Thermo-Sensitive Spikelet Defects 1 acclimatizes rice spikelet initiation and development to high temperature.

Crop reproductive development is vulnerable to heat stress, and the genetic modulation of thermotolerance during the reproductive phase, especially the early stage, remains poorly understood. We isolated a Poaceae-specific FAR-RED ELONGATED HYPOCOTYLS3 (FHY3)/FAR-RED IMPAIRED RESPONSE1 (FAR1)family transcription factor, Thermo-sensitive Spikelet Defects 1 (TSD1), derived from transposase in rice (Oryza sativa) TSD1 was highly expressed in spikelets, induced by heat, and specifically enhanced the thermotolerance of spikelet morphogenesis. Disrupting TSD1 did not affect vegetative growth but markedly retarded spikelet initiation and development, as well as caused varying degrees of spikelet degeneration, depending on the temperature. Most tsd1 spikelets were normal at low temperature but gradually degenerated as temperature increased, and all disappeared at high temperature, leading to naked branches. TSD1 directly promoted the transcription of YABBY1 and YABBY3 and could physically interact with YABBY1 and three TOB proteins, YABBY5, YABBY4, and YABBY3. These YABBY proteins can form either homodimers or heterodimers and play an important role in spikelet morphogenesis, similar to TSD1. Notably, the knockout mutant yab5-ko and double mutant tsd1 yab5-ko resembled tsd1 in spikelet appearance and response to temperature, indicating that these genes likely participate in spikelet development through the cooperative TSD1-YABBY module. These findings reveal a distinctive function of FHY3/FAR1 family genes and a unique TSD1-YABBY complex to acclimate spikelet development to high temperature in rice, providing insight into the regulating pathway of enhancing thermotolerance in plant reproductive development.

Temporal resolution of ultrafast compressive imaging using a single-chirped optical probe.

Ultrafast compressive imaging captures three-dimensional spatiotemporal information of transient events in a single shot. When a single-chirped optical probe is applied, the temporal information is obtained from the probe modulated in amplitude or phase using a direct frequency-time mapping method. Here, we extend the analysis of the temporal resolution of conventional one-dimensional ultrafast measurement techniques such as spectral interferometry to that in three-dimensional ultrafast compressive imaging. In this way, both the amplitude and phase of the probe are necessary for a full Fourier transform method, which obtains temporal information with an improved resolution determined by probe spectral bandwidth. The improved temporal resolution potentially enables ultrafast compressive imaging with an effective imaging speed at the quadrillion-frames-per-second level.

The evolutionary origin and domestication history of goldfish (Carassius auratus).

Goldfish have been subjected to over 1,000 y of intensive domestication and selective breeding. In this report, we describe a high-quality goldfish genome (2n = 100), anchoring 95.75% of contigs into 50 pseudochromosomes. Comparative genomics enabled us to disentangle the two subgenomes that resulted from an ancient hybridization event. Resequencing 185 representative goldfish variants and 16 wild crucian carp revealed the origin of goldfish and identified genomic regions that have been shaped by selective sweeps linked to its domestication. Our comprehensive collection of goldfish varieties enabled us to associate genetic variations with a number of well-known anatomical features, including features that distinguish traditional goldfish clades. Additionally, we identified a tyrosine-protein kinase receptor as a candidate causal gene for the first well-known case of Mendelian inheritance in goldfish-the transparent mutant. The goldfish genome and diversity data offer unique resources to make goldfish a promising model for functional genomics, as well as domestication.

Solanaceous plants switch to cytokinin-mediated immunity against Ralstonia solanacearum under high temperature and high humidity.

