多年生稻稻瘟病抗性评价

利用长雄野生稻(Oryzalongistaminata)地下茎无性繁殖特性培育多年生稻(Perennial Rice,PR)已经成功并开始示范推广.多年生稻表现出一定的稻瘟病抗性,但其所具有的稻瘟病抗性来源尚不清楚.本研究通过田间病情调查、接种鉴定以及抗性基因检测等3种方法,对育成的多年生稻23(PR23)、云大24(...     

A review of the biology and control of selected weed species in the genus Oxalis: O. stricta L., O. latifolia H.B.K. and O. pes-caprae L.

This review considers the distribution, weed problems, biology and control of Oxalis stricta, O. latifolia and O. pes-caprae. The rhizomatous O. stricta is a persistent seed-producing weed which invades horticultural crops in North America. Chemical control is generally most effective in situations where soil-applied residual herbicides can be used; in turfgrass however, foliage-applied herbicides provide suppression only. O. latifolia is widely distributed in a range of annual and perennial crops growing in temperate and tropical locations. This pernicious perennial weed reproduces exclusively by asexual structures, underground bulbs, stolons and tubers. The complexities of the perennating system have rendered ineffective a wide range of herbicide families as a means of restricting the spread of O. latifolia. Similarly, cultural methods of control have not been successful. O. pes-caprae also grows and perennates from bulbs. This weed is essentially a problem in cereal crops in Southern Australia and Mediterranean fruit orchards. Cultural and chemical control difficulties and inadequacies are similar to those in O. latifolia. Future research strategies involving weed physiology, herbicide action and cultural control including biological control are discussed in relation to obtaining improved control methods for the selected Oxalis species.     

Informative ISSR Markers Help Identify Genetically Distinct Accessions of Oryza rufipogon in Yield Improvement

Inter simple sequence repeat(ISSR) polymorphism was used to determine genetic diversity and phylogenetic relationships in 90 genotypes of wild and cultivated species of Oryza from different geographical regions of the world. In all the 17 primers used in ISSR-PCR, a total of 11 464 bands were amplified at 253 band positions/loci. The primer UBC-809 amplified the maximum bands(1 059) at 21 band positions. UBC-810 and UBC-835 amplified the minimum of 391 bands each at 7 and 14 band positions, respectively. The mean polymorphism information content ranged from 0.44 to 0.84 and resolving power ranged from 8.69 to 23.53. Un-weighted pair group method with arithmetic mean dendrogram and population structure based on the 17 primers separated all genotypes into 4 major clusters with a genetic similarity of 53%–100%. The first two clusters consisted of 30 O. rufipogon accessions each. In the third cluster, O. nivara and O. longistaminata grouped as one sub-cluster and all other O. nivara accessions and cultivars grouped as another sub-cluster. The fourth cluster had only five O. rufipogon accessions which can be a source of new genes. Four sub-populations were identified within O. rufipogon and two sub-populations within O. nivara at K = 7. A subset of six primers with high resolving power values were the most informative and grouped all genotypes almost similarly as the 17 primers did. Use of these six highly informative primers in ISSR-PCR is a cost effective and robust method for assessing genetic diversity in large germplasm collections of wild rice species.     

多年生稻育种进展及展望

多年生稻是指头季稻成熟收割后,通过免耕保留稻桩,等到下一个生长季,稻桩地下茎腋芽发出新苗,重新成为可以收割的稻。笔者所在团队以亚洲栽培稻（Oryza sativa）为母本,以来源于非洲的长雄野生稻（O. longistaminata）为父本,通过种间远缘杂交方式培育多年生稻。经过20多年的研究,发现了长雄野生稻地下茎遗传规律,发明了利用长雄野生稻地下茎无性繁殖特性培育多年生稻的方法,创制了一批具有多年生性的育种材料,育成了3个多年生稻品种,创新了以越冬和免耕为核心的多年生稻轻简化生产技术,实现了只需耕种1次即可连续收获4～5年的稻作生产方式。从理论发现、技术发明、品种培育、栽培技术创新到产业化,形成了自成体系、独树一帜的多年生稻研发模式,为农作物尤其是多年生粮食作物的遗传改良与应用提供了借鉴。     

