Search

Ensuring national food security is crucial for strengthening the agriculture sector of China, and it holds both theoretical and practical significance in the context of the “dual circulation” (i. e., domestic and international economic circulations) strategy. This study explores the resilience of China’s food security and its capacity for risk management under the “dual circulation” framework, providing an analysis of the current status, characteristics, influencing factors, and feasible pathways for enhancing food security resilience and risk management capabilities. The study identifies key factors influencing food security resilience and risk management, including the agricultural production base, the level of agricultural technology, food production methods, support policies for food production, and the international trade environment. Feasible pathways for enhancing food security resilience and risk management capabilities include improving the stability of food supply, enhancing the adaptability of food production, promoting the sustainability of food production, maintaining the continuity of policy systems, and strengthening the coordination between domestic and international markets. To achieve these goals, it is recommended to solidify the foundation of grain production capacity, improve technological support for grain production, strengthen intelligent monitoring and management, accelerate the establishment of guarantee systems, and optimize grain import and export trade. These measures will enhance China’s food security resilience and risk management capabilities in the context of “dual circulation”.

Forestalling a large-scale reemergence of poverty is a basic task in the 14th Five-Year Plan period, which entails consolidating and expanding the achievements in poverty alleviation. This means we should manage the risks of people returning to poverty and enhance tiered and targeted assistance of various types to low-income residents, striving for a robust long-term mechanism of poverty reduction. In this paper, we first analyze the main challenges faced by consolidating and expanding the achievements of the battle against poverty in the new development stage. Among others, populations that have been lifted out of poverty falling back into it is complicated in causes, and industries in rural areas are short of sustainable development capacity. Other challenges remain, such as deficient rural medical services, drinking water safety in areas that have shaken off poverty, and outdated rural governance that is out of tune with the new situation. Subsequently, we summarize the basic logic of consolidating and expanding the achievements in poverty alleviation. We put forward three key tasks concerning increasing the institutional supply, relieving resources and environmental constraints, and stimulating endogenous impetus for those who have been lifted out of poverty. Lastly, we propose policy suggestions on consolidating and expanding the achievements in poverty alleviation from five aspects, including building an identification mechanism of low-income rural residents, promoting the performance of rural industries, improving governance capacity in rural areas, conducting rural doctors training programs, and ensuring drinking water safety.

SUMMARY: Citrus is a model plant for studying adventitious embryos, a form of asexual reproduction controlled by a single dominant gene, RWP. This gene has been identified as the causal gene for nucellar embryogenesis, but its function has not yet been fully understood. In this study, we used the fast‐growing Fortunella hindsii as a system to explore chromatin accessibility during the nucellar embryony initiation, emphasizing elevated chromatin accessibility in polyembryonic (PO) genotypes compared to monoembryonic ones (MO). Notably, a higher level of accessible chromatin was observed in one allele of the promoter region of FhRWP, consistent with increased expression of the allele carrying the causal structural variant. By independently performing RNAi and gene editing experiments on PO genotypes, we found the downregulation of FhRWP expression could reduce the number of nucellar embryos, while its knockout resulted in abnormal axillary bud development. In overexpression experiments, FhRWP was identified as having the unique capability of inducing the embryogenic callus formation in MO stem segments, possibly through the regulation of the WUS‐CLV signaling network and the ABA and cytokinin pathway, marking the inaugural demonstration of FhRWP's potential to reignite somatic cells' embryogenic fate. This study reveals the pleiotropic function of RWP in citrus and constructs a regulatory network during adventitious embryo formation, providing a new tool for bioengineering applications in plant regeneration. Significance Statement: FhRWP plays a central role in regulating multiple developmental phenotypes, including axillary bud differentiation, nucellar embryo formation, and somatic embryogenesis in citrus. [ABSTRACT FROM AUTHOR]

Dwarfing is a pivotal agronomic trait affecting both yield and quality. Citrus species exhibit substantial variation in plant height, among which internode length is a core element. However, the molecular mechanism governing internode elongation remains unclear. Here, we unveiled that the transcriptional cascade consisting of B‐BOX DOMAIN PROTEIN 22 (BBX22) and ELONGATED HYPOCOTYL 5 (HY5) finely tunes plant height and internode elongation in citrus. Loss‐of‐function mutations of BBX22 in an early‐flowering citrus (Citrus hindsii "SJG") promoted internode elongation and reduced pigment accumulation, whereas ectopic expression of BBX22 in SJG, sweet orange (C. sinensis), pomelo (C. maxima) or heterologous expression of BBX22 in tomato (Solanum lycopersicum) significantly decreased internode length. Furthermore, exogenous application of gibberellin A3 (GA3) rescued the shortened internode and dwarf phenotype caused by BBX22 overexpression. Additional experiments revealed that BBX22 played a dual role in regulation internode elongation and pigmentation in citrus. On the one hand, it directly bound to and activated the expression of HY5, GA metabolism gene (GA2 OXIDASE 8, GA2ox8), carotenoid biosynthesis gene (PHYTOENE SYNTHASE 1, PSY1) and anthocyanin regulatory gene (Ruby1, a MYB DOMAIN PROTEIN). On the other hand, it acted as a cofactor of HY5, enhancing the ability of HY5 to regulate target genes expression. Together, our results reveal the critical role of the transcriptional cascade consisting of BBX22 and HY5 in controlling internode elongation and pigment accumulation in citrus. Unraveling the crosstalk regulatory mechanism between internode elongation and fruit pigmentation provides key genes for breeding of novel types with both dwarf and health‐beneficial fortification in citrus. [ABSTRACT FROM AUTHOR]

