, BL21(DE3)pLysS, as described earlier (Pandey et al, 2017 ). Proteins from bacterial cells were extracted and purified as described previously (Mehra & Giri, 2016 ; Pandey et al, 2021 ). In vitro pull‐down assay was performed as described earlier (Pandey et al, 2021 ).…”

“…Proteins from bacterial cells were extracted and purified as described previously (Mehra & Giri, 2016 ; Pandey et al, 2021 ). In vitro pull‐down assay was performed as described earlier (Pandey et al, 2021 ).…”