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White-backed planthopper (WBPH) is one of the most serious pests in rice production. Breeding resistant varieties is the most economical and effective strategy to control the white-backed planthopper. In this study, we found that Guangxi wild rice variety 'Y11' had high resistance to white-backed planthopper. The number and survival rate of WBPH were significantly less than the susceptible variety 'Guanghui 998'. These results showed that 'Y11' displayed higher antixenosis and antibiosis against WBPH. Subsequently, 'Y11' was as the donor parent and an indica cultivar 'Guanghui 998' was as the recurrent parent by continuous backcrossing and selfing to obtain the BC3F9 population. Furthermore, to identify the quantitative trait locus (QTL) for white-backed planthopper resistance, we completed the evaluation of this population for WBPH resistance at seedling stage and constructed the genome-wide linkage map. Three QTLs were detected on the three different rice chromosomes, and designed as qWBPH2Y11, qWBPH6Y11, and qWBPH11Y11, respectively. The LOD values were 4.8, 2.5, and 3.7, which accounted for 9.3%, 2.3%, and 5.6% of the phenotypic variation, respectively. All of the resistance alleles were from resistant parent 'Y11'. Plant harboring qWBPH2Y11 was selected from BC3F9 population to continuously backcross with 'Guanghui 998'. The near isogenic line of qWBPH2Y11 was developed by molecular marker assisted selection, which displayed higher resistance to WBPH than the background parent 'Guanghui 998'. The mapping of WBPH resistance QTLs and the development of the near isogenic line in this study will be helpful for cloning resistance genes and breeding resistant in rice cultivars. [ABSTRACT FROM AUTHOR]

Rice is a salt-sensitive crop, and salt stress can cause significant reduction in rice yield. China's total saline area is large and growing rapidly. Therefore, it is necessary to screen for the salt-tolerant rice germplasm and cultivate these varieties. In this study, we evaluated the relative salt damage rate of 419 core germplasm of Guangxi rice landraces at seed germination stage under 1.5% NaCl salt stress, and identified the salt-tolerant loci by whole-genome association analysis. The results showed that the average germination rate under salt stress was 57.67%, which was significantly 92.55% lower than that of control group, and the Shapiro-Wilk test (0.9301) found that the distribution did not conform to normal distribution. Based on 208,993 SNP markers, 419 core germplasm was divided into 6 subgroups. We used general linear model (GLM) and mixed linear model (MLM) analysis to identify 129 and 1 significantly associated SNPs, respectively, which were distributed on chromosomes 1, 2, 3, 4, 5, 6, 8, 9, and 12. Among the 14 regions that were significantly associated with rice salt tolerance, 13 regions overlapped with previously identified or cloned salt tolerance genes. The significantly associated region Chr. 8:10,564,948-10,733,175 was reported for the first time and named qGR8. There were 53 genes in qGR8 region, 34 of which were compared with transcriptome data to obtain the expression profiles. We compared the expression profiles and speculated that LOC_Os08g17370 was a candidate gene. This gene is a member of transmembrane 9 superfamily and is up-regulated in roots and leaves of salt-tolerant parent. Thus, this gene might be a novel salt-tolerant gene in qGR8 region at germination stage in rice. These results lay a foundation for cloning new genes of salt-tolerant and provide new genetic resources for breeding salt-tolerant rice varieties. [ABSTRACT FROM AUTHOR]

Many insect pests, including the brown planthopper (BPH), undergo windborne migration that is challenging to observe and track. It remains controversial about their migration patterns and largely unknown regarding the underlying genetic basis. By analyzing 360 whole genomes from around the globe, we clarify the genetic sources of worldwide BPHs and illuminate a landscape of BPH migration showing that East Asian populations perform closed-circuit journeys between Indochina and the Far East, while populations of Malay Archipelago and South Asia undergo one-way migration to Indochina. We further find round-trip migration accelerates population differentiation, with highly diverged regions enriching in a gene desert chromosome that is simultaneously the speciation hotspot between BPH and related species. This study not only shows the power of applying genomic approaches to demystify the migration in windborne migrants but also enhances our understanding of how seasonal movements affect speciation and evolution in insects.

Background: The white-backed planthopper (WBPH), Sogatella furcifera , causes great damage to many crops (mainly rice) by direct feeding or transmitting plant viruses. The previous genome assembly was generated by second-generation sequencing technologies, with a contig N50 of only 51.5 kb, and contained a lot of heterozygous sequences., Methods: We utilized third-generation sequencing technologies and Hi-C data to generate a high-quality chromosome-level assembly. We also provide a large amount of transcriptome data for full-length transcriptome analysis and gender differential expression analysis., Results: The final assembly comprised 56.38 Mb, with a contig N50 of 2.20 Mb and a scaffold N50 of 45.25 Mb. Fourteen autosomes and one X chromosome were identified. More than 99.5% of the assembled bases located on the 15 chromosomes. 95.9% of the complete BUSCO Hemiptera genes were detected in the final assembly and 16,880 genes were annotated. 722 genes were relatively highly expressed in males, while 60 in the females., Conclusion: The integrated genome, definite sex chromosomes, comprehensive transcriptome profiles, high efficiency of RNA interference and short life cycle substantially made WBPH an efficient research object for functional genomics., Competing Interests: The authors declare no conflict of interest, financial or otherwise., (© 2022 Bentham Science Publishers.)

Objective: To investigate effects of retinol on the expressions of epidermal growth factor (EGF), stem cell factor (SCF), colony-stimulating factor 1 (CSF1) and leukemia inhibitory factor (LIF) in cultured human umbilical-derived mesenchymal stem cells (UCMSCs)., Methods: Human UCMSCs were isolated from human umbilical cord and identified for immunophenotypes. The cells were then cultured in DMEM/F12 media supplemented with 12% fetal bovine serum (FBS), 12% FBS+1 µmol/L retinol, 15% knockout serum replacement (KSR) and 15% KSR+ 1 µmol/L retinol. The expressions of the cytokines EGF, SCF, CSF1 and LIF in the cells were detected using RT-PCR and ELISA., Results: The isolated cells exhibited characteristic immunophenotypes of human UCMSCs and expressed EGF, CSF1 and SCF at both mRNA and protein levels but not LIF protein. Retinol (1 µmol/L) significantly promoted the expressions of SCF and CSF1 at both mRNA and protein levels but did not result in changes of EGF and LIF expressions in human UCMSCs., Conclusion: Retinol at the concentration of 1 µmol/L can promote expression of SCF and CSF1 in human UCMSCs in vitro.