Metabolie Engineering of Flower Color in Ornamental Plants

Abstract

Advances in the knowledge of plant pigment pathways at genetic, biochemical and molecular levels, and the establishment of genetic transformation methods for an increasing number of plant species have paved the way to genetic engineering of flower and plant color for ornamental purposes. From trial-and-error approaches based on the available few genes, the trend is now to comprehensively study the target species, genotypes and pigment pathways to precisely address specific breeding goals. This review examines the state of the art in this field, from the pioneering stages to fundamental and applied research on flavonoids, which is being extended to carotenoids and is also likely to involve other pigments in the near future.     

植物离区发育及调控信号的多样性研究进展

植物器官脱落发生的特定区域叫做离区。植物离区发育及其研究主要集中在番茄、水稻、拟南芥等模式作用与重要的经济作物上。本文主要从植物离区脱落发生的多样性及其调控信号的多样性上进行综述,植物离区脱落的主要形式有：花器官脱落、叶脱落、果实脱落、种子脱落、开裂区脱落、侧根脱落等;主要的调控信号有花发育信号、乙烯与生长素信号、细胞凋亡信号、ROS信号等。旨在为今后经济作物离区相关基因研究提供理论依据和基础,并对今后离区相关研究的前景进行展望。     

烟酰胺腺嘌呤二核苷酸(NAD)合成途径和水稻叶片早衰

叶片是植物进行光合作用的主要场所,其衰老由内源遗传发育信号和外界环境胁迫所启动,是一个非常复杂有序的调控过程。烟酰胺腺嘌呤二核苷酸(nicotinamide adenine dinucleotide,NAD)是脱氢酶的辅酶,在糖酵解、糖异生、三羧酸循环以及呼吸链等代谢中发挥着不可替代的作用。最新研究表明,水稻NAD生物合成参与调控沉默信息调控因子Sirtuins的生物活性、组蛋白H3K9去乙酰化、植物激素茉莉酸(JA)和叶片衰老。本文综述了有关水稻叶片衰老的细胞生理特征、Sirtuins酶活、NAD生物合成以及水稻早衰的OsSRT1-NAD调控途径和OsSRT1-Me OH-JA调控途径,以期阐明水稻叶片衰老的分子机理及其调控途径,为高产育种提供相应的理论参考。     

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.     

The Influence of Plant Growth Regulators and Inflorescence Removal on Plant Growth,Yield, and Skin Color of Red LaSoda Tubers

Foliar applications of the synthetic auxin compound 2,4-dichlorophenoxyacetic acid (2,4-D) have been used to enhance skin color of red potato cultivars for many years. Relatively, little is known about the mode of action of this compound, but it has been proposed that 2,4-D stimulates ethylene production and enhances the activity of enzymes involved in anthocyanin biosynthesis. The objective of this study was to compare several other plant growth regulators to 2,4-D for their effect on plant growth, tuber yield, and skin color of the light red-skinned cultivar “Red Lasoda.” Trials were conducted in 2010 and 2011 to evaluate the effects of foliar applications of the ethylene-stimulating growth regulator ethephon, the ethylene-inhibitor 1-methylcyclopropene (1-MCP), and 2,4-D. Manual inflorescence removal was also included as a treatment to determine the influence of anthocyanin sink competition between tubers and flowers on tuber skin color. Ethephon application caused floral abscission in treated plants and reduced plant height compared to other treatments and the non-treated control. While 2,4-D caused foliar injury and ethephon slightly increased the yield of <56 g tubers, neither growth regulator affected total and marketable yield. Both ethephon and 2,4-D increased tuber skin color at harvest compared to the non-treated control. In contrast, 1-MCP and inflorescence removal had no effect on yield, tuber size, and skin color. The results indicate that ethephon and 2,4-D foliar applications have similar effects on skin color and appearance, supporting the hypothesis that 2,4-D works by stimulating ethylene production within the plant.     

The effect of ethylene and abscisic acid on symptom expression of bacterial ring rot in eggplant and potato

Studies were performed to determine the effect that plant hormones involved with plant senescence (i.e., ethylene and abscisic acid) and photoperiod have on disease development and symptom expression of bacterial ring rot (BRR) caused byCorynebacterium sepedonicum (Spieck & Kotth.) Skapt & Burkh. Potato plants were grown either under a long (14 hr.) or short (10 hr.) photoperiod, while eggplants were grown only under a short (10 hr.) photoperiod. Disease severity ratings of BRR were found to be significantly higher (P=0.05) on potato plants grown under a short photoperiod compared to a long photoperiod. Plant heights of BRR infected plants were found to be significantly greater under the long photoperiod. Endogenous levels of ethylene were found to be significantly (P=0.05) greater in inoculated potato plants grown under a long photoperiod than inoculated plants grown under a short photoperiod. Results suggest that the plant hormones ethylene and abscisic acid do not significantly affect the disease development and symptom expression of BRR.     

