Phosphorus (P) scarcity severely limits crop productivity; yet, mechanisms balancing P allocation between vegetative and reproductive organs remain unclear. Here, we identify OsPH-2 as a phosphate-responsive regulator in rice (Oryza sativa L.). Under low-P (LP) conditions, OsPHI-2 is transcriptionally repressed by the KNOX family factor OSH1 (KNOX family class 1 homeobox gene of rice), which directly binds its promoter. CRISPR-edited OsPHI-2 knockout lines exhibited enhanced biomass and adaptive root-shoot resource allocation under LP, whereas overexpression lines showed impaired panicle development and reduced grain yield. This repression fine-tunes P partitioning by modulating expression of transporters (OsPT2, OsPHO1;2) and vacuolar effluxes (OsVPE1), prioritizing reproductive over vegetative sinks. Haplotype analysis indicated that subspecies-specific P remobilization strategies may be associated with OsPHI-2. Under P deficiency, Indica rice rapidly suppresses OsPHI-2 expression to preferentially remobilize P to panicles, thereby enhancing adaptation to low-P environments. Our study uncovers an OSH1-OsPHI-2 module that coordinates P allocation, providing a genetic target for improving P-use efficiency in rice.

Nitrogen use efficiency (NUE) and grain development are pivotal for rice yield improvement, particularly under low-nitrogen (LN) conditions. Cytochrome P450 CYP51 family members are conserved obtusifoliol 14α-demethylases essential for phytosterol and brassinosteroid (BR) biosynthesis; however, the biological roles of the rice CYP51H subfamily remain largely unclear. Here, we characterized OsCYP51H9, a gene encoding an endoplasmic reticulum-localized protein highly expressed in reproductive and vascular tissues. Loss-of-function mutants (oscyp51h9) and RNAi lines exhibited BR-deficient phenotypes, including reduced plant height, impaired root growth, smaller grains, and erect leaves, which were associated with disrupted phytosterol and BR biosynthesis. While preliminary metabolite profiling indicated a potential link between OsCYP51H9 and triterpene metabolism via β-amyrin, this requires further validation. Notably, under LN conditions, OsCYP51H9-overexpressing plants displayed enhanced root growth, increased grain yield, and higher nitrogen accumulation. This improvement coincided with the upregulation of key nitrogen-responsive transcription factors, including OsWRKY69 and OsDREB1C/B. Collectively, our results suggest that OsCYP51H9 participates in the phytosterol-BR pathway and plays a positive role in rice adaptation to low-nitrogen environments, providing a potential target for molecular breeding.

Pitaya (Hylocereus polyrhizus) is one of the subtropical and tropical fruits, has gained global cultivation interest due to its nutritional, medicinal, and economic value. To improve the adaptability of pitaya on islands or soil salinization, it is of great significance to explore the salt tolerance mechanisms of pitaya. While oxalate has been conventionally characterized as an antinutrient metabolite, emerging evidence underscores its dual role as a stress signaling molecule through homeostatic regulation. Here, we demonstrate that dynamic control of oxalate catabolism is essential for pitaya's salt adaptation. Transcriptomic profiling revealed coordinated upregulation of the oxalate-degrading gene HuAAE3 under salt stress, accompanied by enhanced oxalate accumulation. Notably, the transcription factor HubHLH36 emerged as a central regulator responding to both ionic stress and oxalate. Molecular validation through yeast one-hybrid and dual-luciferase assays unveiled confirmed that HubHLH36 directly activates HuAAE3 transcription by binding to its promoter. Transient overexpression of HuAAE3 or HubHLH36 in pitaya plants significantly reduced oxalate levels, enhanced salt/oxalate tolerance, and alleviated reactive oxygen species (ROS) accumulation. Conversely, virus-induced gene silencing (VIGS) of these genes elevated oxalate content, compromised stress tolerance, and exacerbated ROS production. Heterologous expression in Arabidopsis further validated the conserved function of HubHLH36-HuAAE3 module in conferring salt/oxalate tolerance with ROS mitigation. Our findings establish a novel transcriptional regulatory module where HubHLH36 modulates oxalate homeostasis via HuAAE3 activation, thereby mitigating oxidative stress under salt stress. These mechanistic insights provide genetic targets and theoretical frameworks for developing salt-tolerant pitaya cultivars, offering promising solutions for sustainable agriculture in saline environments.

