Enhancing photosynthetic efficiency is a major goal for improving crop yields under agricultural field conditions and is associated with chloroplast biosynthesis and development.  In this study, we demonstrate that Golden2-like 1a (BnGLK1a) plays an important role in regulating chloroplast development and photosynthetic efficiency.  Overexpressing BnGLK1a resulted in significant increases in chlorophyll content, the number of thylakoid membrane layers and photosynthetic efficiency in Brassica napus, while knocking down BnGLK1a transcript levels through RNA interference (RNAi) had the opposite effects.  A yeast two-hybrid screen revealed that BnGLK1a interacts with the abscisic acid receptor PYRABACTIN RESISTANCE 1-LIKE 1–2 (BnPYL1–2) and CONSTITUTIVE PHOTOMORPHOGENIC 9 SIGNALOSOME 5A subunit (BnCSN5A), which play essential roles in regulating chloroplast development and photosynthesis.  Consistent with this, BnGLK1a-RNAi lines of B. napus display hypersensitivity to the abscisic acid (ABA) response.  Importantly, overexpression of BnGLK1a resulted in a 10% increase in thousand-seed weight, whereas seeds from BnGLK1a-RNAi lines were 16% lighter than wild type.  We propose that BnGLK1a could be a potential target in breeding for improving rapeseed productivity.  Our results not only provide insights into the mechanisms of BnGLK1a function, but also offer a potential approach for improving the productivity of Brassica species.

Identification of the S genotype of Malus plants will greatly promote the discovery of new genes, the cultivation and production of apple, the breeding of new varieties, and the origin and evolution of self-incompatibility in Malus plants.  In this experiment, 88 Malus germplasm resources, such as Aihuahong, Xishuhaitang, and Reguanzi, were used as materials.  Seven gene-specific primer combinations were used in the genotype identification.  PCR amplification using leaf DNA produced a single S-RNase gene fragment in all materials.  The results revealed that 70 of the identified materials obtained a complete S-RNase genotype, while only one S-RNase gene was found in 18 of them.  Through homology comparison and analysis, 13 S-RNase genotypes were obtained: S₁S₂ (Aihuahong, etc.), S₁S₂₈ (Xixian Haitang, etc.), S₁S₅₁ (Hebei Pingdinghaitang), S₁S₃ (Xiangyangcun Daguo, etc.), S₂S₃ (Zhaiyehaitang, etc.), S₃S₅₁ (Xishan 1), S₃S₂₈ (Huangselihaerde, etc.), S₂S₂₈ (Honghaitang, etc.), S₄S₂₈ (Bo 11), S₇S₂₈ (Jiuquan Shaguo), S₁₀S_e (Dongchengguan 13), S₁₀S₂₁ (Dongxiangjiao) and S_eS₅₁ (Xiongyue Haitang).  Simultaneously, the frequency of the S gene in the tested materials was analyzed.  The findings revealed that different S genes had varying frequencies in Malus resources, as well as varying frequencies between intraspecific and interspecific.  S₃ had the highest frequency of 68.18%, followed by S₁ (42.04%).  In addition, the phylogenetic tree and origin evolution analysis revealed that the S gene differentiation was completed prior to the formation of various apple species, that cultivated species also evolved new S genes, and that the S₅₀ gene is the oldest S allele in Malus plants.  The S₁, S₂₉, and S₃₃ genes in apple-cultivated species, on the other hand, may have originated in M. sieversii, M. hupehensis, and M. kansuensis, respectively.  In addition to M. sieversii, M. kansuensis and M. sikkimensis may have also played a role in the origin and evolution of some Chinese apples.

