Biotechnological implications from abscisic acid (ABA) roles in cold stress and leaf senescence as an important signal for improving plant sustainable survival under abiotic-stressed conditions

In the past few years, the signal transduction of the plant hormone abscisic acid (ABA) has been studied extensively and has revealed an unanticipated complex. ABA, characterized as an intracellular messenger, has been proven to act a critical function at the heart of a signaling network operation. It has been found that ABA plays an important role in improving plant tolerance to cold, as well as triggering leaf senescence for years. In addition, there have been many reports suggesting that the signaling pathways for leaf senescence and plant defense responses may overlap. Therefore, the objective was to review what is known about the involvement of ABA signaling in plant responses to cold stress and regulation of leaf senescence. An overview about how ABA is integrated into sugars and reactive oxygen species signaling pathways, to regulate plant cold tolerance and leaf senescence, is provided. These roles can provide important implications for biotechnologically improving plant cold tolerance.     

水稻叶片衰老过程中氨肽酶活性的变化

水稻叶片中存在着氨肽酶,其最适反应pH和最适反应温度分别为8.2℃和40℃,酶促反应的产物量在最初30min内与时间呈直线相关。 水稻叶片衰老过程中叶绿素和蛋白质含量下降,而氨肽酶比活上升;用植物激素延缓或促进叶片衰老蛋白质降解的同时也抑制或促进了氨肽酶比活的上升,说明氨肽酶在水稻叶片衰老蛋白质降解过程中起一定的作用。根据水稻叶片衰老过程中大分子化合物和叶片外部形态的变化,可将叶片衰老过程划分为缓衰期、急衰期和竭衰期。     

Microarray analysis of vegetative phase change in maize

Vegetative phase change is the developmental transition from the juvenile phase to the adult phase in which a plant becomes competent for sexual reproduction. The gain of ability to flower is often accompanied by changes in patterns of differentiation in newly forming vegetative organs. In maize, juvenile leaves differ from adult leaves in morphology, anatomy and cell wall composition. Whereas the normal sequence of juvenile followed by adult is repeated with every sexual generation, this sequence can be altered in maize by the isolation and culture of the shoot apex from an adult phase plant: an 'adult' meristem so treated reverts to forming juvenile vegetative organs. To begin to unravel the as-yet poorly understood molecular mechanisms underlying phase change in maize, we compared gene expression in two juvenile sample types, leaf 4 and culture-derived leaves 3 or 4, with an adult sample type (leaf 9) using cDNA microarrays. All samples were leaf primordia at plastochron 6. A gene was scored as 'phase induced' if it was up- or downregulated in both juvenile sample types, compared with the adult sample type, with at least a twofold change in gene expression at a P-value of < or =0.005. Some 221 expressed sequence tags (ESTs) were upregulated in juveniles, and 28 ESTs were upregulated in adults. The largest class of juvenile-induced genes was comprised of those involved in photosynthesis, suggesting that maize plants are primed for energy production early in vegetative growth by the developmental induction of photosynthetic genes.     

Modified Cetyltrimethylammonium bromide method improves robustness and versatility: The benchmark for plant RNA extraction

A wide range of plant RNA extraction methods are available; however, many of these are limited in their application for a diverse range of plant species. With special emphasis on robustness and versatility, we have improved the cetyltrimethylammonium bromide (CTAB) method and isolated high-quality RNA from 16 different plant species. The major modifications made to the protocol described here were a reduction of sample treatment steps and an increase in β-mercaptoethanol concentration (to 3%) resulting in a robust, rapid and reproducible plant RNA extraction protocol that can be used for a broad range of plant species and tissue types.     

