3´,5´-Cyclic adenosine monophosphate (cAMP) is an important metabolite that is specifically enriched in jujube. However, the effect of cAMP on jujube cellular responses has not been comprehensively studied. Here, we established jujube cell suspension cultures and investigated the calcium influx in response to cAMP treatment through protoplast isolation and fluorescence intensity. Firstly, cAMP treatment could promote jujube growth and increase the content of endogenous cAMP. Using transcriptome analysis with transgenic Arabidopsis plants overexpressing adenylate cyclase (ZjAC) as a positive control, we identified 60 calcium-related differential expressed genes (DEGs) that contributed to the calcium signaling and inter- or intra-cellular responses. Pharmacological treatments such as cAMP and the calcium ionophore A23187 could induce ZjAC expression, the accumulation of cAMP and calcium influx in jujube cells, while ethylene glycol tetraacetic acid (EGTA) or bithionol treatment inhibited these changes. Moreover, the calcium channels and transporters in calcium influx, such as the ZjCNGC2 channel and the mitogen activated protein (MAP) kinase pathway, could be activated by cAMP treatment. In summary, our findings demonstrated that cAMP biosynthesis is dependent on calcium influx and the amplifying effect between calcium and cAMP may be involved in intracellular signal induction, which might contribute to the growth and development of jujube.

Sucrose nonfermenting-related protein kinase 1 (SnRK1) is one of the critical serine/threonine protein kinases.  It commonly mediates plant growth and development, cross-talks with metabolism processes and physiological responses to biotic or abiotic stresses.  It plays a key role in distributing carbohydrates and sugar signal transporting.  In the present study, eight SnRK1 coding genes were identified in sorghum (Sorghum bicolor L.) via sequences alignment, with three for α subunits (SnRK1α1 to SnRK1α3), three for β (SnRK1β1 to SnRK1β3), and one for both γ (SnRK1γ) and βγ (SnRK1βγ).  These eight corresponding genes located on five chromosomes (Chr) of Chr1–3, Chr7, and Chr9 and presented collinearities to SnRK1s from maize and rice, exhibiting highly conserved domains within the same subunits from the three kinds of cereals.  Expression results via qRT-PCR showed that different coding genes of SnRK1s in sorghum possessed similar expression patterns except for SnRK1α3 with a low expression level in grains and SnRK1β2 with a relatively high expression level in inflorescences.  Results of subcellular localization in sorghum leaf protoplast showed that SnRK1α1/α2/α3/γ mainly located on organelles, while the rest four of SnRK1β1/β2/β3/βγ located on both membranes and some organelles.  Besides, three combinations were discovered among eight SnRK1 subunits in sorghum through yeast two hybrid, including α1-β2-βγ, α2-β3-γ, and α3-β3-γ.  These results provide informative references for the following functional dissection of SnRK1 subunits in sorghum.

The relationship between the fate of nitrogen (N) fertilizer and the N application rate in paddy fields in Northeast China is unclear, as is the fate of residual N.  To clarify these issues, paddy field and ¹⁵N microplot experiments were carried out in 2017 and 2018, with N applications at five levels: 0, 75, 105, 135 and 165 kg N ha^–1 (N0, N75, N105, N135 and N165, respectively).  ¹⁵N-labeled urea was applied to the microplots in 2017, and the same amount of unlabeled urea was applied in 2018.  Ammonia (NH₃) volatilization, leaching, surface runoff, rice yield, the N contents and ¹⁵N abundances of both plants and soil were analyzed.  The results indicated a linear platform model for rice yield and the application rate of N fertilizer, and the optimal rate was 135 kg N ha^–1.  N uptake increased with an increasing N rate, and the recovery efficiency of applied N (RE_N) values of the difference subtraction method were 45.23 and 56.98% on average in 2017 and 2018, respectively.  The RE_N was the highest at the N rate of 135 kg ha^–1 in 2017 and it was insignificantly affected by the N application rate in 2018, while the agronomic efficiency of applied N (AE_N) and physiological efficiency of applied N (PE_N) decreased significantly when excessive N was applied.  N loss through NH₃ volatilization, leaching and surface runoff was low in the paddy fields in Northeast China.  NH₃ volatilization accounted for 0.81 and 2.99% of the total N application in 2017 and 2018, respectively.  On average, the leaching and surface runoff rates were 4.45% and less than 1.05%, respectively, but the apparent denitrification loss was approximately 42.63%.  The residual N fertilizer in the soil layer (0–40 cm) was 18.37–31.81 kg N ha^–1 in 2017, and the residual rate was 19.28–24.50%.  Residual ¹⁵N from fertilizer in the soil increased significantly with increasing N fertilizer, which was mainly concentrated in the 0–10 cm soil layer, accounting for 58.45–83.54% of the total residual N, and decreased with increasing depth.  While the ratio of residual N in the 0–10 cm soil layer to that in the 0–40 cm soil layer was decreased with increasing N application.  Furthermore, of the residual N, approximately 5.4% was taken up on average in the following season and 50.2% was lost, but 44.4% remained in the soil.  Hence, the amount of applied N fertilizer should be reduced appropriately due to the high residual N in paddy fields in Northeast China.  The appropriate N fertilizer rate in the northern fields in China was determined to be 105–135 kg N ha^–1 in order to achieve a balance between rice yield and high N fertilizer uptake.

