Gossypium raimondii (2n=2x=26, D₅), an untapped wild species, is the putative progenitor of the D-subgenome of G. hirsutum (2n=4x=52, AD₁), an extensively cultivated species.  Here, we developed a G. hirsutum (recipient)–G. raimondii (donor) introgression population to exploit the favorable QTLs/genes and mapped potential quantitative trait loci (QTLs) from wild cotton species.  The introgression population consisted of 256 lines with an introgression rate of 52.33% for the G. raimondii genome.  The introgression segment length range was 0.03–19.12 Mb, with an average of 1.22 Mb.  The coverage of total introgression fragments from G. raimondii was 386.98 Mb.  Further genome-wide association analysis (Q+K+MLM) and QTL mapping (RSTEP-LRT) identified 59 common QTLs, including 14 stable QTLs and six common QTL (co-QTL) clusters, and one hotspot of micronaire (MIC).  The common QTLs for seed index all showed positive additive effects, while the common QTLs for boll weight all had negative additive effects, indicating that the linkage between seed index and boll weight could be broken.  QTLs for lint percentage showed positive effects and could be beneficial for improving cotton yield.  Most QTLs for fiber quality had negative additive effects, implying these QTLs were domesticated/improved in G. hirsutum.  A few fiber quality QTLs showed positive additive effects, so they could be used to improve cotton fiber quality.  The introgression lines developed could be useful for molecular marker-assisted breeding and mapping QTLs precisely for mining desirable genes from the wild species G. raimondii.  Such genes can improve cultivated cotton in the future through a design-breeding approach. 

Photosynthesis is the basis of crop growth and is sensitive to stress.  Smut (Sporisorium destruens) is the primary disease in the production of broomcorn millet (Panicum miliaceum L.).  This study evaluated the effects of infection with S. destruens on the photosynthesis of the resistant cultivar (BM) and susceptible cultivar (NF).  After inoculation, there was a decrease in the chlorophyll content, gas exchange parameters, and chlorophyll fluorescence of the two cultivars.  Observation of the ultrastructure of diseased leaves showed that the chloroplasts and mitochondria had abnormal morphology, and some vacuoles appeared.  RNA-seq was performed on the flag leaves after inoculation.  In addition to the resistant and susceptible cultivars, the diseased leaves developed from inflorescences were defined as S2.  The analysis showed that the pathways related to photosynthesis stimulated some differentially expressed genes (DEGs) after infection with S. destruens.  More DEGs were induced in the susceptible broomcorn millet NF than in the resistant broomcorn millet BM, and most of those genes were downregulated.  The number of DEGs induced by S2 was greater than that in susceptible cultivar NF, and most of them were upregulated.  These results indicate that infection with S. destruens affects the normal photosynthetic performance of broomcorn millet.  Understanding the mechanism between S. destruens, photosynthesis, and broomcorn millet is an effective measure to prevent the occurrence of smut and enhance its resistance. 

Plastic film mulch in agricultural production becomes essential to maintaining crop yields in arid and semiarid areas. However, the presence of residual film in farmland soil has also drawn much attention. In this study, three experiments were conducted. The first two experimental designs included 0, 450, 1 350, and 2 700 kg ha–1 of residual film pieces of approximately 5 cm side length added to field soil (0–20 cm soil depth) for seven years and added to pots for four years. In the third experiment, 1 350 kg ha^–1 of the residual film with different side lengths (2–5, 5–10, 10–15, and 15–20 cm) was added to field soil for six years to explore the effect of residual film fragment size on soil nutrients, soil microorganisms, crop growth and yields. The residual film had little effect on the soil moisture at a field depth of 0–2 (or 0–1.8) m. There were no significant effects on organic carbon, total nitrogen, inorganic nitrogen, total phosphorus or available phosphorus in the 0–20 cm soil layer. The presence of residual film decreased the richness and diversity of the bacterial community of the surface soil of the residual film, but it had no significant effect on the microbial community of the non-surface soil. The emergence rates of wheat and lentils occasionally decreased significantly with different amounts of residue fragments added to the field. At 450–2 700 kg ha^–1, the residual film reduced the plant height and stem diameter of maize and significantly reduced the shoot biomass of harvested maize by 11–19%. The average yields of maize and potato over the seven years decreased, but there were almost no significant statistical differences among the treatments. These results provide important data for a comprehensive scientific understanding of the effects of residual film on soil and crops in dryland farming systems.

