LlbHLH87 interacts with LlSPT to modulate thermotolerance via activation of LlHSFA2 and LlEIN3 in lily.

Basic helix-loop-helix (bHLH) proteins comprise one of the largest families of transcription factors in plants, which play roles in plant development, secondary metabolism, and the response to biotic/abiotic stresses. However, the roles of bHLH proteins in thermotolerance are largely unknown. Herein, we identified a heat-inducible member of the bHLH family in lily (Lilium longiflorum), named LlbHLH87, which plays a role in thermotolerance. LlbHLH87 was rapidly induced by transient heat stress, and its encoded protein was localized to the nucleus, exhibiting transactivation activity in both yeast and plant cells. Overexpression of LlbHLH87 in Arabidopsis enhanced basal thermotolerance, while silencing of LlbHLH87 in lily reduced basal thermotolerance. Further analysis showed that LlbHLH87 bound to the promoters of HEAT STRESS TRANSCRIPTION FACTOR A2 (LlHSFA2) and ETHYLENE-INSENSITIVE 3 (LlEIN3) to directly activate their expression. In addition, LlbHLH87 interacted with itself and with SPATULA (LlSPT) protein. LlSPT was activated by extended heat stress and its protein competed for the homologous interaction of LlbHLH87, which reduced the transactivation ability of LlbHLH87 for target genes. Compared with that observed under LlbHLH87 overexpression alone, co-overexpression of LlbHLH87 and LlSPT reduced the basal thermotolerance of lily to sudden heat shock, but improved its thermosensitivity to prolonged heat stress treatment. Overall, our data demonstrated that LlbHLH87 regulates thermotolerance via activation of LlEIN3 and LlHSFA2, along with an antagonistic interaction with LlSPT.

HD-Zip I protein LlHOX6 antagonizes homeobox protein LlHB16 to attenuate basal thermotolerance in lily.

Homeodomain-leucine zipper (HD-Zip) I transcription factors are crucial for plant responses to drought, salt, and cold stresses. However, how they are associated with thermotolerance remains mostly unknown. We previously demonstrated that lily (Lilium longiflorum) LlHB16 (HOMEOBOX PROTEIN 16) promotes thermotolerance, whereas the roles of other HD-Zip I members are still unclear. Here, we conducted a transcriptomic analysis and identified a heat-responsive HD-Zip I gene, LlHOX6 (HOMEOBOX 6). We showed that LlHOX6 represses the establishment of basal thermotolerance in lily. LlHOX6 expression was rapidly activated by high temperature, and its protein localized to the nucleus. Heterologous expression of LlHOX6 in Arabidopsis (Arabidopsis thaliana) and overexpression in lily reduced their basal thermotolerance. In contrast, silencing LlHOX6 in lily elevated basal thermotolerance. Cooverexpressing or cosilencing LlHOX6 and LlHB16 in vivo compromised their functions in modulating basal thermotolerance. LlHOX6 interacted with itself and with LlHB16, although heterologous interactions were stronger than homologous ones. Notably, LlHOX6 directly bounds DNA elements to repress the expression of the LlHB16 target genes LlHSFA2 (HEAT STRESS TRANSCRIPTION FACTOR A2) and LlMBF1c (MULTIPROTEIN BRIDGING FACTOR 1C). Moreover, LlHB16 activated itself to form a positive feedback loop, while LlHOX6 repressed LlHB16 expression. The LlHOX6-LlHB16 heterooligomers exhibited stronger DNA binding to compete for LlHB16 homooligomers, thus weakening the transactivation ability of LlHB16 for LlHSFA2 and LlMBF1c and reducing its autoactivation. Altogether, our findings demonstrate that LlHOX6 interacts with LlHB16 to limit its transactivation, thereby impairing heat stress responses in lily.

An AP2/ERF member LlERF012 confers thermotolerance via activation of HSF pathway in lily.

Heat stress transcription factors (HSFs) are core factors of plants in response to heat stress (HS), but their regulatory network is complicated and remains elusive in a large part, especially HSFBs. In this study, we reported that the LlERF012-LlHSFA1 module participates in heat stress response (HSR) by directly regulating HSF pathway in lily (Lilium longiflorum). LlHSFB1 was confirmed as a positive regulator in lily thermotolerance and a heat-inducible AP2/ERF member LlERF012 (Ethylene Response Factor 012) was further identified to be a direct trans-activator of LlHSFB1. Overexpression of LlERF012 elevated the thermotolerance of transgenic Arabidopsis and lily, but silencing LlERF012 reduced thermotolerance in lily. Further analysis showed LlERF012 interacted with LlHSFA1, which led to enhanced transactivation activity and DNA-binding capability of LlERF012. In addition, LlERF012 also directly activated the expression of LlHSFA1 by binding its promoter. As expected, we found that LlERF012 bound the promoters of LlHSFA2, LlHSFA3A, and LlHSFA3B to stimulate their expression, and LlERF012-LlHSFA1 interaction enhanced these activation effects. Overall, our data suggested that LlERF012 was a key factor for lily thermotolerance and the LlERF012-LlHSFA1 interaction synergistically regulated the activity of the HSF pathway including the class A and B members, which might be of great significance for coordinating the functions of different HSFs.

