The miR167-OsARF12 module regulates grain filling and grain size downstream of miR159

Grain weight and quality are always determined by the grain filling. Plant miRNAs have drawn attention as key targets for regulating grain size and yield. Yet the mechanisms underlying the regulation of grain size are largely unclear due to the complex networks controlling this trait. Our earlier studies proved that the suppressed expression of miR167 (STTM/MIM167) substantially increased grain weight. In a field test, the increased yield up to 12.90%-21.94% due to the significantly enhanced grain filling rate. Biochemical and genetic analyses reveal the regulatory effects of miR159 on miR167 expression. Further analysis indicates that OsARF12 is the major mediator of miR167 in regulating rice grain filling. Expectedly, over expressing OsARF12 could resemble the phenotype of STTM/MIM167 plants with respect to grain weight and grain filling rate. Upon in-depth analysis, we found that OsARF12 activates OsCDKF;2 expressions by directly binding to the TGTCGG motif in the promoter region. Flow cytometric analysis in young panicles of plants overexpressing OsARF12 and cell number examination of cdkf;2 mutants verify that OsARF12 positively regulates grain filling and grain size by targeting OsCDKF;2. Moreover, RNA-seq result suggests that miR167-OsARF12 module is involved in the cell development process and hormone pathways. Additionally, plants overexpressing OsARF12 or cdkf;2 mutants present enhanced or reduced sensitivity to exogenous auxin and brassinosteroid (BR) treatments, confirming that OsCDKF;2 targeting by OsARF12 mediates auxin and BR signaling. Our results reveal that miR167-OsARF12 module works downstream of miR159 to regulate rice grain filling and grain size by OsCDKF;2 through controlling cell division and mediating auxin and BR signals

(E)-1-(3,5-Difluoro­phen­yl)-3-(2,4-dimeth­oxy­phen­yl)prop-2-en-1-one

The title compound, C17H14F2O3, is approximately planar, the dihedral angle between the rings being 5.46 (2)°. The H atoms of the central propenone group are trans. The crystal structure is stabilized by inter­molecular C—H⋯F hydrogen bonds

International Asteroid Warning Network Timing Campaign : 2019 XS

Peer reviewe

The Interaction between Auxin and Nitric Oxide Regulates Root Growth in Response to Iron Deficiency in Rice

Fe deficiency (-Fe) is a common abiotic stress that affects the root development of plants. Auxin and nitric oxide (NO) are key regulator of root growth under -Fe. However, the interactions between auxin and NO regulate root growth in response to Fe deficiency are complex and unclear. In this study, the indole-3-acetic acid (IAA) and NO levels in roots, and the responses of root growth in rice to different levels of Fe supply were investigated using wild type (WT), ospin1b and osnia2 mutants. -Fe promoted LR formation but inhibited seminal root elongation. IAA levels, [3H] IAA transport, and expression levels of PIN1a-c genes in roots were reduced under -Fe, suggesting that polar auxin transport from shoots to roots was decreased. Application of IAA to -Fe seedlings restored seminal root length, but not LR density, to levels similar to those under normal Fe (+Fe), and the seminal root length was shorter in two ospin1b mutants relative to WT under +Fe, but not under -Fe, confirming that auxin transport participates in -Fe-inhibited seminal root elongation. Moreover, -Fe-induced LR density and -Fe-inhibited seminal root elongation paralleled NO production in roots. Interestingly, similar NO accumulation and responses of LR density and root elongation were observed in osnia2 mutants compared to WT, and the higher expression of NOA gene under -Fe, suggesting that -Fe-induced NO was generated via the NO synthase-like pathway rather than the nitrate reductase pathway. However, IAA could restore the functions of NO in inhibiting seminal root elongation, but did not replace the role of NO-induced LR formation under -Fe. Overall, our findings suggested that NO functions downstream of auxin in regulating LR formation; NO-inhibited seminal root elongation by decreasing meristem activity in root tips under -Fe, with the involvement of auxin

Nitric Oxide Affects Rice Root Growth by Regulating Auxin Transport Under Nitrate Supply

