对大豆耐萎蔫材料PI471938根系和地上部的性状鉴定、遗传分析及QTL定位

PI471938是从美国引进的大豆耐萎蔫抗旱种质资源。为更好了解和利用该材料,分别在灌水和干旱胁迫条件下比较PI471938与普通大豆品种Dare、丰收黄根系及地上部性状的差异,并配制杂交组合,构建分离群体,利用主基因-多基因混合遗传模型分析杂交后代根系性状的遗传规律。结果表明,在正常灌水和干旱处理条件下,PI471938的根干重、根体积、主根长均显著高于Dare和丰收黄(P0.01),说明根系发达是PI471938耐萎蔫的重要原因。供试亲本和各世代材料的株高、地上部干重均与根干重及根体积显著正相关,可作为对根系性状进行间接选择的指标。在Dare×PI471938杂交组合的F2代,不论在灌水还是干旱条件下,根干重均以微效多基因控制为主,主基因遗传率较低;根体积在灌水条件下表现多基因遗传,而在干旱条件下则由2对加性-显性-上位性主基因+加性-显性多基因控制,主基因遗传率为54.63%。在干旱条件下,丰收黄×PI471938组合的根干重、根体积均以多基因控制为主。以在干旱条件下种植的Dare×PI471938组合的F2代群体为材料,采用SSR标记对大豆根系及地上部性状进行QTL定位,检测到位于3个不同连锁群的5个主效QTL,表型贡献率在16.07%～38.44%之间。     

大豆幼苗根系性状的QTL分析

为研究大豆幼苗期根系性状的遗传规律,以中豆29和中豆32构建的RIL群体为材料,在V2期测定水培幼苗根系性状(主根长、侧根数、根重、根体积和根冠比等)及相关性状(株重、茎叶重和下胚轴重等),以方差分析方法估算遗传参数,并采用复合区间作图法对大豆幼苗期根系等性状进行QTL定位。结果表明,在8个染色体上检测到20个根系及相关性状QTL,其中9个主效QTL位于第11和第14染色体,表型贡献率在10.5%~26.1%之间。在第11和第14染色体上,部分根系性状QTL与地上部性状QTL处于同一位置,其QTL的共位性与形态性状表型相关分析结果一致,反映了根系性状与地上部性状存在一定的关联。     

水、旱条件下小麦苗期部分农艺性状的遗传分析

为研究水分胁迫对小麦幼苗部分农艺性状的影响,分析这些性状与干旱胁迫的关系。以‘青麦6号’和‘烟农24’杂交形成的F2:3群体为材料,采用主基因+多基因混合遗传模型对其进行遗传分析。水、旱2种条件下,根长和根鲜重均为1对加性-显性效应主基因模型;茎鲜重、茎干重、根干重、根茎鲜重比和根茎干重比的最适遗传模型不同。干旱胁迫条件下,茎鲜重主基因遗传率为37%,茎干重、根长、根鲜重、根干重、根茎鲜重比及根茎干重比主基因遗传率分别是51%、81%、74%、56%、50%、68%。茎鲜重、茎干重、根干重等性状,尽管检测到主基因,但在水旱条件下遗传模型不同,可进一步研究其遗传规律。     

利用“永久F2”群体进行小麦幼苗根系性状QTL分析

为了研究小麦苗期根系性状的遗传,以小麦品种花培3号和豫麦57的杂交DH群体组配了一套含168个杂交组合的“永久F₂”群体。利用WinRHIZO根系分析系统测定四叶一心期小麦水培幼苗根系总长度、直径、表面积、体积、根尖数、最大根长、茎叶干重、根干重及根茎干重比9个性状。采用复合区间作图法分析幼苗根系8个性状的QTL,定位了7个加性效应QTL和12对上位性互作QTL,包括加性效应、显性效应,加加互作、加显互作和显显互作,分布在1A、1D、2A、2B、2D、3A、3B、5D、6D和7D染色体上,单个QTL可解释0.01%~11.91%的遗传变异。在染色体2D上XWMC41至XBARC349.2区间检测到同时控制总根长和根干重的一个QTL。上位性对苗期根系生长发育有重要作用。试验结果表明,苗期根系性状的遗传机制较复杂, 因此在育种中要综合考虑根系各性状之间的关系,保证根系协调统一、发达健壮。     