Plant diseases generally tend to be more serious under conditions of high temperature and high humidity (HTHH) than under ambient temperature, but plant immunity against pathogen attacks under HTHH remains elusive. Herein, we used pepper as an example to study how Solanaceae cope with Ralstonia solanacearum infection (RSI) under HTHH by performing RNA-seq combined with the reverse genetic method. The result showed that immunities mediated by salicylic acid (SA) and jasmonic acid (JA) in pepper roots were activated by RSI under ambient temperature. However, upon RSI under HTHH, JA signalling was blocked and SA signalling was activated early but its duration was greatly shortened in pepper roots, instead, expression of CaIPT5 and Glutathione S-transferase encoding genes, as well as endogenous content of trans-Zeatin, were enhanced. In addition, by silencing in pepper plants and overexpression in Nicotiana benthamiana, CaIPT5 was found to act positively in the immune response to RSI under HTHH in a way related to CaPRP1 and CaMgst3. Furthermore, the susceptibility of pepper, tomato and tobacco to RSI under HTHH was significantly reduced by exogenously applied tZ, but not by either SA or MeJA. All these data collectively suggest that pepper employs cytokinin-mediated immunity to cope with RSI under HTHH.

Construction of a High-Density Recombination Bin-Based Genetic Map Facilitates High-Resolution Mapping of a Major QTL Underlying Anthocyanin Pigmentation in Eggplant.

High-density genetic maps can significantly improve the resolution of QTL mapping. We constructed a high-density recombination bin-based genetic map of eggplant based on 200 F2 plants from an interspecific cross (Solanum melongena × S. incanum) using the whole genome resequencing strategy. The map was 2022.8 cM long, covering near 99% of the eggplant genome. The map contained 3776 bins, with 3644 (96.5%) being effective (position non-redundant) ones, giving a nominal average distance of 0.54 cM and an effective average distance of 0.56 cM between adjacent bins, respectively. Using this map and 172 F2:3 lines, a major QTL with pleiotropic effects on two anthocyanin pigmentation-related traits, leaf vein color (LVC) and fruit pericarp color (FPC), was steadily detected in a bin interval of 2.28 cM (or 1.68 Mb) on chromosome E10 in two cropping seasons, explaining ~65% and 55% of the phenotypic variation in LVC and FPC, respectively. Genome-wide association analysis in this population validated the QTL and demonstrated the correctness of mapping two bins of chromosome E02 onto E10. Bioinformatics analysis suggested that a WDR protein gene inside the bin interval with reliable effective variation between the two parents could be a possible candidate gene of the QTL.

BRM: a statistical method for QTL mapping based on bulked segregant analysis by deep sequencing.

MOTIVATION: Bulked segregant analysis by deep sequencing (BSA-seq) has been widely used for quantitative trait locus (QTL) mapping in recent years. A number of different statistical methods for BSA-seq have been proposed. However, determination of significance threshold, the key point for QTL identification, remains to be a problem that has not been well solved due to the difficulty of multiple testing correction. In addition, estimation of the confidence interval is also a problem to be solved. RESULTS: In this paper, we propose a new statistical method for BSA-seq, named Block Regression Mapping (BRM). BRM is robust to sequencing noise and is applicable to the case of low sequencing depth. Significance threshold can be reasonably determined by taking multiple testing correction into account. Meanwhile, the confidence interval of QTL position can also be estimated. AVAILABILITY AND IMPLEMENTATION: The R scripts of our method are open source under GPLv3 license at https://github.com/huanglikun/BRM. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

The transcriptional reprograming and functional identification of WRKY family members in pepper's response to Phytophthora capsici infection.

BACKGROUND: Plant transcription factors (TFs) are key transcriptional regulators to manipulate the regulatory network of host immunity. However, the globally transcriptional reprogramming of plant TF families in response to pathogens, especially between the resistant and susceptible host plants, remains largely unknown. RESULTS: Here, we performed time-series RNA-seq from a resistant pepper line CM334 and a susceptible pepper line EC01 upon challenged with Phytophthora capsici, and enrichment analysis indicated that WRKY family most significantly enriched in both CM334 and EC01. Interestingly, we found that nearly half of the WRKY family members were significantly up-regulated, whereas none of them were down-regulated in the two lines. These induced WRKY genes were greatly overlapped between CM334 and EC01. More strikingly, most of these induced WRKY genes were expressed in time-order patterns, and could be mainly divided into three subgroups: early response (3 h-up), mid response (24 h-up) and mid-late response (ML-up) genes. Moreover, it was found that the responses of these ML-up genes were several hours delayed in EC01. Furthermore, a total of 19 induced WRKY genes were selected for functional identification by virus-induced gene silencing. The result revealed that silencing of CaWRKY03-6, CaWRKY03-7, CaWRKY06-5 or CaWRKY10-4 significantly increase the susceptibility to P. capsici both in CM334 and EC01, indicating that they might contribute to pepper's basal defense against P. capsici; while silencing of CaWRKY08-4 and CaWRKY01-10 significantly impaired the disease resistance in CM334 but not in EC01, suggesting that these two WRKY genes are prominent modulators specifically in the resistant pepper plants. CONCLUSIONS: These results considerably extend our understanding of WRKY gene family in pepper's resistance against P. capsici and provide potential applications for genetic improvement against phytophthora blight.

