基于SSR标记的谷子遗传多样性研究

用21个分布在谷子9条染色体上的SSR标记,对120份来自于核心种质的谷子材料进行遗传多样性研究。21个标记共检查出305个等位变异,各标记检测出的等位变异数在3～26个之间,平均每个位点检测出的等位变异数为14.5个;21个位点的平均多态信息量(PIC)为0.809。基于21个SSR标记的分子鉴定,计算了120份材料间的遗传相似系数,其变化范围为0.8393～0.9672,平均值为0.8906。根据计算的遗传距离,对120份谷子材料进行UPGMA聚类,在遗传相似系数0.8865处这些材料被划分为4个类群,分类结果与这些谷子来源地生态类型总体上表现一致,分别为西北内陆类群、黄土高原内蒙古高原类群、华北平原类群以及华北平原近年育成种类群。     

甜瓜遗传多样性的AFLP分析

利用AFLP(Amplified fragment length polymorphism)分子标记技术对48份甜瓜(Cucumis meloL.)材料遗传多样性和亲缘关系进行了研究.从64对引物中筛选出了10对进行选择性扩增,共扩增出423条带,其中多态性条带172条,多态率为40.66%.聚类分析将供试材料分成了两大类群,即厚皮甜瓜类群和薄皮甜瓜类群,并进一步将厚皮甜瓜类群分成了4个亚类,与甜瓜传统分类结果基本一致.     

国外甜瓜种质资源形态性状遗传多样性分析

对250份国外甜瓜(Cucumis melo)种质资源的19个形态性状多样性进行研究。结果表明, 国外甜瓜种质资源具有丰富的形态多样性, 平均遗传多样性指数为1.378。9个质量性状(果实形状、果皮底色、覆纹颜色、覆纹形状、网纹密度、网纹粗度、果肉颜色、果肉质地和种子颜色)和4个数量性状(单果鲜重、果肉厚度、可溶性固形物含量和种子千粒重)变异明显, 其Shannon’s指数分别大于1.0和1.9。不同生态区间种质资源遗传多样性差异明显, 多样性指数由高到低依次为: 南亚(1.512)、东北欧(1.404)、西欧(1.372)、北美(1.340)和东亚(1.281)。通过聚类分析将所有甜瓜种质划分为四大组群, 即南亚组群、东北欧组群、西欧北美组群和东亚北美组群。以印度为代表的南亚甜瓜种质形态多样性水平较高, 支持了印度次生大陆为甜瓜起源中心的观点。     

Genetic Diversity of Early Maturing Indian Maize (Zea mays L) Inbred Lines Revealed by SSR Markers

A set of 16 popular inbred lines, (8 released and 8 experimental) were analyzed using 24 Simple Sequence Repeats (SSR) markers. In total 71 SSR alleles were identified with a mean of 2.96 alleles per locus. The study revealed 28 rare alleles among the total, out of which 9 were unique to some of the inbred lines. The average Polymorphism Information Content (PIC) and Discrimination Rate (DR) were 0.39 and 0.61, respectively. Genetic similarity expressed as Jaccard’s coefficient varied from 0.23–0.68 with an average of 0.41. Five clusters were obtained by using Unweighted Paired Group Method using Arithmetic Averages (UPGMA). The pattern of grouping did not match well with available pedigree information, which may be attributed to inadequate pedigree information. Inbred lines used in present study revealed heterozygosity ranges from 8.3–33.3% and were clearly distinguished with a minimum set of three markers with high PIC and DR. However, fingerprints obtained using 13 markers with high DR revealed a probability of identical match by chance at 4.06×10^?8. In this study we found SSR as a good tool for characterization of maize genotypes along with morphological markers.     

