Auxin,Cytokinin and Ab sei sic Acid

Abstract

Auxin, cytokinin, and abscisic acid (ABA) are important plant hormones that regulate many growth and developmental processes. In recent years, a number of genes involved in the metabolic and signaling pathways for auxin, cytokinin and ABA have been cloned and characterized. With organ-and tissue-specific or conditionally active gene promoters, it has become possible to manipulate concentrations of plant hormones in planta to create commercially desirable traits. Seedless fruit production and the extension of shelf life of green produce and ornamental plants are two successful examples of manipulating concentrations of these hormones in planta. In this review, we will focus our discussion on the effects of the over-or under-expression of genes involved in the biosynthetic and catabolic pathways of these hormones with an emphasis on their potential applications in ornamental crops.     

Floridean Starch and Floridoside Metabolic Pathways of Neoporphyra haitanensis and Their Regulatory Mechanism under Continuous Darkness

Floridean starch and floridoside are the main storage carbohydrates of red algae. However, their complete metabolic pathways and the origin, function, and regulatory mechanism of their pathway genes have not been fully elucidated. In this study, we identified their metabolic pathway genes and analyzed the changes in related gene expression and metabolite content in Neoporphyra haitanensis under continuous dark conditions. Our results showed that genes from different sources, including eukaryotic hosts, cyanobacteria, and bacteria, were combined to construct floridean starch and floridoside metabolic pathways in N. haitanensis. Moreover, compared with those in the control, under continuous dark conditions, floridean starch biosynthesis genes and some degradation genes were significantly upregulated with no significant change in floridean starch content, whereas floridoside degradation genes were significantly upregulated with a significant decrease in floridoside content. This implies that floridean starch content is maintained but floridoside is consumed in N. haitanensis under dark conditions. This study elucidates the “floridean starch–floridoside” metabolic network and its gene origins in N. haitanensis for the first time.     

Molecular Approaches to Improve Salt Resistance in Crops: Facts and Perspectives

SUMMARY

Because of the expansion of agriculture into marginal environments, enhancement of crop resistance to soil salinity is becoming a frequent objective for breeders. The tools offered by molecular biology to transfer a single or a few genes provide a major hope to reduce the negative impact of broad gene transfer that takes place in wide-cross hybridizations. Due to the presence of osmotic and toxic components in the growth response of plants to salt stress, any attempt to improve plant performance in saline environments should ensure the maintenance of an adequate flux of water into plant tissues, and also avoid the build up of ions into the cell compartments where they can exert toxic effects. Besides, reduction of injury effects due to salinity on plant tissues is a highly desirable objective. Transgenic plants overexpressing ion transporters able to exclude Na⁺ into vacuoles, the enzymes required for the biosynthesis of several osmocompatible, organic solutes, or the enzymes participating in detoxification pathways, have been obtained. Some of these transgenic plants display an enhanced growth relative to their wild type parents in saline environments, although the way in which this resistance is achieved remains essentially unknown. A fourth and promising way to engineer salt resistance in plants is the attempt to manipulate gene regulatory pathways. The extent to which these experiences, mainly with model plants, could be extrapolated to crop plants growing in the field is discussed. It is proposed that a combination of different molecular approaches could be helpful to achieve enhanced salt resistance in crop plants.     

大豆胞囊线虫侵染诱导五寨黑豆早期的转录组分析

利用Illumina Hi SeqTM2000对大豆胞囊线虫侵染前后的抗病大豆品种五寨黑豆的转录组进行检测。将测序的两个文库进行拼接,得到长度大于200bp的reads共20 980 831条,总长度约为4.23Gb,筛选到1 045个差异表达基因。Gene ontology功能显著性富集发现差异表达基因在生物过程注释基因最多,共有1 007个差异表达基因。在COG数据库中对基因产物进行直系同源分类,结果表明众多基因参与到碳水化合物及氨基酸的运输和代谢、次生代谢物质合成及信号传导机制过程,并受胞囊线虫侵染的诱导表达。KEGG代谢通路分析显示差异表达基因在苯丙烷类及氧化磷酸化代谢通路显著富集,说明这两个代谢通路在五寨黑豆抗胞囊线虫病中起重要作用。     