Seed development plays a critical role in determining both crop yield and grain quality in rice. As a key nutrient storage organ, the rice endosperm development not only contributes to grain filling but also plays an essential role during the early stages of seed germination. Amino acid metabolism is active during the process of seed development and seed germination. Asparagine is a primary amino acid responsible for long-distance organic nitrogen transport in plants. Asparagine synthetase catalyzes the synthesis of asparagine from aspartate and glutamine. In this study, CRISPR/Cas9-mediated knockout mutants of the OsASN2 gene of rice were generated. Homozygous mutants exhibited complete failure of seed germination, and heterozygotes could not produce homozygous offspring. Endosperm development of homozygous mutant seeds showed severe defects. Additionally, interacting protein screening combined with pull-down and co-immunoprecipitation (Co-IP) assays confirmed that OsASN2 physically interacted with pyruvate phosphate dikinase OsPPDKB, the mutants of which showed impaired endosperm development. These findings collectively indicate that OsASN2 plays a critical role in seed development and germination in rice.

As a strategic resource for both medicine and essential oil, the healthy development of the Pogostemon cablin industry is crucial for the traditional medicine and fragrance sectors. Bacterial wilt represents one of the most significant threats to patchouli cultivation; however, the molecular mechanisms underlying P. cablin’s response to bacterial wilt remain unexplored. Here, we conducted transcriptome and metabolome analyses, revealing an increase in the expression of genes associated with lipid pathways and a corresponding rise in the concentration of lipid metabolites in P. cablin following infection by the bacterial wilt pathogen SY1. Further lipidomics analysis demonstrated a significant upregulation of ceramide levels due to SY1 infection. Additionally, hormone analysis indicated that SY1 significantly induced an increase in abscisic acid (ABA) concentration, accompanied by the upregulation of genes involved in the ABA synthesis pathway and its downstream signaling pathways. Furthermore, we treated P. cablin seedlings with the ceramide synthase inhibitor FB1, which significantly reduced ceramide concentration in P. cablin. FB1 treatment also inhibited the expression of ABA-synthesizing genes, leading to a notable decrease in ABA concentration and downstream pathway genes. These data indicate that ceramides and ABA may participate in P. cablin’s response to SY1.

Accumulation of cadmium (Cd) in rice is not only harmful to the growth of plants but also poses a threat to human health. Exposure to Cd triggers unfolded protein response (UPR) within cells, a process that is still not completely understood. The study demonstrated that the lack of OsbZIP39, an essential endoplasmic reticulum (ER)-resident regulator of the UPR, resulted in decreased Cd intake and reduced Cd levels in the roots, stems, and grains of rice. Upon exposure to Cd stress, GFP-OsbZIP39 translocated from ER to nucleus, initiating UPR. Further investigation revealed that Cd treatment caused changes in sphingolipid levels in the membrane, influencing the localization and activation of OsbZIP39. Yeast one-hybrid and dual-LUC assays were conducted to validate the interaction between activated OsbZIP39 and the promoter of the defensin-like gene OsCAL2, resulting in an increase in its expression. Different variations were identified in the coding region of OsbZIP39, which may explain the varying levels of Cd accumulation observed in the indica and japonica subspecies. Under Cd treatment, OsbZIP39ind exhibited a more significant enhancement in the transcription of OsCAL2 compared to OsbZIP39jap. Our data suggest that OsbZIP39 positively regulates Cd uptake in rice, offering an encouraging objective for the cultivation of low-Cd rice.

