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NRL3 is essential for the growth and development of rice leaves. In this study, we found that the loss function of NRL3 also delayed heading date under natural long daylight and short daylight conditions. The yeast two-hybrid and the bimolecular fluorescence complementation proved that NRL3 interacts with OsK4, a Snf1-related kinase. OsK4 localized to the nucleus and expressed in various rice tissues. The rhythmic expression pattern of OsK4 was similar to NRL3 under long daylight and short daylight conditions. Knock-out mutants of OsK4 exhibited early heading under long daylight conditions, indicating that it acts as a negative regulator of heading date in rice. Interestingly, the OsK4 mutant under the nrl3 mutant background rescued the late heading phenotype of nrl3 under long daylight conditions, suggesting that OsK4 functions downstream of NRL3. Moreover, both NRL3 and OsK4 controlled heading date through regulating the expression of Hd3a and RFT1 genes. These findings shed light on the heading date regulation in rice and provide a sound theoretical base to improve regional adaptability of rice.

The thermodynamic incompatibility between the soft and hard segments of thermoplastic polyurethane (TPU) results in a microphase‐separated behavior and excellent mechanical properties. However, the effect of the chain extender on the degree of microphase separation (DMS) and the resultant mechanical properties of TPU have not been well studied because of the complex interactions between the soft and hard segments. Herein, hydroxyl‐terminated polybutadiene‐based TPUs(HTPB‐TPUs) without hydrogen bonding between the soft and hard segments are synthesized using hydroxyl‐terminated polybutadiene, toluene diisocyanate, and four different chain extenders, and the effect of the chain extender structure on DMS is analyzed experimentally using a combination of analytical techniques. Furthermore, the solubility parameters of the soft and hard segments, glass transition temperatures, and hydrogen‐bond density of the HTPB‐TPUs, are computed using all‐atom molecular dynamics simulations. The results clearly reveal that the chain extender significantly affects the DMS and thus the mechanical properties of HTPB‐TPUs. This study paves the way for studying the relationship between the structure and properties of TPU. [ABSTRACT FROM AUTHOR]

Combined hepatocellular carcinoma–cholangiocarcinoma (cHCC-CCA) is a challenging primary liver cancer subtype with limited treatment options and a devastating prognosis. Recent studies have underscored the context-dependent roles of SOX9 in liver cancer formation in a preventive manner. Here, we revealed that liver-specific developmental Sox9 elimination using Alb-Cre;Sox9(flox/flox) (LKO) and CRISPR/Cas9-based tumor-specific acute Sox9 elimination (CKO) in SB-HDTVI-based Akt-YAP1 (AY) and Akt-NRAS (AN) cHCC-CCA models showed contrasting responses. LKO abrogates the AY CCA region while stimulating poorly differentiated HCC proliferation, whereas CKO prevents AY and AN cHCC-CCA development irrespective of tumor cell fate. Additionally, AN, but not AY, tumor formation partially depends on the Sox9-Dnmt1 cascade. SOX9 is dispensable for AY-mediated, HC-derived, LPC-like immature CCA formation but is required for their maintenance and transformation into mature CCA. Therapeutic Sox9 elimination using the OPN-CreERT2 strain combined with inducible Sox9 iKO specifically reduces AY but not AN cHCC-CCA tumors. This necessitates the careful consideration of genetic liver cancer studies using developmental Cre and somatic mutants, particularly for genes involved in liver development. Our findings suggest that SOX9 elimination may hold promise as a therapeutic approach for a subset of cHCC-CCA and highlight the need for further investigation to translate these preclinical insights into personalized clinical applications. [ABSTRACT FROM AUTHOR]

Summary: Rice tillering is one of the most important agronomical traits largely determining grain yield. Photosynthesis and nitrogen availability are two important factors affecting rice tiller bud elongation; however, underlying mechanism and their cross‐talk is poorly understood.Here, we used map‐based cloning, transcriptome profiling, phenotypic analysis, and molecular genetics to understand the roles of the Decreased Tiller Number 1 (DTN1) gene that encodes the fructose‐1,6‐bisphosphate aldolase and involves in photosynthesis required for light‐induced axillary bud elongation in rice.Deficiency of DTN1 results in the reduced photosynthetic rate and decreased contents of sucrose and other sugars in both leaves and axillary buds, and the reduced tiller number in dtn1 mutant could be partially rescued by exogenous sucrose treatment. Furthermore, we found that the expression of nitrogen‐mediated tiller growth response 5 (NGR5) was remarkably decreased in shoot base of dtn1‐2, which can be activated by sucrose treatment. Overexpression of NGR5 in the dtn1‐2 could partially rescue the reduced tiller number, and the tiller number of dtn1‐2 was insensitive to nitrogen supply.This work demonstrated that the sugar level regulated by photosynthesis and DTN1 could positively regulate NGR5 expression, which coordinates the cross‐talk between carbon and nitrate to control tiller bud outgrowth in rice. [ABSTRACT FROM AUTHOR]

