Management of anastomotic biliary stricture through utilizing percutaneous transhepatic cholangioscopy.

AIM: Occurrence of anastomotic biliary stricture (AS) remains an essential issue following hepatobiliary surgeries, and percutaneous transhepatic cholangioscopy (PTCS) has great therapeutic significance in handling refractory AS for patients with altered gastrointestinal anatomy after cholangio-jejunostomy. This present study aimed to investigate feasibility of PTCS procedures in AS patients for therapeutic indications. MATERIALS AND METHODS: This study was a single-center, retrospective cohort study with a total number of 124 consecutive patients who received therapeutic PTCS due to AS. Clinical success rate, required number, and adverse events of therapeutic PTCS procedures as well as patients survival state were reviewed. RESULTS: These 124 patients previously underwent choledochojejunostomy or hepatico-jejunostomy, and there was post-surgical altered gastrointestinal anatomy. Overall, 366 therapeutic PTCS procedures were performed for these patients through applying rigid choledochoscope, and the median time of PTCS procedures was 3 (1-11). Among these patients, there were 34 cases (27.32%) accompanied by biliary strictures and 100 cases (80.65%) were also combined with biliary calculi. After therapeutic PTCS, most patients presented with relieved clinical manifestations and improved liver functions. The median time of follow-up was 26 months (2-86 months), and AS was successfully managed through PTCS procedures in 104 patients (83.87%). During the follow-up period, adverse events occurred in 81 cases (65.32%), most of which were tackled through supportive treatment. CONCLUSION: PTCS was a feasible, safe and effective therapeutic modality for refractory AS, which may be a promising alternative approach in clinical cases where the gastrointestinal anatomy was changed after cholangio-jejunostomy.

Mediating effect of gestational weight gain on the preventive effect of exercise during pregnancy on macrosomia: a randomized clinical trial.

OBJECTIVE: We sought to investigate the impact of individualized exercise guidance during pregnancy on the incidence of macrosomia and the mediating effect of gestational weight gain (GWG). DESIGN: A prospective randomized clinical trial. SETTING: A Hospital in Xingtai District, Hebei Province. POPULATION: Older than 20 years of age, mid-pregnancy, and singleton pregnant women without contraindications to exercise during pregnancy. METHODS: A randomized clinical trial was conducted from December 2021 to September 2022 to compare the effects of standard prenatal care with individualized exercise guidance on the incidence of macrosomia. MAIN OUTCOME MEASURE: Incidence of macrosomia. RESULTS: In all, 312 singleton women were randomized into an intervention group (N = 162) or a control group (N = 150). Participants who received individualized exercise guidance had a significantly lower incidence of macrosomia (3.73% vs. 13.61%, P = 0.002) and infants large for gestational age (9.94% vs. 19.73%, P = 0.015). However, no differences were observed in the rate of preterm birth (1.86% vs. 3.40%, P = 0.397) or the average gestational age at birth (39.14 ± 1.51 vs. 38.69 ± 1.85, P = 0.258). Mediation analysis revealed that GWG mediated the effect of exercise on reducing the incidence of macrosomia. CONCLUSION: Individualized exercise guidance may be a preventive tool for macrosomia, and GWG mediates the effect of exercise on reducing the incidence of macrosomia. However, evidence does not show that exercise increases the rate of preterm birth or affects the average gestational age at birth. TRIAL REGISTRATION: The trial is registered at www.clinicaltrails.gov [registration number: NCT05760768; registration date: 08/03/2023 (retrospectively registered)].

Candidate Gene Identification and Transcriptome Analysis of Tomato male sterile-30 and Functional Marker Development for ms-30 and Its Alleles, ms-33, 7B-1, and stamenless-2.