Rye (Secale cereale L., 2n=2x=14, RR) is a significant genetic resource for improving common wheat because of its resistance to multiple diseases and abiotic-stress tolerant traits.  The 1RS chromosome from the German cultivated rye variety Petkus is critical in wheat breeding.  However, its weakened disease resistance highlights the need to identify new resources.  In the present study, a novel derived line called D27 was developed from common wheat and Mexico Rye.  Cytological observations characterized the karyotype of D27 as 2n=42=21 II.  Genomic in situ hybridization indicated that a pair of whole-arm translocated Mexico Rye chromosomes were inherited typically in the mitotic and meiosis stages of D27.  Experiments using fluorescence in situ hybridization (FISH) and gliadin electrophoresis showed that D27 lacked wheat 1DS chromosomes.  They were replaced by 1RS chromosomes of Mexico Rye, supported by wheat simple-sequence repeat markers, rye sequence characterized amplified region markers, and wheat 40K SNP array analysis.  The wheat 1DS chromosomes could not be detected by molecular markers and wheat SNP array, but the presence of rye 1RS chromosomes was confirmed.  Agronomic trait assessments indicated that D27 had a higher tiller number and enhanced stripe rust and powdery mildew resistance.  In addition, dough properties analysis showed that replacing 1DS led to higher viscosity and lower dough elasticity in D27, which was beneficial for cake making.  In conclusion, the novel cytogenetically stable common wheat–Mexico Rye T1DL·1RS translocation line D27 offers excellent potential as outstanding germplasm in wheat breeding programs focusing on disease resistance and yield improvement.  Additionally, it can be valuable for researching the rye 1RS chromosome’s genetic diversity. 

Psathyrostachys huashanica Keng (2n=2x=14, NsNs) is regarded as a valuable wild relative species for common wheat cultivar improvement because of its abundant beneficial agronomic traits.  However, although the development of many wheat–P. huashanica-derived lines provides a germplasm base for the transfer of excellent traits, the lag in the identification of P. huashanica chromosomes in the wheat background has limited the study of these lines.  In this study, three novel nondenaturing fluorescence in situ hybridization (ND-FISH)-positive oligo probes were developed.  Among them, HS-TZ3 and HS-TZ4 could specifically hybridize with P. huashanica chromosomes, mainly in the telomere area, and HS-CHTZ5 could hybridize with the chromosomal centromere area.  We sequentially constructed a P. huashanica FISH karyotype and idiogram that helped identify the homologous groups of introduced P. huashanica chromosomes.  In detail, 1Ns and 2Ns had opposite signals on the short and long arms, 3Ns, 4Ns, and 7Ns had superposed two-color signals, 5Ns and 6Ns had fluorescent signals only on their short arms, and 7Ns had signals on the intercalary of the long arm.  In addition, we evaluated different ways to identify alien introgression lines by using low-density single nucleotide polymorphism (SNP) arrays and recommended the SNP homozygosity rate in each chromosome as a statistical pattern.  The 15K SNP array is widely applicable for addition, substitution, and translocation lines, and the 40K SNP array is the most accurate for recognizing transposed intervals between wheat and alien chromosomes.  Our research provided convenient methods to distinguish the homologous group of P. huashanica chromosomes in a common wheat background based on ND-FISH and SNP arrays, which is of great significance for efficiently identifying wheat–P. huashanica-derived lines and the further application of Ns chromosomes

The efficacies of biological and conventional chemical insecticides against two major insect pests of alfalfa (aphids and thrips) were compared in three sites across China’s alfalfa belt.  In addition, the persistence of the residues of chemical insecticides in alfalfa and their influence on the quality of alfalfa hay were examined.  Efficacy varied among the different biological and chemical insecticides.  The chemical insecticides were significantly more effective than biopesticides in a short time-frame.  The efficacy period of biopesticides was significantly longer than that of chemical insecticides, and the corrected mortality rate of aphids in all regions was above 50% at 14 days after application.  The analysis of pesticide residues showed that the residual doses of all the pesticides were within the allowed ranges after the safe period.  The acid detergent fiber and neutral detergent fiber contents in alfalfa hay were higher and the protein content was lower in chemical insecticide treatments than in biopesticide treatments in Hebei.  The relative feeding value of alfalfa hay treated with Metarhizium anisopliae IPP330189 was the highest among the treatments.  Compared with chemical insecticides, the yield of alfalfa hay was higher in the biopesticides treatments.  Biopesticides show a stronger control effect on insect populations and also a better improvement in the quality of alfalfa hay than chemical insecticides.  This study provides a basis for exploring and developing a comprehensive control regime for alfalfa insect pests in the different alfalfa-growing regions in China, and for reducing chemical insecticide usage and improving forage quality.

