DNA methylation mediated by RdDM pathway and demethylation affects furanone accumulation through regulation of QUINONE OXIDOREDUCTASE in strawberry

Recently,increasing evidence suggests that DNA methylation plays a crucial role in fruit ripening.However,the role of DNA methylation in regulating specific traits,such as flavor,remains unclear.Here,we report a role of DNA methylation in affecting furanone biosynthesis in strawberry.Strawberry quinone oxidoreductase(FaQR)is a key enzyme in furanone biosynthesis.There are four FaQR homologs in strawberry cultivar‘Yuexin’,and one of them,FaQR3,contributes∼50%of FaQR transcripts,indicating a major role of FaQR3 in furanone biosynthesis.Through characterization of levels of DNA methylation and FaQR3 transcript and furanone contents during fruit ripening and after the application of DNA methylation inhibitor,we found that the DNA methylation level of the FaQR3 promoter was negatively correlated with FaQR3 expression and furanone accumulation,suggesting that DNA methylation may be involved in furanone biosynthesis through adjusting FaQR3 expression,and responded to different temperatures consistently.In addition,transient expression of a gene in the RNA-directed DNA methylation(RdDM)pathway,FaAGO4,and enrichment analysis of the 24-nucleotide siRNAs suggested that DNA methylation in the FaQR3 promoter is mediated by the RdDM pathway.Transient RNA interference(RNAi)of FaDML indicated that the demethylation pathway may be involved in regulating furanone accumulation.These findings provide new insights into the role of DNA methylation and demethylation in affecting flavor quality in strawberry during fruit ripening.

Plant genetic engineering and genetically modified crop breeding: history and current status

This review charts the major developments in the genetic manipulation of plant cells that have taken place since the first gene transfer experiments using Ti plasmids in 1983. Tremendous progress has been made in both our scientific understanding and technological capabilities since the first genetically modified(GM)crops were developed with single gene resistances to herbicides, insects, viruses, and the silencing of undesirable genes. Despite opposition in some parts of the world, the area planted with first generation GM crops has grown from 1.7 Mhm^2 in 1996 to 179.7 Mhm^2 in 2015.The toolkit available for genetic modification has expanded greatly since 1996 and recently Nobel Laureates have called on Greenpeace to end their blanket opposition,and plant scientists have urged that consideration be given to the benefits of GM crops based on actual evidence. It is now possible to use GM to breed new crop cultivars resistant to a much wider range of pests and diseases, and to produce crops better able to adapt to climate change.The advent of new CRISPR-based technologies makes it possible to contemplate a much wider range of improvements based on transfer of new metabolic pathways and traits to improve nutritional quality, with a much greater degree of precision. Use of GM, sometimes in conjunction with other approaches, offers great opportunities for improving food quality, safety, and security in a changing world.

基于DArT-Seq SNP的高密度遗传图谱的构建及野生型和栽培型西瓜杂交遗传群体偏分离基因组区域的鉴定

目的与意义:西瓜[Citrullus lanatus (Thunb.) Matsum.et Nakai]是重要的蔬菜作物,在全世界范围内都广泛种植.构建高密度的西瓜遗传图谱和不断利用新开发的标记构建饱和遗传图谱仍然是目前西瓜基因组学研究的重要内容之一.本项研究主要以西瓜自交系‘K3’和野生西瓜种‘PI189225’为亲本构建F2分离群体,利用以DArTseq为基础的SNP标记构建西瓜高密度遗传连锁图谱.

基于DArTseq的SNP标记的西瓜核心种质遗传多样性和群体结构分析

目的与意义:亲本材料是进行育种工作的基础,遗传基础狭窄导致难以培育出突破性品种,因此亟需加强遗传资源的引进及其农艺性状特征和遗传基础的了解与掌握,对现有优良西瓜品种和育种亲本材料进行遗传多样性研究,可有效减少相似遗传背景的组合,减少育种的工作量。同时,随着分子生物学技术的发展,分子标记种类及检测手段日趋完善,利用分子标记技术对植物进行聚类分析,可以快速了解植物的遗传多样性、亲缘关系和品种鉴定等。本研究对37份核心西瓜种质进行遗传多样性分析,确定这些西瓜核心种质材料间的遗传背景差异,为后期育种工作中的亲本组配、等位基因发掘和标记辅助选择等提供参考。

Quantifying relationships between rooting traits and water uptake under drought in Mediterranean barley and durum wheat

In Mediterranean regions drought is the major factor limiting spring barley and durum wheat grain yields. This study aimed to compare spring barley and durum wheat root and shoot responses to drought and quantify relationships between root traits and water uptake under terminal drought.One spring barley（Hordeum vulgare L. cv. Rum） and two durum wheat Mediterranean cultivars（Triticum turgidum L. var durum cvs Hourani and Karim） were examined in soil‐column experiments under well watered and drought conditions. Root system architecture traits, water uptake, and plant growth were measured. Barley aerial biomass and grain yields were higher than for durum wheat cultivars in well watered conditions. Drought decreased grain yield more for barley（47%） than durum wheat（30%, Hourani）. Root‐to‐shoot dry matter ratio increased for durum wheat under drought but not for barley, and root weight increased for wheat in response todrought but decreased for barley. The critical root length density（RLD） and root volume density（RVD） for 90% available water capture for wheat were similar to（cv. Hourani） or lower than（cv. Karim） for barley depending on wheat cultivar. For both species, RVD accounted for a slightly higher proportion of phenotypic variation in water uptake under drought than RLD.

Transcriptional regulation of fleshy fruit texture

Fleshy fruit texture is a critically important quality characteristic of ripe fruit.Softening is an irreversible process which operates in most fleshy fruits during ripening which,together with changes in color and taste,contributes to improvements in mouthfeel and general attractiveness.Softening results mainly from the expression of genes encoding enzymes responsible for cell wall modifications but starch degradation and high levels of flavonoids can also contribute to texture change.Some fleshy fruit undergo lignification during development and post-harvest,which negatively affects eating quality.Excessive softening can also lead to physical damage and infection,particularly during transport and storage which causes severe supply chain losses.Many transcription factors(TFs)that regulate fruit texture by controlling the expression of genes involved in cell wall and starch metabolism have been characterized.Some TFs directly regulate cell wall targets,while others act as part of a broader regulatory program governing several aspects of the ripening process.In this review,we focus on advances in our understanding of the transcriptional regulatory mechanisms governing fruit textural change during fruit development,ripening and postharvest.Potential targets for breeding and future research directions for the control of texture and quality improvement are discussed.

Tomato Flavor： Lost and Found？

Tomato is the highest value fruit crop in the world （Tieman et al., 2017） and a major component of healthy diets as it provides ready sources of vitamins A, C, E, and K, minerals including K and Fe, and lycopene as an antioxidant. However, modern varieties are often described as having little flavor, especially in comparison with traditional or heirloom types.

Tomato molecular biology–special collection of papers for molecular horticulture

Tomato(Solanum lycopersicum)is the second most important vegetable crop globally,after potato,with about 100 million tons fresh fruit being grown on 3.7 million hectares(FAO 2021),and is of great importance in the human diet due to the large amount of fruit consumed.The fruit are eaten both fresh and,equally importantly,as a processed product in puree,soups and canned products.They provide an important dietary source of vitamins and minerals,such as K,Fe and Ca,and are known for the large number of health promoting secondary metabolites,including the carotenoid and flavonoid pigments that give the fruit a spectrum of yellow,red and orange colours.