Ornamental Plant Transformation

Abstract

Ornamental plant transformation has advanced considerably in the last decade. Now over 40 genera have been reported to be transformed. The primary methods of creating transgenic ornamental species have been Agrobacterium tumefaciens-medmtedtransformation and microprojectile bombardment. The vast majority of reports indicate the use of Agrobacteriummedmtedtransformation employing binary vectors and virhelper plasmids or supervirulence genes. Many reports are of transformation with the uidA reporter gene driven by the 35S cauliflower mosaic virus promoter, but recent efforts are now focusing on trait genes including disease resistance, flower color, flower longevity, floral scent and plant habit. Greater use of tissue specific and inducible promoters promises to enhance the functionality and usefulness of introduced trait genes. While technical challenges for production of transgenic ornamental plants still exist, the greatest challenges to realizing the potential benefits of transgenic ornamental plants are questionable public acceptance of transgenic plants and the prohibitive costs of generating environmental impact data needed to gain regulatory clearance.     

Accurate Evaluation of Photoperiodic Sensitivity and Genetic Diversity in Common Buckwheat under a Controlled Environment

Abstract

Photoperiodic sensitivity is one of the most important factors determining whether a crop can adapt to and be cultivated under a broad range of conditions. In common buckwheat (Fagopyrum esculentum Moench), flowering time (flowering of the first flower) is a complex trait influenced by photoperiod, light quality, and temperature, which change daily under natural conditions, and their interaction. Common buckwheat shows a large genetic variation because of the outcrossing reproductive strategy of this species. Thus, flowering time variation within a population reflects both environmental and genotypic variations, and accurate evaluation of photoperiodic sensitivity in common buckwheat requires cultivation under controlled environmental conditions. Here, we investigated photoperiodic sensitivity and its genetic diversity in two buckwheat cultivars, the autumn ecotype Miyazakizairai and the summer ecotype Botansoba, by controlling photoperiod during cultivation under the same temperature regime. Our results showed that (1) the summer ecotype consisted of early-flowering genotypes, including genotypes not found in the autumn ecotype; (2) the autumn ecotype consisted of various genotypes, including early-flowering genotypes and a large number of late-flowering genotypes not found in the summer ecotype; (3) the autumn ecotype showed larger genetic diversity than the summer ecotype in long-day treatments; and (4) genetic diversity first became evident in the 14.5-hr photoperiod in the autumn ecotype, and in the 15.0-hr photoperiod in the summer ecotype. These results support the hypothesis based on previous studies that common buckwheat summer ecotypes were derived from autumn ecotypes by adaptation to climate in northern Japan.     

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.     

MeJA和ET对巴西橡胶树胶乳HbGSK1基因表达的影响

GSK3蛋白与进化过程中的激素信号网络和生物、非生物胁迫响应密切关联。GSK3是否在橡胶树JA和ET信号途径起作用尚不清楚。qPCR分析结果表明，机械伤害、MeJA和ET处理上调胶乳中HbGSK1基因的表达，并且“机械伤害+MeJA”处理的表达水平显著高于机械伤害处理，推测机械伤害通过上调胶乳内源JA含量上调HbGSK1基因的表达；机械伤害上调胶乳中HbGSK1基因的表达，表明HbGSK1蛋白可能参与橡胶树非生物胁迫响应；MeJA和ET处理上调胶乳中HbGSK1基因的表达，表明HbGSK1蛋白可能参与橡胶树JA和ET植物激素信号途径的调节。MeJA和ET处理均上调胶乳中HbGSK1基因的表达，表明JA和ET对HbGSK1基因的表达的调节具有协同作用。     

Improving Rice to Meet Food and Nutritional Needs: Biotechnological Approaches

SUMMARY

The livelihood and calorie needs of large populations based in developing countries is dependent on rice cultivation. More than three billion people consume rice as a staple food. To meet the future demands of the human population, innovative tools such as genomics are being used to improve rice yield increase, for the incorporation of stress resistance/tolerance in rice varieties, and for the improvement of the nutritional quality of rice. These new tools include: sequencing, large-scale analysis of expressed sequence tags, high throughout microarray analysis and genetic transformation. Rice now serves as a model for a science based crop design for the agronomic, nutritional, and economic benefit of farmers. This article discusses the use of biotechnology as a tool to improve the rice plant for the benefit of mankind.     

