燕麦植物激素信号转导通路中响应干旱胁迫的关键基因

植物激素信号转导通路是响应胁迫的重要通路，该通路中基因的表达调控作物的抗旱性。为挖掘燕麦植物激素信号转导通路中响应干旱胁迫的关键基因，本研究对燕麦幼苗进行不同干旱胁迫处理，取叶片进行转录组测序，分析不同处理下基因的表达。结果表明，与正常水分条件相比，轻度干旱胁迫（PEG 10%）诱导624个基因表达发生显著变化（DEGs），重度干旱胁迫（PEG 20%）诱导13 063个。GO富集分析显示，重度干旱胁迫下，DEGs主要富集在对胁迫反应的调节；KEGG分析显示，轻度干旱胁迫下，植物激素信号转导通路中1个ARF和2个CRE1基因表达显著下调，表达量较高，可能为燕麦在该通路中响应轻度干旱胁迫的基因；而重度干旱胁迫下，植物激素信号转导通路富集169个DEGs，其中生长素和脱落酸信号转导过程DEGs较多，分别占植物激素信号转导通路总DEGs的20.7%和15.9%；在8条激素信号转导过程中筛选出12个表达量较高的基因，可能为燕麦在该通路中响应重度干旱胁迫的关键基因。本研究将为今后燕麦抗旱基因的克隆和验证提供依据。     

OsSCE1 Encoding SUMO E2-Conjugating Enzyme Involves in Drought Stress Response of Oryza sativa

Small ubiquitin-like modifier (SUMO)-conjugating enzymes are involved in post-translational regulatory processes in eukaryotes, including the conjugation of SUMO peptides to protein substrate (SUMOylation). SUMOylation plays an important role in improving plant tolerance to abiotic stress such as salt, drought, heat and cold. Herein, we reported the isolation of OsSCE1 (LOC_Os10g39120) gene encoding a SUMO-conjugating enzyme from rice (Oryza sativa cv. Nipponbare) and its functional validation in response to drought stress. The E2 enzyme, OsSCE1, is one of three key enzymes involved in the conjugation of SUMO to its target proteins. Activated SUMO is transferred to the cysteine of an E2 enzyme and then to the target lysine residue of the substrate, with or without the help of an E3 SUMO ligase. Expression of OsSCE1 was strongly induced by polyethylene glycol 6000 (PEG6000) treatment, which suggested OsSCE1 may be involved in the drought stress response. Overexpression of OsSCE1 (OsSCE1-OX) in Nipponbare reduced the tolerance to drought stress. Conversely, the drought tolerance was slightly improved by the knockdown of OsSCE1 (OsSCE1-KD). These results were further supported by measurement of proline content in OsSCE1-OX and OsSCE1-KD transgenic lines under induced drought stress, which showed OsSCE1-KD transgenic lines accumulated higher proline content than the wild type, whereas OsSCE1-OX line had lower proline content than the wild type. These findings suggested OsSCE1 may play a role as a negative regulator in response to drought stress in rice.     

Recent Advances in Marker-Assisted Selection for Drought Tolerance in Pearl Millet

Abstract

Pearl millet [Pennisetum glaucum (L.) R. Br.] is the staple cereal of the hottest, driest areas of the tropics and subtropics. Drought stress is a regular occurrence in these regions, making stress tolerance an essential attribute of new pearl millet cultivars. Recent breeding research has mapped several quantitative trait loci (QTLs) for components of grain and stover yield per se, as well as yield maintenance, under terminal drought stress conditions. We report here the evaluation of these QTLs as possible selection criteria for improving stress tolerance of an elite hybrid cultivar. Initial evaluations, based on hybrids made with topcross pollinators bred from lines selected directly from the mapping population, indicated an advantage to the QTL-based topcross hybrids. This advantage seemed to be related to a particular plant phenotype that was similar to that of the drought tolerant parent of the mapping population. Subsequent evaluations were based on testcross hybrids of drought tolerance QTL introgression lines in the background of the drought-sensitive parent of the mapping population, H 77/833-2. These introgression lines were bred by limited marker-assisted backcrossing of a putative major drought tolerance QTL into H 77/833-2 from the mapping population’s drought tolerant parent. Several of these QTL introgression lines had a significant positive general combining ability for grain yield under terminal stress and significantly out-yielded testcross hybrids made with the original recurrent parent both in unrelieved terminal drought stress and in gradient stress evaluations.     

