水杨酸对NaCl胁迫下水稻(Oryza Saliva L.)幼苗生理活性的影响

用0.2%水杨酸处理1.2%NaCl胁迫下的水稻种子,测定其以下几个生理指标:种子的发芽率、发芽势和幼苗中的酯酶、过氧化氢酶以及抗坏血酸的含量.实验结果显示:外源性水杨酸能够相对提高NaCl胁迫下水稻种子萌发后幼苗的过氧化物酶活性和抗坏血酸的含量,同时也能提高水稻种子的发芽率、发芽势,但对酯酶活性影响不大.研究表明水杨酸能提高水稻种子萌发后幼苗的抗盐性,并使水稻种子出苗整齐、一致.

Si,Fe and Mn Distributions in Rice (Oryza saliva L.) Rhizosphere of Red Earths and Paddy Soils

An experiment using rhizobox was conducted to study Si, Fe and Mn distributions in rice rhizosphcre of red earths and paddy soils. It was found that Si, Fe and Mn distributions in rhizosphere of the paddy soils were characterized by a depleted zone around root surface, beyond which the concentrations gradually rose. From lmm layer to 2mm layer the concentrations dropped and then rose again. Whereas Si and Fe in red earths showed no depleted zone but even accumulated zone around root surface. Mn showed an approximately even distribution in each layer and no depletion was found in root surface layers. This indicated that during rice (Oryza sativa L.)plantation, depletion and accumulation of Si, Fe and Mn in rhizosphere were important features of matured red earths by water culture. The distribution changes of Si, Fe and Mn in relation to soil-root interaction are also discussed.

利用DH群体定位水稻谷粒外观性状的QTL

采用混合线性模型的复合区间作图方法,对水稻“圭630”和“02428”组合的DH群体的谷粒外观性状——粒长、粒宽和粒形进行了数量性状基因定位,同时对定位的主效应和上位性进行了环境效应分析。2002年对粒长、粒宽和粒形分别检测到5、4和2个QTLs;2003年对以上3个性状分别检测到3、4和4个QTLs。其中4个QTLs在2年均检测到,且其贡献率较大。位于第4染色体C22-RG449d区间的QTL效应大,同时影响粒长和粒宽,2年内均被检测到。联合2年数据分析分别检测到6个粒长QTLs、6个粒宽QTLs和3个粒形QTLs,共解释各自性状变异的67.71%、50.08%和29.17%,且影响粒形的3个QTLs同时影响粒长或粒宽。对粒形和粒宽分别检测到4个QTLs与环境之间存在显著互作。本实验中检测到主效应和上位性对谷粒外观性状均具有重要作用,但上位性贡献率相对主效应较小,环境互作效应更小。

光学纯度L(+)-乳酸高产菌株的选育

从60份不同来源的土壤样品中筛选得到米根霉(Rhizopusoryzae)为出发菌株,通过紫外线和60Coγ射线诱变处理,运用推理育种技术,选育到一株有较高的乳酸脱氢酶活性和耐高渗的L(+)-乳酸高产突变株Rhi3-2.该菌株产L(+)-乳酸光学纯度高,最高产量为88.45g/L,较出发菌株提高91.24%,糖利用率提高17.87%,耗糖酸产率提高35.15%.菌株经8次传代培养,L(+)-乳酸产量下降10.7%,是一株性状较稳定可深入研究开发的优良菌株.

Variation in Expression of <i>Sub</i>1 Gene and Association with Submergence Stress Related Traits in Advance Rice (<i>Oryza sativa</i>L.) Genotypes as a Tool of Climate Change Adaptation