Male sterility is a valuable trait for hybrid seed production in tomato (Solanum lycopersicum). The mutants male sterile-30 (ms-30) and ms-33 of tomato exhibit twisted stamens, exposed stigmas, and complete male sterility, thus holding potential for application in hybrid seed production. In this study, the ms-30 and ms-33 loci were fine-mapped to 53.3 kb and 111.2 kb intervals, respectively. Tomato PISTILLATA (TPI, syn. SlGLO2), a B-class MADS-box transcription factor gene, was identified as the most likely candidate gene for both loci. TPI is also the candidate gene of tomato male sterile mutant 7B-1 and sl-2. Allelism tests revealed that ms-30, ms-33, 7B-1, and sl-2 were allelic. Sequencing analysis showed sequence alterations in the TPI gene in all these mutants, with ms-30 exhibiting a transversion (G to T) that resulted in a missense mutation (S to I); ms-33 showing a transition (A to T) that led to alternative splicing, resulting in a loss of 46 amino acids in protein; and 7B-1 and sl-2 mutants showing the insertion of an approximately 4.8 kb retrotransposon. On the basis of these sequence alterations, a Kompetitive Allele Specific PCR marker, a sequencing marker, and an Insertion/Deletion marker were developed. Phenotypic analysis of the TPI gene-edited mutants and allelism tests indicated that the gene TPI is responsible for ms-30 and its alleles. Transcriptome analysis of ms-30 and quantitative RT-PCR revealed some differentially expressed genes associated with stamen and carpel development. These findings will aid in the marker-assisted selection for ms-30 and its alleles in tomato breeding and support the functional analysis of the TPI gene.

Deconstructive Carboxylation of Activated Alkenes with Carbon Dioxide.

Carboxylation with carbon dioxide (CO2 ) represents one notable methodology to produce carboxylic acids. In contrast to carbon-heteroatom bonds, carbon-carbon bond cleavage for carboxylation with CO2 is far more challenging due to their inherent and less favorable orbital directionality for interacting with transition metals. Here we report a photocatalytic protocol for the deconstructive carboxylation of alkenes with CO2 to generate carboxylic acids in the absence of transition metals. It is emphasized that our protocol provides carboxylic acids with obviously unchanged carbon numbers when terminal alkenes were used. To show the power of this strategy, a variety of pharmaceutically relevant applications including the modular synthesis of propionate nonsteroidal anti-inflammatory drugs and the late-stage carboxylation of bioactive molecule derivatives are demonstrated.

Localized Oxidation Embellishing Strategy Enables High-Performance Perovskite Solar Cells.

Perovskite solar cell (pero-SC) has attracted extensive studies as a promising photovoltaic technology, wherein the electron extraction and transfer exhibit pivotal effect to the device performance. The planar SnO2 electron transport layer (ETL) has contributed the recent record power conversion efficiency (PCE) of the pero-SCs, yet still suffers from surface defects of SnO2 nanoparticles which brings energy loss and phase instability. Herein, we report a localized oxidation embellishing (LOE) strategy by applying (NH4 )2 CrO4 on the SnO2 ETL. The LOE strategy builds up plentiful nano-heterojunctions of p-Cr2 O3 /n-SnO2 and the nano-heterojunctions compensate the surface defects and realize benign energy alignment, which reduces surface non-radiative recombination and voltage loss of the pero-SCs. Meanwhile, the decrease of lattice mismatch released the lattice distortion and eliminated tensile stress, contributing to better stability of the devices. The pero-SCs based on α-FAPbI3 with the SnO2 ETL treated by the LOE strategy realized a PCE of 25.72 % (certified as 25.41 %), along with eminent stability performance of T90 >700 h. This work provides a brand-new view for defect modification of SnO2 electron transport layer.

Genome-wide identification and expression analysis of the NRT genes in Ginkgo biloba under nitrate treatment reveal the potential roles during calluses browning.