Efficient and stable expression of foreign genes in cells and transgenic animals is important for gain-of-function studies and the establishment of bioreactors.  Safe harbor loci in the animal genome enable consistent overexpression of foreign genes, without side effects.  However, relatively few safe harbor loci are available in pigs, a fact which has impeded the development of multi-transgenic pig research.  We report a strategy for efficient transgene knock-in in the endogenous collagen type I alpha 1 chain (COL1A1) gene using the clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) system.  After the knock-in of a 2A peptide-green fluorescence protein (2A-GFP) transgene in the last codon of COL1A1 in multiple porcine cells, including porcine kidney epithelial (PK15), porcine embryonic fibroblast (PEF) and porcine intestinal epithelial (IPI-2I) cells, quantitative PCR (qPCR), Western blotting, RNA-seq and CCK8 assay were performed to assess the safety of COL1A1 locus.  The qPCR results showed that the GFP knock-in had no effect (P=0.29, P=0.66 and P=0.20 for PK15, PEF and IPI-2I cells, respectively) on the mRNA expression of COL1A1 gene.  Similarly, no significant differences (P=0.64, P=0.48 and P=0.80 for PK15, PEF and IPI-2I cells, respectively) were found between the GFP knock-in and wild type cells by Western blotting.  RNA-seq results revealed that the transcriptome of GFP knock-in PEF cells had a significant positive correlation (P<2.2e–16) with that of the wild type cells, indicating that the GFP knock-in did not alter the global expression of endogenous genes.  Furthermore, the CCK8 assay showed that the GFP knock-in events had no adverse effects (P_24h=0.31, P_48h=0.96, P_72h=0.24, P_96h=0.17, and P_120h=0.38) on cell proliferation of PK15 cells.  These results indicate that the COL1A1 locus can be used as a safe harbor for foreign genes knock-in into the pig genome and can be broadly applied to farm animal breeding and biomedical model establishment

In maize, two root epidermis-expressed ammonium transporters ZmAMT1;1a and ZmAMT1;3 play major roles in high-affinity ammonium uptake.  However, the transcriptional regulation of ZmAMT1s in roots for ensuring optimal ammonium acquisition remains largely unknown.  Here, using a split root system we showed that ZmAMT1;1a and ZmAMT1;3 transcript levels were induced by localized ammonium supply to nitrogen-deficient roots.  This enhanced expression of ZmAMT1s correlated with increases in ¹⁵NH₄⁺ influx rates and tissue glutamine concentrations in roots.  When ammonium was supplied together with methionine sulfoximine, an inhibitor of glutamine synthase, ammonium-induced expression of ZmAMT1s disappeared, suggesting that glutamine rather than ammonium itself regulated ZmAMT1s expression.  When glutamine was supplied to nitrogen-deficient roots, expression levels of ZmAMT1s were enhanced, and negative feedback regulation could subsequently occur by supply of glutamine at a high level.  Thus, our results indicated an ammonium-dependent regulation of ZmAMT1s at transcript levels, and a dual role of glutamine was suggested in the regulation of ammonium uptake in maize roots.