Floods have now become most detrimental natural catastrophe worldwide due to radical climatic fluxes. Therefore, there is a dire necessity to develop a high yielding rice lines to deal with this scenario. For this purpose, a large scale experiment was conducted including one hundred and fifteen (115) rice genotypes having SUB1 gene imported from International Rice Research Institute (IRRI) Philippines, six local cultivars/approved varieties and three high yielding rice varieties i.e. Sabitri, IR6 and NSICRC222 being used as potential varieties in different countries of Asia as susceptible check and IR64-SUB1 as tolerant check. The genotypic screening was performed using two PCR-based DNA markers i.e. ART5 and SC3. Phenotypic screening was conducted in a natural pond to assess the interaction of SUB1 gene in natural stagnant flood water as well as the suitability of introgression of SUB1 gene into approved varieties and elite rice lines. The genotypes were assessed in terms of plant survival percentage, submergence tolerance index, physical condition, stem elongation, number of grains per panicle, thousand grain weight, grain yields and deviations in these traits after submergence stress. The PCR results suggested that both the primers ART5 and SC3 may be used as potential PCR-based markers for molecular screening of rice genotypes for SUB1 QTL. Furthermore, it confirmed the presence of SUB1 gene in all the lines imported from IRRI, while it was absent in all the local cultivars studied. All the genotypes with submergence tolerant gene (SUB1) showed significantly greater tolerance level in submergence stress of 14 days, as compared to other local cultivars/varieties, authenticating the effectiveness of SUB1QTL in conferring submergence tolerance. Significantly different performances of all the SUB1 genotypes in terms of all the studied traits indicate high Genotypic and Genotypic Environment Interaction (GEI) of SUB1QTL. Employment of SUB1 lines such as R105479:149-18, IR64-SUB1 and Rl05469:81-22-3 in breeding programs for developing flood tolerant rice varieties might further upsurge rice yields in flash flood areas. Correlation analysis revealed that plant survival percentage after submergence, reduced stem elongation during submergence and submergence tolerance index are very important traits for developing submergence tolerant lines.

Enclosed stigma contributes to higher spikelet fertility for rice(Oryza sativa L.) subjected to heat stress

With global warming, rice plants may be subjected to heat stress more regularly during the heatsensitive flowering stage, causing spikelet sterility and grain yield loss.Stigma exsertion is considered to increase pollen reception and promote female reproductive success.The aim of this study was to investigate the role of stigma exsertion on spikelet fertility at high temperatures.Five rice cultivars(Liangyoupeijiu, Shanyou 63, Huanghuazhan, Nagina 22, and IR64) with differing degrees of stigma exsertion were cultivated and exposed to high temperature at anthesis.Heat-tolerant cultivars did not always show a high percentage of spikelets with exserted stigmas, and vice versa.Irrespective of the presence of more pollen grains on exserted stigmas, spikelets with exserted stigmas did not show greater spikelet fertility than spikelets with fewer exserted stigmas or hidden stigmas under heat stress.GA3 application augmented the percentage of spikelets with exserted stigmas;however, it did not increase spikelet fertility under heat stress.Spikelet fertility of whole panicles was negatively correlated with the percentage of spikelets with exserted stigmas, but positively with that with hidden stigmas.Viability of the hidden stigmas was less reduced than that of exserted stigmas under heat stress, suggesting that hidden stigmas have an advantage in maintaining viability.Heat stress delayed anther dehiscence and reduced the viabilities of both exserted stigmas and pollens, thereby causing low spikelet fertility.Together, these results suggest that high spikelet fertility does not depend on stigma exsertion and that enclosed stigma generally contributes to higher spikelet fertility and heat tolerance under high-temperature conditions during flowering in rice.

Morphological and Physiological Responses of Weedy Red Rice (<i>Oryza sativa</i>L.) and Cultivated Rice (<i>O. sativa</i>) to N Supply

Red rice (Oryza sativa L.), a noxious weed in rice production, competes with cultivated rice for nutrients. Accumulation of more N in red rice than in cultivated rice may be due to a mechanism different from that of cultivated rice. To test this assumption, red rice and cultivated rice were grown in nutrient solution to compare their growth and physiological responses to N supply. Experimental design was a split-plot, where main plot factor was rice type (Stf-3, ‘Wells’);split-plot factor was N treatment [T1 (complete nutrient solution);T2 (–NH4NO3);T3 (+NH4NO3 for 24-h post-N deficiency);and T4 (+NH4NO3 for 48-h post-N deficiency)]. Nitrogen deficiency was defined as N sufficiency index (NSI) 4, Stf-3 showed higher increment in root length and surface area than Wells. Shoot tissue concentrations of N and total sugars were measured to determine physiological response in N-deficient and N-supplemented plants. Stf-3 had greater N and sucrose tissue concentrations at N-deficient conditions compared with Wells, implying a stress-adaptive molecular mechanism regulated by N and sucrose availability.