Nitrate is a primary nitrogen source for plant growth, and previous studies have indicated a correlation between nitrogen and browning. Nitrate transporters (NRTs) are crucial in nitrate allocation. Here, we utilized a genome-wide approach to identify and analyze the expression pattern of 74 potential GbNRTs under nitrate treatments during calluses browning in Ginkgo, including 68 NITRATE TRANSPORTER 1 (NRT1)/PEPTIDE TRANSPORTER (PTR) (NPF), 4 NRT2 and 2 NRT3. Conserved domains, motifs, phylogeny, and cis-acting elements (CREs) were analyzed to demonstrate the evolutionary conservation and functional diversity of GbNRTs. Our analysis showed that the NPF family was divided into eight branches, with the GbNPF2 and GbNPF6 subfamilies split into three groups. Each GbNRT contained 108-214 CREs of 19-36 types, especially with binding sites of auxin and transcription factors v-myb avian myeloblastosis viral oncogene homolog (MYB) and basic helix-loop-helix (bHLH). The E1X1X2E2R motif had significant variations in GbNPFs, indicating changes in the potential dynamic proton transporting ability. The expression profiles of GbNRTs indicated that they may function in regulating nitrate uptake and modulating the signaling of auxin and polyphenols biosynthesis, thereby affecting browning in Ginkgo callus induction. These findings provide a better understanding of the role of NRTs during NO3- uptake and utilization in vitro culture, which is crucial to prevent browning and develop an efficient regeneration and suspension production system in Ginkgo.

Transposon Insertion Drove the Loss of Natural Seed Shattering during Foxtail Millet Domestication.

Loss of seed shattering was a key step during cereal domestication, and it greatly facilitated seed harvest of the staple cereal foxtail millet (Setaria italica) because the cereal has very small seeds. However, the genetic basis for this loss has been largely unknown. Here, we combined comparative and association mapping to identify an 855-bp Harbinger transposable element insertion in the second exon of the foxtail millet gene shattering1 (sh1) that was responsible for the loss of seed shattering. The sh1 gene encodes zinc finger and YABBY domains. The insert prevents transcription of the second exon, causing partial loss of the zinc finger domain and then loss of natural seed shattering. Specifically, sh1 functions as a transcription repressor and represses the transcription of genes associated with lignin synthesis in the abscission zone, including CAD2. The diversity of sh1 is highly reduced in foxtail millet, consistent with either a severe domestication bottleneck or a selective sweep. Phylogenetic analysis of sh1 further revealed a single origin of foxtail millet in China. Our results support the theories that transposons were the most active factors in genome evolution driving loss of natural seed shattering during foxtail millet domestication and that sh1 underwent parallel selection during domestication across different cereal species.

A Large Transposon Insertion in the stiff1 Promoter Increases Stalk Strength in Maize.

Stalk lodging, which is generally determined by stalk strength, results in considerable yield loss and has become a primary threat to maize (Zea mays) yield under high-density planting. However, the molecular genetic basis of maize stalk strength remains unclear, and improvement methods remain inefficient. Here, we combined map-based cloning and association mapping and identified the gene stiff1 underlying a major quantitative trait locus for stalk strength in maize. A 27.2-kb transposable element insertion was present in the promoter of the stiff1 gene, which encodes an F-box domain protein. This transposable element insertion repressed the transcription of stiff1, leading to the increased cellulose and lignin contents in the cell wall and consequently greater stalk strength. Furthermore, a precisely edited allele of stiff1 generated through the CRISPR/Cas9 system resulted in plants with a stronger stalk than the unedited control. Nucleotide diversity analysis revealed that the promoter of stiff1 was under strong selection in the maize stiff-stalk group. Our cloning of stiff1 reveals a case in which a transposable element played an important role in maize improvement. The identification of stiff1 and our edited stiff1 allele pave the way for efficient improvement of maize stalk strength.

Safety and efficacy of endovascular recanalization in patients with mild anterior stroke due to large-vessel occlusion exceeding 24 hours.

