OsbZIP81, A Homologue of Arabidopsis VIP1, May Positively Regulate JA Levels by Directly Targetting the Genes in JA Signaling and Metabolism Pathway in Rice

Abstract

Rice (Oryza sativa L.) is one of the most important food crops in the world. In plants, jasmonic acid (JA) plays essential roles in response to biotic and abiotic stresses. As one of the largest transcription factors (TFs), basic region/leucine zipper motif (bZIP) TFs play pivotal roles through the whole life of plant growth. However, the relationship between JA and bZIP TFs were rarely reported, especially in rice. In this study, we found two rice homologues of Arabidopsis VIP1 (VirE2-interacting protein 1), OsbZIP81, and OsbZIP84. OsbZIP81 has at least two alternative transcripts, OsbZIP81.1 and OsbZIP81.2. OsbZIP81.1 and OsbZIP84 are typical bZIP TFs, while OsbZIP81.2 is not. OsbZIP81.1 can directly bind OsPIOX and activate its expression. In OsbZIP81.1 overexpression transgenic rice plant, JA (Jasmonic Acid) and SA (Salicylic acid) were up-regulated, while ABA (Abscisic acid) was down-regulated. Moreover, Agrobacterium, Methyl Jasmonic Acid (MeJA), and PEG6000 can largely induce OsbZIP81. Based on ChIP-Seq and Random DNA Binding Selection Assay (RDSA), we identified a novel cis-element OVRE (Oryza VIP1 response element). Combining ChIP-Seq and RNA-Seq, we obtained 1332 targeted genes that were categorized in biotic and abiotic responses, including α-linolenic acid metabolism and fatty acid degradation. Together, these results suggest that OsbZIP81 may positively regulate JA levels by directly targeting the genes in JA signaling and metabolism pathway in rice.

Abscisic acid promotes jasmonic acid biosynthesis via a ‘SAPK10‐bZIP72‐AOC’ pathway to synergistically inhibit seed germination in rice (Oryza sativa)

“…It is now clear that, together with SAPK8 and 9, SAPK10 could phosphorylate Tiller enhancer to block the GA signaling with elevated endogenous ABA concentration and retarded seedling growth, which is implicated in the ABA‐mediated inhibition of plant growth (Lin et al ., 2015). SAPK10 is also involved in the ABA‐regulated rice flowering via phosphorylating bZIP77 in the FAC‐MADS15 pathway (D. Liu et al ., 2019; X. Liu et al ., 2019).…”

RNA-seq and ChIP-seq as Complementary Approaches for Comprehension of Plant Transcriptional Regulatory Mechanism

“…The depth of the sequence depends on the organism's genome size, the probable binding site's size, and frequencies [116]. For example, 43 million reads are adequate for studying TFs involved in stress response mediated by jasmonic acid (JA) signaling pathway in rice [39] and approximately 25 million reads for analyzing maize endosperm development [117]. To get a reliable result, an ENCODE consortium standard of using two independent biological controls should be followed.…”

“…Albihlal et al (2018) [39] studied resistance to environmental stress and reproductive fitness (seed yield) regulated by heat shock transcription factor A1b (HSFA1b) protein in Arabidopsis thaliana. To unravel the function of HSFA1b, they surveyed its ChIP-seq target and its significance on its RNA-seq transcriptome of wild type under heat stress (HS) and non-stress (NS), and in transgenic HSFA1b-overexpressing plants under NS.…”

“…In addition to its role in Agrobacterium-mediated transformation, it functions in Botrytis attack, salt stress, and ABA responses [166,167]. Liu et al (2019) [39] studied bZIP TF activity using multi-Omics strategy in rice. RNA sequencing output was generated using HiSeq3000 and mapped to Oryza sativa reference genome (RGAP v. 7.0), performed on OsbZIP81.1ox and WT ZH11.…”

F-Box Gene D5RF Is Regulated by Agrobacterium Virulence Protein VirD5 and Essential for Agrobacterium-Mediated Plant Transformation

“…It competes with the host protein CBPs (cap-binding proteins, CBP20 and CBP80) for binding to host protein AtVIP2 [37]. Recently, we identified a VIP1 homologue in rice [38], indicating that rice may have a similar mechanism for Agrobacterium-mediated transformation.…”