水稻化感作用及其分子生态学研究进展

综述了近年来国际上研究水稻化感作用的新进展,比较分析了当前常用于室内评价水稻化感作用潜力的几种生物测试法的优缺点,指出了琼脂迟播共培法是较为理想的室内生物测试法并已广泛应用于化感作用研究中。在此基础上,分析了水稻化感作用的数量遗传特性及其QTL定位的研究现状;阐明了水稻化感作用的遗传多样性及其分子生态特性;并就当前普遍关注的焦点问题：逆境条件（如低氮或高伴生杂草密度胁迫）常引起水稻化感作用潜力增大的生理过程与分子机制作了阐述。结合近年来应用差异蛋白组学和生物信息学的研究实例,阐明了逆境引起水稻化感作用增强与其酚类合成代谢相关酶蛋白表达丰度增加,萜类合成代谢相关酶蛋白表达丰度下降有关。就究竟什么是水稻的化感物质及其作用方式等问题作了分析与讨论．指出水稻的化感抑草效应是其众多化感物质综合作用的结果,应重视区分化感物质对靶标杂草的原生作用和进入土壤生态系统中经生物转化后的次生作用。根据当前植物化感作用研究的发展趋势,阐明了进一步研究水稻化感作用的焦点问题,提出了水稻化感作用的根际生物学特性与分子生态学机制,是未来国际上竞相角逐的重点研究领域,并认为以现代系统生物学理论为指导,运用基因组学、蛋白质组学和代谢组学等技术方法,是揭示这一分子生态学过程与机制的重要技术选择和优先研究领域。     

Allelopathy in wheat (Triticum aestivum)

Wheat (Triticum aestivum) allelopathy has potential for the management of weeds, pests and diseases. Both wheat residue allelopathy and wheat seedling allelopathy can be exploited for managing weeds, including resistant biotypes. Wheat varieties differ in allelopathic potential against weeds, indicating that selection of allelopathic varieties might be a useful strategy in integrated weed management. Several categories of allelochemicals for wheat allelopathy have been identified, namely, phenolic acids, hydroxamic acids and short‐chain fatty acids. Wheat allelopathic activity is genetically controlled and a multigenic model has been proposed. Research is underway to identify genetic markers associated with wheat allelopathy. Once allelopathic genes have been located, a breeding programme could be initiated to transfer the genes into modern varieties for weed suppression. The negative impacts of wheat autotoxicity on agricultural production systems have also been identified when wheat straws are retained on the soil surface for conservation farming purposes. A management package to avoid such deleterious effects is discussed. Wheat allelopathy requires further study in order to maximise its allelopathic potential for the control of weeds, pests and diseases, and to minimise its detrimental effects on the growth of wheat and other crops.     

Genomic analysis of allelopathic response to low nitrogen and barnyardgrass competition in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

To explore the molecular mechanism of allelopathic rice in response to low nitrogen (N) supply or accompanying weed stress, allelopathic rice PI 312777 and its counterpart Lemont were grown under low N supply or co-cultured with barnyardgrass [Echinochloa crus-galli (L.) Beauv.] in hydroponics. The suppression subtractive hybridization (SSH) technique was employed to isolate the up-regulated genes in the treated rice accession. The results indicated that the expression of the genes associated with N utilization was significantly up-regulated in allelopathic rice PI 312777, and the higher efficiency of N uptake and its utilization were also detected in PI 312777 than that in Lemont when the two rice accessions were exposed to low N supply. This result suggested that the allelopathic rice had higher ability to adapt to low N stress than its non-allelopathic counterpart. However, a different response was observed when the allelopathic rice was exposed to accompanying weed (barnyardgrass) co-cultured in full Hoagland solution (normal N supply). It showed that the expression of the genes associated with allelochemical synthesis and its detoxification were all up-regulated in the allelopathic rice when co-cultured with the target weed under normal N supply. The results suggested that the allelopathic rice should be a better competitor in the rice-weed co-culture system, which could be attributed to increasing de novo biosynthesis and detoxification of allelochemicals in rice, consequently resulting in enhanced allelopathic effect on the target and preventing the autotoxicity in this process. These findings suggested that the accompanying weed, barnyardgrass is not only the stressful factor, but also one of the triggers in activating allelopathy in rice. This implies that the allelopathic rice is sensible of the existing target in chemical communication.     