BACKGROUND: Endovascular recanalization (ER) has demonstrated efficacy as a treatment modality for patients presenting with acute ischemic stroke (AIS) caused by large-vessel occlusion (LVO) within a 24-hour timeframe. Nevertheless, the safety and effectiveness of ER in patients with a time of onset exceeding 24 h remain uncertain. OBJECTIVE: To evaluate the safety and efficacy of ER treatment for mild ischemic stroke beyond 24-h from symptom onset. METHODS: A retrospectively maintained database of mild AIS due to LVO from March2018 to September 2022 at a comprehensive stroke center was screened.Patients received ER or standard medical therapies (SMT) for anterior circulation AIS due to LVO > 24-h were selected. RESULTS: We included 47 LVO patients with mild AIS beyond 24-h who suffered neurological deterioration (ND). 34 of these patients underwent ER, the other 13 received SMT. The technical success rate of recanalization was 82.4% (28/34). Patients received ER had significantly lower NIHSS score at discharge and 90-day mRS score (p = 0.028, p = 0.037, respectively) compared to SMT. In addition, they had significantly lower 90-day recurrence of ischemic stroke and lower incidence of moderate-severe stroke (with a NIHSS score at least 5) (p = 0.037, p = 0.033). There were 4 patients (11.7%) had perioperative complications, and no symptomatic intracranial hemorrhage occurred. CONCLUSION: ER treatment for mild AIS due to LVO encountered ND was generally safe and effective, even beyond 24-h, and resulted in a good prognosis and lower 90-day recurrence compared to SMT.

ER for mild anterior stroke might be safe and feasible, even exceeding 24-h;The proposed protocol could be used for individualized treatment decision making;Modelling for heterogeneity of treatment effect.

Efficiency of percutaneous transhepatic cholangioscopy in the treatment of biliary complications after liver transplantation.

BACKGROUND: Percutaneous transhepatic cholangioscopy (PTCS) has provided an alternative therapeutic option for handling refractory biliary complications in liver transplanted recipients. This study aimed to evaluate short-term PTCS efficiency in the management of biliary complications following liver transplantation. METHODS: Clinical data of 25 patients who received therapeutic PTCS due to biliary complications after liver transplantation were retrospectively analyzed. RESULTS: Therapeutic PTCS was successfully performed in 25 patients. Biliary complications were anastomotic strictures in seven cases, intrahepatic cholangiolithiasis in four cases, extra-and intrahepatic cholangiolithiasis in three cases, choledocholithiasis complicated with anastomotic strictures in four cases, intrahepatic cholangiolithiasis complicated with non-anastomotic strictures in one case, intrahepatic cholangiolithiasis complicated with anastomotic strictures in five cases, intrahepatic cholangiolithiasis complicated with anastomotic strictures and ischemic cholangitis in one case. The median time between liver transplantation and first PTCS was 24 months, and median times of PTCS was 2.6. Clinical manifestations were significantly improved in most patients after PTCS, and biliary complications were successfully managed through PTCS in 15 cases, which were partially effective in eight cases and ineffective in two cases. PTCS was more effective in tackling anastomotic strictures and cholangiolithiasis. CONCLUSION: PTCS was an effective therapeutic modality for treating refractory biliary complications following liver transplantation.

A gene regulatory network for tiller development mediated by Tin8 in maize.

The complex gene regulatory network underlying tiller development in maize remains largely unknown. Here we identified two major quantitative trait loci for tiller number, Tin8 on chromosome 8 and the previously known Tb1 on chromosome 1, in a population derived from a teosinte-maize cross. Map-based cloning and association mapping revealed that Tin8, corresponding to Zcn8 encoding a phosphatidylethanolamine-binding-related kinase, is down-regulated in transcription, which results in decreased tiller number. A strong interaction between Tin8 and the key gen Tb1 was detected for tiller number. Further RNA-seq analysis showed that the expression of 13 genes related to tiller development was controlled by Tin8. Our results support the existence of a complex gene regulatory network for the outgrowth of the tiller bud in maize, in which Zcn8 controls 13 tiller-related genes, including four genes for hormonal responses. In particular, Zcn8 represses Gt1, D14, and Tru1 through the interaction with Tb1.