Laboratory mutants of Sclerotinia sclerotiorum (Lib) de Bary, resistant to boscalid, have been extensively characterized.  However, the resistance situation in the lettuce field remains largely elusive.  In this study, among the 172 S. sclerotiorum isolates collected from asparagus lettuce field in Jiangsu Province, China, 132 isolates (76.74%) exhibited low-level resistance to boscalid (Bos^LR), with a discriminatory dose of 5 μg mL^–1.  In comparison to the boscalid-sensitive (Bos^S) isolates, most Bos^LR isolates demonstrated a slightly superior biological fitness, as evidenced by data on mycelial growth, sclerotium production and pathogenicity.  Moreover, most Bos^LR isolates showed comparable levels of oxalic acid (OA) accumulation, increased exopolysaccharide (EPS) content and reduced membrane permeability when compared to the Bos^S isolates.  Nevertheless, their responses to distinct stress factors diverged significantly.  Furthermore, the effectiveness of boscalid in controlling Bos^LR isolates on radish was diminished compared to its efficacy on Bos^S isolates.  Genetic mutations were identified in the SDH genes of Bos^LR isolates, revealing the existence of three resistant genotypes: I (A11V at SDHB, SDHB^A11V), II (Q38R at SDHC, SDHC^Q38R) and III (SDHB^A11V+SDHC^Q38R).  Importantly, no cross-resistance was observed between boscalid and other fungicides such as thifluzamide, pydiflumetofen, fluazinam, or tebuconazole.  Our molecular docking analysis indicated that the docking total score (DTS) of the type I resistant isolates (1.3993) was lower than that of the sensitive isolates (1.7499), implying a reduced affinity between SDHB and boscalid as a potential mechanism underlying the boscalid resistance in S. sclerotiorum.  These findings contribute to an enhanced comprehension of boscalid’s mode of action and furnish valuable insights into the management of boscalid resistance.

The ecological systems services or multi-functionality of paddy rice cultivation are critical to the functioning of the Earth’s life-support system.  We estimated the ecosystem services value (ESV) of paddy rice during 1980–2014 across China.  The results indicated that the ESV of the paddy field in China showed an upward trend during this period.  The share of ESV on CO2 sequestration was the highest, followed by ESV on temperature cooling and greenhouse gas (GHG) emission.  The yield-scaled ESVs of Zones II (southern rice–upland crops rotation regions) and III (southern double rice production regions) were similar and significantly higher than the ESVs of Zones I (northeastern single rice production regions) and IV (Southwest rice–upland crops rotation regions).  Between 1980 and 2014, the ESV of each region increased to varying degrees, except for the ESVs of Guangxi, Zhejiang, Fujian, and Guangdong.  Such effects suggest the existence of a significant spatial–temporal variation in the total amount, structure, and density of ESV of paddy fields in China, which can further guide the development of future options for the adaptation of healthy rice production in China.