小麦化感作用研究进展

小麦是世界第一大粮食作物,在农业生产中占有重要地位．然而,由于人们为保证小麦产量往往施用大量的除草剂和杀菌剂,对环境造成了极大的危害．小麦化感作用是利用小麦活体或残体向环境中释放次生代谢物质对自身或其他生物产生作用,它克服了除草剂和杀菌剂等引起的环境污染问题,具有抑制杂草控制病害的潜力．本文对已有的小麦化感作用的研究进展情况进行了综合评述．其中小麦对杂草、虫害及病害产生防御功能的主要化感物质为异羟肟酸和酚酸类物质．小麦化感物质活性的发挥除了取决于化感物质的种类外,还由小麦自身的遗传因素、环境因素和生物因素的共同作用所决定．小麦化感物质在根际土壤中的滞留、迁移和转化过程、小麦化感作用与土壤生物的关系以及相关的作用机理是小麦化感作用研究的薄弱环节。其研究方法还需进一步探索改进．小麦化感作用在植物保护、环境保护以及作物育种等方面具有广泛的应用前景,促进了小麦抗逆性的增强以及产量和品质的提高．     

Rice allelopathy and the possibility for weed management

In attempts to control weeds in rice, much effort has been focused on rice allelopathy research for more than 30 years. Among screening methods that have been developed, some estimate the allelopathic potential of various rice cultivars in a limited time and space, which is less costly and can be conducted year round. Rice allelopathy activity is variety dependent and origin dependent, where Japonica rice shows greater allelopathic activity than Indica and Japonica–Indica hybrids. Allelopathic characteristics in rice are quantitatively inherited and several allelopathy‐involved traits have been identified. Numerous phytotoxins such as cytokinins, diterpenoids, fatty acids, flavones, glucopyranosides, indoles, momilactones (A and B), oryzalexins, phenols, phenolic acids, resorcinols and stigmastanols have been identified and determined as growth inhibitors in rice. However, the fate and actual modes of action of these compounds as well as other potent rice phytotoxins in nature are not well understood. The question of which compounds play a major role in rice allelopathy has remained obscure; however, rice allelopathy might be attributable to the interaction of all present allelochemicals. Despite locating genes determining or involving allelopathy in rice having attracted much effort, the introduction of these genes into target rice cultivars has not yet been achieved. Success in breeding new rice cultivars having good weed‐suppressing ability would benefit farmers in rice‐cultivating countries and play an important role in sustainable agricultural production.     

元阳梯田地方水稻品种根部内生菌及根际微生物的分离与鉴定

采用组织分离法和土壤稀释涂板法,对元阳哈尼梯田2个地方品种‘月亮谷’和‘红脚老粳’的根部内生细菌及根际土壤细菌进行了分离,研究元阳梯田传统水稻品种特殊的内生菌组成.结果表明: 试验共得到399个菌株.经形态特征及生理生化鉴定,月亮谷根部和其根际土壤分别分离到8和5个属,其中5个属是共有的;红脚老粳的根部和其根际土壤中分别分离到10和7个属,其中6个属是共有的.经分子生物学鉴定,月亮谷根部分离到11个种和5个属,根际土壤分离到8个种和4个属,其中5个种和4个属是共有的;红脚老粳根部分离到9个种和5个属,根际土壤分离到10个种和3个属,其中4个种和2个属是共有的.通过分子生物学鉴定,大部分菌株都可以鉴定到种,而通过形态及生理生化特性只能初步鉴定到属,但两种方法在属层次上的鉴定结果基本一致.元阳地方水稻根部内生细菌及根际土壤细菌具有一定的种属同源性与特异性.     

Allelopathic potential of the phenolics from the roots of Pluchea lanceolata

Aqueous leachates of roots of the perennial weed Pluchea lanceolata (DC.) C. B. Clarke, its root-incorporated soil and rhizosphere soil, interfered with the seedling growth of certain plant species. The soils from the rhizosphere zone of this plant had significantly higher total phenolics and HPLC analysis revealed that phenolic fractions represented by retention times of 1.6, 1.9, 2.5 (simple phenol, chlorogenic acid and phloroglucinol respectively), 3.7 and 4.3 min were contributed by roots of the weed to the soil. The phenolic fraction represented by the retention time 3.3 (formononetin 7-O-glucoside) was detected in the weed's rhizosphere soils and not in the rootincorporated soils. UV spectral studies established the presence of phloroglucinol, simple phenol, chlorogenic acid, formononetin 7-O-glucoside, and methylated coumarins in the root leachate, which affect the seedling growth of mustard ( Brassica juncea ). Present research established the allelopathic potential of P. lanceolata roots, and the possible involvement of allelopathy in its interference success.     