水稻抗旱研究进展与展望

水稻是我国主要粮食作物之一,整个生长阶段对水分的需求远远大于其它作物。然而随着极端气候以及水资源短缺的影响,干旱已经成为造成农作物产量损失最大的非生物胁迫。全面详细地了解水稻抗旱研究相关内容,有助于抗旱水稻品种的培育。本综述从水稻抗旱筛选方法、筛选指标、干旱胁迫条件下产量及其产量相关性状QTL发掘以及抗旱基因的克隆和应用进行论述,并对水稻抗旱品种的培育进行展望。      

Are more productive varieties of Paspalum dilatatum less tolerant to drought?

Paspalum dilatatum Poir., is a perennial C₄ grass widely distributed in the Argentinean Pampas. The response to water availability for materials developed with forage‐production purposes is unknown. We hypothesized that genetic differences between commercial varieties are reflected in their regrowth capacity under water stress. The effect of five levels of constant water supply on three plant varieties (two derived from apomictic materials: ‘Relincho’ and ‘Alonso’ and one from sexually‐derived material: ‘Primo’) were examined in the greenhouse. Leaf‐ and plant‐response traits were followed during 38 d after a single defoliation event. Seven response variables were measured: three of them were morphogenetic (leaf elongation rate, leaf appearance rate and leaf elongation duration) and four were structural (number of live leaves, lamina length, tiller biomass and tiller production). The sexual material showed higher values for growth variables than the apomictic varieties (leaf elongation rate, leaf length and tiller biomass) across the environmental range. Apomictic varieties showed a proportionally similar drought response to the sexual material for the seven variables. No intra‐specific trade‐off (statistical interaction) was found between growth under high water availability conditions and drought tolerance.     

Germination responses of the halophyte Chloris virgata to temperature and reduced water potential caused by salinity,alkalinity and drought stress

Chloris virgata is considered a useful grass species for grassland restoration in northern China. However, little information exists concerning the germination responses of this species to temperature and water potential caused by stress conditions. Experiments were conducted in growth chambers to assess the effect of temperature, salinity, alkalinity, drought and the interactions of temperature and stress on seed germination. Seeds were germinated at three diurnal temperature regimes, with four water potentials in NaCl, NaHCO₃ and PEG solutions. Results showed that optimal germination under stress occurred at 15–25 °C, and germination percentages and rates were inhibited by either an increase or decrease in temperature from the optimal temperature. The inhibitory effects of the low water potential caused by salinity and drought on germination were greater at 25–35 °C, but seeds were subjected to more stress despite the relatively higher water potential because of the alkalinity at this temperature. The recovery percentage under salinity was highest at ?1·2 MPa at 15–25 °C, and more than 80% of seeds also germinated at this water potential after they were transferred from drought stress. However, seeds lost their viability in higher alkalinities under all temperatures, and at 25–35 °C, there was lower recovery percentage under stress. Results suggest that salinity, alkalinity and drought stress have different impacts on seed germination, and the tolerance to stress of C. virgata seeds is affected by the interactions of temperature and water potential caused by salinity, alkalinity and drought. Chloris virgata shows potential utility as a promising grass species in salinity–alkalinity and drought‐stressed environments.     

Constitutive expression of <Emphasis Type="Italic">REL1</Emphasis> confers the rice response to drought stress and abscisic acid

Leaf rolling is one of the most significant symptoms of drought stress in plant. Previously, we identified a dominant negative mutant, termed rolled and erect 1 (hereafter referred to rel1-D), regulating leaf rolling and erectness in rice. However, the role of REL1 in drought response is still poorly understood. Here, our results indicated that rel1-D displayed higher tolerance to drought relative to wild type, and the activity of superoxide dismutase (SOD) and drought responsive genes were significantly up-regulated in rel1-D. Moreover, our results revealed that rel1-D was hypersensitive to ABA and the expression of ABA associated genes was significantly increased in rel1-D, suggesting that REL1 likely coordinates ABA to regulate drought response. Using the RNA-seq approach, we identified a large group of differentially expressed genes that regulate stimuli and stresses response. Consistently, we also found that constitutive expression of REL1 alters the expression of biotic and abiotic stress responsive genes by the isobaric tags for relative and absolute quantification (iTRAQ) analysis. Integrative analysis demonstrated that 8 genes/proteins identified by both RNA-seq and iTRAQ would be the potential targets in term of the REL1-mediated leaf morphology. Together, we proposed that leaf rolling and drought tolerance of rel1-D under normal condition might be caused by the endogenously perturbed homeostasis derived from continuous stressful dynamics.     

