Garlic cultivars are predominantly characterized by their sterility and reliance on asexual reproduction, which have traditionally prevented the use of hybrid breeding for cultivar improvement in garlic. Our investigation has revealed a notable exception in the garlic line G398, which demonstrates the ability to produce fertile pollen. Notably, at the seventh stage of anther development, callose degradation in the sterile line G390 was impeded, while G398 exhibited normal callose degradation. Transcriptome profiling revealed an enhanced expression of the callose-degrading gene, AsaNRF1, in the mature flower buds of the fertile line G398 compared to the sterile line G390. An insertion in the promoter of AsaNRF1 in G390 was identified, which led to its reduced expression at the tetrad stage and consequently delayed callose degradation, potentially resulting in the male sterility of G390. A discriminatory marker was developed to distinguish between fertile G398 and sterile G390, facilitating the assessment of male fertility in garlic germplasm resources. This study introduces a practical approach to harnessing garlic hybridization, which can further facilitate the breeding of new cultivars and the creation of novel male-fertile garlic germplasm using modern molecular biology methods.

Chloroplast development underpins plant growth, by facilitating not only photosynthesis but also other essential biochemical processes. Nonetheless, the regulatory mechanisms and functional components of chloroplast development remain largely uncharacterized due to their complexity. In our study, we identified a plastid-targeted gene, ATYCO/RP8/CDB1, as a critical factor in early chloroplast development in Arabidopsis thaliana. YCO knock-out mutant (yco) exhibited a seedling-lethal, albino phenotype, resulting from dysfunctional chloroplasts lacking thylakoid membranes. Conversely, YCO knock-down mutants produced a chlorophyll-deficient cotyledon and normal leaves when supplemented with sucrose. Transcription analysis also revealed that YCO deficiency could be partially compensated by sucrose supplementation, and that YCO played different roles in the cotyledons and the true leaves. In YCO knock-down mutants, the transcript levels of plastid-encoded RNA polymerase (PEP)-dependent genes and nuclear-encoded photosynthetic genes, as well as the accumulation of photosynthetic proteins, were significantly reduced in the cotyledons. Moreover, the chlorophyll-deficient phenotype in YCO knock-down line can be effectively suppressed by inhibition of PSI cyclic electron transport activity, implying an interaction between YCO and PSI cyclic electron transport. Taken together, our findings de underscore the vital role of YCO in early chloroplast development and photosynthesis.

Constitutive expression of cucumber CsACS2 in Arabidopsis disrupts anther dehiscence and male fertility via ethylene signaling and DNA methylation, revealing new avenues for enhancing crop reproductive traits. The cucumber gene CsACS2, encoding ACC (1-aminocyclopropane-1-carboxylic acid) synthase, plays a pivotal role in ethylene biosynthesis and sex determination. This study investigates the effects of constitutive CsACS2 expression in Arabidopsis thaliana on anther development and male fertility. Transgenic Arabidopsis plants overexpressing CsACS2 exhibited male sterility due to inhibited anther dehiscence, which was linked to suppressed secondary cell wall thickening. RNA-Seq analysis revealed upregulation of ethylene signaling pathway genes and downregulation of secondary cell wall biosynthesis genes, with gene set enrichment analysis indicating the involvement of DNA methylation. Rescue experiments demonstrated that silver nitrate (AgNO₃) effectively restored fertility, while 5-azacytidine (5-az) partially restored it, highlighting the roles of ethylene signaling and DNA methylation in this process. Constitutive CsACS2 expression in Arabidopsis disrupts anther development through ethylene signaling and DNA methylation pathways, providing new insights into the role of ethylene in plant reproductive development and potential applications in crop improvement.

Cucumber (Cucumis sativus L.) is an important horticultural crop worldwide. Sodium (Na+) and chloride (Cl−) in the surface soil are the major limiting factors in coastal areas of Shandong Province in China. Therefore, to understand the mechanism used by cucumber to adapt to sodium chloride (NaCl), we analyzed the phenotypic and physiological indicators of eighteen cucumber germplasms after three days under 100 and 150 mM NaCl treatment. A cluster analysis revealed that eighteen germplasms could be divided into five groups based on their physiological indicators. The first three groups consisted of seven salt-tolerant and medium salt-tolerant germplasms, including HLT1128h, Zhenni, and MC2065. The two remaining groups consisted of five medium salt-sensitive germplasms, including DM26h and M1-2-h-10, and six salt-sensitive germplasms including M1XT and 228. A principal component analysis revealed that the trend of comprehensive scores was consistent with the segmental cluster analysis and survival rates of cucumber seedlings. Overall, the phenotype, comprehensive survival rate, cluster analysis, and principal component analysis revealed that the salt-tolerant and salt-sensitive germplasms were Zhenni, F11-15, MC2065, M1XT, M1-2-h-10, and DM26h. The results of this study will provide references to identify or screen salt-tolerant cucumber germplasms and lay a foundation for breeding salt-tolerant cucumber varieties.