Nitrogen Balance in Forage Rice (Oryza sativa L. cv. Tachisuzuka) Cultivation in Pots with Animal Manure Application

Abstract

Experiments were conducted to evaluate the nitrogen (N) balance in forage rice cultivation using animal manure in 1/2,000a Wagner pots in a greenhouse. The cattle manure and poultry manure were applied at 3 levels of N (0, 14, 28 g available N m^–2) without additional chemical fertilizer application. The pots were designed to simulate the fluid percolation in the paddy field. The results indicated increasing levels of N input improved plant height, tiller number, SPAD value and biomass (straw, grain and root) production, however, N leaching from soil (Andosols) due to percolating water also increased. The planting of rice plants proved to reduce 30% of the N leaching loss. N use efficiency, the ratio of N uptake by plant per unit N application, decreased in higher N application. The N uptake by the above-ground parts occupied about 66% of the whole plants.     

Fate of 15N-labeled Inorganic Fertilizer in an Upland Soil Applied with Sweet Sorghum Bagasse and N Uptake Efficiency by Komatsuna Plants

Abstract

Sweet sorghum bagasse (SSB) is a soil amendment with potential for biofuel production. This study was conducted to determine the appropriate techniques for application of SSB and the effect of incorporation of inorganic fertilizer (IF) on the production of komatuna (Brassica rapa) plants. SSB was applied to the surface of the plant or incorporated into soil. The N fate of IF was evaluated by using ¹⁵N-labeled IF. The combination of surface application of SSB and incorporation of IF to soil decreased the N uptake by komatsuna plants but increased dry weight, whereas the incorporation of IF and SSB gave lower komatsuna dry weight than IF treatment alone. Moreover, the application of SSB tended to increase the N distribution from IF to komatsuna with decreased N loss from the plant-soil system. These results showed that surface application of SSB is effective for increasing crop production due to reduction of N loss and improved N use efficiency.     

水稻WRKY转录因子基因家族响应外源一氧化氮的表达谱分析

一氧化氮(nitric oxide,NO)信号分子与WRKY转录因子均参与植物抗逆、发育与代谢等许多生理过程。采用Agilent水稻全基因组cDNA芯片分析了NO处理后1、6和12h水稻幼苗WRKY转录因子基因的表达谱,鉴定出在1个时间点有两倍或两倍以上表达变化的WRKY基因32个,主要分布在WRKY的Ⅰ和Ⅱ组,其中75%的Ⅱa和45.6%的Ⅱd亚组成员为差异表达基因;鉴定出至少在2个时间点有两倍或两倍以上表达变化的WRKY基因15个,均为早期(1h)应答,且多数(64.2%)持续上调;基因功能预测分析表明,这些基因主要参与生物学过程中的细胞过程、代谢过程和刺激响应,以及分子功能中的转录调节活性和结合;代谢通路分析表明,WRKY24涉及植物与病原菌相互作用代谢通路。实时荧光定量PCR验证结果与芯片杂交结果基本一致,印证了芯片杂交结果的有效性。上述发现提示,NO信号可能参与了WRKY转录因子介导的生物学调控功能,并为这些基因的进一步功能分析奠定基础。     

The Highlighted Roles of Metabolic and Cellular Response to Stress Pathways Engaged in Circulating hsa-miR-494-3p and hsa-miR-661 in Alzheimer’s Disease