[Effects of 1-bromopropane on liver and kidney functions of exposed workers].

OBJECTIVE: To study the effects of 1-bromopropane (1-BP) on liver and kidney functions of exposed workers. METHODS: Occupational health situation in three 1-BP plants was investigated. Fifty-four workers from the 1-BP manufacturing line were chose to be contact group, while 42 workers from non-1-BP manufacturing line as control group. All workers underwent questionnaire survey, liver function test as well as kidney function test. RESULT: Working years has no impact on liver and kidney functions of workers from contact group. Compared with the control, liver and kidney functions test of the two groups showed no statistical difference either. CONCLUSION: The present investigation doesn't prove any impact of occupational 1-BP exposure on worker's liver and kidney functions.

Characteristics of mesoscale eddies in the Mozambique Channel.

The mesoscale eddy characteristics of the Mozambique Warm Current were investigated by detecting and tracking satellite altimetry data from 2010 to 2019. A total of 1,086 eddies were identified in the Mozambique Channel, comprising 509 cyclonic eddies and 577 anticyclonic eddies. The results revealed that the bay area on the northwest coast of Madagascar was the main hotspot of eddy generation, and the mean amplitude and radius of the anticyclonic eddies in the Mozambique Channel were 24.23 cm and 82.7 km, respectively, which are larger than those of the cyclonic eddies. Local wind forcing had a significant impact on the formation of mesoscale eddies in the Mozambique Channel. In winter, the wind stress in the northern and southern areas of the Mozambique Channel exhibited a strong correlation with the distribution of eddy kinetic energy (EKE), where both monsoonal winds in the north and trade winds in the south could facilitate mesoscale anticyclonic eddy formation. In addition, the variability in the number of anticyclonic and cyclonic eddies in the Mozambique Channel may have exerted a significant influence on the seasonal anomalous fluctuations in local sea surface temperatures (SSTs). This study presented a novel analysis of the mesoscale eddy characteristics in the Mozambique Channel.

A LlWRKY33-LlHSFA4-LlCAT2 module confers resistance to Botrytis cinerea in lily.

Gray mold caused by Botrytis cinerea is one of the major threats in lily production. However, limited information is available about the underlying defense mechanism against B. cinerea in lily. Here, we characterized a nuclear-localized class A heat stress transcription factor (HSF)-LlHSFA4 from lily (Lilium longiflorum), which positively regulated the response to B. cinerea infection. LlHSFA4 transcript and its promoter activity were increased by B. cinerea infection in lily, indicating its involvement in the response to B. cinerea. Virus-induced gene silencing (VIGS) of LlHSFA4 impaired the resistance of lily to B. cinerea. Consistent with its role in lily, overexpression of LlHSFA4 in Arabidopsis (Arabidopsis thaliana) enhanced the resistance of transgenic Arabidopsis to B. cinerea infection. Further analysis showed that LlWRKY33 directly activated LlHSFA4 expression. We also found that both LlHSFA4 and LlWRKY33 positively regulated plant response to B. cinerea through reducing cell death and H2O2 accumulation and activating the expression of the reactive oxygen species (ROS) scavenging enzyme gene LlCAT2 (Catalase 2) by binding its prompter, which might contribute to reducing H2O2 accumulation in the infected area. Taken together, our data suggested that there may be a LlWRKY33-LlHSFA4-LlCAT2 regulatory module which confers B. cinerea resistance via reducing cell death and the ROS accumulation.

Ovulatory signal-triggered chromatin remodeling in ovarian granulosa cells by HDAC2 phosphorylation activation-mediated histone deacetylation.

BACKGROUND: Epigenetic reprogramming is involved in luteinizing hormone (LH)-induced ovulation; however, the underlying mechanisms are largely unknown. RESULTS: We here observed a rapid histone deacetylation process between two waves of active transcription mediated by the follicle-stimulating hormone (FSH) and the LH congener human chorionic gonadotropin (hCG), respectively. Analysis of the genome-wide H3K27Ac distribution in hCG-treated granulosa cells revealed that a rapid wave of genome-wide histone deacetylation remodels the chromatin, followed by the establishment of specific histone acetylation for ovulation. HDAC2 phosphorylation activation coincides with histone deacetylation in mouse preovulatory follicles. When HDAC2 was silenced or inhibited, histone acetylation was retained, leading to reduced gene transcription, retarded cumulus expansion, and ovulation defect. HDAC2 phosphorylation was associated with CK2α nuclear translocation, and inhibition of CK2α attenuated HDAC2 phosphorylation, retarded H3K27 deacetylation, and inactivated the ERK1/2 signaling cascade. CONCLUSIONS: This study demonstrates that the ovulatory signal erases histone acetylation through activation of CK2α-mediated HDAC2 phosphorylation in granulosa cells, which is an essential prerequisite for subsequent successful ovulation.