Low -affinity nitrate transporter genes have been identified in subfamilies 4-8 of the rice nitrate transporter 1 (NRT1)/ peptide transporter family (NPF), but the OsNPF3 subfamily responsible for nitrate and phytohormone transport and rice growth and development remains unknown. In this study, we described OsNPF3.1 as an essential nitrate and phytohormone transporter gene for rice tillering and nitrogen utilization efficiency (NUtE). OsNPF3.1 possesses four major haplotypes of its promoter sequence in 517 cultivars, and its expression is positively associated with tiller number. Its expression was higher in the basal part, culm, and leaf blade than in other parts of the plant, and was strongly induced by nitrate, abscisic acid (ABA) and gibberellin 3 (GA3) in the root and shoot of rice. Electrophysiological experiments demonstrated that OsNPF3.1 is a pH -dependent low -affinity nitrate transporter, with rice protoplast uptake assays showing it to be an ABA and GA3 transporter. OsNPF3.1 overexpression significantly promoted ABA accumulation in the roots and GA accumulation in the basal part of the plant which inhibited axillary bud outgrowth and rice tillering, especially at high nitrate concentrations. The NUtE of OsNPF3.1-overexpressing plants was enhanced under low and medium nitrate concentrations, whereas the NUtE of OsNPF3.1 clustered regularly interspaced short palindromic repeats (CRISPR) plants was increased under high nitrate concentrations. The results indicate that OsNPF3.1 transports nitrate and phytohormones in different rice tissues under different nitrate concentrations. The altered OsNPF3.1 expression improves NUtE in the OsNPF3.1-overexpressing and CRISPR lines at low and high nitrate concentrations, respectively.

Bacterial blight of rice is a devastating disease caused by the gram-negative bacteria Xanthomonas oryzae pv. oryzae (Xoo). Chinese Xoo strain pathotypes IV, V, and IX are the major virulent Xoo strain types in South China sequentially from the 1990s to the present. Here, we report the isolation of GD0201 and GD0202, which belong to pathotypes IV and IX, respectively, and the complete genome sequence and transcriptomic analysis of GD0201 (IV), GD1358 (V), and GD0202 (IX). We found that resistance genes xa5, Xa23, and Xa27 confer strong resistance to all three Xoo strains, indicating that they are currently good choices for resistance rice breeding. The genome analysis reveals fewer TAL and non-TAL effector coding genes in GD0202 than in the other two strains, potentially contributing to its strong virulence. Transcriptomic analysis of ZH11 inoculated with the three Xoo strains strongly suggests that three Xoo strains for better infection repress the ethylene response factor (ERF) gene family members. Furthermore, weighted gene co-expression network analysis (WGCNA) and protein-protein interaction (PPI) analysis revealed 14 hub genes potentially associated with rice response to the three Xoo strains. The expression of several hub genes was validated to be induced by all three Xoo strains, suggesting its role in bacterial blight disease response to Xoo strains. Genomic analysis of the Xoo strains belonging to pathotypes IV, V, and IX, identification of effectors and genes related to Xoo virulence in rice plants will provide insights into understanding the molecular mechanism underlying rice-Xoo interaction and the gene expression pattern in response to Xoo infection.