Bulked Segregant Analysis Coupled with Whole-Genome Sequencing (BSA-Seq) Mapping Identifies a Novel pi21 Haplotype Conferring Basal Resistance to Rice Blast Disease.

Basal or partial resistance has been considered race-non-specific and broad-spectrum. Therefore, the identification of genes or quantitative trait loci (QTLs) conferring basal resistance and germplasm containing them is of significance in breeding crops with durable resistance. In this study, we performed a bulked segregant analysis coupled with whole-genome sequencing (BSA-seq) to identify QTLs controlling basal resistance to blast disease in an F2 population derived from two rice varieties, 02428 and LiXinGeng (LXG), which differ significantly in basal resistance to rice blast. Four candidate QTLs, qBBR-4, qBBR-7, qBBR-8, and qBBR-11, were mapped on chromosomes 4, 7, 8, and 11, respectively. Allelic and genotypic association analyses identified a novel haplotype of the durable blast resistance gene pi21 carrying double deletions of 30 bp and 33 bp in 02428 (pi21-2428) as a candidate gene of qBBR-4. We further assessed haplotypes of Pi21 in 325 rice accessions, and identified 11 haplotypes among the accessions, of which eight were novel types. While the resistant pi21 gene was found only in japonica before, three Chinese indica varieties, ShuHui881, Yong4, and ZhengDa4Hao, were detected carrying the resistant pi21-2428 allele. The pi21-2428 allele and pi21-2428-containing rice germplasm, thus, provide valuable resources for breeding rice varieties, especially indica rice varieties, with durable resistance to blast disease. Our results also lay the foundation for further identification and functional characterization of the other three QTLs to better understand the molecular mechanisms underlying rice basal resistance to blast disease.

Estimation of QTL heritability based on pooled sequencing data.

Motivation: Bulked segregant analysis combined with next generation sequencing has proven to be a simple and efficient approach for fast mapping of quantitative trait loci (QTLs). However, how to estimate the proportion of phenotypic variance explained by a QTL (or termed QTL heritability) in such pooled QTL mapping is an unsolved problem. Results: In this paper, we propose a method called PQHE to estimate QTL heritability using pooled sequencing data obtained under different experimental designs. Simulation studies indicated that our method is correct and feasible. Four practical examples from rice and yeast are demonstrated, each representing a different situation. Availability and implementation: The R scripts of our method are open source under GPLv3 license at http://genetics.fafu.edu.cn/PQHE or https://github.com/biotangweiqi/PQHE. The R scripts require the R package rootSolve. Contact: wuwr@fafu.edu.cn. Supplementary information: Supplementary data are available at Bioinformatics online.

Evaluation of Radiation Response in CoCrFeCuNi High-Entropy Alloys.

CoCrFeCuNi high-entropy alloys (HEAs) prepared by arc melting were irradiated with a 100 keV He+ ion beam. Volume swelling and hardening induced by irradiation were evaluated. When the dose reached 5.0 × 1017 ions/cm2, the Cu-rich phases exhibited more severe volume swelling compared with the matrix phases. This result indicated that the Cu-rich phases were favorable sites for the nucleation and gathering of He bubbles. X-ray diffraction indicated that all diffraction peak intensities decreased regularly. This reduction suggested loosening of the irradiated layer, thereby reducing crystallinity, under He+ ion irradiation. The Nix-Gao model was used to fit the measured hardness in order to obtain a hardness value H0 that excludes the indentation size effect. At ion doses of 2.5 × 1017 ions/cm2 and 5.0 × 1017 ions/cm2, the HEAs showed obvious hardening, which could be attributed to the formation of large amounts of irradiation defects. At the ion dose of 1.0 × 1018 ions/cm2, hardening was reduced, owing to the exfoliation of the original irradiation layer, combined with recovery induced by long-term thermal spike. This study is important to explore the potential uses of HEAs under extreme irradiation conditions.