红麻种质资源耐旱性的初步鉴定研究

为鉴定和筛选红麻耐旱种质资源,本研究选用10份红麻野生种和41份红麻栽培品种为材料,51个红麻种质资源进行盆栽和干旱胁迫试验鉴定,根据干旱后叶子的萎蔫程度进行鉴定、比较,获得了51个红麻种质资源的耐旱性评价。已鉴定和筛选出的7个耐旱性较强和8个耐旱性较弱的红麻种质材料,结果对红麻种质资源的评价和进行红麻耐旱性的分子基础研究有一定指导意义。     

Modeling groundnut (Arachis hypogaea L.) performance under drought conditions

Erratic rainfall is often a limiting factor in the semi-arid regions where most groundnut cultivation occurs. As a result, ensuring availability of cultivars that possess inherent tolerance to drought stress has become a priority. Field and box (wooden boxes of 2 m length × 1 m width × 0.3 m depth) experiments were conducted under drought and non-drought conditions to identify physiological and agronomic traits correlated with pod yield (PY). Fifty (50) advanced breeding lines were evaluated. Linear models containing different combinations of total dry matter at maturity, crop growth rate, pod growth rate, partition coefficient, and harvest index were able to predict PY under intermittent drought (adjusted R² range: 0.9798–0.9895). The box experiment was more discriminating of genotypes than field experiments, making it a suitable technique for drought tolerance screening using specific leaf area and leaf chlorophyll content. As a result, screening and pre-selection using the seed-box technique before advanced evaluation on the field is recommended.     

A β-ketoacyl-CoA Synthase OsCUT1 Confers Increased Drought Tolerance in Rice

Drought stress is one of the major environmental factors affecting crop growth and productivity. Cuticular wax plays essential roles in protecting plants from environmental stress via forming a hydrophobic barrier on leaf epidermis. In this study, we analyzed nine members (OsCUT1?OsCUT9) of β-ketoacyl-CoA synthase, the rate-limiting key enzyme for cuticular wax synthesis in rice by homology search and domain prediction. The expression levels of OsCUT genes under different abiotic stresses were investigated and OsCUT1 down-regulated by abiotic stress was selected for further function validation. Compared to the wild type, overexpression of OsCUT1 (OX-OsCUT1) exhibited significantly increased drought resistance. Epicuticular wax was increased on the leaf surface of OX-OsCUT1 and the chlorophyll leaching experiment showed that the cuticular permeability was decreased in the OX-OsCUT1 plants. Moreover, overexpression of OsCUT1 didn’t result in the significant changes of major agronomic traits. In total, these results suggested that OsCUT1 is a promising gene for engineering rice plants with enhanced drought tolerance.     

Evaluation of Agronomic Traits in Chromosome Segment Substitution Lines of KDML105 Containing Drought Tolerance QTL under Drought Stress

Drought is a major abiotic constraint to rice production in rainfed lowland and insufficiently irrigated areas.The improvement of drought tolerant varieties is one of the strategies to reduce the negative effects of drought.Quantitative trait loci(QTLs) for primary and secondary traits related to drought tolerance(DT) on chromosomes 1,3,4,8 and 9 that determined from double haploid lines derived from a cross between CT9993 and IR62266 were introgressed and dissected into small pieces in the genetic background of Khao Dawk Mali 105(KDML105) to develop chromosome segment substitution line(CSSL) population.The CSSLs were evaluated at the reproductive stage for their agronomic performance and yield components under drought stress,and results were compared with irrigated condition.The flowering of CSSL lines was 6 to 7 d earlier than KDML105.The mean values of grain yields in the CSSLs were higher than KDML105 under drought and irrigated conditions.At irrigated condition,the grain yields of introgression lines carrying DT-QTLs from chromosomes 4 and 8 were higher than that of KDML105,whereas other traits showed little difference with KDML105.Analysis indicated that grain yield has positive correlation with plant height,tiller and panicle number per plant,and total grain weight per plant under drought stress while negatively correlated with days to flowering.As mentioned above,CSSLs showing good adaptation under drought stress can be used as genetic materials to improve drought tolerance in Thai rainfed lowland rice breeding program,and as materials to dissect genes underlying drought tolerance.     