Litsea cubeba (Lour.) Per., named as May Cang, is a rare deciduous evergreen tree and cultivated for its ethnopharmacological properties and medicinal uses. In 2020-2023, an outbreak of dieback disease was observed on the stems and branches of L. cubeba with above 80% disease incidence in a 150 hectare plantation in Yiyang, Hunan (N28°39’24”; E112°12’48”). In the early stages, water-soaked lesions appeared on the stems and branches. The infected sites turned elliptical in shape, dark brown, and swelled. The infected branches and stems died gradually. After scraping the bark from the diseased stems and branches under aseptic conditions, diseased tissues (5 mm2) from the diseased-healthy junction were cut off and placed on PDA containing penicillin (50 mg/L) at 25 ℃ to 28 ℃ in the dark for 3 to 4 days. Colonies from different tissues were subcultured by transferring the hyphal tip onto fresh PDA. Colonies with regular margin on PDA reached 60 mm diam after 3 d at 25℃ to 28℃, the aerial mycelia were woolly, grayish-white at first, gradually turned gray black after 14 days. No fruiting bodies were found on medium. On disease stems, conidia were hyaline, aseptate, granular, ellipsoid to obovoid, 18.0 to 33.4 × 5.5 to 9.8 μm (av. 25.6 × 7.4 μm, n=55). The internal transcribed spacers (ITS), 28S nrDNA (LSU), elongation factor 1-alpha (TEF1), and β-tubulin (TUB2) of isolate ACCC35248 and ACCC35249 (stored in the Agricultural Culture Collection of China) were PCR amplified and sequenced for further identification with primer pairs: .ITS1/ITS4 (White et al. 1990), LROR/LR7 (Rehner et al. 1994), EF1-728F/EF-2 (Zhao et al. 2021) and TUB4Rd/TUB2Fd (Woudenberg et al. 2009), respectively. Obtained sequences of ITS, LSU, TEF1 and TUB2 (Genebank accessions nos. PP577627 and PP577624, PP588412 and PP588413, PP584319 and PP584320, PP584321 and PP584322) showed above 99% homology with these sequences of Cophinforma tumefaciens ex-type culture IMI 76762 (ITS: MW810287, TEF: MZ073950 and TUB: MZ073935) and MFLUCC 11-0425 (ITS: JX64680, LSU: JX646817, TEF: JX646865 and TUB: JX646848) (Liu et al, 2012). Phylogenetic analysis with maximum likelihood in MEGA 10.0 using the concatenated ITS-TEF-TUB sequences placed the isolates within the C. tumefaciens clade with 100% bootstrap support. Therefore, the fungus was identified as C. tumefaciens. One-year-old healthy L. cubeba seedlings were surface-sterilized with 75% ethanol, then wounded with sterile needles and a 6-mm-diameter fungal plug of 14-day-old cultures grown on PDA was put on the wound. Sterile PDA plugs were used as controls, and all inoculated sites were wrapped with plastic film. The tests were repeated twice. At 7 days post-inoculation, symptoms were observed at the inoculated sites and the upper branches of the inoculation site died back two months later, while no symptoms were observed on the control plants. C. tumefaciens was re-isolated from the inoculated stems. C. tumefaciens can infect various plants and cause disease worldwide (Zhao et al. 2021), and this is the first report of a quarantine pathogen causing dieback on L. cubeba in China. This information will assist in preventing further spread of this pathogen.

AbstractSugarcane smut, a widespread and destructive disease induced by Sporisorium scitamineum, has a significant effect on sugarcane cultivation. Sphingolipids, crucial components of membranes, play a role in plant resistance regulation. However, the specific function of sphingolipids in sugarcane smut resistance has not been understood. This study revealed that following the S. scitamineum infection, ceramide (Cer) and hydroxyceramide (hCer) levels specifically increased in the sugarcane variety ROC22, along with significant alterations in plant hormone levels. Analysis of lipid composition in S. scitamineum‐sensitive and ‐resistant sugarcane varieties indicated that the resistant variety YT93‐159 had lower Cer and hCer levels compared to the sensitive variety ROC22. Additionally, YT93‐159 displayed an increased level of jasmonoyl‐isoleucine (JA‐Ile) and upregulated the expression of genes linked to the pathway of jasmonic acid (JA). Through experiments using the sugarcane protoplast system, it was observed that exogenous ceramide could influence the expression of genes associated with the salicylic acid and JA pathways. This research was the initial examination into the lipidomics‐based molecular mechanisms underlying sugarcane's resistance to S. scitamineum, offering a theoretical foundation for enhancing sugarcane resistance through genetic engineering.

Patchoulol, a valuable compound belonging to the sesquiterpenoid family, is the primary component of patchouli oil produced by Pogostemon cablin ( P. cablin ). It has a variety of pharmacological and biological activities and is widely used in the medical and cosmetic industries. However, despite its significance, there is a lack of research on the transcriptional modulation of patchoulol biosynthesis. Salicylic acid (SA), is a vital plant hormone that serves as a critical signal molecule and plays an essential role in plant growth and defense. However, to date, no studies have explored the modulation of patchoulol biosynthesis by SA. In our study, we discovered that the application of SA can enhance the production of patchoulol. Utilizing transcriptome analysis of SA-treated P. cablin , we identified a crucial downstream transcription factor, PatWRKY71. The transcription level of PatWRKY71 was significantly increased with the use of SA. Furthermore, our research has revealed that PatWRKY71 was capable of binding to the promoter of PatPTS , ultimately leading to an increase in its expression. When PatWRKY71 was silenced by a virus, the expression of both PatWRKY71 and PatPTS was reduced, resulting in the down-regulation of patchoulol production. Through our studies, we discovered that heterologous expression of PatWRKY71 leads to an increase in the sensitivity of Arabidopsis to salt and Cd, as well as an outbreak of reactive oxygen species (ROS). Additionally, we uncovered the regulatory role of PatWRKY71 in both patchoulol biosynthesis and plant defense response. This discovery provided a theoretical basis for the improvement of the content of patchoulol and the resistance of P. cablin through genetic engineering.

