Identification of anther thermotolerance genes by the integration of linkage and association analysis in maize.

Maize is one of the world's most important staple crops, yet its production is increasingly threatened by the rising frequency of high-temperature stress (HTS). To investigate the genetic basis of anther thermotolerance under field conditions, we performed linkage and association analysis to identify HTS response quantitative trait loci (QTL) using three recombinant inbred line (RIL) populations and an association panel containing 375 diverse maize inbred lines. These analyses resulted in the identification of 16 co-located large QTL intervals. Among the 37 candidate genes identified in these QTL intervals, five have rice or Arabidopsis homologs known to influence pollen and filament development. Notably, one of the candidate genes, ZmDUP707, has been subject to selection pressure during breeding. Its expression is suppressed by HTS, leading to pollen abortion and barren seeds. We also identified several additional candidate genes potentially underly QTL previously reported by other researchers. Taken together, our results provide a pool of valuable candidate genes that could be employed by future breeding programs aiming at enhancing maize HTS tolerance.

HortGenome Search Engine, a universal genomic search engine for horticultural crops.

Horticultural crops comprising fruit, vegetable, ornamental, beverage, medicinal and aromatic plants play essential roles in food security and human health, as well as landscaping. With the advances of sequencing technologies, genomes for hundreds of horticultural crops have been deciphered in recent years, providing a basis for understanding gene functions and regulatory networks and for the improvement of horticultural crops. However, these valuable genomic data are scattered in warehouses with various complex searching and displaying strategies, which increases learning and usage costs and makes comparative and functional genomic analyses across different horticultural crops very challenging. To this end, we have developed a lightweight universal search engine, HortGenome Search Engine (HSE; http://hort.moilab.net), which allows for the querying of genes, functional annotations, protein domains, homologs, and other gene-related functional information of more than 500 horticultural crops. In addition, four commonly used tools, including 'BLAST', 'Batch Query', 'Enrichment analysis', and 'Synteny Viewer' have been developed for efficient mining and analysis of these genomic data.

Using restored heavy metal contaminated soil as brick making material: Risk analysis upon different scenarios, considering the completeness of bricks.

Restored heavy metal contaminated soil (RHMCS) can be utilized as building material, but the risks of heavy metal dissolution (HMD) under different scenarios are not clear. This study focused on sintered bricks made from RHMCS and assessed the HMD process and utilization risks of whole bricks (WB) and broken bricks (BB) under two simulated utilization scenarios of leaching and freeze-thaw. Part of the studied bricks were crushed, which increased the surface area (SSA) 3.43-fold and exposed the inner heavy metals, increasing the HMD in BB. However, the HMD in sintered bricks did not exceed the "Groundwater Quality Standard" and "Integrated Wastewater Discharge Standard" under different utilization scenarios, although the dissolution processes were different. In the leaching scenario, the release rate of HMs (As, Cr, Pb) changed from fast to slow over time; the maximum concentration was 17% of the standard limits. In the freeze-thaw scenario, there was no significant correlation between the release of HMs and freeze-thaw time, and the HMD of As was the highest, reaching 37% of the standard limits. Further analysis of health risks of bricks in the two scenarios found that the carcinogenic risks (CR) and the non-carcinogenic risks (NCR) were below 9.56 × 10-7 and 3.21 × 10-2, respectively, which are both lower than the Guidelines for Health Risk Assessment of Groundwater Pollution issued by Ministry of Ecology and Environment of China. These findings suggest that the utilization risks of RHMCS sintered bricks analyzed in this study are low in both scenarios, and higher completeness of bricks leads to higher safety in product utilization. The results provide a reference for the engineering utilization and disposal of building materials made from RHMCS.

Maize tubulin folding cofactor B is required for cell division and cell growth through modulating microtubule homeostasis.

Tubulin folding cofactors (TFCs) are required for tubulin folding, α/ß tubulin heterodimer formation, and microtubule (MT) dynamics in yeast and mammals. However, the functions of their plant counterparts remain to be characterized. We identified a natural maize crumpled kernel mutant, crk2, which exhibits reductions in endosperm cell number and size, as well as embryo/seedling lethality. Map-based cloning and functional complementation confirmed that ZmTFCB is causal for the mutation. ZmTFCB is targeted mainly to the cytosol. It facilitates α-tubulin folding and heterodimer formation through sequential interactions with the cytosolic chaperonin-containing TCP-1 ε subunit ZmCCT5 and ZmTFCE, thus affecting the organization of both the spindle and phragmoplast MT array and the cortical MT polymerization and array formation, which consequently mediated cell division and cell growth. We detected a physical association between ZmTFCB and the maize MT plus-end binding protein END-BINDING1 (ZmEB1), indicating that ZmTFCB1 may modulate MT dynamics by sequestering ZmEB1. Our data demonstrate that ZmTFCB is required for cell division and cell growth through modulating MT homeostasis, an evolutionarily conserved machinery with some species-specific divergence.

Bioaccessibility and health risk of heavy metals in ash from the incineration of different e-waste residues.