Leaf anatomy of Camellia sect. Oleifera and sect. Paracamellia (Theaceae) with reference to their taxonomic significance

Leaf anatomy of 21 species representing sect. Oleifera H. T. Chang and sect. Paracamellia Sealy in the genus Camellia was investigated using light microscopy. All the shapes of leaf epidermal cells were polygo-nal, and the patterns of anticlinal walls were sinuolate or sinuous, which were important to the classification of these two sections. The stomata were cyclocytic type and only present on the abaxial epidermis in both sampled sections. Seventeen leaf anatomical and cytologic characters were selected and used for the cluster analysis and principle components analyses performed by PAST program. Congruent results were obtained, with sect. Oleifera and sect. Paracamellia consistently grouping in two different clades, and some related species nesting together. This study provided leaf anatomical evidence for the merge of C. lanceoleosa H. T. Chang & J. S. Chiu and C. fluviatilis Hand.-Mazz.; of C. brevistyla Coh. St., C. obtusifolia H. T. Chang, and C. puniceiflora H. T. Chang; and of C. grijsii Hance and C. shensiensis H. T. Chang. In addition, it was also proved that C. tenii Sealy should be segregated from sect. Paracamellia and placed in the sect. Corallina Sealy. For further interest, we suggested that C. phaeoclada H. T. Chang be recognized as a subspecies of C. microphylla (Merr.) Chien. Overall, the results presented provided new insights into the relationships within a number of Camellia plants and sug-gested directions for future studies.     

黄檗落叶化学成分的研究

从黄檗落叶的95％乙醇提取物中分离鉴定了7个化合物,分别为phellodenol-A(1),茵芋苷(skimmin,2),phellodenol E(3),黄檗苷(amurensin,4),黄柏苷(phellamurin,5),(2R) -phellodensin-F(6)和clerosterol 3-Oβ-D-galactopyranoside (7).其中,化合物7为首次从黄柏属植物中分离得到,化合物3和6为首次从该植物中分离得到.     

Radiolabelling studies of fatty acids in pisum sativum and Vicia faba leaves at different temperatures

Leaves of pea and broad bean plants were incubated with acetate-[¹⁴C] at temperatures varying from 7 to 34°. No significant difference was observed in the distribution of radioactivity between phosphatidylcholine and the galactosylglycerides in pea with different temperatures. However, increasing temperatures increased the labelling of phosphatidylcholine in broad bean leaves, at the expense of polar lipids other than the galactosylglycerides. The incubation temperature had no significant effect on the pattern of labelling of the fatty acids of the major leaf lipids. A correlation was seen in the specific radioactivity of oleate and linoleate in phosphatidylcholine and, especially, in the galactosylglycerides. The data emphasise the rapid equilibration of oleate and linoleate (which probably occurs by transacylation) between the two galactosylglycerides and phosphatidylcholine in leaf tissues.     

Cell Wall Proteome of Sugarcane Young and Mature Leaves and Stems

By characterizing the cell wall proteomes of different sugarcane organs (leaves and stems) at two developmental stages (young vs mature/apical vs basal), it is possible to address unique characteristics in each of them. Four‐month‐old leaves show a higher proportion of oxido‐reductases and proteins related to lipid metabolism (LM), besides a lower proportion of proteins acting on polysaccharides, in comparison to 4‐month‐old internodes. It is possible to note that sugarcane leaves and young stems have the highest LM rate than all species, which is assumed to be linked to cuticle formation. The data generated enrich the number of cell wall proteins (CWPs) identified in sugarcane, reaching 277. To our knowledge, sugarcane has now the second higher coverage of monocot CWP in plants.     

不同大气校正方法对森林叶面积指数遥感估算影响的比较

利用TM原始图像以及经过6S模型和基于影像自身的Gilabert模型大气校正后的地面绝对反射率图像,分别计算了褒河流域阔叶林和针阔混交林2种林型的5类光谱植被指数(SR、NDVI、MNDVI、ARVI和RSR),并建立各林型森林叶面积指数与同时相的各个植被指数的相关关系。结果表明,2种大气校正模型均显著提高了各植被指数与森林叶面积指数的相关关系,除了对森林叶面积指数与植被指数SR和NDVI的相关关系影响不显著外,对森林叶面积指数与植被指数MNDVI、ARVI和RSR相关关系的影响均非常显著。说明不同大气校正模型对叶面积指数的遥感估算结果有较大影响。因此,在利用遥感数据进行定量分析、信息提取和生态遥感应用时,不仅要进行大气校正,而且还要慎重选择大气校正模型和植被指数。