Upon Xanthomonas oryzae pv. oryzae ( Xoo ) infection of rice leaves, the invasion induces systematic expression changes for both the coding genes and the non-coding genes, allowing the plant to make corresponding responses. However, the roles of circular RNAs (circRNAs) in rice defending against Xoo remain largely unknown. To address this question, we conducted a whole-transcriptomic analysis to systematically screen the differentially expressed (DE) mRNAs and non-coding RNAs (ncRNAs) in rice responding to Xoo infection. Our results revealed a total of 4076 DE mRNAs, 89 DE long non-coding RNAs (lncRNAs), 82 DE microRNAs (miRNAs), and 14 DE circRNAs identified from Xoo -infected rice plants at 48 h post inoculation. Three circRNAs (ciR52, ciR298, and ciR133) were found to be able to form circular RNAs, and their expression was induced by Xoo infection. ciR133 was found to repress the expression of its parental gene OsARAB (putative arabinofuranosidase gene) during Xoo infection. Overexpression of ciR133 and mutation of OsARAB enhanced rice resistance against Xoo , without compromising main agronomic traits. Our data suggest that circRNAs are associated with rice response to Xoo infection, providing a potential strategy for breeding Xoo -resistant rice plants by manipulating ciR133 and OsARAB .

【Objective】The global warming has led to the increasingly serious heat damage on the heading and flowering stage of rice. To reduce the impact of heat damage on rice production and to ensure food security in China and even the world, new rice germplasms with thermo-tolerance on heading stage should be identified and new thermo-tolerance varieties need be bred.【Method】Guanghui 128 (Qiguizao/Ce64//Minghui 63) was used as the heat resistant parent, through hybridization, multiple crossing and pedigree selection, the lines with high seed setting rate and small variation on heading and flowering stage during the high temperature were screened out for several generations’ breeding process. Then the selected higher generation lines were identified to create new thermos-tolerance rice germplasms in artificial climate chamber (The treated plants will be moved into the chamber on the flowering day, high temperature treatment is 9:00-15:00, 38℃, 15:01-8:59 28℃, the relative humidity is 75%, and the treatment lasts for 7 days), with analysis of agronomic trait.【Result】The new germplasm R203 has stronger thermo-tolerance and higher seed setting rates under both normal and high temperature conditions (94.5% at normal temperature, 81.9% at high temperature, and 86.7% at relative). Its agronomic traits, quality and comprehensive resistance all meet the production standards. Above all, R203 has the potential to breed new thermos-tolerance hybrid rice varieties. The seed setting rates of 7 hybrid combinations with R203 as the male parent and seven three-line male sterile lines as the female parent were between 83.4%-99.4% under natural high temperature conditions. Among them, Taiyou 203, a new three-line medium indica hybrid rice has good qualities, the seed setting rate was 87.9%, the comprehensive relative heat resistance coefficient was 1.11, and the heat resistance reached level 1. In the production test, the yield increased by 5.36% compared with the control, and the yield increase point accounted for 85.71%. It has good high and stable yield, and the rice quality reached the second level of the ministerial standard. Thus Taiyou 203 has good promotion and application value.【Conclusion】Currently, basic research on heat resistance is not enough to support the breeding of new practical heat resistant varieties, the rice resources in areas prone to high temperature and humidity are preferred as materials for breeding new heat tolerance lines, a new heat-resistant rice variety R203 was created by phenotypic selection, and a practical heat-resistant rice variety Taiyou 203 was developed by using heterosis.