小麦化感作用研究进展

小麦是世界第一大粮食作物,在农业生产中占有重要地位.然而,由于人们为保证小麦产量往往施用大量的除草剂和杀菌剂,对环境造成了极大的危害.小麦化感作用是利用小麦活体或残体向环境中释放次生代谢物质对自身或其他生物产生作用,它克服了除草剂和杀菌剂等引起的环境污染问题,具有抑制杂草控制病害的潜力.本文对已有的小麦化感作用的研究进展情况进行了综合评述.其中小麦对杂草、虫害及病害产生防御功能的主要化感物质为异羟肟酸和酚酸类物质.小麦化感物质活性的发挥除了取决于化感物质的种类外,还由小麦自身的遗传因素、环境因素和生物因素的共同作用所决定.小麦化感物质在根际土壤中的滞留、迁移和转化过程、小麦化感作用与土壤生物的关系以及相关的作用机理是小麦化感作用研究的薄弱环节,其研究方法还需进一步探索改进.小麦化感作用在植物保护、环境保护以及作物育种等方面具有广泛的应用前景,促进了小麦抗逆性的增强以及产量和品质的提高.     

化感水稻种质资源鉴定及基因定位研究进展与展望

稻种资源化感作用的鉴定评价与深入研究是化感水稻品种选育的基础.本文概要介绍了化感水稻种质资源鉴定评价方法、化感作用生理生化机理以及化感特性遗传与基因定位方面的主要研究进展,并进一步讨论了水稻化感作用研究与利用的发展方向.     

Role of root-mediated interactions in phytotoxic interference of Ageratum conyzoides with rice (Oryza sativa)

Ageratum conyzoides L. (billy goat weed; Asteraceae) is an annual invasive weed native of tropical America and has now naturalized worldwide, particularly in Southeast Asia. The present study investigated the nature and potential of root-mediated allelopathic interference of A. conyzoides against rice (Oryza sativa). Root and shoot length and biomass accumulation of rice were significantly reduced (by 18–30%) when grown in the rhizosphere soil of the weed indicating the release of putative allelochemicals from the weed into the soil. The growth of rice was also progressively reduced in the soil amended with increasing amounts of root residues (5, 10 and 20 g kg⁻¹ soil) of A. conyzoides. The addition of activated charcoal, an inert material with high affinity for organic biomolecules, partly ameliorated the negative effects of root residues amended in the soil. Further, there was no negative effect on the availability of soil nutrients in the root-amended soils. These were rather nutrient rich with greater electrical conductivity, and higher amount of organic matter, thus indicating no role in observed growth reduction. The reduction in allelopathic effects of root residue upon charcoal addition further indicated that putative phytotoxins released from the weed roots are water-soluble phenolic compounds. A significant amount of water-soluble phenolics were present in rhizosphere (∼6-times higher) and root-amended soils (∼5–10-fold higher) and their content was reduced (to ∼3.6–7.0-fold higher) when charcoal was added. The observed growth reduction in Ageratum rhizospheric or root-amended soils was concomitant with the amount of phenolic compounds. Upon HPLC analyses, these were identified as p-coumaric acid, gallic acid, ferulic acid, p-hydroxybenzoic acid and anisic acid. Under laboratory conditions, these phenolic acids reduced the root length and seedling weight of rice individually as well as in equimolar mixture, though no synergistic effect was noticed. The study concludes that root exudates and residues of A. conyzoides suppress the growth of rice by releasing phenolic allelochemicals into the soil rhizosphere and not through alteration of soil nutrients, and allelopathy plays a significant role in root-mediated negative interference of A. conyzoides.     

水稻化感物质抑草作用机理的分子生物学研究

水稻化感作用是通过水稻植株体向环境中释放化感物质来实现的．水稻化感物质的主要抑草作用机理有：抑制杂草种子的发芽,影响激素平衡,破坏细胞膜系统的完整性,影响光合作用和呼吸作用,干扰对营养和水分的吸收,影响蛋白质合成和基因表达等．水稻化感作用是由多基因控制的,表现为数量性状．利用分子生物学技术和化感生物检测技术等研究手段检测到了多个水稻化感作用的主效应(QTLs)位点,但不同水稻化感种质其主效应QTLs位点明显不同．通过分子辅助选择和建立近等基因系的方法对检测到的QTLs作进一步的精细定位,最终实现水稻化感抑草有利基因的克隆是今后研究的重要方向。     

水稻化感作用及其生理生化特性的研究

选用具有强化感作用的6个水稻品种为供体,大田稗草为受体,研究了水稻化感作用及生理生化特性,结果表明,提高水稻叶片浸提液浓度,可以相应增强对稗草生长的抑制效果,这种抑制效果与杂草的种植密度呈负相关;化感水稻叶片浸提液能显著抑制物质稗草体内超氧化物歧化酶（SOD）和过氧化氢酶（CAT）的活性,从而影响其生长;苯丙氨酸氨解酶（PAL）的活性大小与酚类物质的含量吴正相关;多种酚类物质的化感作用之间可能是增效的,也可能是拮抗的。     