‘弥河银瓜’高效植株再生体系的建立

建立了以薄皮甜瓜品种‘弥河银瓜’子叶为外植体的高效再生体系。取生长5d的甜瓜子叶为外植体,置于MS+2.0mg·L-16-BA+0.5mg·L-1IBA+3.5%蔗糖+0.7%琼脂(pH5.8)的诱导培养基上培养,可获得100%芽分化频率。在不定芽伸长过程中,生长调节剂最佳浓度为0.5mg·L-16-BA+0.1mg·L-1IAA。潮霉素是较合适的筛选抗生素。     

一个获得与缺失变异(PAV)调控甜瓜果实苦味

甜瓜苦味物质严重影响其口感和品质。本研究利用不苦的薄皮甜瓜品系C69和苦的薄皮甜瓜品系C14构建了一个包含100个单株的F2群体。首先利用2b-RAD测序构建一个遗传连锁图谱。其次,结合群体的苦味性状进行全基因组的QTL定位和关联分析。然后,利用2b-RAD测序特有的技术优势进行群体的获得与缺失变异(PAV)的挖掘。最后,利用亲本的重测序信息确定控制苦味性状的关键基因。结果发现,F1的果实表现出强烈的苦味,F2群体中苦与不苦的单株分别为81个和19个,符合3∶1的分离比(χ^2=1.92,P=0.1659),表型表明所用甜瓜材料的苦味主要是由一个显性的基因位点控制。利用477个SNP标记构建一张包含10个连锁群的连锁图谱,总长为337.79 cM,标记间平均间隔0.71 cM。全基因组QTL定位在8号连锁群(对应9号染色体),检测到一个解释表型变异为20%的甜瓜苦味QTL。全基因组关联分析检测到7个SNPs与苦味性状相关,全部位于9号染色体苦味QTL的基因组区域。通过PAV分型分析仅发现一个特有的大片段缺失(21707702~21743072 bp),位于QTL区域,且在所有的不苦株系中存在,而苦的株系中不存在。基于两个亲本材料的深度重测序信息,发现这个PAV的区域更大,约为62 Kb,共涉及到9个连续的基因(MELO3C005601、MELO3C005602、MELO3C005603、MELO3C005604、MELO3C005605、MELO3C005606、MELO3C005607、MELO3C005608和MELO3C005609),其中5个是细胞色素P450基因。构建的系统发育树表明,这5个细胞色素P450基因与参与葫芦素C/B/E合成的细胞色素P450基因簇CYP81Q58、CYP81Q59和CYP712D8在一个进化枝,可能行使类似的功能,为潜在的类似于黄瓜葫芦素C合成的基因簇的一部分。前人通过比较基因组学研究获得的2个控制葫芦素B合成的bHLH转录因子CmBr(MELO3C005610)和CmBt(MELO3C005611)同在9号染色体,与本研究检测到的PAV紧密挨在一起。我们的研究结果为后续不苦甜瓜的育种提供了新的理论支撑和分子辅助育种目标。     

中国甜瓜种质资源形态性状遗传多样性分析

对我国各地257份代表性的甜瓜种质资源的20个形态性状进行调查分析,研究其遗传多样性。结果表明,7个质量性状(果实形状、果皮底色、覆纹颜色、覆纹形状、果肉颜色、果肉质地和种子颜色)和6个数量性状(果实横径、果实纵径、单果鲜重、果肉厚度、可溶性固形物含量和种子千粒重)差异明显,其Shannon’s指数分别大于1.00和1.50。所有种质的平均遗传多样性指数为1.09,不同地区种质资源遗传多样性差异明显,多样性指数高低次序分别为：西北、华中、华东、华北、东北和华南。主座标标分析(PCO)将所有种质划分为3个区域,即厚皮种质优势区、厚皮和薄皮种质混合分布区、薄皮种质优势区,不同地区的种质在PCO图上的分布差异明显,西北地区的厚皮甜瓜种质和华中、华东地区的薄皮甜瓜种质广泛分布于3个区域中,其形态遗传多样性比其他地区的种质更加丰富,支持了新疆地区为厚皮甜瓜次级起源中心、黄淮及长江流域为薄皮甜瓜初级起源中心的观点。     

Reproductive biology of the andromonoecious Cucumis melo subsp. agrestis (Cucurbitaceae)

Background and Aims

Cucumis melo subsp. agrestis (Cucurbitaceae) is cultivated in many African regions for its edible kernels used as a soup thickener. The plant, an annual, andromonoecious, trailing-vine species, is of high social, cultural and economic value for local communities. In order to improve the yield of this crop, the first step and our aim were to elucidate its breeding system.

Methods

Eight experimental pollination treatments were performed during three growing seasons to assess spontaneous selfing, self-compatibility and effects of pollen source (hermaphroditic vs. male flowers). Pollination success was determined by pollen tube growth and reproductive success was assessed by fruit, seed and seedling numbers and characteristics. The pollinator guild was surveyed and the pollination distance determined both by direct observations and by indirect fluorescent dye dispersal.

