水稻黄绿叶突变体djyg的遗传分析与基因定位

在粳稻品种Dongjin大田种植过程中,发现一个黄绿叶自然突变体,命名为djyg。该突变体在苗期表现明显的黄绿叶表型,抽穗以后,叶色逐渐恢复正常。叶绿素含量测定结果表明,在苗期、分蘖盛期及抽穗期叶绿素b的含量分别下降53%、62%、36%。电镜结果表明,分蘖期突变体中基粒、类囊体垛堆凌乱、排列疏松,类囊体基质较为稀薄。qRT-PCR结果证实,PORA、Cab1R、PsbA的表达量在突变体中均较野生型明显下调。遗传分析结果表明,黄绿叶突变体djyg由一对隐性主效核基因控制,图位克隆确定该候选基因为编码叶绿素合成酶基因YGL1的一个新等位基因。该突变体未影响植株的主要农艺性状,可作为一个理想的表型标记应用于杂交稻育种工作中。     

花生高产种质的耐铝毒能力评价

以人工模拟铝毒胁迫盆栽试验,研究了８个不同花生高产早熟种质对铝毒胁迫的反应,吕毒胁迫对花生的主要性状有的抑制作用,鉴定出具有较强耐铝毒胁迫的９３－８１等材料,并通过分析不同性状与铝毒胁迫下产量稳定性的相关性,明确了根系体积和重量是花生耐酸性评价和选择最重要性状,提出了花生耐酸性的综合评价方法 。     

通过生育期基因型选择避免稻瘟病抗性与结实率的遗传累赘

利用重组自交系研究表明,在水稻第6染色体短臂上稻瘟病抗性基因Pi25(t)与控制结实率和每穗实粒数的QTL之间存在遗传累赘。为了验证这种关系,采用了更大的遗传群体进行分析,结果表明稻瘟病抗性与结实率存在遗传累赘,但未检测到稻瘟病抗性与每穗实粒数存在遗传累赘。通过对第7染色体长臂RM2-RM214区间抽穗期基因（qHD 7）型背景进行选择,可以打破或避免稻瘟病抗性与结实率的遗传累赘。为了进一步验证这种关系,选择Pi25(t)区间基因型不同、RM2-RM214区间基因型相同、其他染色体区间基本一致的两个株系发展新群体进行分析,除第6染色体的结实率QTL可以分解成2个效应较小的QTL（qSF 6 1和qSF 6 2）外,当第7染色体RM2-RM214区间基因型为中156背景时,Pi25(t)与结实率QTL（qSF 6 2）存在遗传累赘,且qSF 6 2来自父本谷梅2号的等位基因起减效作用;当第7染色体RM2-RM214区间基因型为谷梅2号背景时,第6染色体上没有检测到结实率QTL。上述结果说明在特定育种材料中对抽穗期基因进行选择可以成功打破或避免稻瘟病抗性与结实率的遗传累赘,为水稻以及其他作物的高产抗病育种提供了一种新途径。     

Characterization of the morphological and physiological traits of rice cultivars with adaptation to unflooded condition during early vegetative growth

This study aimed to characterize the physiological and morphological traits that are associated with adaptation to unflooded soil conditions in rice. Four indica rice cultivars (Puluik Arang, Badari Dhan, Shwe Nang Gyi, and Ratul), which were previously identified as highly or less adaptable to unflooded soil conditions, were grown under flooded and unflooded (soil water potential; －0.10 MPa) soil conditions. Water uptake was measured every day for three weeks, and then the leaf water potential, the stomatal conductance, the dry matter weight, shoot and root morphological traits were measured. Puluik Arang and Badari Dhan exhibited greater leaf area expansion and higher maintenance of root development under the unflooded condition than that by other cultivars. The leaf water potential and stomatal conductance of fully expanded highest leaf in Puluik Arang and Badari Dhan were not affected by unflooded soil regime. Leaf area and root morphological traits were significantly correlated with water uptake regardless of soil moisture regimes. These results suggested that Puluik Arang and Badari Dhan exhibited great water uptake capacity through physiological and morphological adaptation of shoot and root traits to unflooded condition, resulting in great biomass productivity under the condition.     

