miR1432‐OsACOT (Acyl‐CoA thioesterase) module determines grain yield via enhancing grain filling rate in rice

Abstract

Rice grain filling rate contributes largely to grain productivity and accumulation of nutrients. MicroRNAs (miRNAs) are key regulators of development and physiology in plants and become a novel key target for engineering grain size and crop yield. However, there is little studies, so far, showing the miRNA regulation of grain filling and rice yield, in consequence. Here, we show that suppressed expression of rice miR1432 (STTM1432) significantly improves grain weight by enhancing grain filling rate and leads to an increase in overall grain yield up to 17.14% in a field trial. Molecular analysis identified rice Acyl-CoA thioesterase (OsACOT), which is conserved with ACOT13 in other species, as a major target of miR1432 by cleavage. Moreover, overexpression of miR1432-resistant form of OsACOT (OXmACOT) resembled the STTM1432 plants, that is, a large margin of an increase in grain weight up to 46.69% through improving the grain filling rate. Further study indicated that OsACOT was involved in biosynthesis of medium-chain fatty acids. In addition, RNA-seq based transcriptomic analyses of transgenic plants with altered expression of miR1432 demonstrated that downstream genes of miR1432-regulated network are involved in fatty acid metabolism and phytohormones biosynthesis and also overlap with the enrichment analysis of co-expressed genes of OsACOT, which is consistent with the increased levels of auxin and abscisic acid in STTM1432 and OXmACOT plants. Overall, miR1432-OsACOT module plays an important role in grain filling in rice, illustrating its capacity for engineering yield improvement in crops.

A Resource for Inactivation of MicroRNAs Using Short Tandem Target Mimic Technology in Model and Crop Plants

“…While expression of STTM159 in rice under the control of the enhanced 35S promoter led to smaller seed grains and plants (Zhao et al, 2017;Gao et al, 2018), tissue-specific knockdown of miRNAs led to an increase in seed size (Figure 6A-6D; Zhao et al, 2018). To apply STTM technology for crop improvement while avoiding adverse impacts on normal plant development, we used the endosperm-specific promoter Gt13a to downregulate two grain-filling-related miRNAs (miR167 and miR1432) in rice.…”

Genome-wide Small Rna Profiling Reveals Tiller Development in Tall Fescue (Festuca Arundinacea Schreb.)

“…Recently, few works involved in miR5168 mediating plant stress response or development. On the contrary, zma-miR1432-5p was negative with Tillering in tall fescue, which inhibited OsACOT and played an important role in rice grain lling [36]. Additionally, ve novel miRNAs including novel_13, novel_18, novel_2, novel_22, and novel_23 involved in tillering were identi ed in tall fescue, which may play unique roles in the tiller development of grass plants.…”

Fatty Acyl Synthetases and Thioesterases in Plant Lipid Metabolism: Diverse Functions and Biotechnological Applications

“…Loss of function lacs1, lacs2, lacs1 lacs2, lacs1 lacs4, and lacs1 lacs2 lacs4 mutants have decreased cuticular wax load or altered cutin monomer composition (Bessire et al, 2007;Jessen et al, 2011;Lü et al, 2009;MacGregor et al, 2008;Schnurr et al, 2004;Tang et al, 2007;Weng et al, 2010). All of these mutants also display a "glossy stem" phenotype due to deficiencies in the alkane component of cuticular wax (Zhao et al, 2019b). Further, lacs2, lacs1 lacs2, and lacs1 lacs2 lacs4 mutants display physiological phenotypes indicative of a compromised cuticle, such as increased rates of water loss and chlorophyll release from leaves, enhanced susceptibility to bacterial pathogens, and organ fusion (Bessire et al, 2007;Jessen et al, 2011;Lü et al, 2009;Schnurr et al, 2004;Weng et al, 2010;Zhao et al, 2019a).…”

“…While no single mutants of these enzymes produces a seed oil phenotype, the double mutants lacs1 lacs2 and lacs1 lacs9 display a modest reduction in seed oil content, and a proportion of their seeds are malformed due to defects in oil accumulation (Zhao et al, 2010;Zhao et al, 2019a). A lacs4 lacs9 double knockout and lacs1 lacs2 lacs4 triple knockout exhibit a more severe reduction in seed oil content (30% less than wild-type) and a greater proportion of misshapen seeds (Jessen et al, 2015;Zhao et al, 2019b). Although total oil content as a percentage of seed weight in the lacs4 lacs8 mutant does not differ significantly from wild-type, seed size is greatly reduced in this mutant, leading to a large decrease in total fatty acid content per seed (Zhao et al, 2019b).…”