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The short-time heavy rainfall is sudden and easy to cause disaster， which poses a great threat to people's life and property safety.This paper analyzed the spatial and temporal variation characteristics of short-time heavy rainfall （≥20 mm·h-1） in the Sichuan basin and its relationship with geological hazards.The hourly precipitation observation data from high-density regional automatic stations and national stations （1688 stations） was used from 2011 to 2020.The results showed that： （1） The large values of short-time heavy rainfall frequency and rainfall were mainly concentrated in the transition area between high mountains and basins in the southwest and along the Longmen Mountains in the northwest， with more in the west and less in the east overall.（2） The frequency and rainfall were increasing， but the intensity and intensity extremes were decreasing， so the increase in rainfall was caused by the increase in frequency.In the northwestern part of the basin， the frequency and rainfall was the highest， and the interannual variability was the strongest.（3） The short-time heavy rainfall occurred from March to October， one month earlier than in the early 21st century.The frequency peaked in July and was concentrated from 23:00 to 07:00 next day （Beijing Time）， accounting for 56.5% of the whole day.The basin as a whole exhibited a single-peak night rain structure， but the northwestern， northeastern and central parts were bimodal， and the peak time was delayed from south to north.（4） The correlation and composite analysis revealed that the number of geological hazards was highly correlated with the frequency and rainfall of short-time heavy rainfall in the northwest， with correlation coefficients of 0.87 and 0.89， respectively.For the Sichuan basin as a whole， landslides and debris flows showed significant differences between the more frequent and less frequent short-time heavy rainfall.In the northwestern and southwestern parts of the basin， the short-time heavy rainfall had a large impact on various geological hazards.In the northeast， it had an impact on landslides， debris flows and other geological hazards， while in the south， it had an impact on other types of geological hazards.The northwest and northeast had the highest number of geological hazards， accounting for 40.2% and 31.7% of the total， respectively.But the short-time heavy rainfall was more likely to cause casualties in the northwest， and mainly caused direct economic losses and injuries in the northeast.The number of geological hazards in Sichuan basin was increasing， while the economic loss was decreasing， indicating that the disaster prevention and mitigation capacity has been significantly improved.

This study investigates the changes in the drought frequency in 2070–2099 relative to 1970–1999, due to the mean and shape changes of the probability density function (PDF) of the self-calibrated Palmer Drought Severity Index (PDSI), using CMIP5 multi-model historical simulations and projections under the RCP4.5 scenario. For severe droughts defined with PDSIs less than the 10th percentile, it is shown that over 41% of the global land, the increase in the severe drought frequency due to the shape change exacerbates the increase due to the mean change. Over 28% of the global land, the decrease in the drought frequency due to the shape change partially offsets the increase due to the mean change. Over 31% of the global land, the drought frequency increases due to the shape changes, but decreases due to the mean changes. The severe drought frequency due to both PDSI PDF mean and shape changes increases over almost the entire global land. We show that the PDSI standard deviation change is mainly determined by the mean precipitation change, while the PDSI mean change is determined by both mean precipitation and potential evapotranspiration changes. In particular, the PDSI standard deviation increases with the increase in mean precipitation which broadens the PDSI PDF, and thus enhances the severe drought frequency, and vice versa. On the other hand, the PDSI mean decreases with the decrease (increase) in mean precipitation (mean potential evapotranspiration). The difference in the attribution of drought frequency changes to the mean and shape changes over different regions can thus be largely explained by the mean precipitation and potential evapotranspiration changes. We also examine the moderate droughts defined with PDSIs between 10th and 20th percentiles in this study. For the moderate drought frequency, the spatial pattern of its changes due to the PDSI mean changes is similar to that of severe drought but with much smaller magnitudes, while its change in the spatial pattern due to the shape changes differs from severe drought with no significant changes. The moderate drought frequency due to both PDSI PDF mean and shape changes increases over 71% of the global land but decreases over 29% of the land.

As a land–atmosphere coupling “hot spot”, the northern China climate transition zone has a sharp spatial gradient of hydrothermal conditions, which plays an essential role in shaping the spatial and temporal pattern of evapotranspiration-precipitation coupling, but whose mechanisms still remain unclear. This study analyzes the spatial and temporal variation in land–atmosphere coupling strength (CS) in the climate transitional zone of northern China and its relationship with soil moisture and air temperature. Results show that CS gradually transitions from strong positive in the northwest to negative in the southeast and northeast corners. The spatial distribution of CS is closely related to climatic hydrothermal conditions, where soil moisture plays a more dominant role: CS increases first, and then decreases with increasing soil moisture, with the threshold of soil moisture at 0.2; CS gradually transitions from positive to negative at soil moisture between 0.25 and 0.35; CS shows an exponential decreasing trend with increasing temperature. In terms of temporal variation, CS is strongest in spring and weakens sequentially in summer, autumn, and winter, and has significant interdecadal fluctuations. The trend in CS shifts gradually from significantly negative in the west to a non-significant positive in the east. Soil moisture variability dominates the intra-annual variability of CS in the study regions, and determines the interannual variation of CS in arid and semi-arid areas. Moreover, the main reason for the positive and negative spatial differences in CS in the study area is the different driving regime of evapotranspiration (ET). ET is energy-limited in the southern part of the study area, leading to a positive correlation between ET and lifting condensation level (LCL), while in most of the northern part, ET is water-limited and is negatively correlated with LCL; LCL has a negative correlation with P across the study area, thus leading to a negative ET-P coupling in the south and a positive coupling in the north.