大豆籽粒硬实加性和上位性QTL定位

硬实是植物种子的普遍特性, 是影响大豆种子发芽率、生存能力及储存期的重要数量性状, 同时影响着大豆的加工品质。本实验通过对大豆籽粒硬实性状的加性和上位性互作QTL (quantitative trait locus)分析, 明确控制大豆籽粒硬实的重要位点及效应, 旨在为进一步解析硬实性状复杂的遗传机制提供理论依据。以冀豆12和地方品种黑豆(ZDD03651)杂交构建的包含186个家系的F_6:8和F_6:9重组自交系群体为材料, 采用WinQTL Cartographer V. 2.5的复合区间作图法(composite interval mapping, CIM)定位不同年份的籽粒硬实性状相关的加性QTL, 同时采用IciMapping 4.1软件中的完备区间作图法(inclusive composite interval mapping, ICIM)检测籽粒硬实性状的加性及上位性QTL。共检测到3个籽粒硬实性状相关的加性QTL, 分别位于第2、第6和第14染色体, 遗传贡献率范围为5.54%~12.94%。同时检测到4对上位性互作QTL, 分别位于第2、第6、第9、第12和第14染色体, 可解释的表型变异率为2.53%~3.47%。同时检测到籽粒硬实性状加性及上位性互作QTL, 且上位性互作多发生在主效QTL间或主效QTL与非主效QTL间, 表明上位性互作效应在大豆籽粒硬实性状的遗传基础中具有重要的作用。     

早稻渗入系抽穗期根系性状QTL定位

研究稻作抗旱的根系特征及其遗传机理,发掘旱稻有利基因,从水旱稻杂交中选育高产耐旱的稻作品种提供理论基础和研究材料。以强抗旱的旱稻毫格劳为供体亲本,超高产水稻品种沈农265为受体亲本,利用187个SSR标记构建了一套具有180个家系的旱稻渗入系群体,并采用单标记分析法,对抽穗期根系6个性状：最长根长、粗根数、总根数、平均最粗根粗、根干重、总干重进行QTL定位。抽穗期共检测到QTL38个,其中影响上述6个性状的QTL数目分别是6、6、4、6、4和12个,它们的总贡献率分别为29％、27％、21％、33％、23％和61％。此外,在粗根数和总根数中分别检测到3个和1个来自毫格劳的等位基因的加性效应为负,其余均为正。除平均根粗外,其他5个性状的加性效应都较大。89．5％的渗入位点对以沈农265为遗传背景的渗入系的6个性状根系有促进作用;定位到的影响不同根系性状的QTL多数成簇、集中分布;RM3853附近定位到影响4个性状的QTL,推测是一个在抽穗期与根系性状和抗旱密切相关的基因或基因簇。     

基于QTL和转录组测序鉴定甘蓝型油菜耐旱候选基因

干旱胁迫严重限制了甘蓝型油菜种植面积的扩大和产量的提升。耐旱性是由多基因控制的复杂数量性状,将QTL定位与转录组测序相结合,是鉴定甘蓝型油菜耐旱候选基因的有效手段。本研究对甘蓝型油菜干旱敏感品系三六矮和耐旱品系科里纳-2构建的F_2:6和F_2:8重组自交系群体幼苗进行正常灌溉和干旱胁迫处理,测定地上部鲜重、地上部干重、叶片相对含水量、丙二醛和可溶性糖含量,利用SSR和SNP多态性分子标记构建遗传连锁图谱,鉴定耐旱相关QTL和候选区间,结合耐旱材料No11和干旱敏感材料No28的转录组测序,筛选耐旱相关候选基因。研究结果表明:干旱胁迫使甘蓝型油菜幼苗地上部鲜重、地上部干重和叶片相对含水量下降,使叶片丙二醛和可溶性糖含量上升;耐旱相关QTL和候选区间分布于A01、A02、A06、A08、A09、A10、C02、C03、C04、C06和C09染色体;对耐旱材料和干旱敏感材料正常灌溉、干旱24 h、36 h和48 h进行转录组分析,主要差异表达基因显著富集到光合作用、脂肪酸代谢、氨基酸代谢、植物激素信号转导、核糖体、昼夜节律及角质、木栓素和蜡质的生物合...     