Mapping and genetic validation of a grain size QTL qGS7.1 in rice(Oryza sativa L.)

Grain size is a major determinant of grain weight, which is one of the components of rice yield. The objective o this study was to identify novel, and important quantitative trait loci(QTLs) for grain size and weight in rice. QTLs were mapped using a BC4F4 population including 192 backcross inbred lines(BILs) derived from a backcross between Xiaolijing(XLJ) and recombinant inbred lines(RILs). The mapping population was planted in both Lingshui(Hainan, 2015) and Fuyang(Zhejiang, 2016), with the short-and long-day conditions, respectively. A total of 10 QTLs for grain length, four for grain width, four for the ratio of grain length to width, and 11 for grain weight were detected in at least one environment and were distributed across 11 chromosomes. The phenotypic variance explained ranged from 6.76–25.68%, 14.30–34.03%, 5.28–26.50%, and 3.01–22.87% for grain length, grain width, the ratio of grain length to width, and thousand grain weight, respectively. Using the sequential residual heterozygotes(SeqRHs) method, qGS7.1, a QTL for grain size and weight, was mapped in a 3.2-Mb interval on chromosome 7. No QTLs about grain size and weight were reported in previous studies in this region, providing a good candidate for functional analysis and breeding utilization.

G ×E Analysis of Rice Germplasm and NILs Having Bacterial Leaf Blight (BLB) Resistant Genes against Local Isolates of <i>Xanthomonas oryzae</i>at Diverse Agro-Ecological Zones

Rice is food for more than half of the world population and the most consumable cereal in most of the countries. Pakistan is the fifth largest exporter of rice. However, Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae is the most devastating and serious threat to rice production in many countries of the world including Pakistan. To combat this disease, innate genetic resistance of the plant plays vital role along with being environmentally friendly and economical. In this study, thirty-one (31) Near Isogenic Lines (NILs) having Xa4, xa5, Xa7, xa13 and Xa21 reported BLB tolerant genes and 34 locally developed rice lines were investigated under natural field conditions at three agro-ecologically different locations with highest disease occurrence records (BLB hotspots) viz., Sheikhupura, Hafizabad and Gujranwala, Punjab, Pakistan in order to assess their respective genetic resistance and G × E interactions against the disease. Thirty-one (31) lines were categorized under resistant cluster, twenty-eight (28) were moderately resistant, six (6) were moderately susceptible and one (susceptible check) was in susceptible category. Grouping of different lines/varieties under same cluster shows their significantly similar response against BLB disease in corresponding environment. Among the studied NILs, only one line showed polymorphism for all five resistant genes, two lines had four;seven lines had three genes, seven lines showed di-genic while five lines showed mono-genic polymorphism. These resistant lines with multiple-genes for BLB resistance can be evolved as a new BLB resistant variety and also be utilized as donor parent in breeding programs for developing new cultivars with horizontal resistance against more than one target pathotypes and environments. Xa4 and xa13 were found to deliver significant resistance against the local pathotypes in studied germplasm and NILs.

Physiological and genome-wide gene expression analyses of cold-induced leaf rolling at the seedling stage in rice(Oryza sativa L.)

Leaf rolling and discoloration are two chilling-injury symptoms that are widely used as indicators for the evaluation of cold tolerance at the seedling stage in rice. However, the difference in cold-response mechanisms underlying these two traits remains unknown. In the present study, a cold-tolerant rice cultivar, Lijiangxintuanheigu, and a cold-sensitive cultivar, Sanhuangzhan-2, were subjected to low-temperature treatments and physiolog-ical and genome-wide gene expression analyses were conducted. Leaf rolling occurred at temperatures lower than 11℃, whereas discoloration appeared at moderately low temperatures such as 13℃. Chlorophyll contents in both cultivars were significantly decreased at 13℃, but not altered at 11℃. In contrast, the relative water content and relative electrolyte leakage of both cultivars decreased significantly at 11℃, but did not change at 13℃. Expression of genes associated with calcium signaling and abscisic acid (ABA) degradation was significantly altered at 11℃ in comparison with 25℃ and 13℃. Numerous genes in the DREB, MYB, bZIP, NAC, Zinc finger, bHLH, and WRKY gene families were differentially expressed. Many aquaporin genes and the key genes in trehalose and starch synthesis were down regulated at 11℃ in comparison with 25℃ and 13℃. These results suggest that the two chilling injury symptoms are temperature-specific and are controlled by different mechanisms. Cold-induced leaf rolling is associated with calcium and ABA signaling pathways and is regulated by multiple transcriptional regulators. The suppression of aquaporin genes and reduced accumulation of soluble sugars under cold stress results in a reduction in cellular water potential and consequently leaf rolling.