Rice microRNA168a (osa-miR168a) plays important roles in mediating flowering time, grain yield and vigor, seeding growth, and immunity by targeting the RNA-induced silencing complex component Argonaute 1 (AGO1). However, the functions of miR168a exerted by targeting other genes require further clarification before it could be used in rice molecular breeding. In this study, we identified a new target gene of osa-miR168a-5p (miR168a-5p) in rice called OsOFP3 (ovate family protein 3) and investigated the roles of miR168a-5p in response to brassinosteroids (BRs), salt stress, and nitrogen allocation. Up- and downregulated miR168a-5p expression respectively decreased and increased the expression of the BR-negative regulator OsOPF3. The results of RNA ligase-mediated rapid amplification of cDNA ends (5'RLM-RACE) revealed cleavage sites in OsOPF3 and OsNPF2.4 mRNAs. The phenotype of miR168a-5p transgenic rice was BR-associated and included the lamina bending response to BR, short seeds, and low 1000-grain weight. MicroRNA 168a-5p also regulated the expression of the nitrate transporter, OsNPF2.4, which affected nitrogen allocation, and regulated OsAGO1a expression in response to salt stress. Taken together, rice miR168a-5p regulates BR-associated pathways, nitrogen transport, and stress by targeting OsOFP3, OsNPF2.4, and OsAGO1a, respectively, resulting in a series of important agronomic traits for rice breeding.

茉莉酸甲酯能诱导广藿香叶片中百秋李醇含量升高,但是其中的分子机制不清楚.本研究从茉莉酸甲酯处理的广藿香叶片转录组数据中筛选到一个表达量显著增加的基因,经过序列比对发现该基因与唇形科丹参转录因子SmTIFY6b具有高度同源性,因此将其命名为PatTIFY6b.通过生物信息学对PatTIFY6b编码蛋白的结构和功能进行分析和预测,并以广藿香cDNA为模板,克隆得到PatTIFY6b.PatTIFY6b定位于细胞核,在广藿香不同组织中均有表达,叶片中表达量最高.茉莉酸甲酯处理下,PatTIFY6b和百秋李醇合成途径基因具有相似的表达模式,说明茉莉酸甲酯可能通过PatTIFY6b调控百秋李醇的合成.利用原核表达系统,成功表达了 PatTIFY6b蛋白.将PatTIFY6b过表达在双子叶模式植物拟南芥中,筛选到纯合株系PatTIFY6b-ox-17.本研究首次克隆广藿香PayTIFY6b基因并对其功能进行初步探究,为后期研究广藿香百秋李醇生物合成的分子调控机制提供理论基础.

Pitaya (Hylocereus polyrhizus) is cultivated in a broad ecological range, due to its tolerance to drought, heat, and poor soil. The zinc finger proteins regulate gene expression at the transcriptional and post-transcriptional levels, by interacting with DNA, RNA, and proteins, to play roles in plant growth and development, and stress response. Here, a total of 81 CCCH-type zinc finger protein genes were identified from the pitaya genome. Transcriptomic analysis showed that nine of them, including HuTZF3, responded to both salt and heat stress. RT-qPCR results showed that HuTZF3 is expressed in all tested organs of pitaya, with a high level in the roots and stems, and confirmed that expression of HuTZF3 is induced by salt and heat stress. Subcellular localization showed that HuTZF3 is targeted in the processing bodies (PBs) and stress granules (SGs). Heterologous expression of HuTZF3 could improve both salt and heat tolerance in Arabidopsis, reduce oxidative stress, and improve the activity of catalase and peroxidase. Therefore, HuTZF3 may be involved in post-transcriptional regulation via localizing to PBs and SGs, contributing to both salt and heat tolerance in pitaya.