[Association of Haemophilus influenzae infection with environmental and climatic factors in Suzhou, China]. / è‹å·žåœ°åŒºæµæ„Ÿå—œè¡€æ†èŒæ„ŸæŸ“ä¸ŽçŽ¯å¢ƒæ°”å€™çš„ç›¸å ³å› ç´ åˆ†æž.

OBJECTIVES: To investigate the epidemiological characteristics of respiratory Haemophilus influenzae (HI) infection in children in Suzhou, China and its association with climatic factors and air pollutants. METHODS: The data on air pollutants and climatic factors in Suzhou from January 2016 to December 2019 were collected. Respiratory secretions were collected from 7 940 children with acute respiratory infection who were hospitalized during this period, and bacterial culture results were analyzed for the detection of HI. A stepwise regression analysis was used to investigate the association of HI detection rate with air pollutants (PM2.5, PM10, NO2, SO2, CO, and O3) and climatic factors (monthly mean temperature, monthly mean humidity, monthly total rainfall, monthly total sunshine duration, and monthly mean wind speed). RESULTS: In 2016-2019, the 4-year overall detection rate of HI was 9.26% (735/7 940) among the children in Suzhou. The children aged <1 year and 1-<3 years had a significantly higher HI detection rate than those aged ≥3 years (P<0.01). The detection rate of HI in spring was significantly higher than that in the other three seasons, and the detection rate of HI in autumn was significantly lower than that in the other three seasons (P<0.001). The multiple linear regression analysis showed that PM10 and monthly mean wind speed were independent risk factors for the detection rate of HI: the detection rate of HI was increased by 0.86% for every 10 µg/m3 increase in the concentration of PM10 and was increased by 5.64% for every 1 m/s increase in monthly mean wind speed. Air pollutants and climatic factors had a lag effect on the detection rate of HI. CONCLUSIONS: HI is an important pathogen for acute respiratory infection in children in Suzhou and is prevalent in spring. PM10 and monthly mean wind speed are independent risk factors for the detection rate of HI.

Succinate induces skeletal muscle fiber remodeling via SUNCR1 signaling.

The conversion of skeletal muscle fiber from fast twitch to slow-twitch is important for sustained and tonic contractile events, maintenance of energy homeostasis, and the alleviation of fatigue. Skeletal muscle remodeling is effectively induced by endurance or aerobic exercise, which also generates several tricarboxylic acid (TCA) cycle intermediates, including succinate. However, whether succinate regulates muscle fiber-type transitions remains unclear. Here, we found that dietary succinate supplementation increased endurance exercise ability, myosin heavy chain I expression, aerobic enzyme activity, oxygen consumption, and mitochondrial biogenesis in mouse skeletal muscle. By contrast, succinate decreased lactate dehydrogenase activity, lactate production, and myosin heavy chain IIb expression. Further, by using pharmacological or genetic loss-of-function models generated by phospholipase Cß antagonists, SUNCR1 global knockout, or SUNCR1 gastrocnemius-specific knockdown, we found that the effects of succinate on skeletal muscle fiber-type remodeling are mediated by SUNCR1 and its downstream calcium/NFAT signaling pathway. In summary, our results demonstrate succinate induces transition of skeletal muscle fiber via SUNCR1 signaling pathway. These findings suggest the potential beneficial use of succinate-based compounds in both athletic and sedentary populations.

Sodium fluoride causes oxidative damage to silkworm (Bombyx mori) testis by affecting the oxidative phosphorylation pathway.

