SPL6 represses signalling outputs of ER stress in control of panicle cell death in rice

Abstract

Inositol-requiring enzyme 1 (IRE1) is the most conserved transducer of the unfolded protein response that produces either adaptive or death signals depending on the amplitude and duration of its activation. Here, we report that SQUAMOSA PROMOTER-BINDING PROTEIN-LIKE 6 (SPL6)-deficient plants displayed hyperactivation of the endoplasmic reticulum (ER) stress sensor IRE1, leading to cell death in rice panicles, indicating that SPL6 is an essential survival factor for the suppression of persistent or intense ER stress conditions. Importantly, knockdown of the hyperactivated mRNA level of IRE1 rescues panicle apical abortion in the spl6-1 transgenic plants harbouring the IRE1-RNAi constructs, establishing the genetic linkage between the hyperactivation of IRE1 and cell death in spl6-1. Our findings reveal a novel cell survival machinery in which SPL6 represses the transcriptional activation of the ER stress sensor IRE1 in control of ER stress signalling outputs that hinge on a balance between adaptive and death signals for determining cell fates during ER stress.

DEGENERATED PANICLE AND PARTIAL STERILITY 1 (DPS1) encodes a cystathionine β‐synthase domain containing protein required for anther cuticle and panicle development in rice

“…Previously, three mutants, namely totou1 , paa1 and spl6 , related to panicle apical degeneration have been characterized. However, all of these mutants only showed the panicle apical degeneration phenotype, with no effect on fertility in the rest of the panicle (Bai et al ., ; Heng et al ., ; Q. Wang et al ., ). In this study, we report a unique phenotype in the dps1 mutant that displayed degeneration of apical spikelets along with sterile spikelets in the middle portion of panicle (Fig.…”

“…The enhanced PCD in dps1 concurred with the degeneration of apical spikelets, the collapse of anther locules (Figs g, j), and the disrupted ROS homeostasis (Fig. ), indicating a potential correlation among ROS, PCD, and panicle degeneration, which was in good agreement with a previous report that enhanced PCD often causes degenerated apical spikelets and sterile anthers (Q. Wang et al ., ).…”

OsPEX5 regulates rice spikelet development through modulating jasmonic acid biosynthesis

“…Chromatin immunoprecipitation (ChIP) assay was performed as previously described (Wang et al ., ). Briefly, young tobacco leaves co‐transfected with the 35S::OsMYC2‐Flag and recombination plasmids (used in luciferase reporter assays) or rice spikelets (at Sp4‐Sp8 stages) were detached from the transgenic 35S::OsMYC2‐Flag plants were cross‐linked in a fixation buffer with 1% (v/v) formaldehyde under vacuum infiltration for 30 min.…”

Ornithine δ‐aminotransferase is critical for floret development and seed setting through mediating nitrogen reutilization in rice

“…Abnormal floral organ development may lead to infertility. Floral development, from differentiation of floret to completion of double fertilization, is regulated by a complex regulatory network involving multiple genes (Dai et al, 2014;Koshimizu et al, 2018;Wang et al, 2018). Glume is an important protective tissue, it separates the internal tissues from the external environment; it also provides suitable developmental conditions for the stamens, pistil, and even the seed.…”