The evaluation of gridded precipitation datasets is crucial for enhancing precipitation accuracy and supporting its applications. This study comprehensively evaluated the performances of six widely used long-term precipitation datasets in capturing extreme precipitation and streamflow over China using two hydrological models. These datasets include one satellite-reanalysis-gauge dataset (MSWEP V2), two gauged-based datasets (GPCC and CPC), and three reanalysis datasets (NECP-2, MERRA-2, and ERA5). The evaluation was performed at a daily timescale for the period 1982-2020. Compared with the rain gauge observations, GPCC provides the best performance in extreme precipitation estimation, followed by MSWEPV2, CPC, and MERRA-2. All precipitation datasets tend to underestimate annual maximum 1-day precipitation (Rx1) and annual maximum consecutive 5day precipitation (RX5), while they overestimate the extremely wet days (R95p) in dry northwestern China and underestimate it in wet southeastern China. Integrating gauge data into gridded precipitation datasets enhances the accuracy of extreme precipitation measurements. For streamflow simulation, GPCC shows the best performances across most catchments regarding hydrological calibration score (Kling-Gupta efficiency, KGE), except in arid northwestern China, where MSWEP V2 performed best. The ability of precipitation datasets to capture extreme streamflow is associated with considerable uncertainties, depending on the hydrological model used, and no single dataset consistently outperforms others. Besides, the influence of hydrological model selection in streamflow simulations is more significant in dry and high-latitude mountainous regions than in wet and low- latitude regions. This study provides significant insights into the reliability of the latest precipitation datasets and their applications in hydrological modeling, which is expected to serve as a reference for utilizing these datasets.

Alkaline stress with high pH levels could significantly influence plant growth and survival. The enzyme 9-cis-epoxycarotenoid dioxygenase (NCED) serves as a critical bottleneck in the biosynthesis of abscisic acid (ABA), making it essential for regulating stress tolerance. Here, we show that OsNCED3-overexpressing rice lines have increased ABA content by up to 50.90% and improved transcription levels of numerous genes involved in stress responses that significantly enhance seedling survival rates. Overexpression of OsNCED3 increased the dry weight contents of the total chlorophyll, proline, soluble sugar, starch, and the activities of antioxidant enzymes of rice seedlings, while reducing the contents of O2·−, H2O2, and malondialdehyde under hydroponic alkaline stress conditions simulated by 10, 15, and 20 mmol L−1 of Na2CO3. Additionally, the OsNCED3-overexpressing rice lines exhibited a notable increase in the expression of OsNCED3; ABA response-related genes OsSalT and OsWsi18; ion homeostasis-related genes OsAKT1, OsHKT1;5, OsSOS1, and OsNHX5; and ROS scavenging-related genes OsCu/Zn-SOD, OsFe-SOD, OsPOX1, OsCATA, OsCATB, and OsAPX1 in rice seedling leaves. The results of these findings suggest that overexpression of OsNCED3 upregulates endogenous ABA levels and the expression of stress response genes, which represents an innovative molecular approach for enhancing the alkaline tolerance of rice seedlings.

Bacterial blight (BB), which is caused by Xanthomonas oryzae pv. oryzae (Xoo), is an important rice disease responsible for significant yield losses. In the rice-growing regions of South China where BB outbreaks are common, the resistance of cultivars with BB resistance genes Xa4 and Xa21 has been lost because of rapid changes in the Xoo population structure and virulence. In this study, 421 diverse rice accessions were evaluated regarding their resistance to two Xoo strains, namely GD1358 (C5) and IV, which are prevalent pathotypes in South China and overcame the resistance of Xa4 and Xa21, respectively. Using the 4.8mio filtered SNP dataset, we conducted a genome-wide association study, which identified 13 loci associated with BB resistance, including eight new quantitative trait loci (QTL) and five QTL harboring known BB resistance genes: Xa3/Xa26, xa5, Xa35(t), Xa36(t), Xa40, Xa43(t), and xa44(t). Intriguingly, a steep peak was detected on chromosomes 5 and 11. Six QTL including three new ones, were distributed on chromosome 11, whereas a new QTL qBB5.1 and a known QTL were detected on chromosome 5. Haplotype analyses indicated that the LOC_Os05g01610 (OsPRAF2) gene within the qBB5.1 region, which encodes a PRAF protein, is associated with BB resistance. Furthermore, OsPRAF2 knockout lines generated using the CRISPR-Cpf1 system were significantly more resistant to Xoo strains than the wild-type plants. Our results provide researchers and breeders with useful information regarding QTL and gene resources, which may be relevant for developing new BB-resistant rice cultivars.