Soil Microorganisms for Weed Management

Abstract

Traditional methods of weed management have not considered the microbial or other biological factors that influence plant growth; however, incorporating this knowledge may expand weed management possibilities to develop weed-suppressive soils. Alternative weed management strategies are needed to expand the capability of weed control as weed pressures continue to limit optimum yield and the use of synthetic chemical herbicides for weed control becomes more restricted. Biotic factors can influence the distribution, abundance, and competitive abilities of plant species. It has been shown that soil microorganisms are capable of suppressing weeds in the field, and seed decay phenomena are most likely microbial. It is imperative that an understanding of soil microorganisms and their ecology be developed, so that they may be used to benefit agriculture, especially weed management. Further study is required so that the ecological and biological effects of the resident soil microbial population on weed growth can be used effectively in weed management strategies to assist in reducing inputs.     

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.     

Sitona lineatus (Coleoptera: Curculionidae) Larval Feeding on Pisum sativum L. Affects Soil and Plant Nitrogen

Adults of Sitona lineatus (pea leaf weevil, PLW) feed on foliage of several Fabaceae species but larvae prefer to feed on nodules of Pisum sativum L. and Vicia faba L. Indirectly, through their feeding on rhizobia, weevils can reduce soil and plant available nitrogen (N). However, initial soil N can reduce nodulation and damage by the weevil and reduce control requirements. Understanding these interactions is necessary to make integrated pest management recommendations for PLW. We conducted a greenhouse study to quantify nodulation, soil and plant N content, and nodule damage by weevil larvae in relation to soil N amendment with urea, thiamethoxam insecticide seed coating and crop stage. PLWs reduced the number of older tumescent (multilobed) nodules and thiamethoxam addition increased them regardless of other factors. Nitrogen amendment significantly increased soil available N (>99% nitrate) as expected and PLW presence was associated with significantly lower levels of soil N. PLW decreased plant N content at early flower and thiamethoxam increased it, particularly at late flower. The study illustrated the complexity of interactions that determine insect herbivory effects on plant and soil nutrition for invertebrates that feed on N-fixing root nodules. We conclude that effects of PLW on nodulation and subsequent effects on plant nitrogen are more pronounced during the early growth stages of the plant. This suggests the importance of timing of PLW infestation and may explain the lack of yield depression in relation to this pest observed in many field studies. Also, pea crops in soils with high levels of soil N are unlikely to be affected by this herbivore and should not require insecticide inputs.     

Auxin-induced sprout growth inhibition: Role of endogenous ethylene

The role of endogenous ethylene in auxin-mediated tuber sprout growth inhibition was determined in potato (Solanum tuberosum L. cv. Russet Burbank) minitubers. Treatment of tubers with biologically active auxins resulted in a transient, dose-dependent increase in ethylene production and inhibition of sprout growth. Biologically inactive auxin analogs elicited neither response. Continuous exposure to > 0.001 μL L^-1 exogenous ethylene inhibited sprout growth in a dose-dependent manner with complete inhibition occurring at ethylene concentrations ≥1 μL L^-1. In further studies with the active auxin α-naphthalene acetic acid (NAA), the role of ethylene in auxin-induced sprout growth inhibition was determined using ethylene biosynthesis and action inhibitors. The ethylene biosynthesis inhibitor aminoethoxyvinylglycine reduced NAA-induced ethylene biosynthesis by over 80% but had no effect on sprout growth inhibition. The non-competitive ethylene action inhibitor silver thiosulfate had no effect on NAA-induced sprout growth inhibition. Similarly, both the competitive ethylene action inhibitor 2,5-norbornadiene and the irreversible action inhibitor 1-methylcyclopropene were ineffective in reducing NAA-mediated sprout growth inhibition. Collectively, these results do not support the proposal that, in the case of potato tuber sprouts, auxininduced growth inhibition is mediated by endogenous ethylene action.     