Background:Among different roles of miRNAs in AD pathogenesis, hsa-miR-494-3p and hsa-miR-661 functions are poorly understood. Methods:To obtain the gene targets, gene networks, gene ontology, and enrichment analysis of the two miRNAs, some web servers were utilized. Furthermore, the expressions of these miRNAs were analyzed by qRT-PCR in 36 blood sera, including 18 Alzheimer’s patients and 18 healthy individuals. Results:The in silico analysis demonstrated the highlighted roles of metabolic and cellular response to stress pathways engaged in circulating hsa-miR-494-3p and hsa-miR-661 in AD. The qRT-PCR analysis showed that the downregulated expression level of hsa-miR-661 was statistically significant (p < 0.05). Also, the ROC curve of hsa-miR-661 displayed the significant AUC (p = 0.01). Conclusion:Based on our findings, the metabolic and cellular responses to stress pathways are closely connected to these two miRNAs functions. Besides, the qRT-PCR and Roc curve determined hsa-miR-661 could be as a biomarker for diagnosis or prognosis of AD patients. Key Words: Alzheimer’s disease, Serum, Circulating microRNAs     

Possibility of Introducing Winter Legumes,Hairy Vetch and Faba Bean,as Green Manures to Turmeric Cropping in Temperate Region

Abstract

A field experiment was conducted to examine the possibility of introducing winter legumes, hairy vetch and faba bean, as green manures to turmeric cropping in a temperate region. Hairy vetch shoots were incorporated to determine the effect of N and P added as green manure. Higher values in plant height and number of leaves of turmeric were observed in the treatment with incorporation of hairy vetch than in that without incorporation (no-incorporation) throughout the growth periods. The differences in total amounts of N and P of turmeric between incorporation and no-incorporation treatments were the highest on 15 October, when the amount was increased by 8.0 g N and 1.1 g P m^–2 compared with the no-incorporation treatment. From September to October, curcumin content rapidly increased with rhizome thickening, and gradually increased. We also quantified the N and P contribution from faba bean residues to the succeeding turmeric. The total amounts of N and P in turmeric cultivated after incorporating shoot and root residues into previously cultivated faba bean field were 2.5 g N and 1.0 g P m^–2, respectively, larger than incorporating only roots. In previously fallow field, the incorporation of the shoot increased the total amount of N and P in tumeric by 4.5 g and 1.9 g m^–2, respectively, compared with that without incorporation. In the second year after incorporation, growth and nutrient uptake of the turmeric crop did not significantly differ from those without incorporation. In the temperate region, these winter legumes would be used as basal organic matters for turmeric production.     

Nitrogen Uptake by Faba Bean from 15N-Labelled Oilseed-Rape Residue and Chicken Manure with Ryegrass as a Reference Crop

Abstract

The effects of soil amendment with oilseed-rape residue (OSRR) and chicken manure (CM) on the growth and nitrogen (N) uptake of faba bean (Vicia faba L.) were assessed in a pot experiments with Italian ryegrass (Lolium multiflorum Lam.) as a reference crop. A ¹⁵N isotope dilution method was used to estimate the amount of N derived from the residue (OSRR and CM) and from atmosphere through N₂ fixation in the plants. Dry weights (DW) of shoots and whole plants were heaviest in the plants grown on the soil amended with CM (CM plants) followed by the plants grown on the soil amended with OSRR (OSRR plants) and control plants in this order. There were significant differences (p<0.05) in dry weight between CM, OSRR and control plants. DW of roots was also increased by amendment with either CM or OSRR in faba bean, but it was decreased in ryegrass. The amount of total N in both roots and shoots were increased by application of either CM or OSRR in both faba bean and ryegrass. The amount of N₂ fixed by faba bean cultured on 1.2 kg soil amended with 10g residue (CM or OSRR) was 85.9 mg pot-¹ but total N in faba bean derived from OSRR and CM was 192 and 374 mg pot-¹, respectively. The percentage of N derived from atmosphere to total N in faba bean plants ranged from 15.9 to 26.5%. The amount of N taken up by faba bean and ryegrass plants from CM were larger than those from OSRR by 81.0 and 54.3%, respectively. Soil N balance was calculated as the difference between the amount of N applied (including fixed) and taken up by the plants. The N balance of soil amended with OSRR after cultivation of faba bean was 72.2% higher than that of the soil amended with CM, and that after cultivation of ryegrass was 89.9% higher.     