Abstract Background The basic leucine zipper (bZIP) transcription factor family is one of the most abundant and evolutionarily conserved gene families in plants. It assumes crucial functions in the life cycle of plants, including pathogen defense, secondary metabolism, stress response, seed maturation, and flower development. Although the genome of wax gourd has been published, little is known about the functions, evolutionary background, and gene expression patterns of the bZIP gene family, which limits its utilization. Results A total of 61 bZIP genes (BhbZIPs) were identified from wax gourd (Benincasa hispida) genome and divided into 12 subgroups. Whole-genome duplication (WGD) and dispersed duplication (DSD) were the main driving forces of bZIP gene family expansion in wax gourd, and this family may have undergone intense purifying selection pressure during the evolutionary process. We selected BhbZIP58, only one in the member of subgroup B, to study its expression patterns under different stresses, including heat, salt, drought, cold stress, and ABA treatment. Surprisingly, BhbZIP58 had a dramatic response under heat stress. BhbZIP58 showed the highest expression level in the root compared with leaves, stem, stamen, pistil, and ovary. In addition, BhbZIP58 protein was located in the nucleus and had transcriptional activation activity. Overexpression of BhbZIP58 in Arabidopsis enhanced their heat tolerance. Conclusions In this study, bZIP gene family is systematically bioinformatically in wax gourd for the first time. Particularly, BhbZIP58 may have an important role in heat stress. It will facilitate further research on the bZIP gene family regarding their evolutionary history and biological functions.

Abstract Background Wax gourd [Benincasa hispida (Thunb) Cogn. (2n = 2x = 24)] is an economically important vegetable crop of genus Benincasa in the Cucurbitaceae family. Fruit is the main consumption organ of wax gourd. The mature fruit cuticular wax (MFCW) is an important trait in breeding programs, which is also of evolutionary significance in wax gourd. However, the genetic architecture of this valuable trait remains unrevealed. Results In this study, genetic analysis revealed that the inheritance of MFCW was controlled by a single gene, with MFCW dominant over non-MFCW, and the gene was primarily named as BhWAX. Genome-wide association study (GWAS) highlighted a 1.1 Mb interval on chromosome 9 associated with MFCW in wax gourd germplasm resources. Traditional fine genetic mapping delimited BhWAX to a 0.5 Mb region containing 12 genes. Based on the gene annotation, expression analysis and co-segregation analysis, Bhi09G001428 that encodes a membrane bound O-acyltransferase (MBOAT) was proposed as the candidate gene for BhWAX. Moreover, it was demonstrated that the efficiency of a cleaved amplified polymorphic sequences (CAPS) marker in the determination of MFCW in wax gourd reached 80%. Conclusions In closing, the study identified the candidate gene controlling MFCW and provided an efficient molecular marker for the trait in wax gourd for the first time, which will not only be beneficial for functional validation of the gene and marker-assisted breeding of wax gourd, but also lay a foundation for analysis of its evolutionary meaning among cucurbits.

【Objective】Identification and cloning of BhiOXR genes from wax gourd and clarification of its expression characteristics under abiotic stresses would lay a foundation for further studying the function of BhiOXR genes in wax gourd.【Method】BhiOXR gene family members from wax gourd reference genome were identified, full-length CDS primers were designed to clone the BhiOXR genes of the wax gourd by RT-PCR. Seedlings of wax gourd inbred line B227 were treated with low temperature(4℃), high temperature(40℃), salt stress(150 mmol/L NaCl solution) and drought(10% PEG6000 solution).The expression characteristics of BhiOXR genes under the above mentioned abiotic stresses treatment time: 0, 4, 8, 12, 24 h were analyzed by using qRT-PCR.【Result】Six BhiOXR members were identified from wax gourd reference genome, and the fulllength genes were further cloned and bioinformatically analyzed. qRT-PCR analysis results showed that BhiOXR1 responded to low temperature, high temperature and drought stress, but did not respond to salt stress. BhiOXR2a, BhiOXR2b and BhiOXR4 responded to low temperature, salt and drought stresses but not to high temperature stress; BhiOXR3 and BhiOXR5 responded to low temperature, high temperature and salt stresses but not to drought stress.【Conclusion】It is clarified that BhiOXR genes are induced by abiotic stresses as low temperature, high temperature, salt and drought, and different BhiOXR genes have differences in response to abiotic stresses. Therefore, it is speculated that the six BhiOXR members may have different antioxidant effects in the process of resisting different abiotic stresses, which lays a foundation for further exploring the biological functions of BhiOXR genes in wax gourd.