Genetic structure of age classes in Camellia japonica (Theaceae)

Camellia japonica L. (Theaceae), an insect- and bird-pollinated, broad-leaved evergreen tree, is widely distributed in Japan and the southern Korean peninsula. The species has a relatively even age distribution within populations, which may influence the spatial genetic structure of different age classes relative to species with typical L-shaped age distributions. To determine whether the internal spatial genetic structure found in seedlings and young individuals carries over into adults, we used allozyme loci, F-statistics, spatial autocorrelation statistics (Moran's I), and coancestry measures to examine changes in genetic structure among seven age classes in a population (60-m x 100-m area) in southern Korea. In seedlings, weak but significant positive values of Moran's I-statistics and coancestry measures were found for distances less than 14 m, which is consistent with a mechanism of limited seed dispersal combined with overlapping seed shadows. This spatial structure, however, dissipates in older age classes, and in adults genetic variation has an essentially random spatial distribution. Morisita's index of dispersion of individuals in each age class showed that seedlings and juveniles are more highly clustered than are older individuals. These results suggest that self-thinning changes the spatial relationships of individuals, and thus genotypes. A multilocus estimate of FST (0.008) shows a small but statistically significant difference in allele frequencies among age classes. In summary, intrapopulation genetic structure within and among age classes of C. japonica was significant but weak. Despite presumably limited seed dispersal, weak spatial genetic structure in juveniles suggests overlapping seed shadows followed by self-thinning during recruitment. The present study also demonstrates that studies of spatial genetic structure focusing on limited numbers of generations may not be sufficient to reveal the entire picture of genetic structure in populations with overlapping generations.     

Theacrine (1,3,7,9-tetramethyluric acid) synthesis in leaves of a Chinese tea,kucha (Camellia assamica var. kucha)

Theacrine (1,3,7,9-tetramethyluric acid) and caffeine were the major purine alkaloids in the leaves of an unusual Chinese tea known as kucha (Camellia assamica var. kucha). Endogenous levels of theacrine and caffeine in expanding buds and young leaves were ca. 2.8 and 0.6-2.7% of the dry wt, respectively, but the concentrations were lower in the mature leaves. Radioactivity from S-adenosyl-L-[methyl-14C]methionine was incorporated into theacrine as well as theobromine and caffeine by leaf disks of kucha, indicating that S-adenosyl-L-methionine acts as the methyl donor not only for caffeine biosynthesis but also for theacrine production. [8-14C]Caffeine was converted to theacrine by kucha leaves with highest incorporation occurring in expanding buds. When [8-14C]adenosine, the most effective purine precursor for caffeine biosynthesis in tea (Camellia sinensis), was incubated with young kucha leaves for 24 h, up to 1% of total radioactivity was recovered in theacrine. However, pulse-chase experiments with [8-14C]adenosine demonstrated much more extensive incorporation of label into caffeine than theacrine, possibly because of dilution of [14C]caffeine produced by the large endogenous caffeine pool. These results indicate that in kucha leaves theacrine is synthesized from caffeine in what is probably a three-step pathway with 1,3,7-methyluric acid acting an intermediate. This is a first demonstration that theacrine is synthesized from adenosine via caffeine.     

山茶属山茶组的细胞地理学研究

本文总结了山茶组植物的细胞学资料,结合形态和地理学特征讨论了该组植物扩散及分化的规律。山茶组具有相同的染色体基数,变化较大的倍性。其中子房无毛的种类除Ｃ．ｃｈｅｋｉａｎｇｏｌｅｏｓａ Ｈｕ,Ｃ．ｊａｐｏｎｉａｃａ Ｌ．的个别居群外都是二倍体;多倍体主要出现在苞,萼,后发脱落,子房被毛的种类中,分布于南岭以西至西南地区,南岭及南岭在东,以南地区未发现多倍体。     

油茶脂酰辅酶A脱氢酶基因的克隆与表达分析

以国审油茶(Camellia oleifera)良种‘华硕’种子为材料,在已构建的转录组和表达谱数据库基础之上,采用RACE技术,克隆获得油茶脂酰辅酶A脱氢酶基因的全长c DNA序列,命名为Co ACAD(基因登录号KJ910338)。该基因c DNA全长为2702 bp,含有2487 bp的开放读码框,编码828个氨基酸,分子量为92.4113 k D,理论等电点p I为8.47,具有2个比较明显的跨膜区和酪氨酸蛋白激酶活性位点LVHGDFRIDNLVF,存在5个亚结构域;在Co ACAD基因c DNA全长序列的基础上构建表达载体,其中原核表达载体在宿主细胞BL21(DE3)中成功诱导表达,获得表观分子量约为93 k D的目的蛋白;实时荧光定量PCR分析表明,Co ACAD基因在果实膨大期和成熟期上调表达,预示着Co ACAD基因可能在种子发育过程中参与能量供应过程的调控。     