抗旱型玉米苗期根系形态性状的遗传分析

为了进一步揭示玉米苗期根系性状的遗传特性,用来改良材料的抗旱性,本研究以旱敏型材料‘WN897’、抗旱型材料‘Wu109’及二者通过杂交和回交获得的F1、B1、B2和F2为材料,利用主基因+多基因混合遗传模型多世代联合分析方法分析干旱胁迫与正常条件下主根长、侧根数、根冠比和根鲜重的遗传特性。结果表明,在干旱胁迫与正常条件下,侧根数的遗传率均高,而主根长、根冠比及根鲜重的遗传率均较低,根冠比的遗传率在干旱胁迫下明显低于正常条件,根鲜重的遗传率在干旱胁迫下明显高于正常条件。因此,侧根数可以通过单交的方法进行改良,在低世代材料中就可进行有效选择,主根长可以通过复交或多代轮交进行改良;而对于根冠比和根鲜重,鉴于二者均在B2群体中有着较高的遗传率,可以通过多代回交的方法对这两个性状进行改良,在回交后代中进行有效选择。     

不同磷水平下大豆根系性状的遗传特性分析

在田间两种磷水平下,应用大豆RIL群体对根总长、根总表面积、根宽、根冠比、根干重和根磷含量等6个根系性状参数和6个涉及植株磷含量、生物量及产量性状的指标进行遗传特性研究,结果发现在不同磷水平下,大豆重组自交系群体根系性状的变异幅度较大,符合正态分布的特征.土壤磷水平不仅促进了大豆根系形态的变化,同时也影响到根系构型的改变.低磷胁迫条件下,根系性状与植株磷含量、生物量及产量之间呈极显著相关关系,并且这些根系性状都具有较高的广义遗传率(0.47～0.60),可以作为选择指数应用于作物磷营养效率的遗传改良中.在根系性状的6个指标中,以根总长、根总表面积、根干重、根磷含量等4个参数与植株吸磷量、生物量及产量的关系最为密切,可以作为评价不同磷水平下植物基因型差异的可靠指标,而根宽和根冠比则可作为特定的磷胁迫条件下基因型差异的筛选指标.     

旱稻渗入系抽穗期根系性状定位

摘 要：[目的]研究稻作抗旱的根系特征及其遗传机理,发掘旱稻有利基因,从水旱稻杂交中选育高产耐旱的稻作品种提供理论基础和研究材料。[方法]以旱稻豪格劳为供体亲本,水稻沈农265为受体亲本,利用187个SSR标记构建了一套具有180个家系的旱稻渗入系群体,并采用单标记分析法,对拔节期根系6个性状：最长根长、粗根数、总根数、平均最粗根粗、根干重、总干重进行QTL定位。[结果]抽穗期共检测到QTL38个,其中影响上述六个性状的QTL数目分别是6、6、4、6、4和12,它们的总贡献率分别为29%、27%、21%、33%、23%和61%。除此,在粗根数和总根数中分别检测到3个和1个来自豪格劳的等位基因的加性效应为负,其余均为正。除平均根粗外,其它5个性状的加性效应都较大。[结论]89.5%的渗入位点对以沈农265为遗传背景的渗入系的6个性状根系有促进作用;定位到的影响不同根系性状的QTL多数成簇、集中分布;RM3853附近定位到影响四个性状的QTL,推测是一个在抽穗期与根系性状和抗旱密切相关的基因簇。     

