黄土高原丘陵沟壑区抗侵蚀植物叶表皮的生态适应性

采用叶表皮临时装片法研究了黄土高原丘陵沟壑区不同土壤侵蚀环境沟间地、沟谷地和沟间人工刺槐林地6种抗侵蚀植物叶表皮组成细胞的形态特征.结果表明: 沟间地抗侵蚀植物叶的上表皮气孔开度、气孔密度、气孔指数、气孔器长宽比可塑性、气孔器面积可塑性、表皮毛〖JP2〗密度和表皮细胞密度分别比沟谷地提高93.8%、66.8%、17.9%、36.4%、42.3%、199.4%和46.5%,下表皮分别提高90.4%、76.6%、9.8%、47.1%、43.9%、98.2%和50.1%;沟间人工刺槐林地叶上表皮各形态指标分别比沟谷地提高66.7%、20.5%、11.9%、37.9%、19.8%、113.1%和10.8%,叶下表皮分别提高106.7%、45.8%、11.9%、41.3%、21.2%、52.2%和28.1%.沟间地植物叶上、下叶表皮毛长度分别比沟谷地缩短58.8%和29.7%,表皮细胞面积分别比沟谷地减少40.3%和37.0%.沟间人工刺槐林地叶上、下表皮毛长度分别比沟谷地缩短25.0%和23.6%,表皮细胞面积分别比沟谷地减少22.2%和19.2%.抗侵蚀植物通过增加叶表皮气孔开度、气孔密度、气孔指数、气孔器长宽比可塑性、气孔器面积可塑性、表皮毛密度、表皮细胞密度和减少表皮毛长度、表皮细胞面积来适应较强的土壤侵蚀环境.     

Abnormal fatty alcohol metabolism in cultured keratinocytes from patients with Sjögren-Larsson syndrome

Sj?gren-Larsson syndrome (SLS) is an inherited neurocutaneous disorder characterized by ichthyosis, mental retardation, spasticity, and deficient activity of fatty aldehyde dehydrogenase (FALDH). FALDH is an enzyme component of fatty alcohol:NAD oxidoreductase (FAO), which is necessary for fatty alcohol metabolism. To better understand the biochemical basis for the cutaneous symptoms in this disease, we investigated lipid metabolism in cultured keratinocytes from SLS patients. Enzyme activities of FALDH and FAO in SLS cells were <10% of normal. SLS keratinocytes accumulated 45-fold more fatty alcohol (hexadecanol, octadecanol, and octadecenol) than normal, whereas wax esters and 1-O-alkyl-2,3-diacylglycerols were increased by 5.6-fold and 7.5-fold, respectively. SLS keratinocytes showed a reduced incorporation of radioactive octadecanol into fatty acid (24% of normal) and triglyceride (13% of normal), but incorporation into wax esters and 1-O-alkyl-2,3-diacylglycerol was increased by 2.5-fold and 2.8-fold, respectively. Our results indicate that FALDH deficiency in SLS keratinocytes causes the accumulation and diversion of fatty alcohol into alternative biosynthetic pathways. The striking lipid abnormalities in cultured SLS keratinocytes are distinct from those seen in fibroblasts and may be related to the stratum corneum dysfunction and ichthyosis in SLS.     

Heat shock responsiveness analysis of <Emphasis Type="Italic">Athsp70b</Emphasis> upstream region

A 1431-bp upstream fragment of Athsp70b was cloned via PCR amplification and expressed in onion epidermis by particle bombardment. Furthermore, the progressive deletions of the Athsp70b upstream fragment linked to the β-glucuronidase (GUS) coding region were performed. Then, a stable GUS expression was analyzed in tobacco BY2 cells and Arabidopsis. Our present results showed that about a 500-bp region upstream ATG of Athsp70b is suitable to confer heat inducibility to the GUS reporter gene in plants and around 116 bp contain nonperfect heat-sensitive element. This promoter responds to heat, salicylic acid, and benzyladenine. GUS staining was mainly observed in the vascular tissues and root tips, implying that Athsp70b is related to water transportation.     

Perturbed desmosomal cadherin expression in grainy head-like 1-null mice

In Drosophila, the grainy head (grh) gene plays a range of key developmental roles through the regulation of members of the cadherin gene family. We now report that mice lacking the grh homologue grainy head-like 1 (Grhl1) exhibit hair and skin phenotypes consistent with a reduction in expression of the genes encoding the desmosomal cadherin, desmoglein 1 (Dsg1). Grhl1-null mice show an initial delay in coat growth, and older mice exhibit hair loss as a result of poor anchoring of the hair shaft in the follicle. The mice also develop palmoplantar keratoderma, analogous to humans with DSG1 mutations. Sequence analysis, DNA binding, and chromatin immunoprecipitation experiments demonstrate that the human and mouse Dsg1 promoters are direct targets of GRHL1. Ultrastructural analysis reveals reduced numbers of abnormal desmosomes in the interfollicular epidermis. These findings establish GRHL1 as an important regulator of the Dsg1 genes in the context of hair anchorage and epidermal differentiation, and suggest that cadherin family genes are key targets of the grainy head-like genes across 700 million years of evolution.     