Mechanisms controlling phosphorus (P) availability and the roles of microorganisms in the efficient utilization of soil P in the wheat–maize double cropping system are poorly understood.  In the present study, we conducted a pot experiment for four consecutive wheat–maize seasons (2016–2018) using calcareous soils with high (30.36 mg kg^–1) and low (9.78 mg kg^–1) initial Olsen-P content to evaluate the effects of conventional P fertilizer application to both wheat and maize (Pwm) along with a reduced P fertilizer application only to wheat (Pw).  The microbial community structure along with soil P availability parameters and crop yield were determined.  The results showed that the Pw treatment reduces the annual P input by 33.3% without affecting the total yield for at least two consecutive years as compared with the Pwm treatment in the high Olsen-P soil.  Soil water-soluble P concentrations in the Pw treatment were similar to those in the Pwm treatment at the 12-leaf collar stage when maize requires the most P.  Furthermore, the soil P content significantly affected soil microbial communities, especially fungal communities.  Meanwhile, the relative abundances of Proteobacteria and alkaline phosphatase (ALP) activity of Pw were significantly higher (by 11.4 and 13.3%) than those of Pwm in soil with high Olsen-P.  The microfloral contribution to yield was greater than that of soil P content in soil with high Olsen-P.  Relative abundances of Bacillus and Rhizobium were enriched in the Pw treatment compared with the Pwm treatment.  Bacillus showed a significant positive correlation with acid phosphatase (ACP) activity, and Rhizobium displayed significant positive correlations with ACP and ALP in soil with high Olsen-P, which may enhance P availability.  Our findings suggested that the application of P fertilization only to wheat is practical in high P soils to ensure optimal production in the wheat and maize double cropping system and that the soil P availability and microbial community may collaborate to maintain optimal yield in a wheat–maize double cropping system.

Methane (CH₄) emissions from ruminant production are a significant source of anthropogenic greenhouse gas production, but few studies have examined the enteric CH₄ emissions of lactating dairy cows under different feeding regimes in China.  This study aimed to investigate the influence of different dietary neutral detergent fiber/non-fibrous carbohydrate (NDF/NFC) ratios on production performance, nutrient digestibility, and CH₄ emissions for Holstein dairy cows at various stages of lactation. It evaluated the performance of CH₄ prediction equations developed using local dietary and milk production variables compared to previously published prediction equations developed in other production regimes.  For this purpose, 36 lactating cows were assigned to one of three treatments with differing dietary NDF/NFC ratios: low (NDF/NFC=1.19), medium (NDF/NFC=1.54), and high (NDF/NFC=1.68).  A modified acid-insoluble ash method was used to determine nutrient digestibility, while the sulfur hexafluoride technique was used to measure enteric CH₄ emissions.  The results showed that the dry matter (DM) intake of cows at the early, middle, and late stages of lactation decreased significantly (P<0.01) from 20.9 to 15.4 kg d^–1, 15.3 to 11.6 kg d^–1, and 16.4 to 15.0 kg d^–1, respectively, as dietary NDF/NFC ratios increased.  Across all three treatments, DM and gross energy (GE) digestibility values were the highest (P<0.05) for cows at the middle and late lactation stages.  Daily CH₄ emissions increased linearly (P<0.05), from 325.2 to 391.9 kg d^–1, 261.0 to 399.8 kg d^–1, and 241.8 to 390.6 kg d^–1, respectively, as dietary NDF/NFC ratios increased during the early, middle, and late stages of lactation.  CH₄ emissions expressed per unit of metabolic body weight, DM intake, NDF intake, or fat-corrected milk yield increased with increasing dietary NDF/NFC ratios.  In addition, CH₄ emissions expressed per unit of GE intake increased significantly (P<0.05), from 4.87 to 8.12%, 5.16 to 9.25%, and 5.06 to 8.17% respectively, as dietary NDF/NFC ratios increased during the early, middle, and late lactation stages.  The modelling results showed that the equation using DM intake as the single variable yielded a greater R2 than equations using other dietary or milk production variables.  When data obtained from each lactation stage were combined, DM intake remained a better predictor of CH₄ emissions (R²=0.786, P=0.026) than any other variables tested.  Compared to the prediction equations developed herein, previously published equations had a greater root mean square prediction error, reflecting their inability to predict CH₄ emissions for Chinese Holstein dairy cows accurately.  The quantification of CH₄ production by lactating dairy cows under Chinese production systems and the development of associated prediction equations will help  establish regional or national CH₄ inventories and improve mitigation approaches to dairy production.