Radopholus similis (Cobb 1893) Thorne (1949) is a destructive migratory endoparasitic plant nematode.  In this study, the pathogenic process of R. similis infection in Nicotiana benthamiana (tobacco) was studied using quartz sand culture in laboratory.  The results showed that R. similis mainly parasitised the root cortex, leading to cortical cell decomposition and tissue decay.  We optimised the inoculation conditions to establish a method for determining the pathogenicity of R. similis as follows: (1) a glass culture tube was filled with quartz sand (about 1/3 of the height) and sterilised twice; (2) 20-day-old N. benthamiana seedlings were transplanted into test tubes and cultivated for 10 days at (25±1)°C; (3) R. similis female nematodes were inoculated in the root rhizosphere at a rate of 150 nematodes per plant; (4) the number of nematodes, disease severity, and growth of the plant at 30 days post-inoculation (dpi) were determined.  The pathogenicity of eight R. similis populations from different hosts was determined, which proved the feasibility of this method.

The gray leaf spot caused by Cercospora zeina has become a serious disease in maize in China.  The isolates of C. zeina from Yunnan, Sichuan, Guizhou, Hubei, Chongqing, Gansu, and Shaanxi were collected.  From those, 127 samples were used for genetic diversity analysis based on inter-simple sequence repeat (ISSR) and 108 samples were used for multi-gene sequence analysis based on five gene fragments.  The results indicated that populations of C. zeina were differentiated with a relatively high genetic level and were classified into two major groups and seven subgroups.  The intra-population genetic differentiation of C. zeina is the leading cause of population variation in China, and inter-population genetic similarity is closely related to the colonization time and spread direction.  The multi-gene sequence analysis of C. zeina isolates demonstrated that there were nine haplotypes.  Genetic diversity and multi-gene sequence revealed that Yunnan population of C. zeina, the earliest colonizing in China, had the highest genetic and haplotype diversity and had experienced an expansion event.  With the influence of the southwest monsoon in the Indian Ocean, C. zeina from Yunnan gradually moved to Sichuan, Guizhou, Shaanxi, Gansu, and Chongqing.  Meanwhile, C. zeina was transferred directly from the Yunnan into the Hubei Province via seed and then came into Shaanxi, Henan, and Chongqing along with the wind from Hubei.

Significant progress has been achieved in the use of heterosis in soybean and several soybean hybrids have been released in China. However, broad use of hybrid soybean seed is limited due to low seed setting of female parents.  Breeding cytoplasmic male sterile (CMS) lines with high out-crossing rate is necessary to solve the problem.  The objective of this study was to determine the relationship between out-crossing rate of CMS lines and their nectar secretion.  The daily nectar secretion rhythm, meteorological effect on nectar secretion, and differences in nectar secretion among genotypes and years were investigated in 27 soybean CMS lines (A-lines) with their maintainers (B-lines) and restorers (R-lines).  The correlation between out-crossing rate of CMS lines and nectar production was also evaluated.  Nectar secretion had diurnal variation.  Secretion initiated at about 06:00 for most materials and reached a peak at 07:00–08:30 after flower opened, then the nectar secretion decreased gradually.  A sub-peak appeared at about 13:00, while the nectar could not be detected at 17:00.  Nectar secretion was greatly influenced by the weather conditions.  The amount of nectar secretion increased gradually over time during periods of high temperature and no rainfall for several days.  Rainy weather and low temperatures inhibited nectar secretion.  There were obvious variations of nectar amount among different genotypes tested.  Significant nectar variation within a genotype among years was also observed, and the highest nectar secretion was 3-fold higher than the lowest.  The amount of nectar secretion from R-lines was significantly higher than that of A- and B-lines.  There was no significant difference in nectar secretion between A- and B-lines.  A- and B-lines with higher out-crossing rates secreted more nectar.  The amount of nectar secretion of A- and B-lines were significantly positively correlated with the out-crossing rate of A-lines.