(E)-β-Caryophyllene is a sesquiterpene compound widely distributed in plants and functions in plant defence.  However, little is known about the sequence and function of (E)-β-caryophyllene synthase in lima bean (Phaseolus lunatus).  Here, we report a new full-length cDNA (PlCAHS) encoding (E)-β-caryophyllene synthase, a possible key enzyme of plant defence.  The cDNA of PlCAHS contains an open reading frame of 1 761 bp, encoding a protein of 586 amino acids with a predicted mass of 67.95 kDa.  The deduced amino acid sequence shows 52% identity with sesquiterpene synthase MtCAHS of Medicago truncatula.  Based on phylogenetic analysis, PlCAHS is classified as the terpene synthases (TPS)-a subfamily.  The recombinant enzyme, expressed in Escherichia coli, catalysed the formation of a major product (E)-β-caryophyllene (82%) and a minor product α-humulene (18%) from farnesyl diphosphate.  Real-time quantitative PCR (qRT-PCR) analysis found that the PlCAHS transcript was significantly up-regulated in leaves after treatment with spider mites and alamethicin (ALA), suggesting its ecological function in plant defence.  

The ecosystem services value (ESV) of rice system has received increasing attention in agricultural policy decision. Over the last three decades, China’s rice production presented an obviously trend that moving towards north locations. However, the impacts of this migration on the ESV of rice production have not been well documented. In this paper, we analyzed the change of the ESV of rice production in China under “north migration” and “no migration” scenarios during 1980–2014 based on long-term historical data. The results showed that both the positive and negative ESVs of rice production were lower under “north migration” than under “no migration” scenarios. The total ESV during 1980–2014 was reduced by 15.8%. “North migration” significantly reduced the area-scaled ESV since the early 1990s; while its impact on yield-scaled ESV was not significant. The effects of “north migration” on ESV showed great spatial variation. The greatest reduction in total and area-scaled ESV was observed in south locations. While the yield-scaled ESVs of most south locations were enhanced under “north migration” scenario. These results indicated that “north migration” has generated adverse effects on the ESV of rice production. An adjustment in the spatial distribution is essential to protecting the non-production benefits of rice ecosystem.

English grain aphid (EGA) is a destructive insect pest of wheat. To identify the loci associated with EGA resistance and tolerance, 70 bread wheat accessions mainly from central Asia were evaluated for EGA resistance and tolerance traits at two locations, and genotyped with 51 SSR markers. Totally, three accessions showed high or moderate levels resistance and 17 genotypes displayed highly or moderately tolerate to EGA. Genetic diversity of these lines was investigated also. After 97 SSR loci which evenly covered all wheat chromosomes were scanned for association, four SSR loci were significantly associated with EGA resistance and four with EGA tolerance. After association analysis was conducted with dynamic aphid densities, we found four loci Xgwm192b, Xgwm391, Xbarc98, and Xgwm613b were detected continuously at different growing stages of wheat. In addition, the loci of EGA resistance/tolerance and Russian wheat aphid resistance were compared. The results generated in this study would be helpful for utilization of the EGA resistance/tolerance germplasm, and for development of mapping populations in EGA resistance breeding programs.

Two pot experiments were conducted to study the effects of root pruning at the stem elongation stage on non-hydraulic root-sourced signals (nHRS), drought tolerance and water use efficiency of winter wheat (Triticum aestivum). The root pruning significantly reduced the root weight of wheat, but had no effect on root/shoot ratio at the two tested stages. At booting stage, specific root respiration of root pruned plants was significantly higher than those with intact roots (1.06 and 0.94 mmol g-1 s-1, respectively). The soil water content (SWC) at which nHRS for root pruned plants appeared was higher and terminated lower than for intact root plants, the threshold range of nHRS was markedly greater for root pruned plants (61.1-44.6% field water capacity) than for intact root plants (57.9-46.1% field water capacity). At flowering stage, while there was no significant difference in specific root respiration. The SWCs at which nHRS appeared and terminated were both higher for root pruned plants than for intact root plants. The values of chlorophyll fluorescence parameters, i.e., the effective photosystem II quantum yield ( PS II), the maximum photochemical efficiency of PS II (Fv/Fm), coefficient of photochemical quenching (qP), and coefficient of non-photochemical quenching (NPQ), in root pruned plants were significantly higher than in intact root plants, 7 d after withholding of water. Root pruned plants had significantly higher water use efficiency (WUE) than intact root plants in well-watered and medium drought soil, but not in severe drought condition. In addition, root pruning had no significant effect on grain yield in well-watered and medium drought soil, but significantly decreased grain yield in severe drought condition. In conclusion, the current study showed that root pruning significantly altered nHRS sensitivity and improved WUE of winter wheat in well-watered and medium drought soil, but lowered drought tolerance of winter wheat in severe drought soil. This suggests a possible direction of droughtresistance breeding and potential agricultural measure to improve WUE of winter wheat under semiarid conditions.

