Flooding Tolerance in Rice: Focus on Mechanisms and Approaches

Flooding is one of the most hazardous natural disasters and a major stress constraint to rice production throughout the world,which results in huge economic loss.Approximately one-fourth of the global rice crops(approximately 40 million hectares)are grown in rainfed lowland plots that are prone to seasonal flooding.A great progress has been made during last two decades in our understanding of the mechanisms involved in adaptation and tolerance to flooding/submergence in rice.In this review,we summarized the physiological and molecular mechanisms that contribute to tolerance of flooding/submergence in rice.We also covered various features of flooding stress with special reference to rice plants,viz.different types of flooding stress,environmental characterisation of flood water,impact of flooding stress on rice plant and their morphological,physiological and metabolic responses under flooding.A brief discussion on the tolerance mechanism in rice exhibited to different types of flooding will be focused for the future crop improvement programme for development of flooding tolerant rice variety.     

Drought Tolerance in Rice: Focus on Recent Mechanisms and Approaches

Drought stress is a serious limiting factor to rice production,which results in huge economic losses.It is becoming a more serious issue with respect to the global climate change.Keeping in view of the current and forecasted global food demand,it has become essential to enhance the crop productivity on the drought-prone rainfed lands with priority.In order to achieve the production target from rainfed areas,there is a requirement of rice varieties with drought tolerance,and genetic improvement for drought tolerant should be a high priority theme of research in the future.Breeding for drought tolerant rice varieties is a thought-provoking task because of the complex nature and multigenic control of drought tolerant traits would be a major bottleneck for the current research.A great progress has been made during last two decades in our understanding of the mechanisms involved in adaptation and tolerance to drought stress in rice.In this review,we highlighted the recent progresses in physiological,biochemical and molecular adaptation of rice to drought tolerance.A brief discussion on the molecular genetics and breeding approaches for drought tolerance in rice will be focused for the future crop improvement program for development of drought tolerant rice varieties.     

转基因耐盐水稻研究

本文介绍了水稻耐盐转基因研究的意义,综述了目前应用于转基因水稻研究的耐盐基因种类和当前国内外耐盐转基因水稻的研究现状,并对耐盐转基因水稻的研究方向作了展望.     

水稻对盐胁迫的响应及耐盐机理研究进展

我国土壤盐渍化问题日趋严重,在耕地红线内的盐碱地约有9.3×106 hm2,盐胁迫是制约粮食生产的主要非生物胁迫因子之一.水稻是盐碱地改良的先锋作物,全面深入了解水稻对盐胁迫的响应,对盐碱地水稻生产具有重要意义.本文概述了盐胁迫对水稻生长发育、产量和品质形成的影响;从渗透调节、离子平衡等生理层面以及基因层面阐述盐胁迫影...     

水稻耐盐研究与育种进展

培育耐盐品种或通过栽培措施提高水稻的耐盐能力是提高盐碱土地的利用率和经济效益,缓解世界粮食危机的最佳方案之一,意义重大。本文主要论述了盐胁迫对水稻的生理效应;水稻对盐胁迫的生理反应;水稻耐盐性的分子基础以及提高水稻抗盐性的化控和栽培措施等研究进展,提出提高水稻耐盐性有效研究方法与途径。     

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.     

水稻耐盐基因定位与克隆及品种耐盐性分子标记辅助选择改良研究进展

土壤盐渍化严重制约水稻生产发展,提高耐盐性已成为水稻育种的重要目标之一。挖掘水稻耐盐新基因,解析其分子作用机制可以为水稻耐盐性遗传改良奠定基础。本文从定位群体、耐盐性鉴定时期和鉴定方法、耐盐性评价指标、鉴定到的耐盐QTL、耐盐QTL的精细定位和图位克隆等方面,总结了近年来水稻耐盐QTL定位研究中所取得的进展;介绍了水稻耐盐/盐敏感突变体筛选和基因克隆以及耐盐性关联分析的研究近况;并对水稻耐盐性分子标记辅助选择改良的现状作了概述。     