甘蓝型油菜DH群体苗期抗旱性的评价

中国油菜主产区常常受到秋冬旱和春旱危害而影响产量及品质。本文通过盆栽试验,以株高(PH)、根长(RL)、地上部干重(SDW)、根干重(RDW)、根冠比(R/S)、总干重(TDW) 6个性状的抗旱系数作为抗旱性评价指标,对甘蓝型油菜DH(doubled haploid)群体的118个株系及其亲本进行苗期抗旱性评价,筛选极端抗旱DH系。结果表明,与对照相比,干旱严重抑制了甘蓝型油菜苗期的生长,6个评价指标均表现出显著差异,其中根干重的变异系数最大;在对照和干旱条件下,群体各株系各性状均表现出超亲连续分离,大部分呈正态分布,抗旱条件下的分离更为明显;相关性分析表明,地上部干重、根干重和总干重抗旱系数可作为甘蓝型油菜苗期抗旱性的主要评价指标;     

Two Soybean Plant Introductions Display Slow Leaf Wilting and Reduced Yield Loss under Drought

Due to high costs of irrigation, limited availability of irrigation water in many locations and/or lack of irrigation capabilities, genetic improvement for drought tolerance is an effective method to reduce yield loss in soybean [Glycine max (L.) Merr.]. Slow wilting and minimal yield reduction under drought are important traits in evaluating drought tolerance. Two maturity group III soybean plant introductions (PIs, PI 567690 and PI 567731) and two elite cultivars (DKB38‐52 and Pana) were evaluated with and without irrigation on a sandy soil. Drought was imposed by withholding irrigation at full bloom and continued until moderate wilting was shown by the fast leaf wilting in the check cultivar, Pana. Then, irrigation was resumed until maturity. Genotypes were scored for leaf wilting during the stress period, and yields were assessed at the end of the growing season and used to calculate a drought index. Yields of the exotic PIs were lower than those of the checks under both drought and well‐watered conditions. However, the PIs exhibited significantly lower wilting and less yield loss under drought (higher drought index) than check cultivars. The two PIs may have useful genes to develop drought‐tolerant germplasm and cultivars and maybe useful in genetic and physiological studies to decipher mechanisms responsible for improving yield under limited water availability.     

Root characteristic system improves drought tolerance in orchardgrass

Plant genotypes with higher drought tolerance through improved root characteristics are poorly studied in orchardgrass. In the current research, 30 orchardgrass genotypes were polycrossed and the resulting half‐sib families evaluated under both normal and water stress environments. Under water stress conditions, values for most root traits decreased at 0–30 cm soil depth, while at 30–60 cm depths, the root length (RL), root area (RA), root volume, percentage of root dry weight (RDW) and the ratio of root to shoot were increased. We identified drought‐tolerant genotypes with a high combining ability for root characteristics and a high yield potential. High estimates of heritability as well as genetic variation for root traits indicated that phenotypic selection would be successful in order to achieve genetic progress. Indirect selection to improve dry matter yield was most efficient when selecting for RL and RDW under water stress conditions. Significant associations between a drought tolerance index and RL, RA and root volume confirmed the importance of these traits in conferring drought tolerance of orchardgrass.     

Contrasting rice backcross inbred lines (BILs) for grain yield and heading under lowland reproductive stage moisture stress

Identification and understanding the role of physio-morphological drought responsive mechanisms leading to grain yield enhancement under water stress is a critical insight for designing appropriate strategies to breed drought-tolerant cultivars for any drought prone ecology. In this study, three pairs of contrasting BILs with varied maturity were characterized for several agronomical, physiological and morphological traits across a wide range of moisture stress environments at reproductive stage during 2012–2014. Within each group, BILs differ significantly for grain yield, heading, biomass and harvest index under drought stress, but showed similar yield potential, phenology and other traits under control condition. The most tolerant BIL, S-15 out yielded all BILs and standard checks under both conditions. Apart from superior agronomic performance, drought tolerant BILs maintained significantly higher assimilation rate, transpiration rate and transpiration efficiency compared to susceptible BILs under stress in all three groups. In addition, most tolerant BIL (S-15) showed significantly higher stomatal conductance than susceptible BIL (S-55) in early group. Among root traits, significant differences under stress was observed for root dry weight between contrasting BILs in each group, even though tolerant BILs had higher root length and root volume compared to susceptible BILs, which is non-significant. Hence, consideration of root traits an important strategy for drought avoidance in case of rice may not always contributes to significant yield improvement under moisture stress condition. Further, tolerant BILs also recorded significantly higher shoot dry weight and drought recovery score at seedling stage under stress. Our findings suggest that genotypes with higher photosynthetic efficiency and better plant water status are able to produce higher grain yield under drought stress environments.     