小叶锦鸡儿是内蒙古自治区重点开发利用的非竞争性饲料资源之一,目前其产业化利用仍处于瓶颈期,探寻其适宜饲用加工技术已成为当务之急.因此本研究以科尔沁沙地区花期(A1)、果期(A2)和生长季末期(A3)小叶锦鸡儿为原材料,添加糖蜜[不添加(C0)、10 g·kg-1(C1)]和菌剂[不添加(B0)、0.02 g·kg-1(B1)、0.04 g·kg-1(B2)、0.06 g·kg-1(B3)],分期进行青贮加工,以青贮前各生育期样品作为对照(CK1、CK2、CK3).通过评价不同青贮小叶锦鸡儿营养价值的高低筛选出其最佳青贮加工技术.研究结果表明:除磷(P)含量外,小叶锦鸡儿青贮前的各营养成分含量均随生育期推移而变化显著;各生育期小叶锦鸡儿青贮前的营养价值大小排序为:生长季末期>花期>果期.菌剂在果期和生长季末期对青贮小叶锦鸡儿的营养成分影响较大,而糖蜜在花期影响较大,两者几乎不存在交互作用;小叶锦鸡儿青贮后的各营养成分含量在不同生育期之间无明显变化规律.最佳青贮加工技术为A2+B1+C0(果期、添加菌剂0.02 g·kg-1,但不添加糖蜜),各项营养成分指标的权重大小顺序为粗蛋白(CP)>粗纤维(CF)>粗灰分(Ash)>酸性洗涤木质素(ADL)>磷(P)>无氮浸出物(NFE)>粗脂肪(EE)>钙(Ca);经A2+B1+C0处理后,小叶锦鸡儿CP、EE、NFE和Ash含量较3个对照均有提高,分别为15.70％、1.79％、28.16％和5.59％,CF和ADL含量均有下降,分别为40.65％和11.83％.本研究可为我国北方干旱和半干旱地区锦鸡儿属非常规粗饲料的饲用青贮加工提供技术支持,对促进区域固沙植物资源化利用和养殖业的精致发展具有重要意义.

A one-/two-dimensional genome-wide association study (GWAS) strategy was adopted to investigate the genetic systems underlying the reciprocal adaptation of rice (Oryza sativa) and its bacterial pathogen, Xanthomonas oryzae pv. oryzae (Xoo) using the whole-genome sequencing and large-scale phenotyping data of 701 rice accessions and 23 diverse Xoo strains. Forty-seven Xoo virulence-related genes and 318 rice quantitative resistance genes (QR-genes) mainly located in 41 genomic regions, and genome-wide interactions between the detected virulence-related genes and QR-genes were identified, including well-known resistance genes/virulence genes plus many previously uncharacterized ones. The relationship between rice and Xoo was characterized by strong differentiation among Xoo races corresponding to the subspecific differentiation of rice, by strong shifts towards increased resistance/virulence of rice/Xoo populations and by rich genetic diversity at the detected rice QR-genes and Xoo virulence genes, and by genome-wide interactions between many rice QR-genes and Xoo virulence genes in a multiple-to-multiple manner, presumably resulting either from direct protein-protein interactions or from genetic epistasis. The observed complex genetic interaction system between rice and Xoo likely exists in other crop-pathogen systems that would maintain high levels of diversity at their QR-loci/virulence-loci, resulting in dynamic coevolutionary consequences during their reciprocal adaptation.

The Qinghai-Tibet Plateau, also known as the Earth’s “third pole”, is sensitive to climate change due to its extensive areas at high elevation, which are presently dominated by snow and ice. Based on daily maximum and minimum surface air temperature and precipitation records at 94 meteorological stations throughout the Qinghai-Tibet Plateau, the spatial and temporal variation of 16 temperature and 11 precipitation extremal indices were investigated during 1960 to 2016. The warmth indices, including the numbers of warm days, warm nights, summer days, and tropical nights showed significantly increasing trends. In contrast, the cold indices, including the numbers of cool days, cool nights, ice days, and frost days significantly decreased. The number of frost day and ice days showed the fastest decrease (3.9 and 2.7 days/decade, respectively), whereas the growing season length showed the fastest growth trend (2.8 days/decade). The frequency and intensity of cold temperature events increased at high elevations, whereas warm temperature events showed the opposite trend. The regionally averaged monthly maximum 1-day precipitation and maximum consecutive 5-day precipitation increased by 0.17 and 0.70 mm per decade, respectively. In contrast, the number of consecutive dry days (CDD) and consecutive wet days (CWD) decreased at rates of 1.11 and 0.03 days per decade, respectively. The extreme precipitation events were more frequent in low-latitude and high-longitude regions. The strengthening Subtropical High Area (SHA) and Subtropical High Intensity (SHI), westward movement of Subtropical High Western Ridge Point (SHW) have contributed to the changes in climate extremes on the Qinghai-Tibet Plateau.