Cell wall architecture plays a key role in stalk strength and forage digestibility.  Lignin, cellulose, and hemicellulose are the three main components of plant cell walls, and they can impact stalk quality by affecting the structure and strength of the cell wall.  To explore cell wall development during secondary cell wall lignification in maize stalks, conventional and conditional genetic mapping were used to identify the dynamic quantitative trait loci (QTLs) of the cell wall components and digestibility traits during five growth stages after silking.  Acid detergent lignin (ADL), cellulose (CEL), acid detergent fiber (ADF), neutral detergent fiber (NDF), and in vitro dry matter digestibility (IVDMD) were evaluated in a maize recombinant inbred line (RIL) population.  ADL, CEL, ADF, and NDF gradually increased from 10 to 40 days after silking (DAS), and then they decreased.  IVDMD initially decreased until 40 DAS, and then it increased slightly.  Seventy-two QTLs were identified for the five traits, and each accounted for 3.48–24.04% of the phenotypic variation.  Six QTL hotspots were found, and they were localized in the 1.08, 2.04, 2.07, 7.03, 8.05, and 9.03 bins of the maize genome.  Within the interval of the pleiotropic QTL identified in bin 1.08 of the maize genome, six genes associated with cell wall component biosynthesis were identified as potential candidate genes for stalk strength as well as cell wall-related traits.  In addition, 26 conditional QTLs were detected in the five stages for all of the investigated traits.  Twenty-two of the 26 conditional QTLs were found at 30 DAS conditioned using the values of 20 DAS, and at 50 DAS conditioned using the values of 40 DAS.  These results indicated that cell wall-related traits are regulated by many genes, which are specifically expressed at different stages after silking.  Simultaneous improvements in both forage digestibility and lodging resistance could be achieved by pyramiding multiple beneficial QTL alleles identified in this study.

Soybean cyst nematode (SCN) Heterodera glycines is considered as the major constraint to soybean production.  GmSHMT08 at Rhg4 locus on chromosome 08, encoding a serine hydroxylmethyltransferase, is a major gene underlying resistance against H. glycines in Peking-type soybeans.  However, the molecular mechanism underpinning this resistance is less well characterized, and whether GmSHMT08 could interact with proteins in H. glycines remains unclear.  In this study, yeast two-hybrid screening was conducted using GmSHMT08 as a bait protein, and a fragment of a 70-kDa heat shock protein (HgHSP70) was screened from H. glycines that exhibited interaction with GmSHMT08.  This interaction was verified by both GST pull-down and bimolecular fluorescence complementation assays.  Our finding reveals HgHSP70 could be applied as a potential candidate gene for further exploring the mechanism on GmSHMT08-mediated resistance against SCN H. glycines.

Sugar transporters are essential for osmotic process regulation, various signaling pathways and plant growth and development.  Currently, few studies are available on the function of sugar transporters in sorghum (Sorghum bicolor L.).  In this study, we performed a genome-wide survey of sugar transporters in sorghum.  In total, 98 sorghum sugar transporters (SSTs) were identified via BLASTP.  These SSTs were classified into three families based on the phylogenetic and conserved domain analysis, including six sucrose transporters (SUTs), 23 sugars will eventually be exported transporters (SWEETs), and 69 monosaccharide transporters (MSTs).  The sorghum MSTs were further divided into seven subfamilies, including 24 STPs, 23 PLTs, two VGTs, four INTs, three pGlcT/SBG1s, five TMTs, and eight ERDs.  Chromosomal localization of the SST genes showed that they were randomly distributed on 10 chromosomes, and substantial clustering was evident on the specific chromosomes.  Twenty-seven SST genes from the families of SWEET, ERD, STP, and PLT were found to cluster in eight tandem repeat event regions.  In total, 22 SSTs comprising 11 paralogous pairs and accounting for 22.4% of all the genes were located on the duplicated blocks.  The different subfamilies of SST proteins possessed the same conserved domain, but there were some differences in features of the motif and transmembrane helices (TMH).  The publicly-accessible RNA-sequencing data and real-time PCR revealed that the SST genes exhibited distinctive tissue specific patterns.  Functional studies showed that seven SSTs were mainly located on the cell membrane and membrane organelles, and 14 of the SSTs could transport different types of monosaccharides in yeast.  These findings will help us to further elucidate their roles in the sorghum sugar transport and sugar signaling pathways.

Northeast China (NEC) is one of the major maize production areas in China. Agro-climatic resources have obviously changed, which will seriously affect crop growth and development in this region. It is important to investigate the contribution of climate change adaptation measures to the yield and resource use efficiency to improve our understanding of how we can effectively ensure high yield and high efficiency in the future. In this study, we divided the study area into five accumulated temperature zones (ATZs) based on growing degree days (GDD). Based on the meteorological data, maize data (from agro-meteorological stations) and the validated APSIM-Maize Model, we first investigated the spatial distributions and temporal trends of maize potential yield of actual planted cultivars, and revealed the radiation use efficiency (RUE) and heat resource use efficiency (HUE) from 1981 to 2017. Then according to the potential growing seasons and actual growing seasons, we identified the utilization percentages of radiation (P_R) resource and heat resource (P_H) for each ATZ under potential production from 1981 to 2017. Finally, we quantified the contributions of cultivar changings to yield, P_R and P_H of maize. The results showed that during the past 37 years, the estimated mean potential yield of actual planted cultivars was 13 649 kg ha^–1, ranged from 11 205 to 15 257 kg ha^–1, and increased by 140 kg ha^–1 per decade. For potential production, the mean values of RUE and HUE for the actual planted maize cultivars were 1.22 g MJ^–1 and 8.58 kg (°C d)^–1 ha^–1. RUE showed an increasing tendency, while HUE showed a decreasing tendency. The lengths of the potential growing season and actual growing season were 158 and 123 d, and increased by 2 and 1 d per decade. P_R and P_H under potential production were 82 and 86%, respectively and showed a decreasing tendency during the past 37 years. This indicates that actual planted cultivars failed to make full use of climate resources. However, results from the adaptation assessments indicate that, adoption of cultivars with growing season increased by 2–11 d among ATZs caused increase in yield, P_R and P_H of 0.6–1.7%, 1.1–7.6% and 1.5–8.9%, respectively. Therefore, introduction of cultivars with longer growing season can effectively increase the radiation and heat utilization percentages and potential yield.