Key Results

The species is probably pollinated by several Hymenoptera, principally by Hypotrigona para. Pollinator flight distances varied from 25 to 69 cm. No evidence for apomixis or spontaneous self-pollination in the absence of insect visitors was found. The self-fertility index (SFI = 0) indicated a total dependence on pollinators for reproductive success. The effects of hand pollination on fruit set, seed number and seedling fitness differed among years. Pollen tube growth and reproductive success did not differ between self- and cross-pollinations. Accordingly, a high self-compatibility index for the fruit set (SCI = 1·00) and the seed number (SCI = 0·98) and a low inbreeding depression at all developmental stages (cumulative δ = 0·126) suggest a high selfing ability. Finally, pollen origin had no effect on fruit and seed sets.

Conclusions

This andromonoecious species has the potential for a mixed mating system with high dependence on insect-mediated pollination. The selfing rate through geitonogamy should be important.     

Transformation of Recalcitrant Melon (Cucumis melo L.) Cultivars is Facilitated by Wounding with Carborundum

Transformation of the recalcitrant melon (Cucumis melo L.) cultivars Kιrka?aç 637 and Noi Yarok was accomplished by wounding cotyledon explants by vortexing with carborundum prior to inoculation with Agrobacterium tumefaciens. The addition of silver nitrate to the regeneration‐selection medium reduced the transformation efficiency, as the percentage of the explants forming putative transgenic calli and bud‐like protuberances was decreased and no transgenic shoots were produced. Chimeric transgenic plants were obtained after the regeneration of putatively transformed callus, bud‐like protuberances, buds and shoots on selective medium with kanamycin. The treatments producing the most buds or shoots from explants after 30–40 days of cultivation were the most successful for the production of transgenic plants. Only treatments where explants were vortexed with carborundum produced transgenic melon shoots of either cultivar. Subculture every 18–20 days on fresh regeneration‐selection medium containing 50 mg/L kanamycin after either a relatively high (100 mg/L) or low level (50 mg/L) of kanamycin in the first regeneration‐selection medium was necessary for the successful transformation of cultivar Kιrka?aç 637. These techniques are now being used in breeding programs for the production of melon lines bearing resistances to zucchini yellow mosaic virus and cucumber mosaic virus, important viruses limiting agricultural production.     

Physiological Aspects of Melon (Cucumis melo L.) as a Function of Salinity

Journal of Plant Growth Regulation - This study evaluated the effect of saline water irrigation (4.5 dS m−1) on growth, gas exchange and mineral nutrient content in eight melon accessions and...     

Impact of potassium nutrition on postharvest fruit quality: Melon (Cucumis melo L) case study

Among the many plant mineral nutrients, potassium (K) stands out as a cation having the strongest influence on quality attributes that determine fruit marketability, consumer preference, and the concentration of critically important human-health associated phytonutrients. However, many plant, soil, and environmental factors often limit adequate uptake of K from the soil in sufficient amounts to satisfy fruit K requirements during development to optimize the aforementioned quality attributes. The objectives of this review are 1) to summarize published study abstracts on the effects of soil and/or foliar K fertilization as well as diverse K forms, on fruit phytonutrient concentrations; and 2) to illustrate the important role of K forms on fruit quality with a case study of Cucumis melo L (muskmelon) fruit produced with optimal soil applied K . The muskmelon studies will compare commercial sources (forms) of K applied to examine seasonal effects (spring vs. autumn) and the number of foliar K applications during fruit development on fruit marketability (maturity, yield, firmness, soluble solids, sugars, relative sweetness), consumer preference attributes (sugar content, sweetness, texture), and phytochemical concentrations (K, ascorbic acid, and β-carotene concentrations). Numerous studies have consistently demonstrated that specific K fertilizer forms, in combination with specific application regimes, can improve fruit quality attributes. Potassium fertilizer forms in order of effectiveness (Glycine (Gly)-complexed K?=?K₂SO₄?≥?KCl?>?no K?>?KNO₃) when applied wet (foliar or hydroponic) vs. dry (soil) were generally superior in improving fruit marketability attributes, along with many human-health nutrients. The muskmelon case study demonstrated that two K forms: Gly-complexed K and K₂SO₄, combined with a silicone-based surfactant, applied weekly, as a foliar spray, during fruit development, from both autumn and spring-grown plants, had the greatest impact on improving fruit marketability attributes (maturity, yield, firmness, and sugars), as well as fruit quality attributes (human-health bioactive compounds K, ascorbic acid, and β-carotene). Among several foliar applied K salts studied under field conditions so far, salts with relatively low salt indices appeared to have the greatest impacts on fruit quality when applied during the mid- to late-season fruit development periods.     