Plant phenolics in allelopathy

Phenolics are one of the many secondary metabolites implicated in allelopathy. To establish that allelopathy functions in a natural ecosystem, the allelopathic bioassay must be ecologically realistic so that responses of appropriate bioassay species are determined at relevant concentrations. It is important to isolate, identify, and characterize phenolic compounds from the soil. However, since it is essentially impossible to simulate exact field conditions, experiments must be designed with conditions resembling those found in natural systems. It is argued that allelopathic potential of phenolics can be appreciated only when we have a good understanding of 1) species responses to phenolic allelochemicals, 2) methods for extraction and isolation of phenolic allelochemicals, and 3) how abiotic and biotic factors affect phenolic toxicity.     

杂草科学管理——理论基础与实施途径

Scientific management of weeds is theoretically based on ecology.The implementation methods incladeIntensifying the weed biology and ecology research, especially those of the heavy weeds;Intensifying the research of developing competition between the crop and the weed;Utilizing a allelopathy the gene engineering and breeding against the weeds;Utilizing allelopathy between the crop and the weed, and utilizing biological and agricultural measurements to control the weeds.     

不同化感潜力水稻(Oryza sativa L.)苗期的氮素养分效率及相关基因的表达

为了阐明养分水平引起水稻(Oryza sativa L.)化感抑草潜力变化的生理生态机制,研究了不同N素营养处理下,不同化感潜力水稻苗期对N素营养逆境的响应特性及N素养分效率的差异,并运用实时荧光定量RT-PCR技术(FQ-PCR)检测与N素代谢和次生代谢关键酶的基因表达.结果表明:弱化感水稻品种Lemont对N素营养胁迫较敏感,强化感水稻品种PI312777对资源波动的适应性较强,N素养分效率较高.FQ-PCR分析结果显示,在低N条件下Lemont中的亚硝酸还原酶基因(nir),谷氨酰胺合成酶基因(gs)相对表达量均有不同幅度的下调, PI312777分别下调了1.2倍和1.4倍,而Lemont分别下调了3.0倍和1.8倍, Lemont下调的幅度分别是PI312777的2.5倍和1.3倍,但对于苯丙氨酸解氨酶基因(pal)与3-羟基-3甲基戊二酰辅酶A还原酶基因(hmgr)而言, PI312777叶组织中的pal和hmgr均上调表达,与对照相比上调了6.0倍和1.6倍,而Lemont中对应的基因均下调表达,分别下调了1.3倍和6.8倍,佐证了上述差异的分子生态学特性.     

Allelopathy and its coevolutionary implications between native and non‐native neighbors of invasive Cynara cardunculus L.

Invasive plants apply new selection pressures on neighbor plant species by different means including allelopathy. Recent evidence shows allelopathy functions as remarkably influential mediator for invaders to be successful in their invaded range. However, few studies have determined whether native and non‐native species co‐occurring with invaders have evolved tolerance to allelopathy. In this study, we conducted germination and growth experiments to evaluate whether co‐occurring native Juncus pallidus and non‐native Lolium rigidum species may evolve tolerance to the allelochemicals induced by Cyanara cardunculus in Australian agricultural fields. The test species were germinated and grown in pots filled with collected invaded and uninvaded rhizosphere soil of C. cardunculus with and without activated carbon (AC). Additionally, a separate experiment was done to differentiate the direct effects of AC on the test species. The soil properties showed invaded rhizosphere soils had higher total phenolic and lower pH compared with uninvaded soils. We found significant reduction of germination percentage and seedling growth in terms of above‐ and belowground biomass, and maximum plant height and root length of native in the invaded rhizosphere soil of C. cardunculus, but little effect on non‐native grass species. Even soil manipulated with AC showed no significant differences in the measured parameters of non‐native except aboveground biomass. Taken together, the results indicate allelochemicals induced by C. cardunculus exert more suppressive effects on native than non‐native linking the coevolved tolerance of those.     