A mechanized direct seeding of rice with less labor and water usage, has been widely adopted. However, this approach requires varieties that exhibit uniform seedling emergence. Mesocotyl elongation (ME) offers the main drive of fast emergence of rice seedlings from soils; nevertheless, its genetic basis remains unknown. Here, we identify a major rice quantitative trait locus Mesocotyl Elongation1 (qME1), an allele of the Green Revolution gene Semi‐Dwarf1 (SD1), encoding GA20‐oxidase for gibberellin (GA) biosynthesis. ME1 expression is strongly induced by soil depth and ethylene. When rice grains are direct‐seeded in soils, the ethylene core signaling factor OsEIL1 directly promotes ME1 transcription, accelerating bioactive GA biosynthesis. The GAs further degrade the DELLA protein SLENDER RICE 1 (SLR1), alleviating its inhibition of rice PHYTOCHROME‐INTERACTING FACTOR‐LIKE13 (OsPIL13) to activate the downstream expansion gene OsEXPA4 and ultimately promote rice seedling ME and emergence. The ancient traits of long mesocotyl and strong emergence ability in wild rice and landrace were gradually lost in company with the Green Revolution dwarf breeding process, and an elite ME1‐R allele (D349H) is found in some modern Geng varieties (long mesocotyl lengths) in northern China, which can be used in the direct seeding and dwarf breeding of Geng varieties. Furthermore, the ectopic and high expression of ME1 driven by mesocotyl‐specific promoters resulted in rice plants that could be direct‐seeded without obvious plant architecture or yield penalties. Collectively, we reveal the molecular mechanism of rice ME, and provide useful information for breeding new Green Revolution varieties with long mesocotyl suitable for direct‐seeding practice. [ABSTRACT FROM AUTHOR]

Summary: Head rice yield (HRY) measures rice milling quality and determines final grain yield and commercial value. Here, we report that two major quantitative trait loci for milling quality in rice, qMq‐1 and qMq‐2, represent allelic variants of Waxylv/Waxyb (hereafter Wx) encoding Granule‐Bound Starch Synthase I (GBSSI) and Alkali Spreading Value ALKc/ALKb encoding Soluble Starch Synthase IIa (SSIIa), respectively. Complementation and overexpression transgenic lines in indica and japonica backgrounds confirmed that Wx and ALK coordinately regulate HRY by affecting amylose content, the number of amylopectin branches, amyloplast size, and thus grain filling and hardness. The transcription factor OsDOF18 acts upstream of Wx and ALK by activating their transcription. Furthermore, rice accessions with Wxb and ALKb alleles showed improved HRY over those with Wxlv and ALKc. Our study not only reveals the novel molecular mechanism underlying the formation of HRY but also provides a strategy for breeding rice cultivars with improved HRY. [ABSTRACT FROM AUTHOR]

High temperature (HT) affects the production of chlorophyll (Chl) pigment and inhibits cellular processes that impair photosynthesis, and growth and development in plants. However, the molecular mechanisms underlying heat stress in rice are not fully understood yet. In this study, we identified two mutants varying in leaf color from the ethylmethanesulfonate mutant library of indica rice cv. Zhongjiazao‐17, which showed pale‐green leaf color and variegated leaf phenotype under HT conditions. Mut‐map revealed that both mutants were allelic, and their phenotype was controlled by a single recessive gene PALE GREEN LEAF 10 (PGL10) that encodes NADPH:protochlorophyllide oxidoreductase B, which is required for the reduction of protochlorophyllide into chlorophyllide in light‐dependent tetrapyrrole biosynthetic pathway‐based Chl synthesis. Overexpression‐based complementation and CRISPR/Cas9‐based knockout analyses confirmed the results of Mut‐map. Moreover, qRT‐PCR‐based expression analysis of PGL10 showed that it expresses in almost all plant parts with the lowest expression in root, followed by seed, third leaf, and then other green tissues in both mutants, pgl10a and pgl10b. Its protein localizes in chloroplasts, and the first 17 amino acids from N‐terminus are responsible for signals in chloroplasts. Moreover, transcriptome analysis performed under HT conditions revealed that the genes involved in the Chl biosynthesis and degradation, photosynthesis, and reactive oxygen species detoxification were differentially expressed in mutants compared to WT. Thus, these results indicate that PGL10 is required for maintaining chloroplast function and plays an important role in rice adaptation to HT stress conditions by controlling photosynthetic activity. [ABSTRACT FROM AUTHOR]

High temperatures accelerate the accumulation of storage material in seeds, often leading to defects in grain filling. However, the mechanisms regulating grain filling at high temperatures remain unknown. Here, we want to explore the quality factors influenced by the environment and have identified a LATE EMBROYGENESIS ABUNDANT gene, OsLEA1b, a heat-stress-responsive gene in rice grain filling. OsLEA1b is highly expressed in the endosperm, and its coding protein localizes to the nucleus and cytoplasm. Knock-out mutants of OsLEA1b had abnormal compound starch granules in endosperm cells and chalky endosperm with significantly decreased grain weight and grain number per panicle. The oslea1b mutants exhibited a lower proportion of short starch chains with degrees of polymerization values from 6 to 13 and a higher proportion of chains with degrees from 14 to 48, as well as significantly lower contents of starch, protein, and lipid compared to the wild type. The difference was exacerbated under high temperature conditions. Moreover, OsLEA1b was induced by drought stress. The survival rate of oslea1b mutants decreased significantly under drought stress treatment, with significant increase in ROS levels. These results indicate that OsLEA1b regulates starch biosynthesis and influences rice grain quality, especially under high temperatures. This provides a valuable resource for genetic improvement in rice grain quality. [ABSTRACT FROM AUTHOR]