Dataset Information

The OsNAC24-OsNAP protein complex activates OsGBSSI and OsSBEI expression to fine-tune starch biosynthesis in rice endosperm.

ABSTRACT: Starch accounts for up to 90% of the dry weight of rice endosperm and is a key determinant of grain quality. Although starch biosynthesis enzymes have been comprehensively studied, transcriptional regulation of starch-synthesis enzyme-coding genes (SECGs) is largely unknown. In this study, we explored the role of a NAC transcription factor, OsNAC24, in regulating starch biosynthesis in rice. OsNAC24 is highly expressed in developing endosperm. The endosperm of osnac24 mutants is normal in appearance as is starch granule morphology, while total starch content, amylose content, chain length distribution of amylopectin and the physicochemical properties of the starch are changed. In addition, the expression of several SECGs was altered in osnac24 mutant plants. OsNAC24 is a transcriptional activator that targets the promoters of six SECGs; OsGBSSI, OsSBEI, OsAGPS2, OsSSI, OsSSIIIa and OsSSIVb. Since both the mRNA and protein abundances of OsGBSSI and OsSBEI were decreased in the mutants, OsNAC24 functions to regulate starch synthesis mainly through OsGBSSI and OsSBEI. Furthermore, OsNAC24 binds to the newly identified motifs TTGACAA, AGAAGA and ACAAGA as well as the core NAC-binding motif CACG. Another NAC family member, OsNAP, interacts with OsNAC24 and coactivates target gene expression. Loss-of-function of OsNAP led to altered expression in all tested SECGs and reduced the starch content. These results demonstrate that the OsNAC24-OsNAP complex plays key roles in fine-tuning starch synthesis in rice endosperm and further suggest that manipulating the OsNAC24-OsNAP complex regulatory network could be a potential strategy for breeding rice cultivars with improved cooking and eating quality.

SUBMITTER: Jin SK

PROVIDER: S-EPMC10579716 | biostudies-literature | 2023 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

The OsNAC24-OsNAP protein complex activates OsGBSSI and OsSBEI expression to fine-tune starch biosynthesis in rice endosperm.

Jin Su-Kui SK Xu Li-Na LN Leng Yu-Jia YJ Zhang Ming-Qiu MQ Yang Qing-Qing QQ Wang Shui-Lian SL Jia Shu-Wen SW Song Tao T Wang Ruo-An RA Tao Tao T Liu Qiao-Quan QQ Cai Xiu-Ling XL Gao Ji-Ping JP

Plant biotechnology journal 20230711 11

Starch accounts for up to 90% of the dry weight of rice endosperm and is a key determinant of grain quality. Although starch biosynthesis enzymes have been comprehensively studied, transcriptional regulation of starch-synthesis enzyme-coding genes (SECGs) is largely unknown. In this study, we explored the role of a NAC transcription factor, OsNAC24, in regulating starch biosynthesis in rice. OsNAC24 is highly expressed in developing endosperm. The endosperm of osnac24 mutants is normal in appear ...[more]

PMID: 37432878

Similar Datasets

Project description:Control of stage specific spike in ethylene production at anthesis has been a vauable route to potentially enhance genetic ceiling for grain filling of rice spikelet. A number of genes controlling ethylene homeostasis and starch synthesis have been identified so long, but lack of credible information on master modulation of gene expression by miRNAs and their target genes associated with hormonal dynamics obfuscate mechanisms controlling genotype difference in quantum of grain filling. The confusion accounts for consequent shrinkage of options for yield manipulation. In a two by two factorial design, miRNA regulation of spikelet specific grain development in low against high sterile recombinant inbred lines of rice Oryza sativa L. namely CR 3856-62-11-3-1-1-1-1-1-1 (SR 157) and CR 3856-63-1-1-1-1-1-1-1 (SR 159) respectively, and inferior verses superior spikelets were compared during first 10 days after anthesis. Grain filling was poorer in SR159 than SR157 and inferior spikelets in the former were most vulnerable. Between the cultivars, overall expression of unique miRNAs with targets on ethylene pathway genes was higher in SR159 than SR157 and the situation was opposite for auxin pathway genes. Precision analysis in psTarget server database identified up-regulation of MIR2877 and MIR530-5p having Os11t0141000-02 and Os07t0239400-01 (PP2A regulatory subunit-like protein and ethylene-responsive small GTP-binding proteins) and MIR396h having Os01t0643300-02 (an auxin efflux carrier protein) and Os01t0643300-01 (a PIN1-like auxin transport protein), as targets with highest probability at anthesis and 5 days after anthesis respectively, in the inferior spikelet and the fold change values of DGE matched with pattern of gene expression (relative transcript level) in the qRT-PCR studies conducted for relevant miRNAs and protein factors for ethylene and auxin signalling. In conclusion, epigenetic regulation of both auxin and ethylene homeostasis control grain filling of rice spikelet was established, but evidences were more robust for the latter.

Project description:Three starch branching enzyme (BE) isozymes, BEI, BEIIa, and BEIIb, are involved in starch biosynthesis in rice endosperm. Past in vivo and in vitro studies have suggested that each BE isozyme plays a distinct role in forming the fine structure of amylopectin. To elucidate more details of their roles, we prepared DNA constructs in which all the possible combinations of the expressions of these three isozymes were suppressed in developing rice endosperm. Analysis of the chain-length distributions of amylopectin produced under these various conditions confirmed the contributions of the individual BE isozymes to the fine structure of amylopectin in rice endosperm. Among these isozymes, the impact of loss of BEIIb activity on amylopectin fine structure was most remarkable and indicated that it plays a specific role in the synthesis of short chains with a 6-13 degree of polymerization (DP). The contribution of BEI to the amylopectin synthesis was unclear when only BEI activity was reduced. It was clear, however, when both BEI and BEIIb activities were substantially inhibited. The DP11-22 intermediate chains were markedly reduced in the ΔBEI/BEIIb line compared with the ΔBEIIb line, indicating that BEI plays a distinct role in the synthesis of these intermediate chains. Although no substantial change in amylopectin chain profile was detected in the ΔBEIIa line, the role of BEIIa could be deciphered by analyzing amylopectin fine structure from the ΔBEI/BEIIa/BEIIb line in comparison to that from ΔBEI/BEIIb line. This strongly suggests that BEIIa compensates for the role of BEI, rather than that of BEIIb, by forming intermediate chains of DP11-22. In addition, the new possibility that BEIIa is involved in the formation of starch granules in rice endosperm was suggested because the onset temperature for gelatinization of starch granules in the ΔBEIIa/BEIIb line was significantly higher than that in the ΔBEIIb line. In summary, the present study highlights the distinct roles of BEI, BEIIa, and BEIIb in the synthesis of amylopectin in developing rice endosperm.

Dataset Information

The OsNAC24-OsNAP protein complex activates OsGBSSI and OsSBEI expression to fine-tune starch biosynthesis in rice endosperm.

Publications

The OsNAC24-OsNAP protein complex activates OsGBSSI and OsSBEI expression to fine-tune starch biosynthesis in rice endosperm.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets