不同供氮水平下小麦苗期叶绿素含量的QTL及互作研究

由小麦近缘物种硬粒小麦和节节麦发展而来的W7984和现代栽培种Opata.85作亲本,通过一粒传而获得F7重组近交系(RIL)群体。对该群体的111个株系分别在正常供应氮素(N.4.0mmol/L)和低氮胁迫(N.0.4mmol/L)两种情况下进行培养,4周后测定叶片叶绿素含量。根据该群体而构建的遗传图谱包括覆盖整个染色体组的918个RFLP(限制性片段长度多态性)标记,应用这些标记,研究了两种供氮情况下小麦叶片叶绿素含量的QTL(数量性状基因位点)及基因间互作。结果表明,在氮素正常供应情况下,有7个与叶绿素含量有关的QTL,变异解释率在4.30％～13.45％,亲本双方对于叶绿素含量的贡献基本一致;在氮素胁迫下,有9个QTL与叶绿素含量有关,变异解释率在4.04％～11.73％,亲本W7984.对于叶绿素含量的贡献占主导地位。表明小麦近缘物种在低氮胁迫下对于叶绿素含量有重要贡献;且低氮胁迫下,叶绿素含量还受基因间上位效应的影响。氮素正常供应时有1个位点(位于2B染色体上)、低氮胁迫下有2个位点(位于3A和3B染色体上)同时影响小麦干物质产量和叶绿素含量,而且此3个位点的效应都来自亲本W7984。这一发现表明,小麦干物质产量和叶绿素含量之间存在着内在的联系。     

小麦赤霉病抗源望水白的QTL定位

236对SSR引物中共有74对在小麦（Tritium aestivum）抗、感亲本之间有多态性,多态性频率达31.7%.对小麦望水白/安农8455群体的SSR分析表明,在2年资料中都出现的与抗小麦赤霉病（Fusarium head blight）连锁的SSR标记有14个,主要分布在染色体3B和2A上.利用Map Manager QTX软件构建连锁图和QTL定位,有38个标记主要分布于5条染色体上（3B、2A、5A、6B和7B）;根据3年的抗性资料分析,3B上的QTL分别位于XBarc133～Xgwm389、XBarc133～Xgwm389和Xg-wm533.1～Xgwm493之间,LOD为2.58、6.49和2.45,分别能解释10%、23%和9%的表型变异.2001年和2003年的抗性资料分析表明,2A上存在2个抗性QTL,都位于Xgwm95～Xgwm372之间,LOD分别为2.82和2.93,均能解释11%的表型变异.     

小麦萌发期幼苗相关性状耐旱系数的QTL定位

为了检测与小麦幼苗耐旱性相关的数量性状位点,用3个关联重组自交系(RIL)群体,对小麦萌发期幼苗的胚芽鞘长、苗高、最大根长、根数、苗鲜重、茎叶鲜重、根鲜重、根冠鲜重比、苗干重、茎叶干重、根干重、根冠干重比等12个表型性状的耐旱系数进行QTL定位。结果显示,共检测到28个耐旱相关位点,分布在小麦的1BL、1D、2B、3A、3B、3D、4A、6A、6B、6D、7A、7B等12条染色体上,可分别解释表型变异的5.61%~64.22%,其中,6个位点通过同一群体不同性状的耐旱系数检测到,2个位点通过2个群体不同性状的耐旱系数检测到,分别位于4A染色体的Xbarc61~wpt-9675标记区间和6A染色体的wpt-9679~wpt-8177标记区间内,这2个位点实现了在不同群体间的相互验证,可靠性大大提高。这些位点的发现对于小麦萌发期耐旱性的精细定位、图位克隆和分子标记辅助选择具有重要的意义。     