The effects of cadmium stress on the growth, antioxidative enzymes and lipid peroxidation in two kenaf plants, Fuhong 991 and ZM412, were analysed under control (0.5-strength Hoagland’s nutrient solution) or five levels of cadmium stress (0.5- strength Hoagland’s nutrient solution containing different concentrations of Cd2+). The leaves and roots of control and cadmium-stressed plants were harvested after 3 wk. At the same Cd concentration, the Cd tolerance index of Fuhong 991 was higher than that of ZM412, indicating that Fuhong 991 may be more tolerant to Cd than ZM412. The superoxide dismutase (SOD), catalase activity (CAT) and peroxidase (POD) activities fluctuated in the leaves of the Cd-stressed plants compared to the control, whereas the glutathione reductase activity (GR) was much larger than the control for Fuhong 991, ensuring that sufficient quantities of GSH were available to respond to the cadmium stress. In comparison to the control, the dynamic tendency of the SOD, CAT and POD activities in roots of the Cd-stressed plants all increased and then declined, but the POD activity of Fuhong 991 remained nearly unchanged at all of the stress levels. The increase in the enzyme activities demonstrated that Fuhong 991 was more tolerant to cadmium than ZM 412. The lipid peroxidation was enhanced only in the leaves of Cd-stressed ZM 412. These findings indicated that antioxidative activities may play important roles in Cd-stressed Fuhong 991 and ZM 412 and that the leaf and root cell membranes of Fuhong 991 have a greater stability than those of ZM 412. For pollution monitoring purposes, the GR activity in the roots and leaves may serve as a biomarker of Cd for Fuhong 991, whereas lipid peroxidation may serve as biomarker for ZM 412.

Cuscuta campestris, a dodder, can parasitize and suppress a scrambling herbaceous to semi-woody perennial vine, Mikania micrantha, one of the most destructive weeds in the world. To assess the effects of the mixed residue of C. campestris and M. micrantha on the subsequent plant community, we conducted a one-year experiment on the germination and seedling growth of subsequent plant community after the application of C. campestris. Seven treatments of varying proportions of C. campestris and M. micrantha residue on 21 subject trees and shrubs, which were commonly found in South China, resulted in a germination rate of 35.3% for all 8715 seeds from 18 species, ranging from 5.7 to 81.9%; the remaining 3 species failed to germinate. ANOVA analysis showed that the residue did not affect the germination, growth, or mortality of the trees and shrubs. The germinated C. campestris seeds from the residue coiled the seedlings of most of the species, but less than 4% host death caused by C. campestris. In addition, the residue did not affect the germination of the herbaceous seedlings originating from the loam, and the similarity coefficients of the germinated seedlings between the treatments were very high. These results suggested that the residue had no negative impact on the germination and early seedling stages of the tree, shrub and grass species of the subsequent plant community. The use of C. campestris residue had a positive effect on the growth of M. micrantha, but it did not change the trend of M. micrantha being suppressed because re-parasitization occurred soon after the growth restarted. No negative effect was detected on the other species as a result of the parasitization of C. campestris or by the use of the mixed residue. This suggests that C. campestris is likely to be an effective and promising ecologically safe native herbaceous agent for controlling M. micrantha.