Dissection of two quantitative trait loci for grain weight linked in repulsion on the long arm of chromosome 1 of rice(Oryza sativa L.)

Grain weight is a key determinant of grain yield in rice. Three sets of rice populations with overlapping segregating regions in isogenic backgrounds were established in the generations of BC2 F5, BC2 F6 and BC2 F7, derived from Zhenshan 97 and Milyang 46, and used for dissection of quantitative trait loci(QTL) for grain weight. Two QTL linked in repulsion phase on the long arm of chromosome 1 were separated. One was located between simple sequence repeat(SSR) markers RM11437 and RM11615, having a smaller additive effect with the enhancing allele from the maintainer line Zhenshan 97 and a partially dominant effect for increasing grain weight. The other was located between SSR markers RM11615 and RM11800, having a larger additive effect with the enhancing allele from the restorer line Milyang 46 and a partially dominant effect for increasing grain weight. When the two QTL segregated simultaneously, a residual additive effect with the enhancing allele from Milyang 46 and an over-dominance effect for increasing grain weight were detected. This suggests that dominant QTL linked in repulsion phase might play an important role in heterosis in rice. Our study also indicates that the use of populations with overlapping segregating regions in isogenic backgrounds is helpful for the dissection of minor linked QTL.

Irrigation regimes modulate non-structural carbohydrate remobilization and improve grain filling in rice(Oryza sativa L.)by regulating starch metabolism

Recently developed ‘super’ rice cultivars with greater yield potentials often suffer from the problem of poor grain filling, especially in inferior spikelets. Here, we studied the activities of enzymes related to starch metabolism in rice stems and grains, and the microstructures related to carbohydrate accumulation and transportation to investigate the effects of different water regimes on grain filling. Two ‘super’ rice cultivars were grown under two irrigation regimes of well-watered(WW) and alternate wetting and moderate soil drying(AWMD). Compared with the WW treatment,the activities of ADP glucose pyrophosphorylase(AGPase), starch synthase(StSase) and starch branching enzyme(SBE), and the accumulation of non-structural carbohydrates(NSCs) in the stems before heading were significantly improved, and more starch granules were stored in the stems in the AWMD treatment. After heading, the activities of α-amylase, β-amylase, sucrose phosphate synthase(SPS) and sucrose synthase in the synthetic direction(SSs)were increased in the stems to promote the remobilization of NSCs for grain filling under AWMD. During grain filling, the enzymatic activities of sucrose synthase in the cleavage direction(SSc), AGPase, StSase and SBE in the inferior spikelets were increased, which promoted grain filling, especially for the inferior spikelets under AWMD.However, there were no significant differences in vascular microstructures. The grain yield and grain weight could be improved by 13.1 and 7.5%, respectively, by optimizing of the irrigation regime. We concluded that the low activities of key enzymes in carbon metabolism is the key limitation for the poor grain filling, as opposed to the vascular microstructures, and AWMD can increase the amount of NSC accumulation in the stems before heading, improve the utilization rate of NSCs after heading, and increase the grain filling, especially in the inferior spikelets, by altering the activities of key enzymes in carbon metabolism.