Ash from incinerated e-waste dismantling residues (EDR) may cause significant health risks to people through ingestion, inhalation, and dermal contact exposure pathways. Ashes of four classified e-waste types generated by an incineration plant in Zhejiang, China were collected. Total contents and the bioaccessibilities of Cd, Cu, Ni, Pb, and Zn in ashes were measured to provide crucial information to evaluate the health risks for incinerator workers and children living in vicinity. Compared to raw e-waste in mixture, ash was metal-enriched by category incinerated. However, the physiologically based extraction test (PBET) indicates the bioaccessibilities of Ni, Pb, and Zn were less than 50 %. Obviously, bioaccessibilities need to be considered in noncancer risk estimate. Total and PBET-extractable contents of metal, except for Pb, were significantly correlated with the pH of the ash. Noncancer risks of ash from different incinerator parts decreased in the order bag filter ash (BFA) > cyclone separator ash (CFA) > bottom ash (BA). The hazard quotient for exposure to ash were decreased as ingestion > dermal contact > inhalation. Pb in ingested ash dominated (>80 %) noncancer risks, and children had high chronic risks from Pb (hazard index >10). Carcinogenic risks from exposure to ash were under the acceptable level (<10(-6)) both for children and workers. Exposure to ash increased workers' cancer risks and children's noncancer risks. Given the risk estimate is complex including toxicity/bioaccessibility of metals, the ways of exposure, and many uncertainties, further researches are required before any definite decisions on mitigating health risks caused by exposure to EDR incinerated ash are made.

Anaerobic biotransformation of fluoronitrobenzenes and microbial communities in methanogenic systems.

The fluorinated compounds are becoming a ubiquitous class of environmental contaminants because of their widespread applications, and their fate is a matter of great concern under anaerobic environment. In this work, the biotransformation of five fluoronitrobenzenes (FNBs), i.e., 2-fluoronitrobenzene (2-FNB), 3-fluoronitrobenzene (3-FNB), 4-fluoronitrobenzene (4-FNB), 2,4-difluoronitrobenzene (2,4-DFNB), and 2,3,4-trifluoronitrobenzene (2,3,4-TFNB), under methanogenic conditions had been studied by semicontinuous and batch tests for the first time. In 245 days, the five FNBs except 3-FNB were transformed mainly via nitro-reduction, and the reductive defluorination was not observed. During the biotransformation of 3-FNB, the reductive defluorination occurred after 98 days; however, its product was not aniline. The maximum transformation rates of 2-FNB, 3-FNB, 4-FNB, 2,4-DFNB, and 2,3,4-TFNB were 21.21 ± 1.73, 32.14 ± 2.33, 21.33 ± 2.48, 33.89 ± 6.87, and 10.87 ± 0.84 mg FNB (g VSS h)(-1), respectively. With the increase in the number of the fluorous groups, the transformation rates did not increase. Besides, the microbial communities were characterized by means of denaturing gradient gel electrophoresis (DGGE). Results showed that the predominant archaea were Methanobacterium, Methanosphaerula, Methanofollis, Methanospirillum, Methanolinea, and Methanosaeta; the predominant bacteria were Sphingbacteriales, Flavobacteriales, bacteroidales, Deltaproteobacteria, Desulfovibrionales, Clostridates, and Pseudomonadates. Few bacteria found were with high similarity to dechlorinating microorganisms reported. The results demonstrated that the pathways of FNBs biotransformation were different from those of the chloronitrobenzenes under methanogenic conditions.

Reduction of heavy metals in residues from the dismantling of waste electrical and electronic equipment before incineration.

Residues disposal from the dismantling of waste electrical and electronic equipment are challenging because of the large waste volumes, degradation-resistance, low density and high heavy metal content. Incineration is advantageous for treating these residues but high heavy metal contents may exist in incinerator input and output streams. We have developed and studied a specialized heavy metal reduction process, which includes sieving and washing for treating residues before incineration. The preferable screen aperture for sieving was found to be 2.36mm (8 meshes) in this study; using this screen aperture resulted in the removal of approximately 47.2% Cu, 65.9% Zn, 26.5% Pb, 55.4% Ni and 58.8% Cd from the residues. Subsequent washing further reduces the heavy metal content in the residues larger than 2.36mm, with preferable conditions being 400rpm rotation speed, 5min washing duration and liquid-to-solid ratio of 25:1. The highest cumulative removal efficiencies of Cu, Zn, Pb, Ni and Cd after sieving and washing reached 81.1%, 61.4%, 75.8%, 97.2% and 72.7%, respectively. The combined sieving and washing process is environmentally friendly, can be used for the removal of heavy metals from the residues and has benefits in terms of heavy metal recycling.

Flow analysis of heavy metals in a pilot-scale incinerator for residues from waste electrical and electronic equipment dismantling.

The large amount of residues generated from dismantling waste electrical and electronic equipment (WEEE) results in a considerable environmental burden. We used material flow analysis to investigate heavy metal behavior in an incineration plant in China used exclusively to incinerate residues from WEEE dismantling. The heavy metals tested were enriched in the bottom and fly ashes after incineration. However, the contents of heavy metals in the bottom ash, fly ash and exhaust gas do not have a significant correlation with that of the input waste. The evaporation and recondensation behavior of heavy metals caused their contents to differ with air pollution control equipment because of the temperature difference during gas venting. Among the heavy metals tested, Cd had the strongest tendency to transfer during incineration (TCd=69.5%) because it had the lowest melting point, followed by Cu, Ni, Pb and Zn. The exchangeable and residual fractions of heavy metals increased substantially in the incineration products compared with that of the input residues. Although the mass of residues from WEEE dismantling can be reduced by 70% by incineration, the safe disposal of the metal-enriched bottom and fly ashes is still required.

Characterization of residues from dismantled imported wastes.

Residues from the imported wastes dismantling process create a great burden on the ambient environment. To develop appropriate strategies for the disposal of such residues, their characteristics were studied through background value analysis and toxicity leaching tests. Our results showed that the heavy metals concentrations in residues were high, particularly those of Cu (7180 mg kg(-1)), Zn (2783 mg kg(-1)), and Pb (1954 mg kg(-1)). Toxicity leaching tests revealed a high metal releasing risk of such residues if they are disposed of in a landfill. However, the residues of imported wastes were also found to have some intrinsic metal recycling value.