Quantitative trait loci for seedling vigor in rice under field conditions

Previous QTL studies on seedling vigor in rice (Oryza sativa L.) were conducted all based on laboratory germination tests. In the current study, a set of recombinant inbred lines derived from a rice cross were assessed for seedling vigor related traits in natural field environments including two treatments (drained soil and flooded soil). Composite interval mapping identified nine QTL for seedling vigor traits that correlated positively with each other. Individual QTL explained 4–14% of the total trait variation. Among the QTL, three and four were specific to the drained and flooded treatments, respectively, while two others were common between the two treatments. Four QTL (qFV-1-1, qFV-3-2, qFV-5-1 and qFV-10) each simultaneously showed effect on two or more traits with additive effects always in the same direction. The QTL qFV-5-1 could be further resolved into at least two linked loci, qFV-5-1a controlling seedling height and qFV-5-1b controlling seedling dry weight while the QTL qFV-10 could be a single locus with a pleiotropic effect on both seedling height and dry weight. The QTL qFV-1-1 and qFV-3-2 expressed specially under the flooded conditions, each pleiotropically controlling both coleoptile and seedling emergence. These two QTL were completely different from that affecting seedling emergence in the drained conditions. Comparison of the QTL indicated that the QTL mapping results based on field assessments could to some extent coincide with those based on lab tests but the discrepancy between the two kinds of experiments could not be overlooked.     

Differential Proteins Expressed in Rice Leaves and Grains in Response to Salinity and Exogenous Spermidine Treatments

Exogenous application of spermidine(Spd) has been reported to modulate physiological processes and alleviate salt-induced damage to growth and productivity of several plants including rice. Employing a proteomic approach, we aimed at identifying rice leaf and grain proteins differentially expressing under salt stress, and in response to Spd prior to Na Cl treatment. A total of 9 and 20 differentially expressed protein spots were identified in the leaves of salt-tolerant(Pokkali) and saltsensitive(KDML105) rice cultivars, respectively. Differential proteins common to both cultivars included a photosynthetic light reaction protein(oxygen-evolving complex protein 1), enzymes of Calvin cycle and glycolysis(fructose-bisphosphate aldolase and triose-phosphate isomerase), malate dehydrogenase, superoxide dismutase and a hypothetical protein(Os I_18213). Most proteins were present at higher intensities in Pokkali leaves. The photosynthetic oxygen-evolving enhancer protein 2 was detected only in Pokkali and was up-regulated by salt-stress and further enhanced by Spd treatment. All three spots identified as superoxide dismutase in KDML105 were up-regulated by Na Cl but down-regulated when treated with Spd prior to Na Cl, indicating that Spd acted directly as antioxidants. Important differential stress proteins detected in mature grains of both rice cultivars were late embryogenesis abundant proteins with protective roles and an antioxidant protein, 1-Cys-peroxiredoxin. Higher salt tolerance of Pokkali partly resulted from higher intensities and more responsiveness of the proteins relating to photosynthesis light reactions, energy metabolism, antioxidant enzymes in the leaves, and stress proteins with protective roles in the grains.     