Nitrogen Use at the Leaf and Canopy Level

Summary

This chapter reviews how N affects biomass production in a canopy by looking at its effects on radiation interception and radiation use efficiency, and the main processes behind them, i.e., leaf expansion, senescence and photosynthesis. Examples have been mostly drawn from extensive grain crops, but most of them extend to pastures or horticultural crops. Understanding the magnitude and dynamics of N demand and availability during critical periods for yield definition was identified as crucial to improve the efficiency of N use at the crop canopy level. Genetic variability in processes that could influence N use efficiency, and the complexity involved in scaling from cellular to crop level are discussed.     

Growth and Yield of New Rice for Africa (NERICAs) under Different Ecosystems and Nitrogen Levels

Abstract

Scarcity of water and N fertilizer are major constraints to rice production, particularly in developing countries where rainfed upland condition dominates. Improvement of genetic adaptability to inadequate water and N fertilizer is one option to maintain productivity in these regions. NERICAs are expected to yield higher under low input conditions, but growth and yield responses of the cultivars to different ecosystems and N levels remain unknown. The objectives of this study were to characterize the growth and yield performance of NERICAs, in comparison with selected Japanese rice cultivars. The two NERICAs (NERICA 1 and NERICA 5), two Japanese upland cultivars (Toyohatamochi and Yumenohatamochi), and a Japanese lowland cultivar Hitomebore were grown under two ecosystems (irrigated lowland (IL) and rainfed upland (RU)) with two N levels (high (H) and low (L)) for two years. The cultivar difference in the aboveground dry weight and grain yield was the largest in the in RU × L plot, where the values of NERICAs were similar to those in the other plots, but the values of other cultivars were substantially reduced. Regardless of cultivar, N contents of the plants at maturity correlated significantly with the aboveground dry weight at maturity, spikelet number and grain yield per area. These results indicate that NERICAs, compared with the selected Japanese upland cultivars that were bred for drought tolerance, have a higher ability to absorb N under upland conditions, which may contribute to higher biomass production and sink formation, resulting in increased gain yield.     

Structural and physiological responses of the C4 grass Sorghum bicolor to nitrogen limitation

Nitrogen (N) is one of the major nutrients influencing photosynthesis and productivity of C₄ plants as well as C₃ plants. C₄ photosynthesis operates through close coordination between mesophyll (M) and bundle sheath (BS) cells. However, how the development of structural and physiological traits in leaves of C₄ plants is regulated under N limitation remains uncertain. We investigated structural and physiological responses of leaves of the NADP-ME-type C₄ grass Sorghum bicolor to N limitation. Plants were grown under four levels of N supply (.05 to .6 g N per 5-L pot). Decreasing N supply resulted in decreases in net photosynthetic rate, stomatal conductance, leaf N and chlorophyll contents, and the activity ratio of phosphoenolpyruvate carboxylase to ribulose 1,5-bisphosphate carboxylase/oxygenase and increases in δ¹³C values and photosynthetic N use efficiency. Low-N leaves were thinner and had smaller photosynthetic cells, especially in M, resulting in lower M/BS tissue area ratio, and contained smaller and fewer chloroplasts. The BS chloroplasts in the low-N leaves accumulated abundant starch grains. The number of thylakoids per granal stack was reduced in M chloroplasts but not in BS chloroplasts. The low-N leaves had thicker cell walls, especially in the BS cells, which might be associated with less negative δ¹³C values, and fewer plasmodesmata in the BS cells. These data reveal structural and physiological responses of C₄ plants to N limitation, most of which would be related to cellular N allocation, light use, CO₂ diffusion and leakiness, and metabolite transport under N limitation.     