河北省冬小麦品种SSR标记遗传多样性分析

利用79对多态性较高的SSR引物,对河北省1997-2007年间审定的冬小麦品种及国家小麦区试抗旱对照品种晋麦47和洛旱2号,共计87个冬小麦品种进行遗传多样性分析。79对SSR引物共检测出175个等位变异位点,每对引物可产生1~6条等位变异位点,平均2.215条。标记位点多态性信息含量(PIC)变幅为0.824~0.998,平均为0.941;有效等位基因数(Ne)变幅为1.644~20.333,平均4.708;香农指数(H’)变幅为0.148~1.102,平均为0.544,说明河北省冬小麦品种SSR遗传多样性较低。品种间遗传相似系数(GS)变幅为0.184~0.899,平均为0.418,其中河农826与石家庄8号间的遗传相似性最高,GS高达0.899,71-3与藁优9618间的遗传相似性最低,GS为0.184。不同育种单位培育的小麦品种平均遗传相似系数存在较大差异。UPGMA遗传相似性聚类表明,石家庄市小麦新品种新技术研究所培育的小麦品种与其他单位品种存在较大的遗传差异。     

甜瓜乙烯应答因子基因在果实发育成熟过程中的表达特性

根据已报道的甜瓜CMe-ERF1和CMe-ERF2基因cDNA序列设计合成特异性引物,应用RT-PCR技术从甜瓜品种‘河套蜜瓜’成熟果实中克隆得到CMe-ERF1和CMe-ERF2基因cDNA全长编码区序列,分别为498bp和822bp.序列比对分析表明,得到的cDNA序列与已报道的Andes甜瓜相应基因的cDNA序列完全一致.果实不同发育时期实时定量PCR检测结果表明,CMe-ERF1、CMe-ERF2基因表达与甜瓜果实成熟及乙烯生成量显著相关,表明该基因可能对果实成熟起重要作用.     

Genetic Diversity of Grasspea and Its Relative Species Revealed by SSR Markers

The study of genetic diversity between Lathyrus sativus L. and its relative species may yield fundamental insights into evolutionary history and provide options to meet the challenge of climate changes. 30 SSR loci were employed to assess the genetic diversity and population structure of 283 individuals from wild and domesticated populations from Africa, Europe, Asia and ICARDA. The allele number per loci ranged from 3 to 14. The average gene diversity index and average polymorphism information content (PIC) was 0.5340 and 0.4817, respectively. A model based population structure analysis divided the germplasm resources into three subgroups: the relative species, the grasspea from Asia, and the grasspea from Europe and Africa. The UPGMA dendrogram and PCA cluster also demonstrated that Asian group was convincingly separated from the other group. The AMOVA result showed that the cultivated species was quite distinct from its relative species, however a low level of differentiation was revealed among their geographic origins. In all, these results provided a molecular basis for understanding genetic diversity of L. sativus and its relatives.     

国内外甜高粱种质遗传多样性的SSR分析

用24对扩增带型稳定的SSR引物,研究了206份国内外甜高粱种质资源的遗传变异,共检测出220个等位基因,每对引物检测出2～19个等位基因。引物位点的多态信息含量指数(PIC)变幅在0.50～0.87。利用220个多态性标记计算206份甜高粱品种之间的遗传相似系数(GS),范围在0.32～0.96之间。利用SSR标记遗传相似系数矩阵,按UPGMA方法对206份甜高粱品种进行聚类分析,将其分为A、B两大组,B组只包含3个品种,与其他品种遗传关系较远,A组进一步被分成15个类群,农艺性状近似的聚在同一类群。     

Development of SSR markers by next-generation sequencing of Korean landraces of chamoe (Cucumis melo var. makuwa)

