Although excess cadmium (Cd) accumulation is harmful to plants, the molecular mechanisms underlying Cd detoxification and accumulation in Arabidopsis thaliana remain largely undetermined. In this ...study, we demonstrated that the A. thaliana PLANT DEFENSIN 2 gene AtPDF2.5 is involved in Cd tolerance and accumulation. In vitro Cd‐binding assays revealed that AtPDF2.5 has Cd‐chelating activity. Site‐directed mutagenesis of AtPDF2.5 identified eight cysteine residues that were essential for mediating Cd tolerance and chelation. Histochemical analysis demonstrated that AtPDF2.5 was mainly expressed in root xylem vascular bundles, and that AtPDF2.5 was significantly induced by Cd. Subcellular localization analysis revealed that AtPDF2.5 was localized to the cell wall. The overexpression of AtPDF2.5 significantly enhanced Cd tolerance and accumulation in A. thaliana and its heterologous overexpression in rice increased Cd accumulation; however, the functional disruption of AtPDF2.5 decreased Cd tolerance and accumulation. Physiological analysis suggested that AtPDF2.5 promoted Cd efflux from the protoplast and its subsequent accumulation in the cell wall. These data suggest that AtPDF2.5 promotes cytoplasmic Cd efflux via chelation, thereby enhancing Cd detoxification and apoplastic accumulation.
Plants need to accumulate and detoxify cadmium for adapting to and remediating heavy metal polluted soils. The PLANT DEFENSIN 2 protein AtPDF2.5 mediates cadmium tolerance and accumulation in Arabidopsis thaliana by chelating this metal and facilitating the efflux of the AtPDF2.5‐Cd complex from protoplasts, indicating this might be a molecular tool for phytoremediation.
Family background has a significant impact on family firms’ strategies such as innovation investments. Going beyond prior studies that exclusively focus on how family governance and management ...factors determine research and development (R&D) investment decisions, this study investigates a family science factor: family firm owner's birth order, defined as the relative rank of the owner in terms of the age hierarchy among siblings in the family. Joining the family niche model of birth order and socioemotional wealth perspective, we propose that later‐born family firm owners tend to be risk‐takers and invest more in R&D projects compared with their earlier‐born counterparts. We further examine how the two other powerful decision‐makers within family firms (i.e., chairperson of the board and CEO) enable or constrain the owner's birth order–R&D investment relationship. We contend that the positive birth order impact on R&D investment is weaker when a family member is the chairperson of the board, while such a relationship is stronger in the presence of owner–CEO duality. We confirm our hypotheses using a sample of 605 firm‐year observations from Chinese‐listed family firms between 2006 and 2014. This study demonstrates the important impact of family science factors on innovation heterogeneities, which is understudied in the family firm innovation literature.
Pollution by heavy metals limits the area of land available for cultivation of food crops. A potential solution to this problem might lie in the molecular breeding of food crops for phytoremediation ...that accumulate toxic metals in straw while producing safe and nutritious grains. Here, we identify a rice quantitative trait locus we name cadmium (Cd) accumulation in leaf 1 (CAL1), which encodes a defensin-like protein. CAL1 is expressed preferentially in root exodermis and xylem parenchyma cells. We provide evidence that CAL1 acts by chelating Cd in the cytosol and facilitating Cd secretion to extracellular spaces, hence lowering cytosolic Cd concentration while driving long-distance Cd transport via xylem vessels. CAL1 does not appear to affect Cd accumulation in rice grains or the accumulation of other essential metals, thus providing an efficient molecular tool to breed dual-function rice varieties that produce safe grains while remediating paddy soils.
Key message
Plant defensin AtPDF2.6 is not secreted to the apoplast and localized in cytoplasm. AtPDF2.6 is mainly expressed in root vascular bundles of xylem parenchyma cell, and significantly ...induced by Cd stress.
AtPDF2.6
detoxicate cytoplasmic Cd via chelation, thus enhanced Cd tolerance in
Arabidopsis
.
In order to detoxify the heavy metal cadmium (Cd), plants have evolved several mechanisms, among which chelation represents the major Cd-detoxification mechanism. In this study, we aimed to identify a new defensin protein involved in cytoplasmic Cd detoxification by using plant molecular genetics and physiological methods. The results of bioinformatic analysis showed that the
Arabidopsis thaliana
defensin gene
AtPDF2.6
has a signal peptide that may mediate its secretion to the cell wall. Subcellular localization analysis revealed that AtPDF2.6 is localized to the cytoplasm and is not secreted to the apoplast, whereas histochemical analysis indicated that
AtPDF2.6
is mainly expressed in the root xylem parenchyma cells and that its expression is significantly induced by Cd. An in vitro Cd-binding assay revealed that AtPDF2.6 has Cd-chelating activity. Heterologous overexpression of
AtPDF2.6
increased Cd tolerance in
Escherichia coli
and yeast, and
AtPDF2.6
overexpression significantly enhanced Cd tolerance in
Arabidopsis
, whereas functional disruption of
AtPDF2.6
decreased Cd tolerance. These data suggest that AtPDF2.6 detoxifies cytoplasmic Cd via chelation and thereby enhances Cd tolerance in
Arabidopsis
. Our findings accordingly challenge the commonly accepted view of defensins as secreted proteins.