Arsenic Stress Responses and Tolerance in Rice: Physiological,Cellular and Molecular Approaches

Arsenic (As), a potentially toxic metalloid released in the soil environment as a result of natural as well as anthropogenic processes, is subsequently taken up by crop plants. In rice grains, As has been reported in Asia, North America and Europe, suggesting a future threat to food security and crop production. As³⁺ by dint of its availability, mobility and phytotoxicity, is the most harmful species of As for the rice crop. Specific transporters mediate the transport of different species of As from roots to the aboveground parts of the plant body. Accumulation of As leads to toxic reactions in plants, affecting its growth and productivity. Increase in As uptake leads to oxidative stress and production of antioxidants to counteract this stress. Cultivars tolerant to As stress are efficient in antioxidant metabolism compared to sensitive ones. Iron and selenium are found to have ameliorating effect on the oxidative stress caused by As. Microbes, even many indigenous ones, in the plant rhizosphere are also capable of utilizing As in their metabolism, both independently and in association. Some of these microbes impart tolerance to As-stress in plants grown in As contaminated sites.     

Antioxidant Defense Mechanisms of Salinity Tolerance in Rice Genotypes

In order to elucidate the role of antioxidant responses in salinity tolerance in rice genotypes under salt stress, experiments were conducted using four rice varieties, including salt-sensitive BRRI dhan 28 and three salt-tolerant varieties BRRI dhan 47, BINA dhan 8 and BINA dhan 10. Thirty-day-old rice seedlings were transplanted into pots. At the active tillering stage(35 d after transplanting), plants were exposed to different salinity levels(0, 20, 40 and 60 mmol/L NaCl). Salt stress caused a significant reduction in growth for all the rice genotypes. Growth reduction was higher in the salt-sensitive genotype than in the salt-tolerant ones, and BINA dhan 10 showed higher salt tolerance in all measured physiological parameters. The reduction in shoot and root biomass was found to be minimal in BINA dhan 10. Chlorophyll content significantly decreased under salt stress except for BINA dhan 10. Proline content significantly increased in salt-tolerant rice genotypes with increased salt concentration, and the highest proline content was obtained from BINA dhan 10 under salt stress. Catalase and ascorbate peroxidase activities significantly decreased in salt-sensitive genotype whereas significantly increased in salt-tolerant ones with increasing salt concentration. However, salt stress significantly decreased guaiacol peroxidase activity in all the rice genotypes irrespective of salt tolerance. K~+/Na~+ ratio also significantly decreased in shoots and roots of all the rice genotypes. The salt-tolerant genotype BINA dhan 10 maintained higher levels of chlorophyll and proline contents as well as catalase and ascorbate peroxidase activities under salt stress, thus, this might be the underlying mechanism for salt tolerance.     

水稻耐盐性数量性状位点的初步检测

用RFLP分析技术和分蘖株系法对由耐盐性品种Pokkali和盐敏感品种Peta配制的BC1(Peta/Pokkali∥Peta)群体分别检测水稻苗期和成熟期耐盐性数量性状位点(QTLs)。表型鉴定在含(处理)或不含(对照)60 mol/m3 NaCl的营养液中进行,苗期观测盐害级别、苗Na+含量和鲜重/干重比值3项指标,成熟期测定10种农艺性状处理与对照的相对值。从水稻12条染色体上筛选出43个多态性标记,对上述指标分别作点分析,共检出15个连锁标记。连锁标记的分布特点显示,在研究所涉及的基因组范围内存在4个影响苗期耐盐性的QTL,其增效等位基因均来自耐盐品种Pokkali;影响成熟期耐盐性的QTL分布于7条染色体的1或2个连锁区间上,其有利基因来自双亲;RG678和RZ400B~RZ792附近的2个QTL在全生育期都能表达较强耐盐性。     

水稻耐盐分子机制与育种研究进展

盐碱土壤对水稻不同生长发育时期均形成盐胁迫,进而导致水稻产量降低。耐盐水稻选育是提高水稻产量的有效途径。本文分析了盐胁迫对水稻不同发育时期农艺性状的影响,并从渗透调节、离子应答、激素调控和活性氧清除四个方面综述了近年来水稻耐盐分子机制的研究进展。最后,本文总结了水稻耐盐育种现状,并对耐盐水稻新品种的选育和推广进行了展望。     

应用分子标记检测水稻耐盐性的QTL

 利用特三矮2号/CB组合构建了重组自交系群体(RI)。以60个RFLP标记检测142个纯系的基因型。在含有NaCl的电导率为12 dS/m的培养液中鉴定这些纯系的耐盐性。结果表明,RI群体的耐盐性出现超亲分离。构建了一张覆盖11条染色体、含52个标记位点的连锁图。仅检测到一个位于第5染色体的位点(RG13)显著与耐盐性有连锁。该位点的表型贡献率为11.6%。来自母本的该位点可提高耐盐性。分别对RG13与其它59个标记位点间的互作做检测,仅发现3对互作显著,即RG13×RG104; RG13×RG143; RG13×RG716。当来自母本的RG13分别与来自父本的RG104和RG143重组时,均明显提高耐盐性。分别来自母本的RG13和RG716能产生提高耐盐性的互作。这些基因互作结果为超亲分离提供了理论依据。     

盐胁迫下 4 个不同耐盐基因型水稻 Na+ 、K+ 积累效应

选取耐盐性较强的水稻株系‘Fl478’、‘JX99’、‘Pokkali’和盐敏感型品种‘IR29’,设置 6 个 NaCl 浓度梯度处理, 分别为 0、0.1%、0.2%、0.3%、0.4%、0.5%,采用桶栽土培的方法培育至孕穗期,研究盐胁迫对孕穗期水稻植株不同 器官 Na+ 、K+ 分配规律与积累的影响。结果表明：（1）盐胁迫下水稻株系不同器官 Na+ ,K+ 的积累效应存在差异,水稻 株系耐盐性的差异主要表现在根系,而叶鞘对 Na+ 、K+ 的吸收与分配的差异明显。（2）耐盐植株根系聚 Na+ 能力较强, 叶片、叶鞘积累较多的 K+ ,而感盐品种根系积累 K+ 和 Na+ 以缓解根系渗透胁迫,调节根系 Na+ /K+ 平衡稳态,保持水稻 正常的代谢活动。（3）叶鞘是水稻植株关键的 Na+ -K+ 调库,通过吸收和分配 Na+ 来调节根、叶、叶鞘 Na+ /K+ 平衡以提 高水稻耐盐性。（4）耐盐株系叶鞘向叶片选择运输 K+ 的能力、限 Na+ 运输能力强于盐敏感品种,叶鞘对 Na+ 、K+ 吸收 与分配运输能力的大小,决定水稻株系的耐盐性,具体表现耐盐品种叶鞘向吸收与运输 K+ 能力较强、根系限 Na+ 能力 显著高于感盐植株。（5）0.4%~0.5%盐浓度限制水稻叶鞘 Na+ -K+ 库吸收与分配能力,各组织中 Na+ /K+ 失衡,植株耐盐 性降低,受盐害程度加深。（6）盐胁迫促进水稻株系叶鞘向根系吸收较多 Na+ 和向叶片、根系输出 K+ ,却限制 Na+ 对 叶片的分配,保证根系保持较高的 K+ /Na+ ,耐盐幼嫩叶片积累较多的 K+ 以维持叶片组织保卫细胞渗透平衡,保证水稻 植株获得生活必需的光合原料,而盐敏感植株积累的 K+ 主要用于缓解组织渗透胁迫,以维持正常生命活动。     