基于三重测交群体解析玉米株高与穗位高杂种优势QTL

为检测玉米株高、穗位高杂种优势QTL,以121株intermated B73×Mo17(IBM)个体为基础群体,按照三重测交交配设计构建了三重测交群体,通过完备区间作图法对株高、穗位高杂种优势的主效QTL及互作位点进行了分析。在第9染色体上的2个紧密连锁的区段分别定位到了一个株高、穗位高杂种优势加性QTL位点,单个QTL的表型贡献率为14.3%和18.6%。该QTL可能同时对株高、穗位高杂种优势起作用。在第1、第3染色体上检测到2个株高杂种优势超显性QTL,可解释表型变异的9.0%~11.4%;在第1、第6、第8染色体上检测到5个穗位高杂种优势超显性QTL,可解释表型变异的6.6%~16.8%。进一步分析发现,2对加加上位性互作区段及2对显显上位性互作区段对穗位高杂种优势存在上位性贡献,加加互作效应及显显互作效应可共同解释表型变异的40.7%和26.8%。由此可知,加性、显性及两位点互作上位性共同对株高、穗位高杂种优势存在贡献。本研究检测到的主效QTL位点有助于株高、穗位高在杂种优势育种中的进一步应用。     

小麦光温敏核雄性不育系BS20育性的QTL分析

以小麦(Triticum aestivum L.)光温敏不育系BS20×Fu3 DH群体的289个系为材料,于2005-2006年度种植于北京海淀和安徽阜阳,进行了育性(结实率和结实小穗率)的调查.利用SSR标记和分离群体分组分析法(BSA)分析该群体中与育性相关的分子标记,用128对SSR引物,初步构建BS20×Fu3群体的分子标记遗传连锁框架图.BSA的结果表明,与育性连锁的3个标记是Xgwm294、Xgwm374和Xgwm44,分别位于染色体2AL、2BS和7DS;采用混合线性复合区间作图法对小麦育性进行QTL分析,检测到6个QTL,分布在1AS、2BS、2DL、6AL、6BL和7DS染色体,贡献率为1.1%～12.5%,其中7DS上的QTL与2BS、6AL和6BL上的QTL存在显著的互作效应.综合BSA和QTL分析结果,确定染色体7DS和2BS上的QTL重复性较好、贡献率和互作效应较大,为小麦光温敏核雄性不育性状的重要QTL,标记区间分别为Xgum44-Xcfd14和Xgwm148-Xgwm374,贡献率分别为7.2%～12.5%和2.1%～2.5%.     

小麦耐低钾性状的全基因组关联分析

  【目的】  筛选与小麦耐低钾性状相关的标记，为揭示小麦耐低钾性状的遗传机理奠定基础。  【方法】  本研究以198份中国黄淮南片麦区的小麦品种 (系) 作为供试群体。小麦种子发芽后，幼苗在正常钾营养液中生长4天，然后在低钾 (0.01 mmol/L) 和正常钾 (2 mmol/L) 营养液中生长25天。调查生物量，分析地上部和根部钾含量，计算小麦7个性状的相对值，利用小麦35K SNP芯片结合Q + K混合线性模型 (mixed linear model，MLM) 对7个耐低钾性状进行全基因组关联 (genome-wide association study，GWAS) 分析，筛选位于显著关联位点上的候选基因并进行功能注释，对显著关联位点进行等位变异分析，发掘优异等位变异。  【结果】  低钾胁迫条件下，地上部、根部、全株钾累积量和钾累积量根冠比显著降低，地上部、根部、全株钾利用指数显著升高。群体结构分析和PCA分析均将供试群体分为2个亚群。通过GWAS分析，共检测到75个显著关联单核苷酸多态性 (single nucleotide polymorphism，SNP) 标记 (P < 0.001)，分布在除1A、3B、3D、4D和6A染色体外的16条染色体上。通过候选基因搜寻及注释，共筛选出13个可能与小麦耐低钾胁迫相关的候选基因。等位变异分析共挖掘了 14 个优异等位变异，其中 6 个优异等位变异在供试群体中出现的频率较大。  【结论】  7个耐低钾性状均具有明显的数量性状特征，变异系数范围为20.66%～30.44%。40%的SNP标记分布在2B、5B和6B染色体上，21个SNP位点与多个耐低钾性状显著关联，单个SNP标记解释的表型贡献率的变异范围为5.78%～11.22%。TraesCS4A02G335400、TraesCS2B02G306000、TraesCS5B02G260000可能参与物质转运过程，TraesCS1D02G350600和TraesCSU02G105300可能参与逆境胁迫响应等生理过程，TraesCS2A02G000200可能参与逆境胁迫下的信号转导过程。     

不同磷、钾处理小麦苗期氮营养性状的QTL分析

【目的】 对不同浓度磷、钾处理下小麦苗期氮养分效率相关性状进行QTL分析,以深入理解磷、钾与氮养分效率的相互关系,为氮营养相关性状的图位克隆及分子标记辅助选择育种奠定基础。 【方法】 采用苗期液培试验,以“川35050 ×山农483”组合衍生的小麦重组自交系群体(131个株系)为研究材料,设置了中磷中钾(MPMK)、高磷(HP)、低磷1 (LP1)、低磷2 (LP2)、低磷3 (LP3),高钾(HK)、低钾1 (LK1)、低钾2 (LK2)、低钾3 (LK3)共9个处理,对不同磷、钾处理下的氮养分效率相关性状进行研究,并结合分子标记遗传图谱,从整个基因组水平对与小麦苗期氮养分效率相关的10个性状进行QTL定位及遗传分析。 【结果】 不同处理下的10个性状共检测到137个QTL,位于除3D外的20条染色体上,大部分QTL (89.05%)仅在单一处理下被定位到,有3个QTL (QRnue-1A.2、QSnue-1A.1和QTnue-1A.1)可在至少4个处理中被检测到,有5个QTL (QRnue-1A.1、QTnue-1A.1、QSnc-4A、QRnc-6A.3和QSnue-6B)可同时在低磷和低钾环境中被检测到。本研究还检测到至少包含3个以上QTL的QTL簇17个,分别位于1A、1B、2B、2D、3A、3B、4A、4B、5D、6A、6B、6D和7A染色体上,共涉及66个QTL,占QTL总数的48.18%。其中,有5个QTL簇仅与特定磷、钾处理有关,大多数QTL簇均同时定位了不同磷、钾处理的不同性状,许多QTL簇位点还与前人定位的生物量、产量及其他养分有关。 【结论】 磷、钾的供应能够显著影响小麦苗期对氮素的吸收利用及其相关QTL的表达。影响苗期小麦氮养分效率相关性状的QTL大多数仅在特定处理下被检测到,但大多数QTL会形成QTL簇,构成了控制氮养分效率的QTL热点,许多热点区域也与前人定位的许多成株期性状如生物量、产量及其他养分效率有关,这些QTL/基因密集区域及其特点的发现,为我们深入理解小麦氮养分效率的遗传控制特点及其与磷、钾养分供应的关系提供了新的视角,也为这些重要位点的克隆及其应用提供数据支持。     

小麦苗期耐盐相关性状的QTL分析

以小麦敏盐品种太空6号和耐盐品种德抗961杂交形成的F2和F2:3家系为试验材料,选取小麦8条染色体上的321对SSR引物进行亲本间多态性的筛选,在太空6号和德抗961之间表现多态性的SSR引物为52个,位点为54个,其中barc172和cfa2121两个引物分别有两个多态性位点。对这54个位点进行连锁分析,构建了包含42个SSR标记、覆盖小麦基因组8条染色体的遗传连锁图,共704.5cM,标记间平均间距为16.8 cM。采用复合区间法进行耐盐QTL分析。对于4个性状共定位到6个QTL,分别位于5A,5B,5D染色体。对于发芽率,检测到1个QTL,位于染色体5D上,在标记cfd40~gwm182之间,贡献率为7.68%,表现加性效应;对于苗高,检测到2个QTL,分别位于染色体5D和5A上,在标记gwm182~wmc215及barc141~wmc415之间,贡献率分别为9.3%和8.14%,分别表现为显性和部分显性;对于根长,检测到2个QTL,均位于染色体5B上,在标记gwm234与wmc326及barc140与barc142之间,贡献率分别为8.74%和8.40%,分别表现为部分显性和超显性;对于鲜重,检测到1个QTL,位于染色体5D上,在标记wmc215~cfd29之间,贡献率为12.60%,表现超显性。与所得的QTL位点距离较近的SSR标记,如barc141等,可望为耐盐小麦品种的分子标记辅助选择提供参考信息。     

波兰小麦品系XN555×普通小麦品系中13衍生重组自交系(RILs)群体中籽粒品质相关性状QTL定位

小麦籽粒品质相关性状属于数量性状,由多基因控制。为了探索小麦(Triticum aestivum L.)品质相关性状的遗传基础,以波兰小麦(Triticum polonicum L.)品系XN555×普通小麦品系中13产生的重组自交系(recombinant inbred lines,RILs)群体(包含99个F10株系)为研究材料,采用SSR(simple sequence repeat)分子标记技术构建遗传连锁图谱;根据2012年和2013年的表型数据,采用完备区间作图法(inclusive composite interval mapping,ICIM)定位籽粒硬度、籽粒蛋白质含量、面粉蛋白质含量和湿面筋含量等品质性状QTL。获得了由241个SSR标记位点组成的A、B染色体组的14个连锁群图谱,覆盖基因组1 338.92 cM,标记间的平均遗传距离为5.56 cM。共定位24个品质性状QTL,分布在1A、3A、4A、5A、6A、1B、2B、3B和5B等9条染色体上。其中,籽粒蛋白质含量和面粉蛋白质含量各7个QTL,湿面筋含量和籽粒硬度各5个QTL,4个性状的单个QTL可分别解释表型变异的8.30%～29.69%、6.90%～29.50%、10.10%～18.43%和7.93%～30.49%。两年都在6A染色体的Xbarc104～Xcfa2114标记区间内与Xbarc104相距1.2 cM处检测到湿面筋含量QTL,并于2012年和2013年分别检测出了面粉蛋白质含量和籽粒蛋白质含量的QTL。本研究为利用波兰小麦改良普通小麦以及在小麦品质改良中应用分子标记辅助选择提供依据。     

不同生长环境下水稻氮、磷、钾利用相关性状的QTL定位分析

【目的】鉴定影响水稻氮、磷、钾利用相关性状的QTL,为开展水稻养分高效利用分子标记辅助选择育种和肥高效基因的图位克隆提供依据。【方法】以云南强耐冷(2级)粳稻地方品种丽江新团黑谷与十和田杂交、回交获包含105个株系的孕穗期耐冷性近等基因系BC4F8及双亲为材料,在云南白邑(冷水胁迫)、寻甸(自然低温胁迫)和玉溪(正常生长环境)3种生长环境下进行水稻氮、磷、钾养分吸收相关性状的鉴定,并利用构建的含有180个SSR标记,全长为1820.6 c M,标记间平均距离为15.67 c M的遗传图谱,用基于完备区间作图法的QTL Ici Mapping V3.2软件对16个性状进行QTL定位分析。【结果】3种环境下共检测到56个QTL,分布在第1、2、3、4、5、6、7、9和10染色体上,单个性状QTL数为1~10个,单个QTL可解释的各自性状表型贡献率为8.88%~35.30%。其中,氮、磷、钾利用效率QTLs数分别为12个、27个和17个。而q TNA-1a、q TPA-1、q PHI-1、q PHI-6、q PHI-7b和q KHI-6共6个QTL在冷害和正常环境下均能检测到,稳定性较高,其贡献率变幅为10.63%~31.57%。在第1、3、4、5、6、7和10染色体上有13个标记区域存在QTL成族分布,单个QTL位点控制的性状数为2~5个,其中共同控制磷总吸收量、磷素干物质生产效率、磷素收获指数、每100 kg籽粒需钾量和钾素收获指数等性状的位点数最多。【结论】获得56个影响氮、磷、钾利用相关性状的QTL,且发现的13个QTL富集区可作为水稻氮、磷、钾高效利用分子育种的重要候选区域。     

Low phosphorus effects on the metabolism of rice seedlings

Abstract

Phosphorus‐stress‐induced (Psi) changes in shoot and root phosphorus (P) content (SPC and RPC) and use efficiency (SPUE and RPUE) defined as dry biomass production per unit of absorbed P, root acid phosphatase activity (RAPA), and excreted acid phosphatase activity (EAPA), were investigated for 5 rice genotypes under P‐sufficient (10 ppm Pi) and P‐stressed (0.5 ppm Pi) solution culture conditions. Genotypic tolerance to P‐stress was assessed based on less decrease in shoots and roots P content and larger increase in shoots and roots P use efficiency with decreasing P concentration from 10 ppm to 0.5 ppm in the culture solution. Plants were harvested 2 and 4 weeks after growing, respectively, for the parameter measurements. Significant (#0.01) genotypic differences in SPC and RPC were observed under P‐sufficient and P‐stressed conditions with the differences decreasing with length of growing period. On the contrary, significant (#0.01) genotypic differences in SPUE and RPUE were only found under P‐stress condition, but not under P‐sufficient condition, suggesting that genotypic variation in tolerance to P‐stress in terms of PUE could be screened under P‐stress conditions. More than 2‐fold genotypic differences in Psi‐RAPA and Psi‐EAPA were obtained after 2 weeks, followed by a decrease in Psi‐EAPA, but not in Psi‐RAPA. After 2 weeks, Psi‐EAPA was highly correlated to decrease in SPC and decrease in RPC measured after 2 and 4 weeks, respectively. Significant negative correlations were also found between decrease in SPC and increase in RPUE, and between decrease in SPC and decrease in RPC. The implications of these results in evaluating rice genotypic tolerance to P‐stress is discussed.     

Path and Correlation Analyses of the Factors affecting Biomass Production of Brassica Cultivars under Phosphorus‐Deficiency Stress Environment

Abstract

Path analysis is a statistical technique that partitions correlations into direct and indirect effects and distinguishes between correlation and causation, whereas correlation in general measures the extent and direction (positive or negative) of a relationship occurring between two or more variables. The estimates of correlation and path coefficients can help us to understand the role and relative contribution of various plant traits in establishing growth behavior of crop cultivars under given environmental conditions. Dependence of shoot dry‐matter (SDM) production of six hydroponically grown Brassica cultivars on various growth parameters and characteristics of P metabolism was investigated using the modified Johnson's nutrient solution to maintain deficient (10 µM) and adequate (200 µM) P levels. Root dry‐matter (RDM), total dry‐matter, P content in shoot, and P‐utilization efficiency (PUE) had significant and positive effects on production of SDM in a P‐deficient environment. Root–shoot ratio (RSR), however, negatively affected SDM of cultivars exposed to P‐deficient conditions and did not show any impact on SDM production in either of the two treatments. In a pot study, six Brassica cultivars were grown in a sandy loam soil that was deficient in NaHCO₃‐extractable P (3.9 mg P kg^?1 soil) for 49 days. Significant positive correlations were observed between SDM and some other plant traits such as RDM, leaf area per plant, P uptake, and PUE, at both genotypic and phenotypic levels. The correlations of SDM with RSR, however, were not observed, implying that relative partitioning of biomass into roots or shoots had little role to play in SDM production by Brassica cultivars under P‐deficiency stress. Path analysis revealed that favorable impact of RDM and leaf area on SDM production was indirect through positive effect of these parameters on P uptake and PUE. Thus, under P‐deficiency stress, better P acquisition and efficient P utilization by the cultivars for biomass synthesis collectively formed the basis of higher SDM production by the cultivars, evidencing that P uptake and utilization efficiency are two important plant traits for selecting P‐deficiency‐stress‐tolerant Brassica cultivars.     

The combination of localized phosphorus and water supply indicates a high potential for savings of irrigation water and phosphorus fertilizer

Water and phosphorus (P) are often unevenly distributed in the soil profile, thus limiting water and P uptake and plant growth. A soil column and a split‐root experiment were conducted to quantify the effect of localized water and P supply on shoot growth, root morphology, specific P uptake (SPU), P‐use efficiency (PUE), and water‐use efficiency (WUE) of maize (Zea mays L.). Our results indicate that roots preferentially grow in the layer or compartment with both adequate water and P supply, subsequently stimulating SPU, PUE, and WUE, and enhancing shoot growth. Compared with the treatments in which both layers and compartments were supplied with adequate P and/or water, the growth of maize was maintained or minimally affected. SPU, PUE, and WUE were increased when both P and water were supplied in one layer or one compartment only. These findings show that normal plant growth with an adequate P uptake was achieved even if part of the roots were supplied with 2/3 (soil column experiment) and 1/2 (split‐root experiment) of the phosphorus and water supplied in the full‐phosphorus and full‐water treatment. Changes in root morphology under water stress conditions induced by the application of phosphorus and water in deeper soil layers or to a part of the roots may have substantial practical implications for agricultural production and environmental protection.     

Relative Phosphorus Utilization Efficiency,Growth Response,and Phosphorus Uptake Kinetics of Brassica Cultivars under a Phosphorus Stress Environment

Abstract

Plants grown in highly weathered or highly alkaline calcareous soils often experience phosphorus (P) stress but never a P‐free environment. Thus, applications of mineral P fertilizers are often required to achieve maximum yield, but recovery of applied P fertilizers is notoriously low. Phosphorus deprivation elicits a complex array of morphological, physiological, and biochemical adaptations among plant species and genotypes to enhance P acquisition and utilization efficiency. Ten Brassica cultivars were grown hydroponically to investigate their relative efficiency to utilize deficiently (20‐µM) and adequately (200‐µM) supplied P, using Johnson's modified solution. Cultivars differed significantly (P<0.001) in biomass accumulation. Orthophosphate concentration and uptake in shoot and root, absolute and relative growth rate, and P‐utilization efficiency (PUE) were also significantly different among various Brassica cultivars. Root‐shoot ratio and specific absorption rate were substantially increased in plants subjected to low P supply. Shoot and root dry‐matter yield as well as total biomass production correlated significantly (P<0.01) with their total P uptake and PUE. Cultivars, which were efficient in P utilization, were also efficient accumulators of biomass under adequate as well as deficient levels of P supply. As part of the study, kinetic parameters of P uptake were evaluated for six contrasting Brassica cultivars in PUE, grown in nutrient solution. The kinetic parameters related to P influx were maximal transport rate (Vmax), the Michaelis–Menten constant (Km), and the external concentration when net uptake is zero (Cmin). Lower Km and Cmin values were indicative of P‐uptake ability of the cultivars, evidencing their adaptability to P‐stress conditions. In another experiment, six cultivars were exposed to no P nutrition for 27 days after initial feeding on optimum nutrition for 14 days. All the cultivars retranslocated P from aboveground parts to their roots during growth in P‐free conditions, the magnitude of which was variable in different cultivars. Phosphorus concentration at 41 days after transplanting was higher in developing leaves than developed leaves. Translocation of absorbed P from metabolically inactive sites to active sites in plants growing under P‐stress conditions may have helped the tolerant cultivars to establish a better rooting system, which provided basis for tolerance against P‐deficiency stress and increased PUE.     

DETECTION AND VERIFICATION OF QUANTITATIVE TRAIT LOCI AFFECTING TOLERANCE TO LOW PHOSPHORUS IN RICE

Phosphorus (P)-deficiency in rice (Oryza sativa L.) may cause yields reductions. This research was conducted to map quantitative trait loci (QTL) for tolerance to low-P stress in a double-haploid (DH) line, and to verify these loci in another SSD9 population, which is the ninth generation of single-seed-distribution population derived from the same parents. Two populations were cultured solution at different period. By using the linkage map, QTLs for traits associated with tolerance to low-P stress were located. Results indicated that for DH population, one restricted fragment length polymorphism (RFLP) marker located on chromosome 6 was closely associated with relative root dry weight, relative shoot dry weight, and relative total dry weight. Two QTLs affected relative P uptake content. One micro-effect QTL was found to be associated with relative P utilization efficiency. For relative amounts of root exuded acid phosphatase, relative P allocation between shoot and root, relative plant P concentration, and relative shoot P concentration, one micro-effect QTL was detected for each one. Quantitative trait loci for 3 traits were detected for both DH and SSD9 populations, but the loci for each located trait were inconsistent between two populations; the reason for inconsistency in QTLs was analyzed. The main reason could be the difference in solution environment.     

Inorganic orthophosphate for diagnosing the phosphorus status of wheat plants

Winter wheat (Triticum aestivum L) was grown to the 6‐leaf stage hydroponically under wide‐ranging conditions of phosphorus (P) supply. Tissue concentrations of inorganic orthophosphate (Pi) were measured in different plant parts and related to growth. The Pi was extracted from microwave‐dried plant material which is an effective and practical way of preserving Pi at levels close to those prevailing in fresh tissue. Extremely deficient wheat contained low levels of “metabolic”; Pi (1.4 mM), while wheat abundantly supplied with P accumulated Pi to concentrations of 40 mM without adverse effects on growth. The main effect of P on shoot growth was to increase the number and weight of tillers. The maximum weight of different organs was attained with different internal Pi concentrations. Critical leaf Pi (last fully expanded main‐shoot leaf) and critical whole shoot Pi for maximum whole shoot growth were 2.8 mM (0.043%) and 2.6 mM (0.040%), respectively. The Pi in mature main‐shoot leaves was closely related to whole shoot Pi. The diagnosis of plant nutrient status using P “storage pool”; concentrations is discussed.     

不同水分条件下水稻苗期根系性状的QTL分析

以超级杂交稻协优9308(协青早B/中恢9308)衍生的234个重组自交系(RIL)为材料,在正常水分和20%聚乙二醇(PEG-6000)模拟水分胁迫处理下对水稻苗期最长根长、总根长、根表面积、根体积、根平均直径、根尖数、根鲜重和根冠比进行QTL定位分析。采用复合区间作图法,共检测到影响8个根部性状的21个QTL,单个QTL可解释的表型变异介于4.80%～11.35%。其中,正常水分条件下检测到7个QTL,分布在第2、3、9、10、11染色体上;水分胁迫条件下检测到14个QTL,分布在第2、3、5、6、9染色体上。不同水分条件下检测到的QTL位点差异很大,表明不同水分条件下的遗传机制不同。在第3和第6染色体上各检测到1个根部性状的QTL簇,尤其在第3染色体RM6283-RM7370区间发现苗期根系性状与抗旱性及产量相关性状之间存在连锁关系,利用这些QTL紧密连锁的分子标记进行辅助选择,可望同时对多个相关性状进行遗传改良。     

Increases in phosphatase and β‐glucosidase activities in wheat seedlings in response to phosphorus‐deficient growth

The ability of plants to utilize P efficiently is important for crops growing in P‐deficient soils or on soils with a high P‐fixing capacity. The purpose of this work was to investigate early physiological changes which occur when wheat (Triticum aestivum L.) seedlings were grown under P‐deficient conditions. Wheat plants were grown in a greenhouse and watered with nutrient solution containing or lacking P. During the interval 12 to 18 days after planting, the dry weight of wheat seedlings was similar regardless of P treatment, although the P‐deficient plants had a greater proportion of the total plant weight in the roots. Sixteen days after planting, the roots and leaves of P‐deficient plants had only 20 to 30% the P content of P‐sufficient plants. After 16 days, plants grown under P stress had 41% more p‐nitrophenol phosphatase activity and 70% more β‐glucosidase activity in shoot homogenates than was found in P‐sufficient plants. Changes in both enzyme activities may be involved in the mobilization of plant resources during the early stages of P‐deficient growth.