青稞法尼基转移酶β亚基编码基因HbERA1的克隆及表达分析

ERA1(Enhanced response to ABA)基因编码法尼基转移酶(Farnesyl transferase)β亚基,该酶在干旱胁迫下对ABA信号负向调控因子的修饰起着关键作用。本研究以青稞(Hordeum vulgare subsp.vulgare)抗旱品种喜马拉雅10号为材料,利用RT-PCR技术克隆获得了ERA1基因全长cDNA序列,命名为HbERA1(登录号:KJ699392)。生物信息学分析表明,该基因全长1 401bp,可编码466个氨基酸序列,蛋白分子量为51.14kD,等电点为5.00。Prosite Scan分析结果表明,HbERA1含有多个干旱胁迫响应蛋白的作用位点,如酪蛋白激酶Ⅱ磷酸化位点、N-糖基化位点、蛋白激酶C磷酸化位点及N-豆蔻酰化位点。利用实时定量PCR方法研究了HbERA1在干旱胁迫条件下及复水后不同时间点的表达情况,发现在水分过剩处理下(土壤绝对含水量15.5%),HbERA1在土壤绝对含水量为33.4%时表达量最高,并随着土壤绝对含水量的下降而下调表达;进行干旱胁迫后(15.5%)基因表达量也明显下调表达;复水后表达逐渐恢复,复水8h时超过正常表达水平,表明HbERA1基因可能参与调控水涝和干旱胁迫双重信号传导。     

野生二粒小麦PYL基因家族的鉴定及其在逆境胁迫下的表达特性分析

脱落酸(ABA)是一类重要的植物内源激素,在调控植物生长发育和胁迫响应等方面发挥着关键作用。基因作为ABA的受体,在ABA信号转导过程中发挥着重要作用。为深入发掘野生二粒小麦PYL基因,本研究利用生物信息学对野生二粒小麦的PYL家族进行全基因组鉴定与分析。结果在野生二粒小麦基因组中共鉴定到24个PYL基因(TdPYLs),分布在1A、1B、2A、2B、3A、3B、4A、4B、7A和7B染色体上,且所有成员均含有PYR-PYL-RCAR-like功能域;系统进化分析发现,24个TdPYL基因可分为3个亚家族,同一亚家族成员间具有相似的基因结构和保守结构域;对这些PYL基因的启动子顺式元件进行预测,发现它们含有大量与逆境胁迫、光调节和ABA响应相关的元件;基于RNA-seq数据的表达特性分析发现,它们在不同组织中以及逆境胁迫下表达差异明显,并鉴定到多个与组织特异性以及胁迫响应相关的PYL基因;进一步对PYL基因的单倍型组成进行分析,发现在野生二粒小麦、栽培二粒小麦和硬粒小麦中PYL基因的遗传变异和单倍型组成具有明显的差异,发生了显著的遗传分化。本研究为深入揭示野生二粒小麦PYL基因的调控功能及其进化机制研究提供了有益信息。     

马铃薯资源抗旱性鉴定和筛选

干旱是马铃薯生产的重要限制因子之一.本研究利用42个马铃薯材料(品种),采用正常浇水和干旱胁迫两种理,对供试材料进行了抗旱能力评价.结果表明:虎头和高原7号等四倍体品种以及CE 66和HS 66等二倍体材料抗旱能力较强,其中高原7号和虎头等品种在干旱胁迫下表现出了较高产量,适宜应用于抗旱育种.干旱胁迫下,植株株高普遍降...     