Identification of Chromosomal Regions Controlling the Leaf Photosynthetic Rate in Rice by Using a Progeny from Japonica and High-yielding Indica Varieties

Abstract

The whole-leaf photosynthetic rate in rice plants is controlled by various physiological processes. In a high-yielding indica rice variety, Habataki, the leaf photosynthetic rate (LPR) of the uppermost fully expanded leaves was approximately 130 to 140% of that in a japonica variety, Sasanishiki, from booting to the early ripening stage. We characterized the difference in the LPR between Habataki and Sasanishiki. Leaves of Habataki contained higher levels of nitrogen and, as a consequence, of Rubisco, and had higher stomatal conductance that was associated with higher hydraulic conductance from roots to leaves than those of Sasanishiki. These features were responsible for the higher LPR of Habataki. An analysis of chromosome segment substitution lines (CSSLs) in which chromosome segments from Habataki were substituted into the genetic background of Sasanishiki showed that three genetic regions on chromosomes 4, 5 and 11 were responsible for the increase in the LPR. Each of these regions was estimated to increase the LPR by 15 to 30%, and we showed that they were associated with higher activity of mesophyll photosynthesis due to higher leaf nitrogen content and greater stomatal conductance. Leaf nitrogen content and stomatal conductance may be useful parameters for further quantitative trait locus analysis of efficient photosynthesis in leaves.     

两份新株型水稻品系的农艺性状与遗传特性分析

[目的]理想株型水稻能提高光合作用效率、经济产量和抗病能力.通过探究两份新株型水稻种质的农艺性状变异和遗传特性,为水稻高产抗病育种提供优异理想株型种质资源.[方法]以两个重组自交系中发现的两份自然重组的新株型种质08yi和RIL60以及由同一自交系选育出来的常规种质08yc和RILc为材料,进行不同生长时期的株型构成因...     

Genetic bases of source-,sink-,and yield-related traits revealed by genome-wide association study in Xian rice

The source-sink relationship determines the ultimate grain yield.We investigated the genetic basis of the relationship between source and sink and yield potential in rice.In two environments,we identified quantitative trait loci(QTL)associated with sink capacity(total spikelet number per panicle and thousand-grain weight),source leaf(flag leaf length,flag leaf width and flag leaf area),source-sink relationship(total spikelet number to flag leaf area ratio)and yield-related traits(filled grain number per panicle,panicle number per plant,grain yield per plant,biomass per plant,and harvest index)by genome-wide association analysis using 272 Xian(indica)accessions.The panel showed substantial variation for all traits in the two environments and revealed complex phenotypic correlations.A total of 70 QTL influencing the 11 traits were identified using 469,377 high-quality SNP markers.Five QTL were detected consistently in four chromosomal regions in both environments.Five QTL clusters simultaneously affected source,sink,source–sink relationship,and grain yield traits,probably explaining the genetic basis of significant correlations of grain yield with source and sink traits.We selected 24 candidate genes in the four consistent QTL regions by identifying linkage disequilibrium(LD)blocks associated with significant SNPs and performing haplotype analysis.The genes included one cloned gene(NOG1)and three newly identified QTL(qHI6,qTGW7,and qFLA8).These results provide a theoretical basis for high-yield rice breeding by increasing and balancing source–sink relationships using marker-assisted selection.     

Inheritance and QTL Mapping of Salt Tolerance in Rice

An F2 population derived from the cross between Jiucaiqing (japonica) and IR36 (indica) was used to analyze the inheritance of salt tolerance in rice by genetic model of major-genes plus polygenes, and to map the corresponding QTLs by SSR molecular markers. Rice plants of P1, P2, F1 and F2 at 5- to 6- leaf stage were treated under 140 mmol/L NaCI for 10 days. Three indices representing the ability of salt tolerance of rice seedlings were measured, including salt tolerance rating (STR), Na^ /K^ ratio in roots and dry matter weight of shoots (DWS). STR, Na^ /K^ and DWS were all controlled by two major genes with modification by polygenes. Heritability of these traits from major genes was 17.8, 53.3 and 52.3%, respectively. The linkage map constructed by 62 SSR molecular markers covered a total length of about 1 142 cM. There were three QTLs detected for STR located on chromosome 1, 5 and 9, two QTLs for DWS on chromosomes 8 and 9, and two QTLs for Na^ /K^ on chromosomes 2 and 6, one on each chromosome respectively. Single QTL accounted for 6.7 to 19.3% of phenotypic variation. Identification method of salt tolerance in rice and breeding of rice varieties with salt tolerance based on molecular markers assisted selection had been discussed.     