Stress-induced allelopathic activity and momilactone B in rice

Allelopathic activity of rice extracts and root exudates against Echinochloa crus-galli increased by heavy metal, cantharidin and jasmonic acid treatments. Since cantharidin (protein phosphatase inhibitor) acts as an elicitor and jasmonic acid is an important signaling molecule regulating inducible defense genes against the pathogen infection, heavy metal stress and pathogen infection may increase alleopathic activity of rice. These treatments also increased the concentrations of momilactone B in rice extracts and root exudates, suggesting that the production of momilactone B in rice and the secretion of momilactone B from rice into the rhizosphere may be enhanced by the treatments. As momilactone B possesses strong phytotoxic and allelopathic activities, the elevated production and secretion of momilactone B of rice by heavy metals, cantharidin and jasmonic acid may contribute to the increasing allelopathic activity of rice. Enhancement of the secretion of momilactone B into the rhizosphere may provide a competitive advantage for root establishment through local suppression of pathogen and inhibition of the growth of competing plant species. Therefore, allelopathy of rice may be one of the inducible defense mechanisms and may be regulated several environmental factors.     

稻田水氮氧环境因子对水稻生长发育、光合作用和氮利用的调控研究进展

水分和氮素是影响水稻生长发育的两个重要环境因子。适宜的水氮耦合模式可通过“以水调氮、以水控氧”调控稻田根际氮形态和溶氧量等环境因子,促进良好根系形态构建,提高叶片光合速率和光合产物“源-库”分配平衡,提高水稻群体质量和产量形成。同时,稻田水氮氧环境因子驱动的微生物调控机制在水稻-土壤系统氮高效利用方面也发挥重要作用。本文重点阐述了水氮耦合下水分、氮形态和溶氧量对水稻生长发育、光合作用、碳氮代谢、稻田氮转化过程及其微生物调控机制等方面的研究进展,展望并提出了未来亟待加强的研究方向:1)开展水氮耦合下水稻根际溶氧量时空动态分布特征及氧环境调控关键因子研究;2)明确不同基因型水稻根源信号增氧响应特征及其对水稻生长发育的影响调控机制;3)阐明根际氧环境驱动的关键微生物过程对稻田氮转化和氮素利用的影响。     

Unravelling the beneficial role of microbial contributors in reducing the allelopathic effects of weeds

The field of allelopathy is one of the most fascinating but controversial processes in plant ecology that offers an exciting, interdisciplinary, complex, and challenging study. In spite of the established role of soil microbes in plant health, their role has also been consolidated in studies of allelopathy. Moreover, allelopathy can be better understood by incorporating soil microbial ecology that determines the relevance of allelopathy phenomenon. Therefore, while discussing the role of allelochemicals in plant–plant interactions, the dynamic nature of soil microbes should not be overlooked. The occurrence and toxicity of allelochemicals in soil depend on various factors, but the type of microflora in the surroundings plays a crucial role because it can interfere with its allelopathic nature. Such microbes could be of prime importance for biological control management of weeds reducing the cost and ill effects of chemical herbicides. Among microbes, our main focus is on bacteria—as they are dominant among other microbes and are being used for enhancing crop production for decades—and fungi. Hence, to refer to both bacteria and fungi, we have used the term microbes. This review discusses the beneficial role of microbes in reducing the allelopathic effects of weeds. The review is mainly focused on various functions of bacteria in (1) reducing allelopathic inhibition caused by weeds to reduce crop yield loss, (2) building inherent defense capacity in plants against allelopathic weed, and (3) deciphering beneficial rhizospheric process such as chemotaxis/biofilm, degradation of toxic allelochemicals, and induced gene expression.     

不同胁迫条件下化感与非化感水稻PAL多基因家族的差异表达

水稻苯丙氨酸解氨酶(PAL)调控酚酸类化感物质的合成代谢。编码PAL的基因是一个基因家族,包含至少11个基因成员,并受不同环境条件的调控。为了明确PAL基因家族中调控水稻化感作用的特定基因成员,本研究运用实时荧光定量PCR技术分析了低氮及稗草胁迫条件下强化感水稻PI312777与非化感水稻Lemont中根系的11个PAL成员基因的表达差异。结果表明,低氮和稗草胁迫条件下,PI312777和Lemont中的 PAL4和PAL10均不表达,其余9个PAL基因成员发生了不同程度的表达变化。其中,PAL11均上调表达,其分别在低氮处理和稗草胁迫的PI312777中上调3.29倍和1.07倍,而在相同处理下的Lemont中上调3.92倍和1.08倍;PAL3和PAL9则仅在低氮和稗草胁迫条件下的PI312777中上调表达,低氮胁迫分别为1.83倍和2.66倍,稗草胁迫为1.46倍和2.65倍;而这两个基因在相同处理下的Lemont中表达下调,低氮胁迫下调1.05和1.24倍,稗草胁迫下调1.14和1.16倍,推测PAL3和PAL9可能与胁迫初期调控水稻化感作用有关。