Bacillus bingmayongensis sp. nov., isolated from the pit soil of Emperor Qin's Terra-cotta warriors in China.

A Bacillus-like isolate, strain FJAT-13831(T), isolated from the No. 1 pit soil of Emperor Qin's Terra-cotta Warriors in Xi'an City, China, was studied to determine its taxonomic status. Dominant fatty acids of this organism included iso-C15:0, iso-C17:0, C16:0, iso-C13:0, anteiso-C15:0, and iso-C17:1ω5c. Comparative 16S rRNA gene sequence analysis confirmed the affiliation of this isolate to the genus Bacillus and indicated that it was closely related to Bacillus pseudomycoides DSM 12442(T) (99.72 % similarity). A phylogenetic analysis of the gyrB gene sequence similarities exhibited independent clustering of the isolate FJAT-13831(T) and showed 93.8 % (<95 %) sequence similarity with its closest phylogenetic neighbour B. pseudomycoides DSM 12442(T). Separate standing of the strain FJAT-13831(T) was supported by a whole genome-based phylogenetic analysis with an average nucleotide identity value of 91.47 (<95 %) between isolate FJAT-13831(T) and B. pseudomycoides DSM 12442(T) and was consistent with the results of DNA-DNA hybridization (69.1 % relatedness). These findings support the conclusion that the isolate FJAT-13831(T) represents a novel species, for which the name Bacillus bingmayongensis sp. nov. is proposed. The type strain is FJAT-13831(T) (= CGMCC 1.12043(T) = DSM 25427(T)).

A review on three-dimensional electrochemical technology for the antibiotic wastewater treatment.

The potential genotoxicity and non-biodegradability of antibiotics in the natural water bodies threaten the survival of various living things and cause serious environmental pollution and destruction. Three-dimensional (3D) electrochemical technology is considered a powerful means for antibiotic wastewater treatment as it can degrade non-biodegradable organic substances into non-toxic or harmless substances and even completely mineralize them under the action of electric current. Therefore, antibiotic wastewater treatment using 3D electrochemical technology has now become a hot research topic. Thus, in this review, a detailed and comprehensive investigation was conducted on the antibiotic wastewater treatment using 3D electrochemical technology, including the structure of the reactor, electrode materials, the influence of operating parameters, reaction mechanism, and combination with other technologies. Many studies have shown that the materials of electrode, especially particle electrode, have a great effect on the antibiotic wastewater treatment efficiency. The influence of operating parameters such as cell voltage, solution pH, and electrolyte concentration was very significant. Combination with other technologies such as membrane and biological technologies has effectively increased antibiotic removal and mineralization efficiency. In conclusion, the 3D electrochemical technology is considered as a promising technology for the antibiotic wastewater treatment. Finally, the possible research directions of the 3D electrochemical technology for antibiotic wastewater treatment were proposed.

Glucan Synthase-like 2 is Required for Seed Initiation and Filling as Well as Pollen Fertility in Rice.

BACKGROUND: The Glucan synthase-like (GSL) genes are indispensable for some important highly-specialized developmental and cellular processes involving callose synthesis and deposition in plants. At present, the best-characterized reproductive functions of GSL genes are those for pollen formation and ovary expansion, but their role in seed initiation remains unknown. RESULTS: We identified a rice seed mutant, watery seed 1-1 (ws1-1), which contained a mutation in the OsGSL2 gene. The mutant produced seeds lacking embryo and endosperm but filled with transparent and sucrose-rich liquid. In a ws1-1 spikelet, the ovule development was normal, but the microsporogenesis and male gametophyte development were compromised, resulting in the reduction of fertile pollen. After fertilization, while the seed coat normally developed, the embryo failed to differentiate normally. In addition, the divided endosperm-free nuclei did not migrate to the periphery of the embryo sac but aggregated so that their proliferation and cellularization were arrested. Moreover, the degeneration of nucellus cells was delayed in ws1-1. OsGSL2 is highly expressed in reproductive organs and developing seeds. Disrupting OsGSL2 reduced callose deposition on the outer walls of the microspores and impaired the formation of the annular callose sheath in developing caryopsis, leading to pollen defect and seed abortion. CONCLUSIONS: Our findings revealed that OsGSL2 is essential for rice fertility and is required for embryo differentiation and endosperm-free nucleus positioning, indicating a distinct role of OsGSL2, a callose synthase gene, in seed initiation, which provides new insight into the regulation of seed development in cereals.