Extreme climatic events have become a global concern. Understanding changes in these events is essential to support efforts to reduce their impacts. We investigated the spatial and temporal variation of 15 temperature and 11 precipitation extremal indices based on daily observations from 1960 to 2016 at 794 meteorological stations in mainland China. The regionally averaged temperature index trends were consistent with global warming. An abrupt change in the trends for warmth-related indices mainly occurred from 1990 to 2000, and the year with an abrupt change for cold-related indices appeared earlier (mainly around 1990). The numbers of warm days, warm nights, summer days, and tropical nights increased significantly. In contrast, the numbers of cool days, cool nights, ice days, and frost days decreased significantly. The coldest night temperature had a strong and significant warming trend (0.4 degrees C center dot decade(-1)), whereas the number of frost days showed the fastest decrease (2.6 days center dot decade(-1)). The warmth and extremal indices decreased significantly with increasing latitude, whereas warming trends increased significantly with increasing longitude, and the warmth indices and extremal daily indices decreased with increasing elevation. The number of consecutive wet days decreased fastest, at 0.09 days center dot decade(-1), and the daily intensity index increased fastest, at 0.09 mm center dot day(-1)per decade. The extreme precipitation events decreased significantly with increasing latitude, but increased with increasing longitude. Large-scale atmospheric circulation indices (the Arctic Oscillation and the Western Pacific Subtropical High Intensity and Area indices) and the Western Ridge Point strongly influenced the warm and cold extremes and contributed significantly to climate change in mainland China. The Western Ridge Point and Subtropical High Area were the dominant drivers of extreme temperature and precipitation events, respectively, in mainland China.

High-quality soil moisture (SM) datasets are in great demand for climate, hydrology, and other fields, but detailed evaluation of SM products from various sources is scarce. Thus, using 670 SM stations worldwide, we evaluated and compared SM products from microwave remote sensing [Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) (C- and X-bands) and European Space Agency's Climate Change Initiative (ESA CCI)], land surface model [Global Land Data Assimilation System (GLDAS)], and reanalysis data [ECMWF Re-Analysis-Interim (ERA-Interim) and National Centers for Environmental Prediction (NCEP)] under different time scales and various climates and land covers. We find that: (a) ESA CCI and GLDAS have the closest values to the in situ SM on the annual scale, whereas others overestimate the SM; ERA-Interim (averaged R = 0.58) and ESA CCI (averaged R = 0.54) correlate best with the in situ data, while GLDAS performs worst. (b) Overall, the deviations of each product vary in seasons. ESA CCI and ERA-Interim products are closer to the in situ SM at seasonal scales, and AMSR-E and NCEP perform worst in December-February and June-August, respectively. (c) Except for NCEP and ERA-Interim, others can well reflect the intermonthly variation of the in situ SM. (d) Under various climates and land covers, AMSR-E products are less effective in cold climates, whereas GLDAS and NCEP products perform poorly in arid or temperate and dry climates. Moreover, the Bias and R of each SM product differ obviously under different forest types, especially the AMSR-E products. In summary, SM from ESA CCI is the best, followed by ERA-Interim product, and precipitation is an important auxiliary data for selecting high-quality SM stations and improving the accuracy of SM from GLDAS. These results can provide a reference for improving the accuracy of the above SM products.