The aim of this research was to study the influence of chlorsulfuron residue and cadmium on the enzymatic activity and photosynthetic apparatus of maize (Zea mays L.) plants.  Chlorsulfuron and cadmium at 0.001 and 5.0 mg kg^–1, respectively, were mixed and applied to soil prior to planting.  The levels of chlorsulfuron- and cadmium-induced stress to plants were estimated by growth, chlorophyll content, lipid peroxide content, enzyme activities, and major fluorescence parameters of chlorophyll (revealed by the fluorescence imaging system FluorCam).  Chlorsulfuron negatively affected the chlorophyll content, photochemical efficiency of photosystem II in the dark-adapted state, the maximum efficiency of photosystem II, photochemical quenching coefficient, and steady-state fluorescence decline ratio in the leaves of maize seedlings.  However, cadmium did not produce noticeable changes.  Plants that were exposed to both chlorsulfuron and cadmium showed an obvious increase in the steady-state fluorescence decline ratio.  These results implied that the seedlings possessed more resistance to cadmium than to chlorsulfuron and their resistance to chlorsulfuron toxicity was enhanced by the presence of cadmium.  The results also suggested that chlorophyll fluorescence imaging reveals overall alterations within the leaves but may not reflect small-scale effects on tissues, as numeric values of specific parameters are averages of the data collected from the whole leaf.

Soybean mosaic virus (SMV) is one of the major viral pathogens affecting soybean crops worldwide.  Three SMV resistance genes, R_SC4, R_SC8, and R_SC14Q , have been identified and mapped on soybean chromosomes 14, 2, and 13 from Dabaima, Kefeng 1, and Qihuang 1 cultivars, respectively.  Soybean cultivar Nannong 1138-2 is widely grown in the Yangtze River Valley of China.  In this study, crosses were made between Qihuang 1×Kefeng 1 and Dabaima×Nannong 1138-2.  Ten simple sequence repeat (SSR) markers linked to three resistance loci (R_SC4, R_SC8, and R_SC14Q ) were used to assist pyramided breeding.  Pyramided families containing three resistance loci (R_SC4, R_SC8, and R_SC14Q ) were evaluated by inoculating them with 21 SMV strains from China.  Results indicated that the 10 markers can be used effectively to assist the selection of resistant individuals containing R_SC4, R_SC8, and R_SC14Q .  A total of 53 F6 plants were confirmed to contain three homozygous alleles conferring resistance to SMV.  Five F₇ homozygous pyramided families exhibited resistance to 21 strains of SMV and showed desirable agronomic traits using dual selection.  The strategy of pyramiding resistance gene derived from different varieties has practical breeding value in providing broad-spectrum resistance against the existing strains of SMV in China.  

In this study we report the results of a decade-long breeding program for japonica super rice made by Nanjing Branch of Chinese National Center for Rice Improvement in Jiangsu Academy of Agricultural Sciences.  We concluded that selection of parents with good comprehensive traits and complementary advantages and disadvantages of both parents in the hybrid combination, and early selection of high heritability traits in earlier segregating generations could significantly improve the breeding efficiency.  The use of closely-linked functional markers in pyramiding of multiple genes could greatly increase breeding efficiency, avoiding time-consuming and laborious steps that were used in traditional breeding program.  It is also important to coordinate the yield components with variety characteristics such as yield stability, wide adaptability, lodging resistance, and an attractive grain appearance during late growth stage of rice.

Water shortage has threatened sustainable development of agriculture globally as well as in the North China Plain (NCP).  Irrigation, as the most effective way to increase food production in dry land, may not be readily available in the situation of drought.  One of the alternatives is to supply plants with enough nutrients so that they can be more sustainable to the water stress.  The objective of this study was to explore effects of irrigation and sulphur (S) application on water consumption, dry matter accumulation (DMA), and grain yield of winter wheat in NCP.  Three irrigation regimes including no irrigation (rainfed, I₀) during the whole growth period, once irrigation only at jointing stage (90 mm, I₁), and twice respective irrigation at jointing and anthesis stages (90 mm plus 90 mm, I₂), and two levels of S application including 0 (S₀) and 60 kg ha^–1 (S₆₀) were designed in the field experiment in NCP.  Results showed that increasing irrigation times significantly increased mean grain yield of wheat by 12.5–23.7% and nitrogen partial factor productivity (NPFP) by 21.2–45.0% in two wheat seasons, but markedly decreased crop water use efficiency (YWUE).  Furthermore, S supply 60 kg ha^–1 significantly increased mean grain yield, YWUE, IWUE and NPFP by 5.6, 6.1, 23.2, and 5.6% (across two wheat seasons), respectively.  However, we also found that role of soil moisture prior to S application was one of important greater factors on improving the absorption and utilization of storage water and nutrients of soil.  Thus, water supply is still the most important factor to restrict the growth of wheat in the present case of NCP, supplying 60 kg ha^–1 S with once irrigation 90 mm at the jointing stage is a relatively appropriate recommended combination to improve grain yield and WUE of wheat when saving water resources is be considered in irrigated wheat farmlands of NCP.