Combined transcriptome and proteome analysis revealed the molecular regulation mechanisms of zinc homeostasis and antioxidant machinery in tobacco in response to different zinc supplies.

Zinc (Zn) is an essential micronutrient for plants. Adequate regulation of Zn uptake, transport and distribution, and adaptation to Zn-deficiency stress or Zn-excess toxicity are crucial for plant growth and development. However, little has been done to understand the molecular responses of plants toward different Zn supply levels. In the present study, we investigated the growth and physiological responses of tobacco seedlings grown under Zn-completely deficient, Zn-limiting, Zn-normal, and Zn-4-fold sufficient conditions, respectively, and demonstrated that Zn deficiency/limitation caused oxidative stress and impaired growth of tobacco plants. Combined transcriptome and proteome analysis revealed up-regulation of genes/proteins associated with Zn uptake and distribution, including ZIPs, NAS3s, and HMA1s, and up-regulation of genes/proteins involved in regulation of oxidative stress, including SODs, APX1s, GPX6, and GSTs in tobacco seedlings in response to Zn deficiency/limitation, suggesting that tobacco possessed mechanisms to regulate Zn homeostasis primarily through up-regulation of the ZIPs-NAS3s module, and to alleviate Zn deficiency/limitation-induced oxidative stress through activation of the antioxidant machinery. Our results provide novel insights into the adaptive mechanisms of tobacco in response to different Zn supplies, and would lay a theoretical foundation for development of varieties of tobacco or its relatives with high tolerance to Zn-deficiency.

Genome sequence of the aerobic bacterium Bacillus sp. strain FJAT-13831.

Bacillus sp. strain FJAT-13831 was isolated from the no. 1 pit soil of Emperor Qin's Terracotta Warriors in Xi'an City, People's Republic of China. The isolate showed a close relationship to the Bacillus cereus group. The draft genome sequence of Bacillus sp. FJAT-13831 was 4,425,198 bp in size and consisted of 5,567 genes (protein-coding sequences [CDS]) with an average length of 782 bp and a G+C value of 36.36%.

Optimization of BSA-seq experiment for QTL mapping.

Deep sequencing-based bulked segregant analysis (BSA-seq) has become a popular approach for quantitative trait loci (QTL) mapping in recent years. Effective statistical methods for BSA-seq have been developed, but how to design a suitable experiment for BSA-seq remains unclear. In this paper, we show in theory how the major experimental factors (including population size, pool proportion, pool balance, and generation) and the intrinsic factors of a QTL (including heritability and degree of dominance) affect the power of QTL detection and the precision of QTL mapping in BSA-seq. Increasing population size can improve the power and precision, depending on the QTL heritability. The best proportion of each pool in the population is around 0.25. So, 0.25 is generally applicable in BSA-seq. Small pool proportion can greatly reduce the power and precision. Imbalance of pool pair in size also causes decrease of the power and precision. Additive effect is more important than dominance effect for QTL mapping. Increasing the generation of filial population produced by selfing can significantly increase the power and precision, especially from F2 to F3. These findings enable researchers to optimize the experimental design for BSA-seq. A web-based program named BSA-seq Design Tool is available at http://124.71.74.135/BSA-seqDesignTool/ and https://github.com/huanglikun/BSA-seqDesignTool.

Comprehensive Genetic Analysis of Monokaryon and Dikaryon Populations Provides Insight Into Cross-Breeding of Flammulina filiformis.