“神舟四号”航天搭载水稻变异性状的田间调查

通过对“神舟四号”卫星搭载水稻种子及其后代的研究,结果表明:6个搭载品种种子的发芽率、存苗率、结实率及植株的性状在当代(SP1)与对照相比均没有明显的变化;但在SP2代株高、生育期、分蘖、叶色、芒和红叶耳等性状上发生明显的变异,选择出一些突变株。突变株经SP3代,SP4代验证,最后获得32株高突变体,27株早熟突变株,20株多分蘖突变株,还获得一些农艺性状稳定性状且表现良好的株系,以及独杆、无芒、叶色黄化和类病变等有功能基因研究价值的突变体。

水稻几个披垂叶突变体的表型研究及其遗传分析

随着水稻功能基因组学的发展,水稻突变体已成为研究相关基因功能与表达的良好实验材料。同时,水稻突变体还可以为当今水稻常规育种和分子育种提供新的种质资源。本文主要阐述了几个水稻披垂叶突变体在株型、株高、穗粒数、结实率、千粒重等方面的特征特性,并分析了它们在与正常植株杂交后F1、F2群体表现。研究表明,突变体与野生型正常植株杂交的F1代在经济学性状和生物学性状上均表现出超亲优势,而在F2群体中表现出有规则的分离,3个突变体中披垂叶性状均为隐性基因控制。在突变体材料MR304中,控制披垂性状的为2对隐性基因,其中1对为主效基因。在突变体材料MR168和MR312中,控制披垂性状的均为单隐性基因。

不同遗传背景及环境中水稻(Oryza sativa L.)穗长的QTLs和上位性分析

以粳稻Azucena为父本与舢稻IR64杂交发展的一双单倍体（DH）群体，与籼稻IR1552杂交发展的一重组自交系（RI）群体为材料，应用分子标记图谱对2个群体在大田和盆栽2个环境下的穗长进行QTLs及上位性效应分析。DH群体中共检测到6个穗长QTLs，位于第1、4条染色体上的3个QTLs，在2个环境中稳定表达，未检测到上位性效应，加性效应为穗长遗传主效应。R1群体中，共检测到3个穗长QTLs及6对互作效应位点，位于策4条染色体上的1个QTL及位于第1、12条染色体上的2个互作位点在2个环境中稳定表达，上位性效应表现为遗传主效应。在2个群体中均检测到的与穗长相关的1个QTL位于第4条染色体RG163～RZ23区间内，遗传正效应等位基因来源于Azucena；位于第1条染色体与RG323连锁的位点在DH群体中表现为1个QTL，但在RI群体中表现为互作位点。

一个新的水稻黄绿叶突变体ygl-9108的鉴定与基因定位

本研究旨在对水稻黄绿叶突变体ygl-9108进行表型分析和基因定位,为后续图位克隆该叶色相关基因奠定基础。以黄绿叶突变体ygl-9108为试材,利用突变体ygl-9108和‘五山丝苗’杂交的F2群体进行基因定位。结果表明,与野生型相比,突变体的株高、有效穗数、穗长、每穗粒数、结实率、粒宽、千粒重和单株谷重均显著下降,下降比例分别为21.5%、21.2%、14.6%、19.2%、11.0%、10.2%、12.9%和52.2%。透射电镜观察显示,突变体叶肉细胞的叶绿体数量大量减少,类囊体结构异常。遗传分析表明,突变体的表型由一个隐性核基因控制。利用图位克隆方法,ygl-9108被定位于水稻第11号染色体两InDel标记11Y39和11Y45之间,物理距离约为147 kb,该区间内未见有叶色相关基因的报道,表明ygl-9108是一个新的黄绿叶调控基因。本研究结果为ygl-9108的克隆和功能分析奠定了坚实的基础。

微卫星标记分析籼粳亚种间的遗传多样性

208对引物中具有多态性的引物123对,占所用引物的59.13%.不同染色体的微卫星分析的多态性不同,染色体9,10微卫星的多态性高于其它染色体,染色体12上的微卫星标记的多态性最差,仅为46.15%.聚类分析表明,所有的供试材料可分为两群,即籼稻群和粳稻群.聚类结果与亲本材料亲缘关系基本一致,说明微卫星标记能较好地区分籼稻和粳稻.由于农艺性状是基因表达的结果,易受环境影响,聚类结果不能从整体上充分反应品种间的遗传变异.42份常用杂交水稻亲本材料聚类分析表明,恢复系和不育系遗传基础均较狭窄,但恢复系和不育系之间的遗传距离相对较远,从一定程度上反映了遗传距离与杂种优势正相关.