Extreme meteorological disaster effects on grain production is mainly determined by the interaction between danger degree of hazard-induced factors and vulnerability degree of hazard-affected bodies.  This paper treats physical exposure, sensitivity of the response to the impact, and capabilities of disaster prevention and mitigation as a complex system for vulnerability degree of hazard-affected bodies, which included the external shocks and internal stability mechanism.  Hazard-induced factors generate external shocks on grain production systems though exposure and sensitivity of hazard-affected body, and the result can be represented as affected area of grain.  By quantile regression model, this paper depicts the quantitative relationship between hazard-induced factors of extreme meteorological disaster and the affected area in the tail of the distribution.  Moreover, the model of production function have also been utilized to expound and prove the quantitative relationship between the affected area and final grain output under the internal stability mechanism of the agricultural natural resources endowment, the input factors of agricultural production, and the capacity of defending disaster.  The empirical study of this paper finds that impact effects of drought disaster to grain production system presents the basic law of “diminishing marginal loss”, namely, with the constant improvement of the grade of drought, marginal affected area produced by hazard-induced factors will be diminishing.  Scenario simulation of extreme drought impact shows that by every 1% reduction in summer average rainfall, grain production of Jilin Province will fell 0.2549% and cut production of grain 14.69% eventually.  In response to ensure China’s grain security, the construction of the long-term mechanism of agricultural disaster prevention and mitigation, and the innovation of agricultural risk management tools should be also included in the agricultural policy agenda.

    The small heat shock protein (sHSP) chaperones are required for protecting cellular proteins from damage, as well as refolding denatured proteins. This study was carried out to investigate the temporal-spatial expression patterns of two sHSP genes in rice. These two genes, named as Os16.9A and Os16.9B, are reverse duplicated genes that adjacently located on chromosome 1 and probably share the same or overlapping DNA region as a promoter. The interval sequence between the start codons of the two genes which are transcribed in opposite directions is only about 2.6 kb. Semi-quantitative RT-PCR was carried out to detect the expression of the two genes under normal growth conditions and different stress conditions. The expression patterns of the two genes were in detail investigated by using β-glucuronidase (GUS) reporter gene fusion system. Results showed that heat shock stress can induce high level expression of the two genes. Under normal growth conditions, Os16.9A and Os16.9B expressed in vegetative organs and young panicles. GUS staining combined with cytological observations showed that the two genes expressed mainly in the vascular tissues of roots, stems and young panicles, implicating that Os16.9A and Os16.9B play important roles not only for heat shock response, but also for normal development in rice.

The objective of this study was to verify the supposition that efflux might be involved in the drug resistance of Riemerella anatipestifer isolates. Two broad-spectrum efflux pump inhibitors, carbonyl cyanide 3-chlorophenylhydrazone (CCCP) and Phe-Arg-β-naphthylamide (PAβN), on the contribution of minimum inhibitory concentrations of amikacin, streptomycin, chloramphenicol, tetracycline, ceftriaxone, ceftazidime, nalidixic acid, levofloxacin, enrofloxacin, as well as ciprofloxacin against 69 clinical R. anatipestifer isolates were investigated. We first reported that the two efflux pump inhibitors could restore the antimicrobial susceptibility of R. anatipestifer isolates. It is suggested that active efflux system is possible to be linked with the development of resistance in R. anatipestifer isolates.