Bombyx mori was used to study the molecular mechanism of fluoride induced reproductive toxicity. In our previous study, we confirmed the physiological and biochemical effects of NaF on reproductive toxicity, and we found that the molecular mechanism of NaF induced reproductive damage may be associated with the oxidative phosphorylation pathway. To further study the function of NaF exposure on the oxidative phosphorylation pathway in the testis in Bombyx mori, and the relationship between oxidative phosphorylation and oxidative stress, we measured the changes in the main ROS (O2- and H2O2) in the testis, the activity of the main electron transport chain complex enzymes in the oxidative phosphorylation pathway and the transcription levels of the corresponding genes; we additionally performed pathological observations of the silkworm testis after exposure to 200 mg/L NaF solution for different times. The content of O2- and H2O in the silkworm gonads increased significantly at 24 h, 72 h and 120 h after NaF stress. The activity of mitochondrial complexes I, III, IV and V in the silkworm testis was significantly greater than that in the control group. RT-PCR analysis suggested that the mRNA transcription levels of NADH-CoQ1, Cyt c reductase, Cyt c oxidase and ATP synthase genes were up-regulated significantly. Histopathological investigation showed that the damage to the silkworm testis was more severe with increasing NaF exposure times. These results indicated that NaF stress affects the NADH respiratory chain of the mitochondrial electron transport chain and increases the activity of related enzyme complexes, thus destroying the balance of the electron transport chain. Subsequently, the content of ROS in cells significantly increases, thus resulting in oxidative stress reactions in cells. These results enable better understanding of the testis-damaging molecular toxicological mechanism of NaF.

Palladium-catalyzed oxidative dehydrogenative carbonylation reactions using carbon monoxide and mechanistic overviews.

Carbon monoxide, which is an abundant and inexpensive carbonyl source, has been widely applied to synthesize carbonyl-containing compounds, for example ketones, esters, and amides. These types of compounds are ubiquitous in natural products, pharmaceuticals, as well as in functional materials. This review focuses on the palladium-catalyzed dehydrogenative C-H/X-H (X = C, N, O) carbonylation transformations under oxidative conditions. The related C-H bonds here include C(sp)-H, C(sp2)-H, and C(sp3)-H bonds. From a step- and atom-economy perspective, transition metal-catalyzed oxidative dehydrogenative C-H/X-H carbonylation reactions with CO constitute one of the most efficient strategies for the construction of versatile carbonyl groups, without the requirement of pre-functionalized substrates.

Efficient Stereoselective Carbocyclization to cis-1,4-Disubstituted Heterocycles Enabled by Dual Pd/Electron Transfer Mediator (ETM) Catalysis.

An efficient Pd/ETM (ETM = electron transfer mediator)-cocatalyzed stereoselective oxidative carbocyclization of dienallenes under aerobic oxidation conditions has been developed to afford six-membered heterocycles. The use of a bifunctional cobalt complex [Co(salophen)-HQ] as hybrid ETM gave a faster aerobic oxidation than the use of separated ETMs, indicating that intramolecular electron transfer between the hydroquinone unit and the oxidized metal macrocycle occurs. In this way, a class of important cis-1,4-disubstituted six-membered heterocycles, including dihydropyran and tetrahydropyridine derivatives were obtained in high diastereoselectivity with good functional group compatibility. The experimental and computational (DFT) studies reveal that the pendent olefin does not only act as an indispensable element for the initial allene attack involving allenic C(sp3)-H bond cleavage, but it also induces a face-selective reaction of the olefin of the allylic group, leading to a highly diastereoselective formation of the product. Finally, the deuterium kinetic isotope effects measured suggest that the initial allenic C(sp3)-H bond cleavage is the rate-limiting step, which was supported by DFT calculations.

Efficient Heterogeneous Palladium-Catalyzed Oxidative Cascade Reactions of Enallenols to Furan and Oxaborole Derivatives.

A heterogeneous palladium-catalyzed oxidative cyclization of enallenols has been developed for the construction of highly substituted furan and oxaborole derivatives. The heterogeneous catalyst (Pd-AmP-MCF) exhibits high activity, high site- and stereoselectivity, and efficient palladium recyclability in the transformations.

krn1, a major quantitative trait locus for kernel row number in maize.