为了明确黄瓜种质对氯化钠的不同耐性,解析黄瓜耐盐的分子机理,本研究以耐盐种质MC2065、盐敏感种质白黄瓜和21份其他黄瓜种质为材料,设置5个NaCl浓度,50、100、150、200、250 mmol·L-1分别开展适宜NaCl浓度筛选,以及适宜浓度处理后耐盐指数、叶绿素、保护酶等9个生理生化指标的测定与分析.结果表明,100和150 mmol·L-1可以作为耐盐鉴定的适宜浓度.NaCl浓度为100 mmol·L-1时,白黄瓜盐害指数为35.94％,出现明显盐害胁迫,而MC2065盐害指数为4.69％,未表现出明显盐害症状;NaCl浓度为150 mmol·L-1时,两个材料均表现明显盐害症状,白黄瓜出现半数以上叶片枯萎,而MC2065出现半数以下叶片枯萎.聚类分析发现,21份材料分为3个类群,第一类群包括ZQ3、N26-5-1、寿水1、DRTJY-2、莱西、翠玉、20S077-1,属于耐盐种质;第二类群包括DJ04、DY-1、XY1、YY9123、M2XT、D1503、X805,属于中耐盐种质;第三类群包括F6-3-1、SJ11-1、XB23、20S091-1、HLT-921h、AZ-1、DRT345,属于盐敏感种质.主成分分析发现,黄瓜种质综合得分趋势与聚类分析、黄瓜幼苗存活率高低趋势基本一致.本研究结果为黄瓜耐盐机理的研究提供了参考,也为黄瓜耐盐品种的育种工作奠定了基础.

Cucumber (Cucumis sativus L.) is a vital vegetable crop worldwide. Mg2+ and NO3− in the surface soil are the major limiting factors to continuous cropping in the main cucumber-producing areas of Shandong province in China. This study aimed to understand the magnesium nitrate- adaption in cucumber. Using a relatively salt tolerant cultivar ‘MC2065’ as experiment material, we analyzed the rate of water loss and changes in transcriptome profiles of cucumber leaves treated with 80 mM Mg(NO3)2 at different wilting stages for 0, 3, 12, and 24 h (T0-CK, T3, T12, T24 groups, respectively). The results showed that magnesium nitrate stress increased the rate of water loss in leaves. A total of 7465 differentially expressed genes (DEGs) were identified from a pool of 15923 genes. The maximum number of DEGs (4373) were observed at T12 vs. T0. For T3 vs. T0 and T24 vs. T0, there were 3763 and 3889 DEGs, respectively. Statistical analysis of gene expression showed 1075 DEGs significant expressed at T3, T12 and T24, compared to CK. Gene Ontology (GO) gene functional analysis of the DEGs identified 52 functionally enriched groups, within the categories of metabolic process, cell part and catalytic activity. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis found DEGs related to plant hormone signal transduction (ko04075) and DNA replication of secondary metabolites were significantly in 86 pathways. Notably, the SAUR family in auxin signal transduction pathway had the highest number of DEGs, followed by PYL and ARR family in abscisic acid and cytokinin pathway. The unique DEGs identified in this study provide crucial information for further study on salt response mechanisms and genetic enhancement of salt resistance in cucumber.

分子标记是继形态学、细胞学和生化标记后的新型技术,随着分子生物学的迅猛发展,该技术已在蔬菜育种上广泛应用.本文概述了分子标记的概念及分类,包括典型标记技术的原理及优缺点,详述其近年在黄瓜(Cucumis sativus)外观、品质、产量与性型、抗逆、种质资源鉴定以及品种纯度鉴定方面相关基因定位上的应用,最后对其在基因定位及辅助选择育种方面的应用前景进行了展望.

Plant ascorbate peroxidase (APX) genes play significant roles in environmental stress response and development. However, the knowledge about them in the important vegetable cucumber is scarce. In this paper, 6 APX genes in cucumber genome were identified through bioinformatics method. And their chromosome location, gene exon-intron structure, phylogeny, and cis-elements were systematically analyzed. The results showed that cucumber APX genes distribute in different chromosomes, and their putative coding sequence size ranges from 750 bp to 1425 bp. They all have 8 or more exons, and their putative encoded proteins are predicted to localize in cytosol or chloroplast. There are typical ascorbate peroxidase domain, myristoylation sites, and phospharylation sites in APXs encoded proteins of cucumber. And also, multiple cis-elements responsive to different environmental stimuli and hormones are existed in cucumber APX upstream sequences, which suggests they may have some roles in environmental stress responses.