油茶CoSAD基因载体的构建、鉴定及功能分析

为揭示油茶( Camellia oleifera Abel)硬脂酰-ACP脱饱和酶( SAD)基因(即CoSAD基因)的功能,构建了该基因的原核表达载体pET28b-CoSAD、植物表达载体pBI121-CoSAD和RNA干扰载体pBI121-CoSAD RNAi,并采用PCR扩增及双酶切方法对3类载体进行鉴定;在此基础上,对原核表达载体中的CoSAD基因进行诱导表达分析,并对pBI121-CoSAD转化的拟南芥〔Arabidopsis thaliana ( Linn.) Heynh.〕sad突变体植株和pBI121-CoSAD RNAi转化的拟南芥野生型植株进行转基因鉴定和主要脂肪酸成分含量分析。 PCR扩增和双酶切结果显示：从 pET28b-CoSAD、pBI121-CoSAD和pBI121-CoSAD RNAi 载体的阳性克隆中均可获得目的条带,表明这3类载体均构建成功;用1 mmol·L-1 IPTG分别诱导0.5、1.0、2.0、3.0、4.0和5.0 h,CoSAD基因均能够在pET28b-CoSAD转化的大肠杆菌BL21感受态细胞中正常表达,能够获得与预测结果相符的相对分子质量约47000的特异目的蛋白条带,且蛋白活性随诱导时间的延长而升高。从pBI121-CoSAD转化的拟南芥突变体植株和pBI121-CoSAD RNAi转化的拟南芥野生型植株中也均可扩增出目的条带。 GC-MS分析结果显示：与拟南芥野生型植株相比,其突变体植株的硬脂酸和棕榈酸含量较高、油酸和棕榈油酸含量较低;但突变体植株经pBI121-CoSAD转化后,硬脂酸和棕榈酸含量降低而油酸和棕榈油酸含量提高;野生型植株经过pBI121-CoSAD RNAi转化后,硬脂酸和棕榈酸含量提高、油酸和棕榈油酸含量降低,表明pBI121-CoSAD转化能够促进拟南芥sad突变体植株体内饱和脂肪酸向不饱和脂肪酸转化,而pBI121-CoSAD RNAi转化对拟南芥SAD基因的表达有明显的抑制作用,这2种重组质粒均可影响拟南芥植株的脂肪酸含量。研究结果表明：油茶CoSAD基因具有调控饱和脂肪酸(硬脂酸和棕榈酸)向不饱和脂肪酸(油酸和棕榈油酸)转化的功能,对茶油的脂肪酸组成具有关键的调控作用。     

Design and selection of trap color for capture of the tea leafhopper,Empoasca vitis,by orthogonal optimization

The tea leafhopper, Empoasca vitis (Göthe) (Hemiptera: Cicadellidae), is a major pest of the tea plant, Camellia sinensis (L.) O. Kuntze (Theaceae). In this study, the RGB color model was used to describe the colors of sticky traps. The most effective color for attraction of E. vitis was investigated by orthogonal optimization. The selected color was verified in tea gardens and the most effective height for positioning of color sticky traps for capturing tea leafhoppers was investigated. After the determination of the effect of the three color parameters and their interactions by orthogonal optimization, the color gold (RGB: 255, 215, 0) was selected as the most effective color to trap tea leafhoppers. In tea gardens, more leafhoppers were captured using gold sticky traps (RGB: 226, 204, 4) than using commercially available yellow sticky traps. The most effective height of gold sticky traps for trapping leafhoppers was 40–60 cm above the tea canopy. Few lady beetles were captured at this height. We conclude that the orthogonal optimization method is a convenient and efficient method to screen digitally generated colors for attracting and trapping of pests.     

A novel cold-regulated gene from Camellia sinensis, CsCOR1, enhances salt- and dehydration-tolerance in tobacco

In present research, the full-length cDNA and the genomic sequence of a novel cold-regulated gene, CsCOR1, were isolated from Camellia sinensis L. The deduced protein CsCOR1 contains a hydrophobic N-terminus as a signal peptide and a hydrophilic C-terminal domain that is rich in glycine, arginine and proline. Two internal repetitive tridecapeptide fragments (HSVTAGRGGYNRG) exist in the middle of the C-terminal domain and the two nucleotide sequences encoding them are identical. CsCOR1 was localized in the cell walls of transgenic-tobaccos via CsCOR1::GFP fusion approach. The expression of CsCOR1 in tea leaves was enhanced dramatically by both cold- and dehydration-stress. And overexpression of CsCOR1 in transgenic-tobaccos improved obviously the tolerance to salinity and dehydration.     

Isolation and characterization of brassinosteroids from immature seeds of Camellia sinensis (O) Kuntze

Brassinosteroids play an important role in growth and development of plants. They have been reported universally in all the plants. The present study deals with the presence of these compounds in immature tea seeds. Five brassinosteroids, i.e. 6-deoxo-28-norcathasterone, 6-deoxo-28-norteasterone, 3-dehydro-6-deoxo-28-norteasterone, 6-deoxo-28-nortyphasterol and 6-deoxo-28-norcastasterone have been isolated and identified by GC–MS. The identified brassinosteroids and their derivatives are active constituents of late C-6 oxidation pathway, thereby suggesting the biosynthesis of brassinosteroids in tea seeds by late C-6 oxidation pathway.