Biochar is increasingly proposed as a soil amendment, with reports of benefits to soil physical, chemical and biological properties. In this study, different biochars were produced from 6 feedstocks, including straw and poultry manure, at 3 pyrolysis temperatures (200, 300 and 500°C) and then added separately to a calcareous soil. Their effects on soil properties and maize growth were evaluated in a pot experiment. The biochars derived from crop straw had much higher C but smaller N concentrations than those derived from poultry manure. Carbon concentrations, pH and EC values increased with increasing pyrolysis temperature. Biochar addition resulted in increases in mean maize dry matter of 12.73% and NPK concentrations of 30, 33 and 283%, respectively. Mean soil pH values were increased by 0.45 units. The biochar-amended soils had 44, 55, 254 and 537% more organic C, total N, Olsen-P and available K, respectively, than the control on average. Both feedstocks and pyrolysis temperature determined the characteristics of the biochar. Biochars with high mineral concentrations may act as mineral nutrient supplements.

To evaluate the possible genetic interrelationships between flour components and the sedimentation volume (SD), a doubled haploid (DH) population comprising 168 lines were used to identify the conditional quantitative trait loci (QTLs) for SD in three environments. Ten additive QTLs and 15 pairs of epistatic QTLs were detected for SD through unconditional and conditional QTL mapping. Three major additive QTLs were detected for SD conditioned on the seven quality traits. Two additive QTLs were found to be independent of these traits. Three additive QTLs were suppressed by three of the seven traits because of non-detection in unconditional mapping. Three pairs of epistatic QTLs were completely affected by the seven traits because of detection in unconditional mapping but no-detection in conditional mapping. Twelve pairs of epistatic QTLs were detected in conditional mapping. Our results indicated that conditional mapping could contribute to a better understanding of the interdependence of different and closely correlated traits at the QTL molecular level, especially some minor QTLs were found. The conditional mapping approach provides new insights that will make it possible to avoid the disadvantages of different traits by breeding through molecular design.

Drought caused by extreme climate change has become more severe and unpredictable, causing imperceptible effects on leaf photosynthesis in foxtail millet.  To investigate the damage, we performed light drought (LD) and heavy drought (HD) treatments at both the elongation (Y) and booting stages to obtain a comprehensive understanding of the morphological, anatomical, physiological, transcriptome, and metabolome levels.  Under drought stress, the length and area of leaves decreased, especially during the HD treatment at the booting stage.  The number of mesophyll cells and the area of large vascular bundles were both decreased under LD and HD treatments at the booting stage, as well as with more blurring vascular bundle structure and Kranz anatomy.  However, these numbers decreased but with no significance under Y-LD and Y-HD treatments at the elongation stage.  The net photosynthetic rate, stomatal conductivity, transpiration rate, and intercellular CO₂ concentration significantly decreased at the booting stage.  In addition, the efficiency of electron transfers in photosystem II (PS II) decreased.  Conjunction analyses of the transcriptome and metabolome were utilized to uncover the underlying mechanism at the booting stage.  The results showed that there was no common differentially enriched pathway in the transcriptome and metabolome under LD treatment but thirty-two pathways were enriched in both the transcript and metabolome under HD treatment.  Among these, three pathways arginine, proline metabolism, tyrosine metabolism, ubiquinone, and other terpenoid-quinone biosynthesis pathways were differentially enriched in both the transcript and metabolome.  The accumulation of Homogentisate, Salidroside, Homoprotocatechuate, L-DOPA, Tyramine, and L-Tyrosine increased under drought stress.  Although genes related to PSII and the Calvin cycle were slightly up-regulated under LD conditions, they were down-regulated under HD condition.  The metabolites of Ribose-5P, Glycerate-3P, D-Fructosel 1,6P₂, and D-Fructose-6P were all decreased in both the LD and HD treatments, especially D-Fructose-6P, confirming that drought stress had a negative effect on the Calvin cycle.  The results revealed that regardless of the severity of drought, photosynthetic function was compromised not only at the morphological and anatomical levels but also in terms of impaired ATP synthase and inhibited photosynthetic CO₂ assimilation.