Flammulina filiformis, as one of the most popular edible fungi in East Asia, is produced in an industrialized and standardized way. However, its monotonous variety and product convergence have seriously restricted the development of the industry. In this study, 11 cultivated strains and 13 wild strains of F. filiformis were collected from multiple regions of China and Japan and were performed genome sequencing. Together with genome data of six strains previously released, in total 23 dikaryons (formed by two monokaryons mating, can making fruiting body), 35 monokaryons (formed by protoplast-regenerating of dikaryon and isolating) were used for genetic diversity and population structure analysis based on the high-throughput genotyping. Firstly, a set of SNP markers with intrapopulation polymorphism including 849,987 bi-allelic SNPs were developed and basically covered all of 11 chromosomes with a high distribution density of 24.16 SNP markers per kb. The cultivated dikaryotic strains were divided into three subgroups, and their breeding history was made inferences, which is consistent with the available pedigree records. The wild dikaryotic strains were divided into two subgroups and showed varied contributions of genetic components with high genetic diversity. All the investigated dikaryons have a symmetric distribution pattern with their two constituent monokaryons in principal component analysis. Finally, we summarized the pedigree relationship diagram of F. filiformis main strains including six modules, and the genotypes of hybrids can be directly phased by the known parental allele according to it. This study provides a method to distinguish two sets of monokaryon haplotypes, and several valuable genetic resources of wild F. filiformis, and an effective strategy for guiding F. filiformis breeding based on the population structure and pedigree relationship in future.

LUX ARRHYTHMO Interacts With ELF3a and ELF4a to Coordinate Vegetative Growth and Photoperiodic Flowering in Rice.

The evening complex (EC) plays a critical role in photoperiod flowering in Arabidopsis. Nevertheless, the underlying functions of individual components and coordinate regulation mechanism of EC genes in rice flowering remain to be elucidated. Here, we characterized the critical role of LUX ARRHYTHMO (LUX) in photoperiod perception and coordinating vegetative growth and flowering in rice. Non-functional alleles of OsLUX extremely extended vegetative phase, leading to photoperiod-insensitive late flowering and great increase of grain yield. OsLUX displayed an obvious diurnal rhythm expression with the peak at dusk and promoted rice flowering via coordinating the expression of genes associated with the circadian clock and the output integrators of photoperiodic flowering. OsLUX combined with OsELF4a and OsELF3a or OsELF3b to form two ECs, of which the OsLUX-OsELF3a-OsELF4a was likely the dominant promoter for photoperiodic flowering. In addition, OsELF4a was also essential for promoting rice flowering. Unlike OsLUX, loss OsELF4a displayed a marginal influence under short-day (SD) condition, but markedly delayed flowering time under long-day (LD) condition. These results suggest that rice EC genes share the function of promoting flowering. This is agreement with the orthologs of SD plant, but opposite to the counterparts of LD species. Taken together, rice EC genes display similar but not identical function in photoperiodic flowering, probably through regulating gene expression cooperative and independent. These findings facilitate our understanding of photoperiodic flowering in plants, especially the SD crops.

Transcriptome Analyses Indicate Significant Association of Increased Non-Additive and Allele-Specific Gene Expression with Hybrid Weakness in Rice (Oryza sativa L.).

The heterosis in hybrid rice is highly affected by the environment and hybrid weakness occurs frequently depending on the genotypes of the hybrid and its parents. Hybrid weakness was also observed in our field experiments on nine rice hybrids produced by 3 × 3 incomplete diallel crosses. Among the nine hybrids, five displayed mid-parent heterosis (MPH) for grain yield per plant, while four showed mid-parent hybrid weakness (MPHW). A sequencing analysis of transcriptomes in panicles at the seed-filling stage revealed a significant association between enhanced non-additive gene expression (NAE) and allele-specific gene expression (ASE) with hybrid weakness. High proportions of ASE genes, with most being of mono-allele expression, were detected in the four MPHW hybrids, ranging from 22.65% to 45.97%; whereas only 4.80% to 5.69% of ASE genes were found in the five MPH hybrids. Moreover, an independence test indicated that the enhancements of NAE and ASE in the MPHW hybrids were significantly correlated. Based on the results of our study, we speculated that an unfavorable environment might cause hybrid weakness by enhancing ASE and NAE at the transcriptome level.