Effect of drought stress on root yield and some morpho-physiological traits in different genotypes of sugar beet (<Emphasis Type="Italic">Beta vulgaris</Emphasis> L.)

To study the effects of different levels of drought stress on root yield and some morpho-physiological traits of sugar beet genotypes, a study was conducted in the research farm of Islamic Azad University of Birjand, Iran in 2013 as strip-split plot experiments based on randomized complete block design. Different levels of drought stress were considered as vertical factor in three levels including normal irrigation, moderate stress, and severe stress. Horizontal factor was assigned to five varieties of sugar beet. Drought stress had a significant effect on root dry weight, total dry weight, root yield, and leaf temperature at 1% probability level and on leaf dry weight, crown dry weight, and harvest index at 5% probability level. Drought stress had an adverse effect on root yield of investigated genotypes of sugar beet. Under normal conditions, the mean of root yield was higher than middle and severe drought stress. Different investigated genotypes of sugar beet responded to drought stress based on their yield potential. The highest positive correlation of root yield was observed with root dry weight (r=0.977**). Stepwise regression analysis and path coefficient analysis showed that root dry weight and petiole dry weight are the most important traits that can affect root yield of sugar beet under drought stress and can used as selection criteria in investigated cultivars of sugar beet. Finally, 7221 genotypes can be considered as tolerant genotypes in the next studies. In comparison, Jolgeh cultivar (as susceptible control) yielded well in areas with normal irrigation, but under moderate and severely stresses its root yield was reduced.     

Mapping of QTL associated with waterlogging tolerance and drought resistance during the seedling stage in oilseed rape (Brassica napus)

Soil waterlogging and drought are major environmental stresses that suppress rapeseed (Brassica napus) growth and yield. To identify quantitative trait loci (QTL) associated with waterlogging tolerance and drought resistance at the rapeseed seedling stage, we generated a doubled haploid (DH) population consisting of 150 DH lines from a cross between two B. napus lines, namely, line No2127-17 × 275B F₄ (waterlogging-tolerant and drought-resistant) and line Huyou15 × 5900 F₄ (waterlogging-sensitive and drought-sensitive). A genetic linkage map was constructed using 183 simple sequence repeat and 157 amplified fragment length polymorphism markers for the DH population. Phenotypic data were collected under waterlogging, drought and control conditions, respectively, in two experiments. Five traits (plant height, root length, shoot dry weight, root dry weight and total dry weight) were investigated. QTL associated with the five traits, waterlogging tolerance coefficient (WTC) and drought resistance coefficient (DRC) of all the traits were identified via composite interval mapping, respectively. A total of 28 QTL were resolved for the five traits under control conditions, 26 QTL for the traits under waterlogging stresses and 31 QTL for the traits under drought conditions. Eleven QTL were detected by the WTC, and 19 QTL related to DRC were identified. The results suggest that the genetic bases of both waterlogging tolerance and drought resistance are complex. Some of the QTL for waterlogging tolerance-related traits overlapped with QTL for drought resistance-related traits, indicating that the genetic bases of waterlogging tolerance and drought resistance in the DH population were related in some degree.     

不同烤烟品种对干旱胁迫的响应

为了研究烤烟新品种豫烟1 3号的抗旱性,以主栽品种中烟100为对照品种,采用盆栽试验研究了干旱胁迫对农艺性状、地上部鲜重、干重、根系指标、酶活性和产量的影响.结果表明,干旱条件下,中烟100和豫烟13号株高和茎围明显降低;干旱对根、茎、叶干重影响较大,直接影响单株产量,干旱条件下2个品种产量显著低于正常供水处理,与中烟100相比,豫烟13号产量受干旱影响程度较小;与中烟100相比较,干旱务件下豫烟13号酶活性增加幅度大.综合各指标来看,豫烟13号抗旱能力优于中烟100.     