水稻(Oryza sativa L.)温敏核不育系在有利于遗传型鉴别环境下的遗传改良(英文)

低不育起点温度(CSP)、高自繁育性和高的异交结实率对于水稻温敏核雄性不育系配制纯合的杂交种子和获得经济的自繁种子有重要意义。本研究分析了不同环境对这些性状选择效率的影响,结果表明,温敏核雄性不育系的雄性不育起点温度、自繁雄性可育性、柱头外露率和穗伸出率、生长势和适应性的选择效应受环境影响。在某种环境下遗传材料的这些性状过高的表达并没有导致高的区分度,因为在这种情况下性状在株间表现较整齐一致,温敏核雄性不育基因(tms)在高温下雄性不育性也表现相似的结果,因此认为有必要在适当有利于区分遗传型的环境下进行选择。在相对较低的温度条件下选择低的CSP和高的自繁雄性可育性有较高的选择效率;在较高的湿度条件下选择柱头外露较有效,而高的温度下选择穗的抽出率效率高,在相对低的土壤肥力环境下改良不育系的生长活力和适应性效率高。

The auxin transporter OsAUX1 regulates tillering in rice(Oryza sativa)

Tillering is an important agronomic trait of rice(Oryza sativa)that affects the number of effective panicles,thereby affecting yields.The phytohormone auxin plays a key role in tillering.Here we identified the high tillering and semi-dwarf 1(htsd1)mutant with auxin-deficiency root characteristics,such as shortened lateral roots,reduced lateral root density,and enlarged root angles.htsd1 showed reduced sensitivity to auxin,but the external application of indole-3-acetic acid(IAA)inhibited its tillering.We identified the mutated gene in htsd1 as AUXIN1(OsAUX1,LOC_Os01g63770),which encodes an auxin influx transporter.The promoter sequence of OsAUX1 contains many SQUAMOSA PROMOTER BINDING PROTEIN-LIKE(SPL)binding sites,and we demonstrated that SPL7 binds to the OsAUX1 promoter.TEOSINTE BRANCHED1(OsTB1),a key gene that negatively regulates tillering,was significantly downregulated in htsd1.Tillering was enhanced in the OsTB1 knockout mutant,and the external application of IAA inhibited tiller elongation in this mutant.Overexpressing OsTB1 restored the multi-tiller phenotype of htsd1.These results suggest that SPL7 directly binds to the OsAUX1 promoter and regulates tillering in rice by altering OsTB1 expression to modulate auxin signaling.

亚热带地区水稻(Oryza sativa L.)气孔臭氧通量和产量的响应关系

基于开放式臭氧浓度升高O_3-FACE(Free-Air Concentration Elevation of O_3)实验平台,利用前期水稻O_3-FACE试验的基础数据,通过建立水稻产量与不同评价指标(累积气孔O_3吸收通量PODY和O_3浓度指标AOTX)的响应关系,比较了水稻产量损失与各评价指标的相关性差异,通过对暴露剂量、吸收通量相关参数取值与产量损失的观察和分析结果的比较,找出更为合理的农作物臭氧风险评估阈值。结果表明:随着通量阈值Y[0~11 nmol O_3·m^(-2)PLA·s^(-1)(PLA:projected leaf area,投影叶面积)]和暴露浓度阈值X(0~50 n L·L^(-1))的增加,回归分析R^2值逐渐增加,当Y为11 nmol O_3m^(-2)PLA·s^(-1)和X为50 n L·L^(-1)时,气孔臭氧吸收通量POD11和累积暴露剂量AOT50与水稻相对产量的相关性最大,当通量阈值Y为8~13 nmol O_3·m^(-2)PLA·s^(-1)和暴露阈值X为46~58 n L·L^(-1)时,可获得较高的R^2值取值范围,分别为0.70~0.75和0.70~0.745。参考文献发现,目前地表臭氧污染可能引起的水稻产量损失范围为5%~8%,对照圈中POD9~10和AOT40~45产量损失的预测值亦在这区间,但前者R^2值(0.73~0.74)明显高于后者R^2值(0.64~0.69),表明基于气孔臭氧通量的评价指标能更好地反映水稻产量的变化。通过进一步分析发现,当通量阈值Y为9 nmol O_3·m^(-2)PLA·s^(-1)时,能更准确地评估水稻产量损失,且其R^2值(0.73)高于通量指标POD6(0.57)。以上研究结果表明,通量指标POD9更适合评估亚热带地区O_3污染对水稻作物的影响。