Auxin regulates cell division and elongation of the primordial cells through its concentration and then shaped the plant architecture.  Cell division and elongation form the internode of soybean and result in different plant heights and lodging resistance.  Yet the mechanisms behind are unclear in soybean.  To elucidate the mechanism of the concentration difference of auxin related to stem development in soybean, samples of apical shoot, elongation zone, and mature zone from the developing stems of soybean seedlings, Charleston, were harvested and measured for auxin concentration distributions and metabolites to identify the common underlying mechanisms responsible for concentration difference of auxin.  Distribution of indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), and methylindole-3-acetic acid (Me-IAA) were determined and auxin concentration distributions were found to have a complex regulation mechanism.  The concentrations of IAA and Me-IAA in apical shoot were significantly different between elongation zone and mature zone resulting in an IAA gradient.  Tryptophan dependent pathway from tryptamine directly to IAA or through indole-3-acetonitrile to IAA and from indole-3-propionic acid (IPA) to IAA were three primary IAA synthesis pathways.  Moreover, some plant metabolites from flavonoid and phenylpropanoid synthesis pathways showed similar or reverse gradient and should involve in auxin homeostasis and concentration difference.  All the data give the first insight in the concentration difference and homeostasis of auxin in soybean seedlings and facilitate a deeper understanding of the molecular mechanism of stem development and growth.  The gathered information also helps to elucidate how plant height is formed in soybean and what strategy should be adopted to regulate the lodging resistance in soybean.

Theileria luwenshuni and Theileria uilenbergi are important tick-borne pathogens and cause substantial losses to the sheep industry in China.  The improvement in detection techniques has allowed the identification of multi-homing parasitism in Theileria parasites.  Herein we evaluated the experimental infectivity of T. luwenshuni and T. uilenbergi in Chinese Kunming mice by screening blood samples of experimentally inoculated mice by microscopic examination (ME) and PCR.  T. luwenshuni infected Chinese Kunming mice and 20 mice inoculated with this parasite were positive by ME and PCR.  In addition, T. uilenbergi infected mice and 20 mice inoculated with this species were positive by ME and PCR.  However, the number of red blood cells and the levels of hemoglobin of 40 infected mice had no obvious changes in the course of infection.  Our results demonstrated the multi-homing parasitism of T. luwenshuni and T. uilenbergi, which were believed to be parasites of sheep and goats.  This study was the first to demonstrate the infection of T. luwenshuni and T. uilenbergi in Kunming mice. 

Cereal cyst nematode (Heterodera avenae, CCN) distributes worldwide and has caused severe damage to cereal crops, and a model host will greatly aid in the study of this nematode.  In this research, we assessed the sensitivity of 25 inbred lines of Brachypodium distachyon to H. avenae from Beijing, China.  All lines of B. distachyon were infested by second-stage juveniles (J2s) of H. avenae from Daxing District of Beijing population, but only 13 inbred lines reproduced 0.2–3 cysts/plant, showing resistance.  The entire root system of the infested B. distachyon appeared smaller and the fibrous roots were shorter and less numerous.  We found that a dose of 1 000 J2s of H. avenae was sufficient for nematode infestation.  We showed that Koz-1 of B. distachyon could reproduce more cysts than TR2A line.  Line Koz-1 also supported the complete life cycles of 5 CCN geographical populations belonging to the Ha1 or Ha3 pathotype group.  Our results suggest that B. distachyon is a host for CCN.

Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is one of the most damaging diseases to wheat in the world.  The cultivation of resistant varieties of wheat is essential for controlling the powdery mildew epidemic.  Wheat landraces are important resources of resistance to many diseases.  Mapping powdery mildew resistance genes from wheat landraces will promote the development of new varieties with disease resistance.  The Chinese wheat landrace Baiyouyantiao possesses characteristic of disease resistance to powdery mildew.  To identify the resistance gene in this landrace, Baiyouyantiao was crossed with the susceptible cultivar Jingshuang 16 and seedlings of parents and F₁, BC₁, F₂, and F_2:3 were tested with Bgt isolate E09.  The genetic results showed that the resistance of Baiyouyantiao to E09 was controlled by a single recessive gene, tentatively designated PmBYYT.  An Illumina wheat 90K single-nucleotide polymorphism (SNP) array was applied to screen polymorphisms between F₂-resistant and F₂-susceptible DNA bulks for identifying the chromosomal location of PmBYYT.  A high percentage of polymorphic SNPs between the resistant and susceptible DNA bulks was found on chromosome 7B, indicating that PmBYYT may be located on this chromosome.  A genetic linkage map of PmBYYT consisting of two simple sequence repeat markers and eight SNP markers was developed.  The two flanking markers were SNP markers W7BL-8 and W7BL-15, with genetic distances of 3 and 2.9 cM, respectively.  The results of this study demonstrated the rapid characterization of a wheat disease resistance gene and SNP marker development using the 90K SNP assay.  The flanking markers of gene PmBYYT will benefit marker-assisted selection (MAS) and map-based cloning in breeding wheat cultivars with powdery mildew resistance.

Powdery mildew, caused by Blumeria graminis f. sp. tritici, is one of the most severe wheat diseases.  Mining powdery mildew resistance genes in wheat cultivars and their appliance in breeding program is a promising way to control this disease.  Genetic analysis revealed that a single dominant resistance gene named PmTm4 originated from Chinese wheat line Tangmai 4 confers resistance to prevailing isolates of B. graminis f. sp. tritici isolate E09.  Detailed comparative genomics analyses helped to develop closely linked markers to PmTm4 and a fine genetic map was constructed using large F₂ population, in which PmTm4 was located into a 0.66-cM genetic interval.  The orthologous subgenome region of PmTm4 in Aegilops tauschii was identified, and two resistance gene analogs (RGA) were characterized from the corresponding sequence scaffolds of Ae. tauschii draft assembly.  The closely linked markers and identified Ae. tauschii orthologs in the mapping interval provide an entry point for chromosome landing and map-based cloning of PmTm4.

Pre-harvest sprouting (PHS) occurs frequently in most of the wheat cultivation area worldwide, which severely reduces yield and end-use quality, resulting in substantial economic loss.  In this study, quantitative trait loci (QTL) for PHS resistance were mapped using an available high-density single nucleotide polymorphism (SNP) and simple sequence repeat (SSR) genetic linkage map developed from a 269 recombinant inbred lines (RILs) population of Yanda 1817×Beinong 6.  Using phenotypic data on two locations (Beijing and Shijiazhuang, China) in two years (2012 and 2013 harvesting seasons), five QTLs, designated as QPhs.cau-3A.1, QPhs.cau-3A.2, QPhs.cau-5B, QPhs.cau-4A, and QPhs.cau-6A, for PHS (GP) were detected by inclusive composite interval mapping (ICIM) (LOD≥2.5).  Two major QTLs, QPhs.cau-3A.2 and QPhs.cau-5B, were mapped on 3AL and 5BS chromosome arms, explaining 6.29–21.65% and 4.36–5.94% of the phenotypic variance, respectively.  Precise mapping and comparative genomic analysis revealed that the TaVp-1A flanking region on 3AL is responsible for QPhs.cau-3A.2.  SNP markers flanking QPhs.cau-3A.2 genomic region were developed and could be used for introgression of PHS tolerance into high yielding wheat varieties through marker-assisted selection (MAS).

Understanding the sequence diversity of rice blast resistance genes is important for breeding new resistant rice cultivars against the rice blast fungus Magnaporthe oryzae. In this study, we selected 24 rice cultivars with different genetic backgrounds to study the allelic diversity of rice blast resistance genes Piz-t, Pita and Pik. For Piz-t, a total of 17 allelic types were found within the 24 cultivars. Blast inoculations showed that most of the mutations can affect the function of the resistance gene. For Pita, except for the difference at the 918th amino acid, a majority of the 21 mutations were detected among the cultivars. Inoculations with blast isolates carrying Avr-Pita revealed that cultivars with mutations in other sites except for the 918th amino acid did not affect the function of the Pita gene. For Pik, a total of six allelic types were found within the 24 cultivars, but five of them lost the function of the resistance gene. In addition, we found that Piz-t, Pita and Pik were expressed constitutively in the 24 rice cultivars and the expression level was not related to resistance. Our results have provided the sequence diversity information of the resistance genes Piz-t, Pita and Pik among the popular rice cultivars grown in the northeast region of China.