Photosynthesis affects crop growth and yield. The roles of microRNAs (miRNAs) in photosynthesis are little known. In the present study, the role of the OsNF-YB7–OsMIR5810–OsMRLP6 regulatory module in photosynthesis was investigated. The malectin-like protein gene OsMRLP6 was identified as a target gene of osa-miR5810 (miR5810). Overexpression in rice of miR5810 or down-expression of OsMRLP6 resulted in reduced expression of genes involved in chloroplast development and photosynthesis and decreased net photosynthetic rate, finally leading to lower shoot biomass and grain yield. Down-expression of miR5810 and overexpression of OsMRLP6 showed the opposite effect. Overexpression of transcription factor OsNF-YB7 elevated expression of OsMIR5810 in rice seedlings by binding to its promoter. The OsNF-YB7–OsMIR5810–OsMRLP6 regulatory module affects photosynthesis to mediate growth and grain yield.

Peptide transport is important for plant tissues where rapid proteolysis occurs, especially during germination and senescence, to enhance redistribution of organic nitrogen (N). However, the biological role of peptide transporters is poorly investigated in rice. We characterized the function of the peptide transporter OsNPF8.1 of rice nitrate transporter 1/peptide transporter family (NPF). Ectopic expression of OsNPF8.1 in yeast revealed that OsNPF8.1 encoded a high-affinity di-/tri-peptide transporter, and the osnpf8.1 mutants had a lower uptake rate of the fluorescent-labelled dipeptide c in leaves of rice seedlings. Histochemical assays showed that OsNPF8.1 was highly expressed in mesophyll cells and vascular parenchyma cells, but not detected in root hairs and epidermises. Expression of OsNPF8.1 was induced by N deficiency, drought, NaCl and abscisic acid, and kept at a high level in senescing leaves. Under N deficiency conditions, compared with the wild type Zhonghua 11, the osnpf8.1 mutants grew slower at the seedling stage, and had lower grain yield and lower N content in the grains. In contrast, OsNPF8.1-over-expressing rice (OsNPF8.1-OE) grew faster at the seedling stage and had a higher grain yield. The osnpf8.1 seedlings were less tolerant to salt and drought stresses. These results suggested that stress-induced organic N transportation mediated by OsNPF8.1 might contribute to balance plant growth and tolerate to salt/drought stress and N-deficiency.

Long non-coding RNAs (lncRNAs) regulate gene expression in eukaryotic organisms. Research suggests that lncRNAs may be involved in the regulation of nitrogen use efficiency in plants. In this study, we identified 1628 lncRNAs based on the transcriptomic sequencing of rice roots under low-nitrogen (LN) treatment through the implementation of an integrated bioinformatics pipeline. After 4 h of LN treatment, 50 lncRNAs and 373 mRNAs were significantly upregulated, and 17 lncRNAs and 578 mRNAs were significantly downregulated. After 48 h LN treatment, 43 lncRNAs and 536 mRNAs were significantly upregulated, and 42 lncRNAs and 947 mRNAs were significantly downregulated. Moreover, the interaction network among the identified lncRNAs and mRNAs was investigated and one of the LN-induced lncRNAs (lncRNA24320.6) was further characterized. lncRNA24320.6 was demonstrated to positively regulate the expression of a flavonoid 3 '-hydroxylase 5 gene (OsF3 ' H5). The overexpression of lncRNA24320.6 was shown to improve nitrogen absorption and promote growth in rice seedlings under LN conditions. Our results provide valuable insights into the roles of lncRNAs in the rice response to nitrogen starvation.

The clustering of transgenes at a chromosome location minimizes the number of segregating loci that needs to be introgressed to field cultivars. Transgenes could be efficiently stacked through site-specific recombination and a recombinase-mediated in planta gene stacking process was described previously in tobacco based on the Mycobacteriophage Bxb1 site-specific integration system. Since this process requires a recombination site in the genome, this work describes the generation of target sites in the Japonica rice genome. Agrobacterium-mediated gene transfer yielded ~4000 random-insertion lines. Seven lines met the criteria of being single copy, not close to a centromere, not inserted within or close to a known gene or repetitive DNA, having precise recombination site sequences on both ends, and able to express the reporter gene. Each target line tested was able to accept the site-specific integration of a new gfp-containing plasmid and in three of those lines, we regenerated fertile plants. These target lines could be used as foundation lines for stacking new traits into Japonica rice.