Nitrogen fertilizer is an important agronomic measure that greatly affects crop yield and grain quality.  This two-year study aimed to explore the effects of four nitrogen levels on the morphology, lamellar and crystalline structure, pasting, and rheological properties of proso millet (PM) starch, and to investigate potential food applications of PM.  The results showed that the starch surface became uneven and the structure of the starch granules shifted towards greater complexity with increasing nitrogen level.  Nitrogen increased the relative crystallinity, ordered structure, and average repeat distance, leading to a stable starch structure and contributing to a higher gelatinization enthalpy.  Furthermore, nitrogen significantly increased peak, breakdown, setback, and final viscosities but decreased apparent amylose content, which caused the shear resistance and storage capacity of PM starch-based foods to deteriorate during processing and transport.  Rheological analysis showed that PM starch exhibited the typical characteristics of a pseudoplastic fluid.  Under nitrogen treatment, PM starch gels showed high potential for application in 3D printing products due to a high resistance to shear thinning, gel strength, and yield stress, presumably owing to the significantly higher G′ than G′′, and the lower amylose content, which in turn promoted the formation of a stable network structure in water to immobilize more water.  Our study provides a reference for the application of PM starch in the food industry and for the development of PM cropping-management programs to improve quality.

Pathogens secrete multiple enzymes that can degrade the cell wall, thereby weakening the host's cell wall and facilitating the penetration of the pathogen into the plant. In this study, we identified VdGH7a, a glycoside hydrolase family 7 (GH7) cellobiohydrolase from Verticillium dahliae, which exhibited hydrolytic activity against 1,4-β-glucan. Interestingly, we found that VdGH7a induced cell death in Nicotiana benthamiana when signal peptides were present. However, this phenomenon was effectively prevented by the carbohydrate-binding type-1 (CBM1) protein domain. Furthermore, we observed that the knockout of VdGH7a significantly reduced the pathogenicity of V. dahliae to cotton plant, as evidenced by the inability of the knockout mutants to penetrate cellophane membrane. Additionally, these knockout mutants displayed diminished ability to exploit carbon sources, rendering them more susceptible to osmotic and cell wall stresses. Moreover, VdGH7a interacted with an osmotin-like protein (GhOLP1) in cotton through yeast two-hybrid screening, and further confirmed using bi-molecular fluorescence complementation (BiFC) and luciferase complementation imaging (LCI). Furthermore, virus-induced gene silencing technology was employed to silence GhOLP1, causing cotton's salicylic acid (SA) content and resistance to V. dahliae were both reduced, whereas heterologous overexpression of GhOLP1 in Arabidopsis increased both resistance and the expression of genes involved in the SA signaling pathway. Collectively, these findings demonstrate a virulence strategy whereby the secreted protein VdGH7a from V. dahliae interacts with GhOLP1 to stimulate host immunity and play a significant role in plant resistance against V. dahliae.

Cultivar mixtures increases crop diversification and grain yield stability.  It is a major challenge to achieve high grain yield and nitrogen use efficiency with environmentally friendly practices.  However, it is currently unclear whether the cultivar mixtures of maize can improve nitrogen use efficiency.  A two-year field experiment was conducted using two maize cultivars with different roots angles and leaf angles planted in monoculture or in mixtures under four nitrogen levels N0 (0 kg N ha^-1), N140 (140 kg N ha^-1), N280 (280 kg N ha^-1) and N340 (340kg N ha^-1).  Cultivar mixtures significantly increased light interception of middle canopy, dry matter accumulation and total roots length under N0, N140, and N280 conditions.  Light interception of middle canopy positively related to dry matter accumulation and thus increased grain yield.  And light interception of whole canopy positively related to total lateral root length, while the increased total lateral root length of outer nodal roots significantly improved nitrogen accumulation and nitrogen use efficiency.  Thus, cultivar mixtures promoted an optimal canopy structure and good root growth, then improved grain yield and nitrogen use efficiency.  These findings could deepen our understanding of the facilitating effect of canopy structure and root traits of cultivar mixtures on the collaborative promotion of grain yield and nitrogen use efficiency.