The plasmodesmata-associated β-1,3-glucanase gene GhPdBG regulates fiber development in cotton

Trichomes are specialized structures that originate from epidermal cells of organs in higher plants.The cotton fiber is a unique single-celled trichome that elongates from the seed coat epidermis.Cotton(Gossypium hirsutum)fibers and trichomes are models for cell differentiation.In an attempt to elucidate the intercellular factors that regulate fiber and trichome cell development,we identified a plasmodesmal β-1,3-glucanase gene(designated GhPdBG)controlling the opening and closing of plasmodesmata in cotton fibers.Structural and evolutionary analysis showed haplotypic variation in the promoter region of the GhPdBG gene among 352 cotton accessions,but high conservation in the coding region.GhPdBG was expressed predominantly in cotton fibers and localized to plasmodesmata(PD).Expression patterns of PdBG that corresponded to PD permeability were apparent during fiber development in G.hirsutum and G.barbadense.The PdBG-mediated opening-closure of PD appears to be involved in fiber development and may account for the contrasting fiber traits of these two species.Ectopic expression of GhPdBG revealed that it functions in regulating fiber and trichome length and/or density by modulating plasmodesmatal permeability.This finding suggests that plasmodesmal targeting of GhPdBG,as a switch of intercellular channels,regulates single-celled fiber and trichome development in cotton.

高通量测序分析PIK3CA突变型与野生型结直肠癌的肠道菌群特征

目的:采用16S rDNA二代高通量测序技术,研究PIK3CA突变型与野生型结直肠癌患者中的肠道菌群特征。方法:选取2016年12月至2017年12月华中科技大学同济医学院附属协和医院结直肠癌患者19例,采用16S rDNA高通量测序技术分析PIK3CA突变型(n=4)和PIK3CA野生型(n=15)之间肿瘤组织中微生物多样性和组成差异。结果:在门水平上,结直肠癌患者的肠道菌群主要由变形菌门、栖热菌门、放线菌门、厚壁菌门和拟杆菌门组成,占总群落的98%以上。Alpha多样性分析显示,PIK3CA突变型与野生型结直肠癌患者之间微生物多样性有显著性差异,且PIK3CA突变型患者中微生物多样性明显高于野生型。Beta多样性分析显示PIK3CA突变型与野生型结直肠癌患者的肿瘤微生物特征有显著性差异。Spearman关联网络分析结果显示,在PIK3CA野生型结直肠癌肿瘤组织中,双歧杆菌属与假单胞菌呈正相关。结论:PIK3CA突变型与野生型结直肠癌患者肿瘤组织中的微生物群落结构有显著性差异,且PIK3CA突变患者中的肠道微生物多样性更丰富。

QTL Mapping for Cucumber Fruit Size and Shape with Populations from Long and Round Fruited Inbred Lines

To gain insight into the molecular and genetic basis of fruit size and shape in cucumber,we conducted Quantitative Trait Locus(QTL)mapping with F2 and BC1F1 populations derived froma cross between the Northern-China type inbred line CNS21 and the Southern-China type inbred line RNS7.Populations were evaluated during two developmental stages,ovary at anthesis and commercial fruit(immature fruit).A total of 13 major-effect QTLs(R2>10%)were detected for six traits,and one of them,fruit shape index 2.1,explained more than 50%of phenotypic variation.All QTLs distributed on chromosome(chr)1 and 2.We constructed a physical map containing almost all of the QTLs with their physical location from previous studies.For fruit size and shape,the highest number of QTLs were mapped on chr1 and chr6,and the fewest number were mapped on chr2 and chr7.At least one consensus region was presented on each chromosome.In addition,three candidate genes were predicted between the long-fruited and round-fruited inbred lines by comparing the sequences of the consensus region of chr3,where many QTLs for marketable fruit length had been detected.Our results provide a base for additional QTLs and molecular markers for fruit size and shape in cucumber breeding.

CsMYB60 directly and indirectly activates structural genes to promote the biosynthesis of flavonols and proanthocyanidins in cucumber

Flavonols and proanthocyanidins(PAs)are the main pigments in the black spines of cucumber(Cucumis sativus)fruit,and CsMYB60 is a key regulator of the biosynthesis of flavonols and PAs.However,in cucumber,the tissue distribution pattern of flavonols and PAs and the mechanism of their biosynthesis regulated by CsMYB60 remain unclear.In this study,we clarified the tissue-specific distribution of flavonoids and the unique transcriptional regulation of flavonoid biosynthesis in cucumber.CsMYB60 activated CsFLS and CsLAR by binding to their promoters and directly or indirectly promoted the expression of CsbHLH42,CsMYC1,CsWD40,and CsTATA-box binding protein,resulting in the formation of complexes of these four proteins to increase the expression of Cs4CL and interact with CsTATA-box binding protein to regulate the expression of CsCHS,thereby regulating the biosynthesis of flavonols and PAs in cucumber.Our data provide new insights into the molecular mechanism of flavonoid biosynthesis,which will facilitate molecular breeding to improve fruit quality in cucumber.