玉米CaM基因家族鉴定及特性分析

利用玉米基因组等多种数据库搜索CaM家族基因,对玉米CaM基因家族进行筛选与鉴定,对家族成员的基因结构、等电点、分子量、亚细胞定位、蛋白保守域等蛋白基本特性进行分析。同时分析不同组织和干旱胁迫条件下该类基因的表达情况,进一步利用qRT-PCR技术检测5个具有代表性的CaM基因在干旱处理条件下的表达变化。结果显示,共获得14个CaM基因,根据3’-UTR序列构建的系统进化树显示可分为4个亚家族。根据蛋白质的氨基酸序列,可分为3种亚型。家族成员蛋白分子量大多数为16.8 kD左右,等电点介于4.10～4.30,该家族蛋白保守结构域由3～4个EF手型结构域组成,主要定位于细胞质和细胞核。Zmcal4、Zmcal5和Zmcal6基因在各组织中表达非常低,干旱会抑制家族大部分成员的表达,覆水处理后,Zmcal3-1、Zmcal3-2、Zmcal3-3、Zmcal3-4的表达可恢复到对照水平,推测这几个基因可能参与干旱胁迫反应。qRT-PCR结果表明,干旱会抑制CaM基因的表达,随着干旱处理时间的增加,CaM基因的表达量逐渐降低,与生信分析结果一致。     

Effect of drought on biomass allocation in two invasive and two native grass species dominating the mixed‐grass prairie

Control of exotic plant species invading the native prairie relies on our understanding of the eco‐physiological mechanisms responsible for the spread of these species as they compete with native plants for soil resources. We used a greenhouse pot experiment to study vegetative biomass allocation in response to drought stress in two exotic grass species, Kentucky bluegrass (Poa pratensis L.) and smooth brome (Bromus inermis Leyss), and two native species, western wheatgrass (Pascopyrum smithii (Rydb.) A. Löve) and green needlegrass (Stipa viridula Trin.). The experiment was conducted over 3 months in 2010 and again in 2011 in a factorial design of four species and two drought treatments. The proportional data of biomass allocation to shoots, roots, rhizomes and crowns (shoot base) of grass seedlings were analysed by both the nonparametric Mann–Whitney U‐test on the original data and one‐way anova on the arcsine‐transformed data. Our data suggest a clear distinction between the two invasive and two native species in potential competitiveness in soil resource use, with the two exotic species having higher biomass allocation to roots than the two native species and the native species having a higher biomass allocation to crowns than the two exotic species. It is interesting to note that the strongly rhizomatous smooth brome did not produce rhizomes in the first season's growth, regardless of the water stress level. The effect of drought stress on biomass allocation manifested itself more on rhizomes or crowns than on roots or shoots of the four studied grass species, with the effects species‐specific in nature.     

干旱条件下我国不同年代玉米品种保绿性比较

选用35个玉米品种(农家种4个, 双交种4个, 单交种27个), 在海南三亚设置正常浇水和花期干旱两个处理, 鉴定每个品种在干旱环境下的保绿性, 比较不同年代品种的持绿性。结果发现, 干旱导致玉米叶片叶绿素含量下降, 衰老启动时间提前, 干旱条件下品种的衰老启动时间、最大衰老速度出现时间均随年代更替而延后, 最大衰老速度均随着年代更替而下降, 即玉米的保绿性均随着年代更替而提高, 与正常浇水条件下的趋势相似。玉米保绿性与叶绿素含量均与产量呈显著相关;在干旱处理条件下, 品种保绿性均随年代更替而提高, 我国的玉米育种中已经对持绿性进行了改良, 耐旱性也得到提高。     

Gene expression microarrays and their application in drought stress research

Initial physiological adjustments in response to drought stress lead to drastic changes in gene expression. The traditional approaches of assessing such drought-induced changes in gene expression involve measuring the differences in mRNA levels of one or few genes at a time. DNA expression microarray technology is a powerful tool that can monitor changes in expression of a large number of genes simultaneously. Expression microarrays also provide new insights into physiological and biochemical pathways of drought tolerance, and thus can lead to identification of novel candidate genes that can rapidly advance breeding for drought tolerance. This review describes the basic principles and potential applications of gene expression microarrays in understanding and improving drought tolerance in plants. A case study is presented involving hybridization of field-grown panicle samples from drought tolerant and susceptible rice germplasm targets with probes from a normalized panicle cDNA library. Results indicate contrasting drought responses among both upland versus lowland-adapted cultivars and also between traditional and improved upland types.