Nitrogen (N) is a major essential nutrient for plant growth, and rice is an important food crop globally. Although ammonium (NH4+) is the main N source for rice, nitrate (NO3-) is also absorbed and utilized. Rice responds to NO3- supply by changing root morphology. However, the mechanisms of rice root growth and formation under NO3- supply are unclear. Nitric oxide (NO) and auxin are important regulators of root growth and development under NO3- supply. How the interactions between NO and auxin in regulating root growth in response to NO3- are unknown. In this study, the levels of indole-3-acetic acid (IAA) and NO in roots, and the responses of lateral roots (LRs) and seminal roots (SRs) to NH4+ and NO3-, were investigated using wild-type (WT) rice, as well as osnia2 and ospin1b mutants. NO3- supply promoted LR formation and SR elongation. The effects of NO donor and NO inhibitor/scavenger supply on NO levels and the root morphology of WT and nia2 mutants under NH4+ or NO3- suggest that NO3--induced NO is generated by the nitrate reductase (NR) pathway rather than the NO synthase (NOS)-like pathway. IAA levels, [3H] IAA transport, and PIN gene expression in roots were enhanced under NO3- relative to NH4+ supply. These results suggest that NO3- regulates auxin transport in roots. Application of SNP under NH4+ supply, or of cPTIO under NO3- supply, resulted in auxin levels in roots similar to those under NO3- and NH4+ supply, respectively. Compared to WT, the roots of the ospin1b mutant had lower auxin levels, fewer LRs, and shorter SRs. Thus, NO affects root growth by regulating auxin transport in response to NO3-. Overall, our findings suggest that NO3- influences LR formation and SR elongation by regulating auxin transport via a mechanism involving NO

MicroRNAs meet with quantitative trait loci: Small powerful players in regulating quantitative yield traits in rice

MicroRNAs (miRNAs) are small noncoding RNAs which regulate various functions related to growth, development, and stress responses in plants and animals. Rice, Oryza sativa, is one of the most important food crops of the world. In rice, a number of quantitative trait loci (QTL) controlling yield‐related traits have been identified. Some of them are actually controlled by miRNAs, which control various yield‐related quantitative traits in rice. On one hand, many of these miRNAs are found to regulate more than one yield‐related traits, such as tillering, grain size, and branch number of a panicle. On the other hand, a rice yield‐related trait is usually controlled by multiple miRNAs, for example, grain size being controlled by miR156, miR167, miR396, miR397, and miR1432. In rare case, a single miRNA may specifically regulate only one yield‐related trait, such as, miR444 regulating rice tillering. In this review, we focus on the functions of miRNAs in controlling yield‐related quantitative traits in rice, including panicle grain number, grain weight/size, panicle length and branching, tiller number per plant, spikelet number, seed setting rate, and leaf inclination, and discuss how to modulate the expression of these miRNAs using modern molecular biology tools to promote grain yield

Co-overexpression of genes for nitrogen transport, assimilation, and utilization boosts rice grain yield and nitrogen use efficiency

Nitrogen (N) fertilization is necessary for obtaining high rice yield. But excessive N fertilizer reduces rice plant N efficiency and causes negative effects such as environmental pollution. In this study, we assembled key genes involved in different nodes of N pathways to boost nitrate and ammonium uptake and assimilation, and to strengthen amino acid utilization to increase grain yield and nitrogen use efficiency (NUE) in rice. The combinations OsNPF8.9a × OsNR2, OsAMT1;2 × OsGS1;2 × OsAS1, and OsGS2 × OsAS2 × OsANT3 optimized nitrate assimilation, ammonium conversion, and N reutilization, respectively. In co-overexpressing rice lines obtained by co-transformation, the tiller number, biomass, and grain yield per plant of the OsAMT1;2 × OsGS1;2 × OsAS1-overexpressing line exceeded those of wild-type ZH11, the OsNPF8.9a × OsNR2 × OsGS1;2 × OsAS1-overexpressing line, and the OsGS2 × OsAS2 × OsANT3-overexpressing line. The glutamine synthase activity, free amino acids, and nitrogen utilization efficiency (NUtE) of the OsAMT1;2 × OsGS1;2 × OsAS1-overexpressing line exceeded those of ZH11 and other lines that combined key genes. N influx efficiency was increased in the OsAMT1;2 × OsGS1;2 × OsAS1-overexpressing line and OsNPF8.9a × OsNR2 × OsGS1;2 × OsAS1-overexpressing line under a low ammonium and a low nitrate treatment, respectively. We propose that combining overexpression of OsAMT1;2, OsGS1;2, and OsAS1 is a promising breeding strategy for systematically increasing rice grain yield and NUE by focusing on key nodes in the N pathway

Characterization and expression patterns of microRNAs involved in rice grain filling.

MicroRNAs (miRNAs) are upstream gene regulators of plant development and hormone homeostasis through their directed cleavage or translational repression of the target mRNAs, which may play crucial roles in rice grain filling and determining the final grain weight and yield. In this study, high-throughput sequencing was performed to survey the dynamic expressions of miRNAs and their corresponding target genes at five distinct developmental stages of grain filling. In total, 445 known miRNAs and 45 novel miRNAs were detected with most of them expressed in a developmental stage dependent manner, and the majority of known miRNAs, which increased gradually with rice grain filling, showed negatively related to the grain filling rate. Detailed expressional comparisons revealed a clear negative correlation between most miRNAs and their target genes. It was found that specific miRNA cohorts are expressed in a developmental stage dependent manner during grain filling and the known functions of these miRNAs are involved in plant hormone homeostasis and starch accumulation, indicating that the expression dynamics of these miRNAs might play key roles in regulating rice grain filling