科尔沁沙地是中国北方严重的沙漠化区域之一,理解其沙质草地生物量积累对降水变化的响应有利于该区域的生态恢复和后续经营管理.在植被-土壤水分耦合模型的基础上结合植被阈值-迟滞响应模式(T-D),在点尺度上模拟科尔沁沙质草地生长季植被生物量积累过程对降水变化的响应.结果 表明(1)植被生物量积累对降水量变化表现出明显的非线性响应.降水量增加,促进植被生物量积累,反之则抑制生物量积累,但在同等程度的降水量变化下生物量积累对降水增加的响应远大于对降水量减少的响应.(2)生物量积累对降水频率变化的响应与单次有效降水量变化在干早年和湿润年都显著正相关,但与累计有效降水量相关性微弱,而与有效降水间隔变化只在干旱年显著相关,表明在不同年份间降水频率变化实际上通过改变单次有效降水量和有效降水间隔来影响生物量的积累.(3)生物量积累过程对降水频率变化存在明显的响应阈值,但该阈值在不同的降水量和降水特征下并不相同.科尔沁沙质草地植被生物量积累过程对降水变化有明显的响应,植被-土壤水分耦合模拟与T-D模型的结合能有效地在日尺度上识别这种响应,这为探究植被和降水关系提供了新工具.

在半干旱地区,降水是制约草本植物群落结构与物种组成最主要的生态因子,而植物群落特征对降水变化的响应研究仍有很多不确定性.针对此现象,于2018年生长季在科尔沁沙地运用野外增减雨装置开展控制试验,通过自然对照、减少30％降水量、减少60％降水量、5月起连续干旱45 d、6月起连续干旱45 d、增加30％降水量、增加60％降水量7种试验处理,以期揭示草本植物群落特征及其物种组成对降水变化的响应,从而为植物生长对降水变化的适应机制研究提供理论依据.研究结果表明:1)减少60％降水量将造成沙地草本群落向单一结构发展,使物种丰富度指数、优势度指数和多样性指数显著减少,其减少率依次为8.57％、1.36％和4.80％,同时降低植物生产力.2)5月起连续干旱45 d对沙地草本植物物种组成、物种多样性和群落生产力无显著影响.3)6月起连续干旱45 d影响沙地草本植物多个物种重要值,导致物种密度减少,但对植物物种多样性和群落生产力影响不显著.半干旱沙地植物群落对长期干旱事件响应较大,对短期极端干旱事件具有一定的抵抗力.

封育是退化沙地植被恢复与生态重建的重要措施,理解长期处于封育状态下不同类型沙地植物群落特征变化及其影响因素有利于沙地植被恢复和生态重建。该文基于对科尔沁沙地长期封育的流动沙丘（2005年封育）、固定沙丘（1985年封育）和沙质草地（1997年封育）连续多年（2005–2017年）的植物群落调查,结合土壤种子库、土壤养分以及气象数据,分析了植物群落特征变化及其对环境变化的响应。研究结果表明流动沙丘植被盖度显著增加,群落生物量和物种多样性年际间波动变化,但无明显趋势;固定沙丘植物群落存在逆行演替趋势,具体表现为群落生物量、灌木和半灌木以及豆科优势度显著下降,而一年生和多年生杂类草优势度显著增加;沙质草地群落物种丰富度和多年生禾草优势度存在降低趋势,并且一年生杂类草优势度明显高于其他功能群,群落存在退化现象。3类沙地土壤种子密度变化不显著,而种子丰富度在流动沙丘显著增加,在固定沙丘和沙质草地有下降趋势,土壤养分仅有有效氮和有效磷含量增加。回归分析结果表明气温和降水是影响年内生物量积累的主要因素,但对年际间群落生物量和物种丰富度变化影响不大。除趋势对应分析结果显示土壤种子库与植物群落之间存在很高的相似性,典型相关分析结果表明沙质草地植物群落与土壤养分紧密相关,而固定沙丘群落主要与土壤水分紧密相关。综合以上结果可知,封育33年的固定沙丘群落和封育21年的沙质草地群落都存在退化现象,而封育11年的流动沙丘群落正在缓慢恢复,因此封育年限的设定对退化沙地植被恢复至关重要,封育时间过长不仅不利于植物群落恢复,反而会使群落发生逆行演替,建议封育年限的设定应综合考虑植被退化程度、土壤养分状况、土壤种子库基础以及气候条件等因素的影响。

水分是干旱半干旱沙地生态系统最大的限制因子,研究植被盖度和土壤水分之间的关系有助于沙地生态恢复和保护.基于生长季科尔沁沙质草地不同植被盖度下土壤水分动态和降水的观测试验,分析了沙质草地植被盖度和土壤水分的耦合关系.结果 表明:在土壤剖面上土壤水分存在明显的分层结构,依次为水分剧变层(0～40 cm)、缓变层(40～100 cm)和稳定层(100～180 cm);植被盖度对土壤水分有很大影响,不同植被盖度下土壤含水量存在显著差异,土壤水分与盖度之间呈倒“V”型关系,土壤水分状况在28％的盖度下最优;不同的植被盖度下土壤水分对降水的响应也存在差异,在13％盖度下响应最敏感,28％和46％的盖度下响应微弱,后二者的土壤水分也相对稳定.在沙地生态恢复建设过程中合理的植被盖度配置可提高降水利用效率,并能使土壤水分和植被达到一种良好的平衡状态,从而有利于生态系统的稳定.