两个水稻抗褐飞虱隐性基因的遗传分析与初步定位

选用抗褐飞虱的海南普通野生稻渗入系WB01与感虫品种9311杂交,构建F2群体。采用141个具有多态性的SSR标记对303个F2:3株系进行分析,并应用MapMaker/EXP3.0和Windows QTL Cartographer2.0对水稻抗褐飞虱的数量性状基因座进行检测和遗传效应分析。共检测到2个抗性QTL,分别位于第4和第8染色体上,LOD值分别为2.92和3.15,贡献率分别为11.3%和14.9%。     

Effects of Silicon on Tolerance to Water Deficit and Heat Stress in Rice Plants (Oryza sativa L.), Monitored by Electrolyte Leakage

Summary

To evaluate the positive efTects of silicon on the stress tolerance of rice plants, we measured the electrolyte leakage (El) from leaf tissue caused by desiccation with polyethylene glycol (PEG) and by high temperature to estimate the integrity of cell membranes. The El caused by 30% and 40% solutions of PEG decreased with the increase in the level of Si in leaves. In leaves of plants grown with 100 ppm Si02, the level of polysaccharides in cell walls, which is one of the factors related to tolerance to desiccation, was 1.6-fold higher than that in leaves of plants grown without Si. Ultrastructural observations of leaves revealed that polymerized Si accumulated in the walls of epidermal cells but not in those of the mesophyll cells, which are probably the main sites of El. These findings suggested that silicon in rice leaves is involved in the water relations of cells, such as mechanical properties and water permeability and plays a role in preventing El through the synthesis and functions of cell walls. The El caused by high temperature (42.5° C) was also lower in the leaves grown with Si than in the leaves grown without Si, suggesting the involvement of silicon in the thermal stability of lipids in cell membranes. These results suggested that silicon prevents the structural and functional deterioration of cell membranes when rice plants are exposed to environmental stress.     

水稻高节位分蘖的QTL定位和互作分析

 高节位分蘖是水稻生产中常见的现象,同时高节位分蘖与水稻的驯化也存在密切的联系。利用来源于窄叶青8号与京系17及春江06与台中本地1号的两个加倍单倍体（DH）群体（分别简称为ZJDH群体和TCDH群体）为材料,对水稻高节位分蘖的遗传特征进行了研究。采用复合区间作图法,在ZJDH群体中共定位到qHOT3、qHOT6-1和qHOT8等3个QTL,分别位于第3、6和8染色体上;对TCDH群体的QTL定位共检测到相关位点2个,分别位于第6和12染色体上。同时,在两个群体中分别检测到4对和7对上位性互作位点。QTL比较分析表明在两个群体中分别定位到的第6染色体上的QTL所在区间可能一致,说明水稻第6染色体对高节位分蘖具有重要的影响。     

A simple method for squeezing juice from rice stems and its use in the high-throughput analysis of sugar content in rice stems

Sugar content in rice (Oryza sativa L.) stem is an agronomically important trait for rice used in straw silage or whole-crop silage. However, the mechanisms underlying sugar accumulation in rice stems remain unclear, mainly due to the time-consuming method for measuring sugar content. Here, we established a simple method for squeezing stem juice from rice plants, similar to that used during breeding selection in sugarcane or sorghum. The Brix value of the stem juice, which can easily be measured using a portable refractometer, significantly correlated with the soluble sugar contents in the stem juice and tended to correlate with those in stem tissues. This indicates that the Brix value of the stem juice can be used for estimating the sugar content in rice stems. This simple estimation method will be a useful tool for high-throughput analysis of sugar content in rice stems during mutant screening, QTL analysis, and breeding selection.