The oriental melon (Cucumis melo var. makuwa), called ‘chamoe’ in Korean, is a popular fruit crop cultivated mainly in Asia and a high-market value crop in Korea. To provide molecular breeding resources for chamoe, we developed and characterized genomic SSR markers from the preliminary Illumina read assemblies of Gotgam chamoe (one of the major landraces; KM) and SW3 (the breeding parent). Mononucleotide motifs were the most abundant type of markers, followed by di-, tri-, tetra-, and pentanucleotide motifs. The most abundant dinucleotide was AT, followed by AG and AC, and AAT was the most abundant trinucleotide motif in both assemblies. Following our SSR-marker development strategy, we designed a total of 370 primer sets. Of these, 236 primer sets were tested, exhibiting 93 % polymorphism between KM and SW3. Those polymorphic SSRs were successfully amplified in the netted and Kirkagac melons, which respectively exhibited 81 and 76 % polymorphism relative to KM, and 32 and 38 % polymorphism relative to SW3. Seven selected SSR markers with a total of 17 alleles (2–3 alleles per locus) were used to distinguish between KM, SW3, and four chamoe cultivars. Our results represent the first attempt to provide genomic resources for Korean landraces for the purposes of chamoe breeding, as well as to discover a set of SSR markers capable of discriminating chamoe varieties from Korea and the rest of Asia, which possess little genetic diversity. This study establishes a highly efficient strategy for developing SSR markers from preliminary Illumina assemblies of AT-rich genomes.     

Heterologous Expression and Biochemical Characterization of Two Lipoxygenases in Oriental Melon,Cucumis melo var. makuwa Makino

Lipoxygenases (LOXs) are a class of non-heme iron-containing dioxygenases that catalyse oxidation of polyunsaturated fatty acids to produce hydroperoxidation that are in turn converted to oxylipins. Although multiple isoforms of LOXs have been detected in several plants, LOXs in oriental melon have not attracted much attention. Two full-length LOX cDNA clones, CmLOX10 and CmLOX13 which have been isolated from oriental melon (Cucumis melo var. makuwa Makino) cultivar “Yumeiren”, encode 902 and 906 amino acids, respectively. Bioinformatics analysis showed that CmLOX10 and CmLOX13 included all of the typical LOX domains and shared 58.11% identity at the amino acid level with each other. The phylogenetic analysis revealed that CmLOX10 and CmLOX13 were members of the type 2 13-LOX subgroup which are known to be involved in biotic and abiotic stress. Heterologous expression of the full-length CmLOX10 and truncated CmLOX13 in Escherichia coli revealed that the encoded exogenous proteins were identical to the predicted molecular weights and possessed the lipoxygenase activities. The purified CmLOX10 and CmLOX13 recombinant enzymes exhibited maximum activity at different temperature and pH and both had higher affinity for linoleic acid than linolenic acid. Chromatogram analysis of reaction products from the CmLOX10 and CmLOX13 enzyme reaction revealed that both enzymes produced 13S-hydroperoxides when linoleic acid was used as substrate. Furthermore, the subcellular localization analysis by transient expression of the two LOX fusion proteins in tobacco leaves showed that CmLOX10 and CmLOX13 proteins were located in plasma membrane and chloroplasts respectively. We propose that the two lipoxygenases may play different functions in oriental melon during plant growth and development.     

甜瓜种质资源遗传多样性的SRAP分析

为研究甜瓜材料之间的亲缘关系及其分类, 更有效地利用种质资源, 为培育新品种提供依据, 文章采用 SRAP (Sequence-related amplified polymorphism)技术对61份甜瓜种质资源的遗传多样性进行研究。结果表明: 从42对引物组合中筛选出16对扩增条带清晰、多态性高的引物组合分析供试材料, 共检测出452个位点, 其中265个为多态性位点, 多态性比率达58.63％, 平均每对引物组合产生28.56个位点和16.56个多态性位点。61份材料间的相似系数为0.48～0.93, 平均为0.73。这些结果说明, 供试甜瓜材料具有较为丰富的遗传多样性。聚类分析结果表明, 61个甜瓜品种中首先可分为薄皮甜瓜与厚皮甜瓜两大类, 彼此亲缘关系最远。以遗传相似系数0.74为截值, 可把供试材料分为5个类群。在生态区域中, 新疆厚皮甜瓜的Nei’s基因多样性指数(0.2231)和Shannon’s信息指数(0.3422)最高。