Regulation of root-to-leaf Na and Cl transport and its association with photosynthetic activity in salt-tolerant soybean genotypes

ABSTRACT

Soil salinity is a major constraint to sustainable crop production. Genetic improvements are needed for growing soybean in salinity-prone environments. Salt-tolerant soybean genotypes alleviate a reduction in photosynthesis and growth under saline conditions; however, the detailed mechanisms involved remain unclear. Here, we aimed to clarify how Na and Cl root-to-leaf transport is quantitatively regulated, and to identify whether photosynthetic tolerance depends on traits associated with either stomata or with mesophyll tissues. Two pairs of pot-grown soybean near-isogenic lines (NILs) consisting of tolerant and susceptible counterparts, derived from a cross between salt-tolerant FT-Abyara and salt-sensitive C01, were subjected to salinity treatment in a rainout greenhouse. Comparison of photosynthetic responses between genotypes indicated that genotypic differences in salinity tolerance depended on the ability for sustained CO₂ assimilation in mesophyll tissues, rather than stomatal conductance. The ratio of photosynthetic rate to intercellular CO₂ concentration (A/Ci) declined exponentially with increasing Na and Cl concentration regardless of genotype, but tolerant genotypes effectively kept both elements at significantly low levels. Under saline conditions, tolerant genotypes reduced Na and Cl content at the two transport pathways: from root to stem, and from stem to leaf, but the reduction of Cl at each pathway was only minor. These results suggest that integrating genetic capacity for Cl transport regulation and osmotic adjustment should be an important target in salinity-tolerance soybean breeding.     

Effect of Leaf Phosphorus and Potassium Concentration on Chlorophyll Meter Reading in Rice

Abstract

Chlorophyll meter (SPAD) is a convenient tool to estimate leaf nitrogen (N) concentration of rice plants. There is no information on the effects of leaf phosphorus (P) and potassium (K) concentration on SPAD readings and on the relationship between SPAD values and leaf N concentration in the literature. In 1996 dry season, cv IR72 was grown at the International Rice Research Institute (IRRI) and the Philippine Rice Research Institute (PhilRice) under various N, P and K fertilizer combinations. SPAD measurements were made on the topmost fully expanded leaves at mid-tillering and panicle initiation. The leaves were then detached, dried and analyzed for N, P and K. The SPAD values were highly correlated with leaf N concentration (r = 0.93 to 0.96). Fertilizer-K application did not affect SPAD values, leaf N concentration, or the relationship between the two. Phosphorus deficiency reduced leaf N concentration at mid-tillering, but increased leaf N concentration at panicle initiation when the same amount of N was applied. The SPAD values were 1 to 2 units greater for zero-P plants than P-treated plants at a given leaf N concentration at mid-tillering. At panicle initiation, the relationship between SPAD values and leaf N concentration was not significantly affected by leaf P status. These results suggest that a different regression equation between SPAD values and leaf N concentration should be used to estimate leaf N concentration of P-deficient and P-sufficient rice leaves at vegetative stage using a SPAD.     

槟榔不同发育时期果实转录组特征分析

槟榔（Areca catechu L.）果实是四大南药之一。槟榔果的研究主要集中在生理生化、生防菌、有效成分及药理、加工和利用等方面,对槟榔果的发育及其次生物质形成的分子机制尚不清楚。本研究对不同发育时期的槟榔果皮和果核进行转录组测序,鉴定槟榔果不同发育时期的关键基因,以探讨果实发育相关基因的表达特征及次生物质形成有关的基因调控。结果显示,槟榔果皮中检测到4491个差异基因,其中617个差异基因共参与了111条KEGG代谢通路,生物过程代谢类有82个通路,共257个差异基因被注释,参与次生代谢途径共有5个,共27个差异基因。槟榔果核中检测到5443个差异基因,其中898个差异基因共参与了118条通路,466个差异基因被注释在生物代谢类通路上,共涉及89条通路,参与次生代谢相关的基因有53个,参与次生代谢途径共7条。进一步分析表明：随着果实的发育,果皮中80%次级代谢通路差异相关基因呈下调表达趋势;而果核中71.4%次级代谢通路差异相关基因呈上调表达趋势。本研究结果在转录组水平揭示了槟榔果发育的生物学过程,发现了不同时期槟榔果皮和果核中次级代谢相关调控基因表达的变化规律,也为槟榔的遗传育种研究奠定了基础。     