Kernel row number is a fundamental component of maize (Zea mays) yield and an important target for maize breeding. The revolutionary transition from the two-rowed teosinte to maize with increased kernel row numbers dramatically enhanced yields during domestication. Kernel row number is controlled by many quantitative trait loci (QTLs), however most genes responsible for these QTLs remain uncharacterised and the molecular genetic mechanisms are unknown. Here, we combined map-based cloning and association mapping to identify a major QTL for kernel row number, krn1, which is likely to correspond to an existing gene (ids1/Ts6) encoding an AP2 domain protein homologous to the product of the wheat key domestication gene Q. The increased expression of ids1/Ts6 in two maize mutants increased spikelet pair meristem numbers and then enhanced kernel row numbers. Nucleotide diversity analysis further revealed that ids1/Ts6 and Q were under strong parallel selection in maize and wheat that increased their yields during domestication or improvement. RNA-seq revealed that ids1/Ts6 is involved in multiple pathways regulating spikelet pair meristem development, involving several key genes such as fea3, fea4 and ra3. The cloning of the krn1 gene will pave a new way to efficiently improve maize yield in the near future.

An Efficient Approach to Regio- and Stereodefined Fully-Substituted Alkenylsilanes by Pd-Catalyzed Allenic C(sp3 )-H Oxidation.

A highly efficient palladium-catalyzed functionalization of allenylsilanes to give regio- and stereodefined fully-substituted alkenylsilanes has been developed. This oxidative coupling reaction showed good functional group compatibility with exclusive regio- and stereoselectivity. The pending olefin on the silyl group was shown to be an indispensable element for the initial allenic C(sp3 )-H bond cleavage, and performs as the directing group to control the overall selectivity. The addition of substoichiometric amounts of Et3 N was found to increase the reaction rate leading to a higher reaction yield. The reaction can be easily scaled up and applied for the late-stage functionalization of natural products and pharmaceutical compounds, including amino acids and steroid derivatives. The newly introduced functional groups include aryl, alkynyl, and boryl groups. The highly strained four-membered ring, silacyclobutene was obtained when B2 pin2 was employed as the coupling partner. Mechanistic studies, including kinetic isotope effects, showed that the allenic C(sp3 )-H bond cleavage is the rate-limiting step.

Identification of a candidate gene underlying qKRN5b for kernel row number in Zea mays L.

KEY MESSAGE: A quantitative trait locus for kernel row number, qKRN5, was dissected into two tightly linked loci, qKRN5a and qKRN5b. Fine mapping, comparative analysis of nucleotide sequences and gene expression established the endonuclease/exonuclease/phosphatase family protein-encoding gene Zm00001d013603 as a causal gene of qKRN5b. Maize grain yield is determined by agronomically important traits that are controlled by interactions among and between genes and environmental factors. Considerable efforts have been made to identify major quantitative trait loci (QTLs) for yield-related traits; however, few were previously isolated and characterized in maize. In this study, we divided a QTL for kernel row number (KRN), qKRN5, into two tightly linked loci, qKRN5a and qKRN5b, using advanced backcross populations derived from near-isogenic lines. KRN was greater in individuals that were homozygous for the NX531 allele, which showed coupling-phase linkage. The major QTL qKRN5b had an additive effect of approximately one kernel row. Furthermore, fine mapping narrowed qKRN5b within a 147.2-kb region. The upstream sequence Zm00001d013603 and its expression in the ear inflorescence showed obvious differences between qKRN5b near-isogenic lines. In situ hybridization located Zm00001d013603 on the primordia of the spikelet pair meristems and spikelet meristems, but not in the inflorescence meristem, which indicates a role in regulating the initiation of reproductive axillary meristems of ear inflorescences. Expression analysis and nucleotide sequence alignment revealed that Zm00001d013603, which encodes an endonuclease/exonuclease/phosphatase family protein that hydrolyzes phosphatidyl inositol diphosphates, is the causal gene of qKRN5b. These results provide insight into the genetic basis of KRN and have potential value for enhancing maize grain yield.