Background: With the rapid development of single-cell sequencing technology, histological studies are no longer limited to conventional homogenized tissues. Laser microdissection enables the accurate isolation of specific tissues or cells, and when combined with next-generation sequencing, it can reveal important biological processes at the cellular level. However, traditional laser microdissection techniques have often been complicated and time-consuming, and the quality of the RNA extracted from the collected samples has been inconsistent, limiting follow-up studies. Therefore, an improved, simple, and efficient laser microdissection method is urgently needed. Results: We omitted the sample fixation and cryoprotectant addition steps. Instead, fresh samples were embedded in Optimal Cutting Temperature medium within 1.5 ml centrifuge tube caps, rapidly frozen with liquid nitrogen, and immediately subjected to cryosectioning. A series of section thicknesses of citrus rind were tested for RNA extraction, which showed that 18 μm thickness yielded the highest quality RNA. By shortening the dehydration time to one minute per ethanol gradient and omitting the tissue clearing step, the resulting efficient dehydration and preserved morphology ensured high-quality RNA extraction. We also propose a set of laser microdissection parameters by adjusting the laser power to optimal values, reducing the aperture size, and lowering the pulse frequency. Both the epidermal and subepidermal cells from the citrus rind were collected, and RNA extraction was completed within nine hours. Using this efficient method, the transcriptome sequencing of the isolated tissues generated high-quality data with average Q30 values and mapping rates exceeding 91%. Moreover, the transcriptome analysis revealed significant differences between the cell layers, further confirming the effectiveness of our isolation approach. Conclusions: We developed a simple and rapid laser microdissection method and demonstrated its effectiveness through a study based on citrus rind, from which we generated high-quality transcriptomic data. This fast and efficient method of cell isolation, combined with transcriptome sequencing not only contributes to precise histological studies at the cellular level in citrus but also provides a promising approach for cell-specific transcriptome analysis in a broader range of other plant tissues. [ABSTRACT FROM AUTHOR]

Summary: Self‐incompatibility (SI) is a widespread prezygotic mechanism for flowering plants to avoid inbreeding depression and promote genetic diversity. Citrus has an S‐RNase‐based SI system, which was frequently lost during evolution. We previously identified a single nucleotide mutation in Sm‐RNase, which is responsible for the loss of SI in mandarin and its hybrids. However, little is known about other mechanisms responsible for conversion of SI to self‐compatibility (SC) and we identify a completely different mechanism widely utilized by citrus. Here, we found a 786‐bp miniature inverted‐repeat transposable element (MITE) insertion in the promoter region of the FhiS2‐RNase in Fortunella hindsii Swingle (a model plant for citrus gene function), which does not contain the Sm‐RNase allele but are still SC. We demonstrate that this MITE plays a pivotal role in the loss of SI in citrus, providing evidence that this MITE insertion prevents expression of the S‐RNase; moreover, transgenic experiments show that deletion of this 786‐bp MITE insertion recovers the expression of FhiS2‐RNase and restores SI. This study identifies the first evidence for a role for MITEs at the S‐locus affecting the SI phenotype. A family‐wide survey of the S‐locus revealed that MITE insertions occur frequently adjacent to S‐RNase alleles in different citrus genera, but only certain MITEs appear to be responsible for the loss of SI. Our study provides evidence that insertion of MITEs into a promoter region can alter a breeding strategy and suggests that this phenomenon may be broadly responsible for SC in species with the S‐RNase system. [ABSTRACT FROM AUTHOR]