Identification of drought responsive QTLs during vegetative growth stage of rice using a saturated GBS-based SNP linkage map

Drought is a major abiotic constraint for rice production worldwide. The quantitative trait loci (QTLs) for drought tolerance traits identified in earlier studies have large confidence intervals due to low density linkage maps. Further, these studies largely focused on the above ground traits. Therefore, this study aims to identify QTLs for root and shoot traits at the vegetative growth stage using a genotyping by sequencing (GBS) based saturated SNP linkage map. A recombinant inbred line (RIL) population from a cross between Cocodrie and N-22 was evaluated for eight morphological traits under drought stress. Drought was imposed to plants grown in 75 cm long plastic pots at the vegetative growth stage. Using a saturated SNP linkage map, 14 additive QTLs were identified for root length, shoot length, fresh root mass, fresh shoot mass, number of tillers, dry root mass, dry shoot mass, and root-shoot ratio. Majority of the drought responsive QTLs were located on chromosome 1. The expression of QTLs varied under stress and irrigated condition. Shoot length QTLs qSL1.38 and qSL1.11 were congruent to dry shoot mass QTL qDSM1.38 and dry root mass QTL qDRM1.11, respectively. Analysis of genes present within QTL confidence intervals revealed many potential candidate genes such as laccase, Calvin cycle protein, serine threonine protein kinase, heat shock protein, and WRKY protein. Another important gene, Brevis radix, present in the root length QTL region, was known to modulate root growth through cell proliferation and elongation. The candidate genes and the QTL information will be helpful for marker-assisted pyramiding to improve drought tolerance in rice.     

Understanding physiological and morphological traits contributing to drought tolerance in barley

Drought stress is a major limiting factor for crop production in the arid and semi‐arid regions. Here, we screened eighty barley (Hordeum vulgare L.) genotypes collected from different geographical locations contrasting in drought stress tolerance and quantified a range of physiological and agronomical indices in glasshouse trails. The experiment was conducted in large soil tanks subjected to drought treatment of eighty barley genotypes at three‐leaf stage and gradually brought to severe drought by withholding irrigation for 30 days under glasshouse conditions. Also, root length of the same genotypes was measured from stress‐affected plants growing hydroponically. Drought tolerance was scored 30 days after the drought stress commenced based on the degree of the leaf wilting, fresh and dry biomass and relative water content. These characteristics were related to stomatal conductance, stomatal density, residual transpiration and leaf sap Na, K, Cl contents measured in control (irrigated) plants. Responses to drought stress differed significantly among the genotypes. The overall drought tolerance was significantly correlated with relative water content, stomatal conductance and leaf Na⁺ and K⁺ contents. No significant correlations between drought tolerance and root length of 6‐day‐old seedling, stomatal density, residual transpiration and leaf sap Cl^? content were found. Taking together, these results suggest that drought‐tolerant genotypes have lower stomatal conductance, and lower water content, Na⁺, K⁺ and Cl^? contents in their tissue under control conditions than the drought‐sensitive ones. These traits make them more resilient to the forthcoming drought stress.     

玉米自交系幼苗生物量积累及根系形态对两种氮素水平的反应及聚类分析

为探讨低氮胁迫对玉米自交系幼苗生物量和根系形态的影响,以35份玉米自交系为材料,测定了两个氮素水平处理后14d玉米幼苗的单株干重、地上部干重、根干重、根冠比、总根长、根表面积、根体积、根平均直径、侧根数和初生根长。结果表明,低氮胁迫下玉米幼苗根干重、根冠比、根总表面积、根体积、侧根数、根平均直径和初生根长显著增加,地上部干重和单株干重显著减小,而总根长没有明显变化。通过主成分分析和聚类分析发现,同一氮素水平下,玉米幼苗各性状的综合表现存在基因型差异,且在正常氮素和低氮条件下均可以分为6组。低氮处理后,选取的9个自交系地上部氮素积累量均显著降低,PH4CV、B73和XY4的根系氮素积累量显著增加,其余6个自交系显著降低。此外,只有XY4的氮素吸收和利用效率均较高。综合分析表明,XY4是低氮高效型玉米自交系。