Bacterial blight disease of rice,caused by Xanthomonas oryzae pv.oryzae (Xoo),is one of the most devastating rice diseases worldwide.In this study,total 174 of rice core germplasm materials from 26 provinces of China were evaluated resistance to BB by inoculation with six representative Xoo strains of China and the Philippines.The results showed there was distinct difference of bacterial blight resistance among cuhivars from rice different cultivation regions,and subgroup specificity between indica and japonica rice.Six japonica cultivars and seven indica cultivars were resistant to two or more than two Xoo strains,among them,Shangujiu,Maguzi,Baoerfu and Gu154 exhibited broader resistance spectrums.These results will provide useful information for improvement bacterial blight resistance in rice breeding program.

Bacterial blight, which is caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the most devastating rice diseases worldwide. The development and use of disease-resistant cultivars have been the most effective strategy to control bacterial blight. Identifying the genes mediating bacterial blight resistance is a prerequisite for breeding cultivars with broad-spectrum and durable resistance. We herein describe a genome-wide association study involving 172 diverse Oryza sativa ssp. indica accessions to identify loci influencing the resistance to representative strains of six Xoo races. Twelve resistance loci containing 121 significantly associated signals were identified using 317,894 single nucleotide polymorphisms, which explained 13.3-59.9% of the variability in lesion length caused by Xoo races P1, P6, and P9a. Two hotspot regions (L11 and L12) were located within or nearby two cloned R genes (xa25 and Xa26) and one fine-mapped R gene (Xa4). Our results confirmed the relatively high resolution of genome-wide association studies. Moreover, we detected novel significant associations on chromosomes 2, 3, and 6-10. Haplotype analyses of xa25, the Xa26 paralog (MRKc; LOC_Os11g47290), and a Xa4 candidate gene (LOC_11g46870) revealed differences in bacterial blight resistance among indica subgroups. These differences were responsible for the observed variations in lesion lengths resulting from infections by Xoo races P1 and P9a. Our findings may be relevant for future studies involving bacterial blight resistance gene cloning, and provide insights into the genetic basis for bacterial blight resistance in indica rice, which may be useful for knowledge-based crop improvement.

Anther cuticle and pollen exine are the major protective barriers against various stresses. The proper functioning of genes expressed in the tapetum is vital for the development of pollen exine and anther cuticle. In this study, we report a tapetum-specific gene, Abnormal Pollen Vacuolation1 (APV1), in maize that affects anther cuticle and pollen exine formation. The apv1 mutant was completely male sterile. Its microspores were swollen, less vacuolated, with a flat and empty anther locule. In the mutant, the anther epidermal surface was smooth, shiny, and plate-shaped compared with the three-dimensional crowded ridges and randomly formed wax crystals on the epidermal surface of the wild-type. The wild-type mature pollen had elaborate exine patterning, whereas the apv1 pollen surface was smooth. Only a few unevenly distributed Ubisch bodies were formed on the apv1 mutant, leading to a more apparent inner surface. A significant reduction in the cutin monomers was observed in the mutant. APV1 encodes a member of the P450 subfamily, CYP703A2-Zm, which contains 530 amino acids. APV1 appeared to be widely expressed in the tapetum at the vacuolation stage, and its protein signal co-localized with the endoplasmic reticulum (ER) signal. RNA-Seq data revealed that most of the genes in the fatty acid metabolism pathway were differentially expressed in the apv1 mutant. Altogether, we suggest that APV1 functions in the fatty acid hydroxylation pathway which is involved in forming sporopollenin precursors and cutin monomers that are essential for the development of pollen exine and anther cuticle in maize.

Improving the salt tolerance of direct-seeding rice at the seed germination stage is a major breeding goal in many Asian rice-growing countries, where seedlings must often establish in soils with a high salt content. Thus, it is important to understand the genetic mechanisms of salt tolerance in rice and to screen for germplasm with salt tolerance at the seed germination stage. Here, we investigated seven seed germination-related traits under control and salt-stress conditions and conducted a genome-wide association study based on the re-sequencing of 478 diverse rice accessions.