Molecular Dissection of the Relationships among Tiller Number,Plant Height and Heading Date in Rice

Abstract

Appropriate plant height, tiller number and heading date are important traits for maximizing rice production. In order to understand the genetic basis of the relationships among these three plant traits, we mapped quantitative trait loci (QTLs) using a recombinant inbred population and detected two-locus interactions for plant height and tiller number at two growth stages and for heading date in two years. There were significant negative correlations between tiller number and plant height, and between tiller number at maturity and heading date. A significant positive correlation was observed between heading date and plant height at maturity. A total of 29 QTLs for the three traits were identified over the two years. Results show that QTLs and majority of two-locus interactions for plant height and tiller numbers at 35 days after transplanting were different from those at maturity, indicating that different genes and interactions control the traits at different developmental stages. A large proportion of QTLs and interactions could only be detected in one year, suggesting that QTLs and two-locus interactions for the traits were dependent on the environment. Results suggest that pleiotropy and/or close linkage of genomic regions and pleiotropy of common two-locus combinations may be the genetic basis for the close correlations among the three traits. A QTL with a large effect for heading date, which was located in RG424-RZ667 on chromosome 6, also showed large effects on tiller number and plant height at maturity.     

NO延缓果蔬成熟衰老与抗病机理研究进展

一氧化氮是具有生物活性和信号转导作用的易扩散小分子气体,果蔬细胞通过一氧化氮合酶(NOS)、硝酸还原酶或非生化反应途径产生NO。内源NO可通过抑制乙烯的生物合成和调控环化核苷酸在植物组织中的水平来延缓植物组织的成熟和衰老,延长果蔬贮藏货架期;NO还可诱导采后果蔬产生抗病防卫反应,提高果蔬的抗病胁迫能力。着重概述NO在果蔬采后延缓成熟衰老、诱导抗病等方面的作用及其机理研究进展。     

不同环境条件下籼型杂交稻株高的发育遗传研究

采用数量性状的加性 显性发育遗传模型分析了按NCⅡ交配设计的两套籼型三系杂交水稻在两种环境条件下株高的发育遗传规律。供试材料和环境均会影响水稻株高表现,且环境对株高的影响随发育进程的推进不断减小。在不同发育阶段,水稻株高主要受加性和显性效应基因共同控制,但影响程度会随供试材料的改变而有所不同;基因型与环境互作效应会对株高产生一定影响;控制株高的遗传效应在各发育时期均有新的表现,且加性效应的表达比显性效应的表达更为活跃;条件环境互作效应亦会对株高发育遗传产生一定影响,前期影响尤其大;水稻株高的群体平均优势总体上随发育进程的推进而逐渐增加,至成熟期达到最大;群体超亲优势的变化规律因供试材料的不同而略微出现一些差异,但均在后期趋于稳定,且均为正值。在多数发育时期,水稻株高条件群体平均优势达到正向显著或极显著水平,而条件群体超亲优势达到负向显著或极显著水平,即群体平均优势和群体超亲优势在各时期均有新的表现,但其表现的大小和方向均有所不同。     

秋石斛兰F_1代主要观赏性状的遗传表现

以秋石斛兰为亲本,配制成6个杂交组合,对杂交F_1代的植株性状、花部性状和开花期进行统计分析。结果表明,杂种F_1代的株幅、叶宽、花梗长、花径等4个数量性状的平均值分别占中亲值的99.63%、96.18%、97.01%和99.77%,均较中亲值有所下降,表现出一定程度的衰退现象,但由于组合内存在一定的变异幅度,选育植株较大、花径较大或花梗更长的个体是可能的;在植株的株高、叶长、单枝花朵数、花色及始花期等方面表现出超亲优势,尤其是单枝花朵数和花色遗传优势明显;在花色遗传上,无论是以白色花还是以红色系列花作母本,F_1代均表现为红色系列且分离广泛,表明红色系列遗传能力更强。     

Flower Development and Photoperiodic Control of Flowering in Rice

Floral transition,which is referred to as a plant’s transition from vegetative stage to reproductive stage,is considered to be a critical developmental switch in higher plants,for a timely flowering is a major factor of reproductive success.Endogenous and environmental cues,such as photoperiod,light quality,plant hormones concentrations and temperature,provide information to the plants whether the environment is favorable for flowering.These cues promote,or prevent,flowering through a complex genetic network,mediated by a careful orchestration of temporal and spatial gene expression.One of such cues is photoperiod.Rice(Oryza sativa L.) serves as a powerful model species for the understanding of flowering in higher plants,including flower development and photoperiodic control of flowering.In this review,we overviewed and discussed the flower development and its model.We also overviewed the photoperiodic pathways in rice flowering control,and summarized the pathways at molecular level.