    Studying the changes in nutrient use strategies induced by grazing can provide insight into the process of grassland degradation and is important for improving grassland quality and enhancing ecosystem function. Dominant species in meadow steppe can optimize their use of limiting resources; however, the regulation of nutrient use strategies across grazing gradients is not fully understood. Therefore, in this study, we report an in situ study in which the impact of grazing rates on nutrient use strategies of Leymus chinensis, the dominant plant species in eastern Eurasian temperate steppes, was investigated. We conducted a large randomized controlled experiment (conducted continuously for five years in grassland plots in a natural pasture in Hailar, eastern Mongolia Plateau, China) to assess the effects of grazing rate treatments (0.00, 0.23, 0.34, 0.46, 0.69, and 0.92 adult cattle unit (AU) ha^–1) on L. chinensis along a grazing gradient and employed a random sampling approach to compare the accumulation, allocation, and stoichiometry of C, N, and P in leaves and stems. Our findings demonstrated the follows: (i) The height of L. chinensis decreased with an increase in the grazing gradient, and the concentrations of C, N, and P significantly increased; (ii) the accumulation of C, N, and P per individual was negatively correlated with the concentration of aboveground tissues, suggesting that there was a tradeoff in L. chinensis between nutrient accumulation and concentration at the individual scale; (iii) the leaf-to-stem ratio of C, N, and P accumulation increased with grazing intensity, indicating a tradeoff in nutrient allocation and plant size at the individual plant level; and (iv) grazing rates were negatively correlated with the ratios of C:N and C:P in the stem; however, these ratios in leaves significantly increased with grazing intensity. Our findings suggest that L. chinensis in meadow steppe adapts to grazing disturbance through tradeoffs between plant size and nutrient use strategies. Moreover, our results imply that grazing produces a compensatory effect on nutrient use efficiency between the stems and leaves of L. chinensis.

Powdery mildew, caused by Blumeria graminis f. sp. tritici, is one of the most devastating wheat diseases. Wild emmer wheat (Triticum turgidum ssp. dicoccoides) is a promising source of disease resistance for wheat. A powdery mildew resistance gene conferring resistance to B. graminis f. sp. tritici isolate E09, originating from wild emmer wheat, has been transferred into the hexaploid wheat line WE4 through crossing and backcrossing. Genetic analyses indicated that the powdery mildew resistance was controlled by a single dominant gene, temporarily designated MlWE4. By mean of comparative genomics and bulked segregant analysis, a genetic linkage map of MlWE4 was constructed, and MlWE4 was mapped on the distal region of chromosome arm 5BL. Comparative genetic linkage maps showed that genes MlWE4, Pm36 and Ml3D232 were co-segregated with markers XBD37670 and XBD37680, indicating they are likely the same gene or alleles in the same locus. The co-segregated markers provide a starting point for chromosome landing and map-based cloning of MlWE4, Pm36 and Ml3D232.

Based on climate data from 254 meteorological stations, this study estimated the effects of climate change on rice planting boundaries and potential yields in the southern China during 1951-2010. The results indicated a significant northward shift and westward expansion of northern boundaries for rice planting in the southern China. Compared with the period of 1951-1980, the average temperature during rice growing season in the period of 1981-2010 increased by 0.4°C, and the northern planting boundaries for single rice cropping system (SRCS), early triple cropping rice system (ETCRS), medium triple cropping rice system (MTCRS), and late triple cropping rice system (LTCRS) moved northward by 10, 30, 52 and 66 km, respectively. In addition, compared with the period of 1951-1980, the suitable planting area for SRCS was reduced by 11% during the period of 1981-2010. However, the suitable planting areas for other rice cropping systems increased, with the increasing amplitude of 3, 8, and 10% for ETCRS, MTCRS and LTCRS, respectively. In general, the light and temperature potential productivity of rice decreased by 2.5%. Without considering the change of rice cultivars, the northern planting boundaries for different rice cropping systems showed a northward shift tendency. Climate change resulted in decrease of per unit area yield for SRCS and the annual average yields of ETCRS and LTCRS. Nevertheless, the overall rice production in the entire research area showed a decreasing trend even with the increasing trend of annual average yield for MTCRS.