柳属的叶表皮微形态特征及其分类学意义

研究了29种柳属( Salix )植物在扫描电镜下的叶表皮微形态特征.结果表明:柳属的角质层蜡质纹饰可以划分为:痂状蜡质层,壳状平滑蜡质层,具凸起颗粒的蜡质层,具颗粒的蜡质层,锥形纤维体和鳞片状纤维体6种类型.其中锥形纤维体和鳞片状纤维体均为柳属所特有的蜡质类型,后者为前者的变型,这两种蜡质纹饰类型多见于较为进化的皱纹柳亚属和黄花柳亚属,故推测其可能为柳属中较为进化的性状.研究还发现气孔有外拱盖扁平和隆起呈脊状2种类型.而气孔外拱盖内缘为浅波状的类型仅见于高山和北极的类群中,因而推测该类型可能同高山和极地的低温等环境有关.气孔外拱盖的形态及其角化的情况以及蜡质类型是稳定的鉴别特征,对于柳属植物,尤其是一些表型相似的种类有很好的鉴别作用,但对于组、亚属的界定作用不大.     

黑龙江椴树属植物叶表皮形态学观察

利用扫描电子显微镜对紫椴（Tilia amurensis Rupr.）及糠椴（T. mandshurica Rupr.et Maxim.）叶片的微观形态结构特征进行观察,并进行微观形态结构的比较研究。研究结果表明紫椴与糠椴叶片上表皮微观形态相同,而下表皮气孔器的形态类型、蜡质纹饰和角质膜的形态特征、单位面积上星状毛的数量均表现出很大的差异。这些微观形态差异可作为区分紫椴和糠椴的分类学依据。     

鸢尾属（Iris）植物叶片表皮微形态特征的研究

对12种鸢尾叶片的表皮特征进行了观察和研究,结果表明野鸢尾、单花鸢尾、北陵鸢尾3种鸢尾各自的上下表皮细胞的形状及气孔密度等有明显区别,而其余9种鸢尾叶片各自上下表皮形态均无明显差异。12种鸢尾的气孔类型均属于横列型,且气孔均是随机分布,气孔保卫细胞的长轴与叶脉平行,叶脉处无气孔分布。不同种鸢尾之间叶片表皮特征具有显著差异,可为鸢尾属植物的分类提供依据。     

Cell-specific localization of Na+ in roots of durum wheat and possible control points for salt exclusion

Sodium exclusion from leaves is an important mechanism for salt tolerance in durum wheat. To characterize possible control points for Na(+) exclusion, quantitative cryo-analytical scanning electron microscopy was used to determine cell-specific ion profiles across roots of two durum wheat genotypes with contrasting rates of Na(+) transport from root to shoot grown in 50 mm NaCl. The Na(+) concentration in Line 149 (low transport genotype) declined across the cortex, being highest in the epidermal and sub-epidermal cells (48 mm) and lowest in the inner cortical cells (22 mm). Na(+) was high in the pericycle (85 mm) and low in the xylem parenchyma (34 mm). The Na(+) profile in Tamaroi (high transport genotype) had a similar trend but with a high concentration (130 mm) in the xylem parenchyma. The K(+) profiles were generally inverse to those of Na(+). Chloride was only detected in the epidermis. These data suggest that the epidermal and cortical cells removed most of the Na(+) and Cl(-) from the transpiration stream before it reached the endodermis, and that the endodermis is not the control point for salt uptake by the plant. The pericycle as well as the xylem parenchyma may be important in the control of net Na(+) loading of the xylem.     

Physiological function of IspE, a plastid MEP pathway gene for isoprenoid biosynthesis, in organelle biogenesis and cell morphogenesis in Nicotiana benthamiana

Isoprenoid biosynthesis in plants occurs by two independent pathways: the cytosolic mevalonate (MVA) pathway and the plastidic methylerythritol phosphate (MEP) pathway. In this study, we investigated the cellular effects of depletion of IspE, a protein involved in the MEP pathway, using virus-induced gene silencing (VIGS). The IspE gene is preferentially expressed in young tissues, and induced by light and methyl jasmonate. The GFP fusion protein of IspE was targeted to chloroplasts. Reduction of IspE expression by VIGS resulted in a severe leaf yellowing phenotype. At the cellular level, depletion of IspE severely affected chloroplast development, dramatically reducing both the number and size of chloroplasts. Interestingly, mitochondrial development was also impaired, suggesting a possibility that the plastidic MEP pathway contributes to mitochondrial isoprenoid biosynthesis in leaves. A deficiency in IspE activity decreased cellular levels of the metabolites produced by the MEP pathway, such as chlorophylls and carotenoids, and stimulated expression of some of the downstream MEP pathway genes, particularly IspF and IspG. Interestingly, the IspE VIGS lines had significantly increased numbers of cells of reduced size in all leaf layers, compared with TRV control and other VIGS lines for the MEP pathway genes. The increased cell division in the IspE VIGS lines was particularly pronounced in the abaxial epidermal layer, in which the over-proliferated cells bulged out of the plane, making the surface uneven. In addition, trichome numbers dramatically increased and the stomata size varied in the affected tissues. Our results show that IspE deficiency causes novel developmental phenotypes distinct from the phenotypes of other MEP pathway mutants, indicating that IspE may have an additional role in plant development besides its role in isoprenoid biosynthesis. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Genbank accession number for IspE: ABO87658.