We previously described a Brassica napus chlorophyll-deficient mutant (ygl) with yellow-green seedling leaves and mapped the related gene, BnaC.YGL, to a 0.35 cM region. However, the molecular mechanisms involved in this chlorophyll defect are still unknown. In this study, the BnaC07.HO1 gene (equivalent to BnaC.YGL) was isolated by the candidate gene approach, and its function was confirmed by genetic complementation. Comparative sequencing analysis suggested that BnaC07.HO1 was lost in the mutant, while a long noncoding-RNA was inserted into the promoter of the homologous gene BnaA07.HO1. This insert was widely present in B. napus cultivars and down-regulated BnaA07.HO1 expression. BnaC07.HO1 was highly expressed in the seedling leaves and encoded heme oxygenase 1, which was localized in the chloroplast. Biochemical analysis showed that BnaC07.HO1 can catalyze heme conversion to form biliverdin IXα. RNA-seq analysis revealed that the loss of BnaC07.HO1 impaired tetrapyrrole metabolism, especially chlorophyll biosynthesis. According, the levels of chlorophyll intermediates were reduced in the ygl mutant. In addition, gene expression in multiple pathways was affected in ygl. These findings provide molecular evidences for the basis of the yellow-green leaf phenotype and further insights into the crucial role of HO1 in B. napus.

Different mitotype-specific markers were developed to distinguish different cytoplasms in Brassica napus L.

Cytoplasmic male sterility (CMS) in plants is a maternally inherited inability to produce functional pollen. CMS is generally caused by aberrant mitochondrial genes that are often chimeric in structure and frequently co-transcribed with conventional mitochondrial genes (Hanson and Bentolila, 2004). In many instances, male sterility can be recovered by nuclear-encoded restorer of fertility (Rf) genes. CMS/Rf systems serve as an excellent model to study mitochondrial-nuclear coevolution and interaction in plants as well as as a useful genetic tool for breeding to exploit hybrid vigor in crops (Chen and Liu, 2014).

Background: The Polima (pol) system of cytoplasmic male sterility (CMS) and its fertility restoration gene Rfp have been used in hybrid breeding in Brassica napus, which has greatly improved the yield of rapeseed. However, the mechanism of the male sterility transition in pol CMS remains to be determined.Results: To investigate the transcriptome during the male sterility transition in pol CMS, a near-isogenic line (NIL) of pol CMS was constructed. The phenotypic features and sterility stage were confirmed by anatomical analysis. Subsequently, we compared the genomic expression profiles of fertile and sterile young flower buds by RNA-Seq. A total of 105,481,136 sequences were successfully obtained. These reads were assembled into 112,770 unigenes, which composed the transcriptome of the bud. Among these unigenes, 72,408 (64.21%) were annotated using public protein databases and classified into functional clusters. In addition, we investigated the changes in expression of the fertile and sterile buds; the RNA-seq data showed 1,148 unigenes had significantly different expression and they were mainly distributed in metabolic and protein synthesis pathways. Additionally, some unigenes controlling anther development were dramatically down-regulated in sterile buds.Conclusions: These results suggested that an energy deficiency caused by orf224/atp6 may inhibit a series of genes that regulate pollen development through nuclear-mitochondrial interaction. This results in the sterility of pol CMS by leading to the failure of sporogenous cell differentiation. This study may provide assistance for detailed molecular analysis and a better understanding of pol CMS in B. napus.

A chlorophyll-deficient mutant with yellow-green leaves of Brassica napus was obtained by treatment with the chemical mutagen ethyl methanesulfonate. Compared with the wild type at seedling stage, the mutant displayed decreased total chlorophyll content, less granal stacks and granal membranes. Genetic analysis confirmed that the mutant phenotype was controlled by a recessive gene, which was designated as BnaC.ygl. Mapping of the gene was subsequently conducted in two populations with yellow-green leaves (population IBC8 and IIBC4, which comprised 3,472 and 5,288 individuals, respectively). Analysis on the public simple sequence repeat markers (SSR) showed that four SSR markers linked to BnaC.YGL gene displayed polymorphism. Based on the information of these SSR markers, the BnaC.YGL gene was mapped to the linkage group N17. From a survey of amplified fragment length polymorphism (AFLP), 15 of 47 AFLP markers were successfully converted into sequence characterised amplified region (SCAR) markers. BnY5 and CB10534, the closest flanking markers, were 0.32 and 0.03 cM away from the BnaC.YGL gene, respectively. And in the two populations, 18 makers cosegregated with BnaC.YGL. BLAST analysis revealed that the sequences of the makers displayed highly conserved homology with C06 of B. oleracea. The collinearity of makers to makers on N17 and on C06 showed that there might be an inversion occurring on the N17 group. These results are expected to accelerate the process of cloning the BnaC.YGL gene and facilitate the understanding of the biological processes of chloroplast development in Brassica napus.