Stalk related traits, comprising plant height (PH), ear height (EH), internode number (IN), average internode length (AIL), stalk diameter (SD), and ear height coefficient (EHC), are significantly correlated with yield, density tolerance, and lodging resistance in maize. To investigate the genetic basis for stalk related traits, a doubled haploid (DH) population derived from a cross between NX531 and NX110 were evauluated under two densities over 2 yr. The additive quantitative trait loci (QTLs), epistatic QTLs were detected using inclusive composite interval mapping and QTL-by-environment interaction were detected using mixed linear model. Differences between the two densities were significant for the six traits in the DH population. A linkage map that covered 1 721.19 cM with an average interval of 10.50 cM was constructed with 164 simple sequence repeat (SSR). Two, two, seven, six, two, and eight additive QTLs for PH, IN, AIL, EH, SD, and EHC, respectively. The extend of their contribution to penotypic variation ranged from 10.10 to 31.93%. Seven QTLs were indentified simultaneously under both densities. One pair, two pairs and one pair of epistatic effects were detected for AIL, SD and EHC, respectively. No epistatic effects were detected for PH, EH, and IN. Nineteen QTLs with environment interactions were detected and their contribution to phenotypic variation ranged from 0.43 to 1.89%. Some QTLs were stably detected under different environments or genetic backgrounds comparing with previous studies. These QTLs could be useful for genetic improvement of stalk related traits in maize breeding.

Agricultural production plays an important role in affecting atmospheric nitrous oxide (N2O) concentrations. Field measurements were conducted in Dalian City, Liaoning Province in Northeast China from two consecutive years (2009 and 2010) to estimate N2O emissions from a spring maize field, a main cropping system across the Chinese agricultural regions. The observed flux data in conjunction with the local climate, soil and management information were utilized to test a process-based model, DeNitrification-DeComposition (DNDC), for its applicability for the cropping system. The validated DNDC was then used for exploring strategies to reduce N2O emissions from the target field. The results showed that the major N2O pulse emissions occurred with duration of about 3-5 d after fertilizer application in both years 2009 and 2010, which on average accounted for about 60% of the total N2O emissions each year. Rainfall and fertilizer application were the major factors influencing the N2O emissions from spring maize field. The average N2O fluxes from the CK (control plot, without fertilization) and FP (traditional chemical N fertilizer) treatments were 23.1 and 60.6 μg m-2 h-1 in 2009, respectively, and 21.5 and 64.3 μg m-2 h-1 in 2010, respectively. The emission factors (EFs) of the applied N fertilizer (270 kg N ha-1) as N2ON were 0.62% in 2009 and 0.77% in 2010, respectively. The comparison of modeled daily N2O emission fluxes against observations indicated that the DNDC model had a good performance even if without adjusting the internal parameters. The modeled results showed that management practices such as no-till, changing timing or rate of fertilizer application, increasing residue incorporation, and other technically applicable measures could effectively reduce N2O emissions from the tested fields. Our study indicated that avoiding application of N fertilizers at heavy rainfall events or splitting the fertilizer into more applications would be the most feasible approaches to reduce N2O emissions from spring maize production in Northeast China.

Modification of unsaturated fatty acid (FA) levels has been found to accompany multiple abiotic stress acclimations in many plants. Delta 12 fatty acid desaturase (FAD2) plays a critical role in the synthesis of polyunsaturated FAs in plant cells by converting oleic acid (18:1) to linoleic acid (18:2). To better understand the relationship between polyunsaturated FAs metabolism and stress adaptation, the expression of FAD2 gene and changes in the FA compositions under various abiotic stresses and phytohormone treatments in Arabidopsis thaliana was investigated in this study. A 1 423-bp promoter of the FAD2 gene was cloned and characterized from Arabidopsis. Several putative hormone- and stressinducible cis-elements were identified in the cloned promoter, which include salt- and pathogen-inducible GT-1 motifs, low-temperature-responsive MYC element, dehydration-responsive MYB element, and GA signaling related WRKY71OS element. To investigate the fine regulation of FAD2 gene, a recombinant FAD2 promoter-GUS construct was introduced into Arabidopsis plants. Histochemical study showed that the promoter was ubiquitously active and responsive not only to exogenous phytohormones including ABA, 24-eBL, and SA but also to darkness, temperature, salt, and sucrose stresses in Arabidopsis seedlings. Consistent with the expression change, treatments with exogenous 24-eBL, ABA, SA, and NaCl resulted in reduction in polyunsaturated FAs in Arabidopsis seedlings. These findings suggest that the FAD2 gene with a wide variety of putative response elements in its promoter is responsive to multiple phytohormones and abiotic stresses and therefore may play an important role in stress responses of Arabidopsis during plant growth and seed development.