Engineering for Drought Tolerance in Horticultural and Ornamental Plants

Abstract

Drought is one of the major factors limiting plant growth and productivity. Plant adaptation to drought is dependent on molecular networks for drought perception, signal transduction, expression of a subset of genes and production of metabolites that protect and maintain the structure of cellular components. In general, the drought response pathways can be classified into two categories: one is dependent on the stress hormone abscisic acid (ABA) and the other is ABA-independent. Many genes in these pathways have been identified, thereby providing guidance in choosing genes for engineering of drought tolerance. The review highlights the genes that mediate drought response and tolerance, and discusses lessons learned from engineering for drought tolerance in model plants, such as Arabidopsis, rice and tobacco. Because success of drought tolerance engineering is dependent on not only protein coding regions but also appropriate promoters, this article also reviews the promoters that are crucial for successful engineering of stress tolerance.     

Effects of the Temperature Lowered in the Daytime and Night-time on Sugar Accumulation in Sugarcane

Abstract

Sugarcane (Saccharum spp.) is a major crop grown for sucrose production. In Japan, its sucrose concentration is highest in winter. We examined the effects of the temperature lowered in the daytime and night-time (LDT and LNT, respectively) on sugar assimilation. Since photosynthetic and respiration rates change with temperature, we assumed that plants under LNT (LNT plants) would have low respiration rates and thus high sugar yields, whereas those under LDT (LDT plants) would have low rates of photosynthesis and thus low sugar yields. However, because of their acclimatisation to the reduced temperatures, LNT and LDT plants had sugar yields that were similar, or superior, to those of control plants. Sugar yield depends on biomass and sugar concentration; the stems of LNT and LDT plants did not grow as tall as those of the controls, but the sucrose concentrations in their stems were higher than in the controls. ¹³C analysis revealed no difference in the partitioning of photosynthates to the soluble sugar fraction between control plants and those treated with low temperature. Control plants had higher glucose concentrations in the stem than treated plants, in which new photosynthates appeared to be partitioned preferentially into sucrose. Low temperature enhanced the sucrose concentration in the sugarcane stem not by improving the carbon budget, but by promoting the partitioning of carbon to stored sucrose.     

Anticancer Activities of Plant Secondary Metabolites: Rice Callus Suspension Culture as a New Paradigm

Plant natural products including alkaloids,polyphenols,terpenoids and flavonoids have been reported to exert anticancer activity by targeting various metabolic pathways.The biological pathways regulated by plant products can serve as novel drug targets.Plant natural compounds or their derivatives used for cancer treatment and some novel plant-based compounds which are used in clinical trials were discussed.Callus suspension culture with secondary metabolites can provide a continuous source of plant pharmaceuticals without time and space limitations.Previous research has shown that rice callus suspension culture can kill>95%cancer cells with no significant effect on the growth of normal cells.The role of candidate genes and metabolites which are likely to be involved in the process and their potential to serve as anticancer and anti-inflammatory agents were discussed.Large scale production of plant callus suspension culture and its constituents can be achieved using elicitors which enhance specific secondary metabolites combined with bioprocess technology.     

Protein quality of diets based on tuber,legume, and cereal in weanling rats

Weanling male rats (45–55 g) were studied to evaluate the protein quality of diets based on combinations of yam (YA); dehulled brown bean (DBB), dehulled white bean (DWB); and corn flour (PA) that provided 1.6 g N/100 g of diet. Casein served as the reference protein. Rats fed combinations of PA, DBB, and DWB had increases in food intake, weight gain, N intake, digested and retained N, and liver N compared to those of the casein control group and the other test groups (P < 0.05). Supplementation of YA with DBB or DWB reduced weight gain, protein efficiency ratio (PER), N intake, digested and retained N, NPU and liver N values of the animals when compared with those fed the casein and the other diets containing YA. Combinations of DBB or DWB with PA appear to be the best mixtures as shown by food and N intakes, digested and retained N, liver N, and weight gain. These mixtures may possibly be economic sources of N for weaning children where these are staples in the diet.