Molecularly tagged genes and quantitative trait loci in cucumber with recommendations for QTL nomenclature

Cucumber,Cucumis sativus L.(2n=2x=14),is an important vegetable crop worldwide.It was the first specialty crop with a publicly available draft genome.Its relatively small,diploid genome,short life cycle,and selfcompatible mating system offers advantages for genetic studies.In recent years,significant progress has been made in molecular mapping,and identification of genes and QTL responsible for key phenotypic traits,but a systematic review of the work is lacking.Here,we conducted an extensive literature review on mutants,genes and QTL that have been molecularly mapped or characterized in cucumber.We documented 81 simply inherited trait genes or major-effect QTL that have been cloned or fine mapped.For each gene,detailed information was compiled including chromosome locations,allelic variants and associated polymorphisms,predicted functions,and diagnostic markers that could be used for marker-assisted selection in cucumber breeding.We also documented 322 QTL for 42 quantitative traits,including 109 for disease resistances against seven pathogens.By alignment of these QTL on the latest version of cucumber draft genomes,consensus QTL across multiple studies were inferred,which provided insights into heritable correlations among different traits.Through collaborative efforts among public and private cucumber researchers,we identified 130 quantitative traits and developed a set of recommendations for QTL nomenclature in cucumber.This is the first attempt to systematically summarize,analyze and inventory cucumber mutants,cloned or mapped genes and QTL,which should be a useful resource for the cucurbit research community.

Regulation of Photoassimilate Distribution between Source and Sink Organs of Crops through Light Environment Control in Greenhouses

Photosynthesis, the most important physiological process in plants, can produce not only ATP and NADPH used in other processes but also carbohydrate, the key factor for crop yield. Production of photoassimilates is often influenced by various environmental factors such as light, temperature, CO2, water, mineral elements and leaf stage and position. Here we focused on the light-mediated regulation of photoassimilate translocation in plants and the application of light environment control in greenhouse production. We also reviewed the effects of other factors including leaf age and position, air temperature, CO2 concentration and water and mineral element supply on photoassimilate translocation in plants. Finally some perspectives have been proposed.

The Co-Involvement of Light and Air Temperature in Regulation of Sex Expression in Monoecious Cucumber (<i>Cucumis sativus</i>L.)

The combination effects of light and air temperature, which were expressed as photothermal ratio (PTR), on the growth and sex expression of three monoecious cucumbers (Cucumis sativus L. cv. “Xintaimici”, “Jinyan 3” and “Jinyan 4”) were studied with hydroponics in this research. The results showed that with the increase of PTR, different growth responses were observed in the three cucumber cultivars. In contrast, high PTR (H-PTR, 0.86 mol·m-2·degree-day-1) significantly increased the total number of female nodes and decreased the total number of male nodes of the three monoecious cucumber cultivars compared with cucumbers grown under low PTR (L-PTR, 0.64 mol·m-2·degree-day-1). More photoassimilate was partitioned to fruits of three cucumber cultivars with the increase of PTR, indicating that PTR-mediated femaleness of monoecious cucumber might be attributed to the enhancement of photoassimilate translocation from source organs to sink organs.

Genome-Wide Identification of Two-Component Signal Transduction System Genes in Melon (<I>Cucumis melon</I>L.)

Two-component system (TCS) is responsible for cytokinin signaling, which plays critical roles in plant development and physiological process. This system is generally composed of two signaling factors, a histidine kinase (HK) and a response regulator (RR) that is associated with a histidine phosphotransfer (HP) protein. In this study, we performed systematic investigation on TCS genes in melon (Cucumis melon L.). We identified 44 TCS genes in melon, including 18 HK(L)s (9 HKs and 9 HKLs), 5 HPs (4 authentic and 1 pseudo), and 21 RRs (7 Type-A, 8 Type-B, and 6 pseudo). The classification and structure of these melon TCS members were introduced in detail as well. Our results provided new insights into the characteristics of the melon TCS genes and might benefit their functional study in future.

Ethyl Methanesulfonate (EMS)-Mediated Mutagenesis of Cucumber (<i>Cucumis sativus</i>L.)

Ethyl methanesulfonate (EMS) is a stable and effective chemical mutagen. In this study, cucumber (Cucumis sativus L. cv. “Shannong No. 5”) seeds were treated by 1% EMS for 12 h, 24 h and 48 h to optimize EMS mutagenesis and determined median lethal dose of EMS (1% EMS and 24 h) for “Shannong No. 5”. After treated by 1% EMS for 24 h, 541 M1 plants were grown in greenhouse for phenotype investigation. The fertility of M1 cucumbers was very low, and only 79 lines produced seeds after self crossing. 60 independent M2 families comprising 600 M2 plants were investigated for phenotypic alteration, and 11 individual mutant lines were isolated into six groups: short-fruit mutants, long-fruit mutants, small-flower mutants, big-flower mutants, opposite-tendril mutants and clustered-leaf mutants. The mutation frequency was 18.3%. Two selected representatives, short-fruit mutants and clustered-leaf mutants, showed 1:3 of segregation ratio in M2 populations. This ratio is consistent with classic Mendelian model, indicating that the two kinds of mutants may be controlled by a single recessive gene, respectively. Long-fruit phenotype was stably inherited and no segregation was observed in M3 generation, indicating that this mutant line may be homozygous.