As a consequence of industrial development, soil Cd pollution leads to crop contamination by Cd, posing a threat to food safety and human health. Excessive accumulation of Cd in plants also inhibits ...their growth via oxidative stress damage to their photosynthetic systems. Through evolutionary selection, plants have developed a set of efficient strategies to respond to Cd in their environments. These include the accumulation and detoxification of heavy metals. Cd is absorbed by plant roots through the apoplastic and symplastic pathways and then translocated to plant shoots via xylem loading, long-distance transport, and phloem redistribution. Simultaneously, plants initiate a series of mechanisms to reduce Cd toxicity, including cell wall adsorption, cytoplasmic chelation, and vacuolar sequestration. This review summarizes current knowledge of Cd accumulation and detoxification in plants.
The catalytic transfer hydrogenation of furfural to the fuel additives 2‐methylfuran (2‐MF) and 2‐methyltetrahydrofuran (2‐MTHF) was investigated over various bimetallic catalysts in the presence of ...the hydrogen donor 2‐propanol. Of all the as‐prepared catalysts, bimetallic Cu‐Pd catalysts showed the highest catalytic activities towards the formation of 2‐MF and 2‐MTHF with a total yield of up to 83.9 % yield at 220 °C in 4 h. By modifying the Pd ratios in the Cu‐Pd catalyst, 2‐MF or 2‐MTHF could be obtained selectively as the prevailing product. The other reaction conditions also had a great influence on the product distribution. Mechanistic studies by reaction monitoring and intermediate conversion revealed that the reaction proceeded mainly through the hydrogenation of furfural to furfuryl alcohol, which was followed by deoxygenation to 2‐MF in parallel to deoxygenation/ring hydrogenation to 2‐MTHF. Finally, the catalyst showed a high reactivity and stability in five catalyst recycling runs, which represents a significant step forward toward the catalytic transfer hydrogenation of furfural.
Identifying the intermediates: The catalytic transfer hydrogenation of biomass‐derived furfural to fuel additives 2‐methylfuran and 2‐methyltetrahydrofuran is performed over a bimetallic Cu‐Pd catalyst in the presence of 2‐propanol. The reaction proceeds via the intermediate furfuryl alcohol, which is then deoxygenated/hydrogenated to the desired products.
Summary
Extensive mutational screening studies have documented genes regulating anther and pollen development. Knowledge concerning how formation of male germinal cell is arithmetically controlled in ...natural populations, under different environmental conditions, is lacking.
We counted pollen number within a single anther and a maize–teosinte BC2S3 recombinant inbred line population to identify ZmCCT10 as a major determinant of pollen number variation.
ZmCCT10 was originally identified as a photoperiod‐sensitive negative regulator of flowering. ZmCCT10 inactivation, after transposon insertion within its promoter, is proposed to have accelerated maize spread toward higher latitudes, thus allowing temperate maize to flower under long‐day conditions. We showed that the active ZmCCT10 allele decreased pollen formation. As different active and inactive ZmCCT10 alleles have been found in natural maize populations, this represents the first report of a gene controlling pollen number in a crop natural population. These findings suggest that higher pollen number, which provides a competitive advantage in open‐pollinated populations, may have been one of the major driving forces for the selection of an inactive ZmCCT10 allele during tropical maize domestication.
We provide evidence that ZmCCT10 has opposite effects on cell proliferation of archesporial and tapetum cells and it modulates expression of key regulators during early anther development.
Given that women CEOs are usually more risk averse, engage less in opportunistic behavior, and provide higher quality earnings than men CEOs, we argue that firms with women CEOs are likely to face ...lower operational and information risk and thus enjoy cheaper external funds. Using a large sample of Chinese -share listed firms operating from 2006 to 2012, we find consistent evidence that Chinese banks tend to impose lower loan costs on firms with women CEOs compared to firms with men CEOs. This effect is more pronounced (1) for non-stateowned enterprises than for state-owned enterprises, (2) for firms without political connections than for firms with political connections, and (3) during non-crisis periods. We do not find any significant effects for firms with women chairpersons, CFOs, or directors.
This study, conducted in the context of China, investigates how the military experience of top executives influences their corporate philanthropy. Using a data set of 12,437 firm-year observations ...from China’s A-share firms listed on the Shanghai and Shenzhen stock exchanges between 2004 and 2013, we found that firms run by military top executives significantly donate less than those led by non-military top executives. Moreover, the reduction effect of military experience on corporate philanthropy is found to be more pronounced for firms located in regions with less developed markets, especially when firms’ chairmen have military background. This may be because military top executives are reluctant to illegitimately use corporate philanthropy due to a strong sense of ethics gained from their military service experience. These results are robust after adopting the propensity score matching (PSM) method to tackle the potential sample selection bias. Our findings provide a new interpretation of military experience and have important implications for understanding corporate philanthropy in China and in emerging markets in general.
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