番茄耐盐性研究进展

通过总结近年来国内外番茄耐盐性的研究进展,阐明番茄耐盐性生理生化及分子机理,为今后番茄耐盐品种的选育及在盐碱地种植番茄提供参考。     

Haplotyping of Rice Genotypes Using Simple Sequence Repeat Markers Associated with Salt Tolerance

Salt stress is a major problem in most of the rice growing areas in the world. A major QTL Saltol associated with salt tolerance at the seedling stage has been mapped on chromosome 1 in rice. This study aimed to characterize the haplotype diversity at Saltol and additional QTLs associated with salt tolerance. Salt tolerance at the seedling stage was assessed in 54 rice genotypes in the scale of 1 to 9 score at EC = 10 d Sm-1 under controlled environmental conditions. Seven new breeding lines including three KMR3/O. rufipogon introgression lines showed similar salt tolerant ability as FL478 and can be good sources of new genes/alleles for salt tolerance. Simple sequence repeat(SSR) marker RM289 showed only two alleles and RM8094 showed seven alleles. Polymorphic information content value varied from 0.55 for RM289 to 0.99 for RM8094 and RM493. Based on 14 SSR markers, the 54 lines were clearly separated into two major clusters. Fourteen haplotypes were identified based on Saltol linked markers with FL478 as the reference. Alleles of RM8094 and RM3412 can discriminate between the salt tolerant and susceptible genotypes clearly and hence can be useful in marker-assisted selection at the seedling stage. Other markers RM10720 on chromosome 1 and RM149 and RM264 on chromosome 8 can also distinguish tolerant and susceptible lines but with lesser stringency.     

外界K＋水平对水稻幼苗耐盐性的影响

外界Ｋ~＋水平对水稻幼苗耐盐性的影响晏斌，戴秋杰（江苏省农业科学院，南京２１００１４）ＥｆｆｅｃｔｏｆＥｘｔｅｒｎａｌＫ~＋ＬｅｖｅｌｏｎＳａｌｔＴｏｌｅｒａｎｃｅｏｆＲｉｃｅＳｅｅｄｌｉｎｇｓ￥ＹＡＮＢｉｎ，ＤＡＩＱｉｕｊｉｅ（ＪｉａｎｇｓｕＡｃａｄ...     

太湖流域粳稻地方品种韭菜青的苗期耐盐性遗传分析

为了研究太湖流域强耐盐粳稻地方品种韭菜青的苗期耐盐性遗传机理,配制了韭菜青/IR26籼粳杂交组合,在盐胁迫条件下,运用剥蘖分株法鉴定了P[sub]1[/sub]、P[sub]2[/sub]、F[sub]1[/sub]和F[sub]2[/sub]苗期的盐害级别和根系Na+/K+两个耐盐相关指标。结果表明,在0.8%的NaCl胁迫下,亲本的两个耐盐相关指标有明显的差异,F[sub]1[/sub]均表现出超亲优势,F[sub]2[/sub]呈正态混合分布。采用主基因 多基因遗传模型进行遗传分析,发现韭菜青苗期的盐害级别和根系Na[sup]+[/sup]/K[sup]+[/sup]均由2对主效基因控制,并存在多基因修饰。盐害级别的主基因遗传率仅为16.10%,而根系Na[sup]+[/sup]/K[sup]+[/sup]的主基因遗传率高达50.78%,两个指标的主基因加多基因共同解释的遗传率都在70%以上。     

大麦发芽期的耐盐性研究

通过对 7个大麦品种在不同盐 (NaCl)浓度条件下发芽率、苗高和相对生长率的比较分析。结果表明 :1 大麦发芽率同时受种子原始活力和盐浓度的影响 ,在盐碱土的种植大麦 ,应选择高活力种子种植 ;2 大麦苗高既受品种本身遗传因素的影响又受品种盐浓度的影响 ,应根据土壤盐浓度选择适宜的品种种植 ;3 发芽率和幼苗的相对生长率应同时作为衡量品种是否耐盐的指标 ,被研究品种发芽期最大耐盐 (NaCl)的浓度为 0 5 %。