SUMMARY: The biogenesis and differentiation (B&D) of amyloplasts contributes to fruit flavor and color. Here, remodeling of starch granules, thylakoids and plastoglobules was observed during development and ripening in two kiwifruit (Actinidia spp.) cultivars – yellow‐fleshed 'Hort16A' and green‐fleshed 'Hayward'. A protocol was developed to purify starch‐containing plastids with a high degree of intactness, and amyloplast B&D was studied using label‐free‐based quantitative proteomic analyses in both cultivars. Over 3000 amyloplast‐localized proteins were identified, of which >98% were quantified and defined as the kfALP (kiwifruit amyloplast proteome). The kfALP data were validated by Tandem‐Mass‐Tag (TMT) labeled proteomics in 'Hort16A'. Analysis of the proteomic data across development and ripening revealed: 1) a conserved increase in the abundance of proteins participating in starch synthesis/degradation during both amyloplast B&D; 2) up‐regulation of proteins for chlorophyll degradation and of plastoglobule‐localized proteins associated with chloroplast breakdown and plastoglobule formation during amyloplast differentiation; 3) constitutive expression of proteins involved in ATP supply and protein import during amyloplast B&D. Interestingly, two different pathways of amyloplast B&D were observed in the two cultivars. In 'Hayward', significant increases in abundance of photosynthetic‐ and tetrapyrrole metabolism‐related proteins were observed, but the opposite trend was observed in 'Hort16A'. In conclusion, analysis of the kfALP provides new insights into the potential mechanisms underlying amyloplast B&D with relevance to key fruit quality traits in contrasting kiwifruit cultivars. [ABSTRACT FROM AUTHOR]

Summary: Carotenoids contribute to fruit coloration and are valuable sources of provitamin A in the human diet. Abscisic acid (ABA) plays an essential role in fruit coloration during citrus fruit ripening, but little is known about the underlying mechanisms. Here, we identified a novel bZIP transcription activator called CsbZIP44, which serves as a central regulator of ABA‐mediated citrus carotenoid biosynthesis. CsbZIP44 directly binds to the promoters of four carotenoid metabolism‐related genes (CsDXR, CsGGPPs, CsBCH1 and CsNCED2) and activates their expression. Furthermore, our research indicates that CsHB5, a positive regulator of ABA and carotenoid‐driven processes, activates the expression of CsbZIP44 by binding to its promoter. Additionally, CsHB5 interacts with CsbZIP44 to form a transcriptional regulatory module CsHB5‐CsbZIP44, which is responsive to ABA induction and promotes carotenoid accumulation in citrus. Interestingly, we also discover a positive feedback regulation loop between the ABA signal and carotenoid biosynthesis mediated by the CsHB5‐CsbZIP44 transcriptional regulatory module. Our findings show that CsHB5‐CsbZIP44 precisely modulates ABA signal‐mediated carotenoid metabolism, providing an effective strategy for quality improvement of citrus fruit and other crops. [ABSTRACT FROM AUTHOR]

Abstract Background Three gametoclonal plants of Citrus clementina Hort. ex Tan., cv. Nules, designated ESP, FRA, and ITA (derived from three labs in Spain, France, and Italy, respectively), were selected for cytological and molecular characterization in order to elucidate genomic rearrangements provoked by haploidization. The study included comparisons of their ploidy, homozygosity, genome integrity, and gene dosage, using chromosome counting, flow cytometry, SSR marker genotyping, and array-Comparative Genomic Hybridization (array-CGH). Results Chromosome counting and flow cytometry revealed that ESP and FRA were haploid, but ITA was tri-haploid. Homozygous patterns, represented by a single peak (allele), were observed among the three plants at almost all SSR loci distributed across the entire diploid donor genome. Those few loci with extra peaks visualized as output from automated sequencing runs, generally low or ambiguous, might result from amplicons of paralogous members at the locus, non-specific sites, or unexpected recombinant alleles. No new alleles were found, suggesting the genomes remained stable and intact during gametogenesis and regeneration. The integrity of the haploid genome also was supported by array-CGH studies, in which genomic profiles were comparable to the diploid control. Conclusions The presence of few gene hybridization abnormalities, corroborated by gene dosage measurements, were hypothetically due to the segregation of hemizygous alleles and minor genomic rearrangements occurring during the haploidization procedure. In conclusion, these plants that are valuable genetic and breeding materials contain completely homozygous and essentially intact genomes.

SUMMARY: Chromoplasts act as a metabolic sink for carotenoids, in which plastoglobules serve as versatile lipoprotein particles. PGs in chloroplasts have been characterized. However, the features of PGs from non‐photosynthetic plastids are poorly understood. We found that the development of chromoplast plastoglobules (CPGs) in globular and crystalloid chromoplasts of citrus is associated with alterations in carotenoid storage. Using Nycodenz density gradient ultracentrifugation, an efficient protocol for isolating highly purified CPGs from sweet orange (Citrus sinensis) pulp was established. Forty‐four proteins were defined as likely comprise the core proteome of CPGs using comparative proteomics analysis. Lipidome analysis of different chromoplast microcompartments revealed that the nonpolar microenvironment within CPGs was modified by 35 triacylglycerides, two sitosterol esters, and one stigmasterol ester. Manipulation of the CPG‐localized gene CsELT1 (esterase/lipase/thioesterase) in citrus calli resulted in increased lipids and carotenoids, which is further evidence that the nonpolar microenvironment of CPGs contributes to carotenoid accumulation and storage in the chromoplasts. This multi‐feature analysis of CPGs sheds new light on the role of chromoplasts in carotenoid metabolism, paving the way for manipulating carotenoid content in citrus fruit and other crops. [ABSTRACT FROM AUTHOR]