多年生稻白叶枯病抗性评价

利用长雄野生稻地下茎无性繁殖特性培育多年生稻已经成功,并在生产上进行了示范推广。为明确多年生稻品种（系）对白叶枯病的抗性表现,通过田间病情调查、抗性水平鉴定和水稻白叶枯病抗性基因检测3种方法,对多年生稻品种（系）多年生稻23（简称PR23,下同）、云大24（PR24）、云大25（PR25）、云大101（PR101）、云大107（PR107）及其父本长雄野生稻、母本RD23和F₁（RD23/长雄野生稻）的白叶枯病抗性进行评价。结果表明,长雄野生稻高抗白叶枯病;尽管PR23、PR24、PR25、PR107携带白叶枯病抗性基因Xa1、Xa4、Xa23、xa25的等位基因,但在田间自然发病条件下均易感白叶枯病,说明这几个抗性基因对这4个多年生稻品种（系）不起抗病作用;而PR101在田间自然发病条件下表现为抗白叶枯病,并含有白叶枯病抗性等位基因xa25、Xa27,说明这2个基因可能是PR101抗白叶枯病的基因。本研究结果为明确多年生稻对白叶枯病菌的抗病反应,以及抗白叶枯病育种和多年生稻生产布局提供了一定依据。     

Assessment of allelopathic potential of barnyard grass (Echinochloa crus-galli) on rice (Oryza sativa L.) cultivars

Laboratory, greenhouse and field studies were conducted to assess the allelopathic potential of 44 rice cultivars (Oryza sativa L.) on barnyard grass (Echinochloa crus-galli P. Beauv. var. oryzicola Ohwi). Rice cultivars exhibited marked differences in the inhibition of barnyard grass growth and development. In the laboratory, Gin shun rice cultivar extracts exhibited the greatest activity on the weed seedling growth, reducing dry weight by 61%, while Kasarwala mundara cultivar extracts exhibited the greatest activity on seed germination, reducing germination by 23% and germination speed by 46%. In a greenhouse study of a residue mixture, the Philippine 2 cultivar showed the greatest inhibition percentage on seedling emergence (57%), total seedling length (74%) and dry weight (73%). In the field study, the Juma 10 cultivar demonstrated the most inhibitory effect by reducing barnyard grass tiller number (80%), leaf area (49%) and leaf (61%) and stem (74%) dry weight (68%). These results suggest that there are differences among the varieties for allelopathic inhibition of barnyard grass, and that the development of barnyard grass suppressive rice cultivars that have greater allelopathic potential may be possible.     

New genes for resistance to green leafhopper, Nephotettix virescens (distant) in rice, Oryza sativa L.

The inheritance of resistance to the green leafhopper, Nephotettix virescens (Distant) (Homoptera: Cicadellidae), in 12 cultivars of rice (Oryza sativa L.) was studied at Joydebpur, Bangladesh. The resistance of Kosatawee is governed by a single recessive gene. The remaining 11 varieties possess single dominant genes for resistance, which are different from the genes Glh 1, Glh 2, Glh 3 and Glh 5. The single dominant genes conveying resistance in TAPL 796, Ptb 18 and IR36 are allelic to each other but are non-allelic to the dominant resistance gene of Maddai Karuppan. The resistance genes in TAPL 796 and Maddai Karuppan were designated Glh 6 and Glh 7 respectively. The dominant resistance gene in Sulai is independent of Glh 6, but its allelic relationship to Glh 7 is not known. The allelic relationships of the dominant genes for resistance of Sulai, TAPL 628, TAPL 651, Leu-Wei-Theu, Bir-co-se-mao-17, Gu-win-gu-gi-goo, and Dikwee to Glh 6 and Glh 7 need to be investigated.     

不同普通野生稻居群的根表铁膜形成能力

为深入了解普通野生稻的根表铁膜形成能力及其与根系特征的关系,本研究对海南省不同地区的8个普通野生稻居群进行了水培铁胁迫试验。结果表明:普通野生稻的根表铁膜随居群而异。HLY、XLB、HQF等3个居群具有较强的根表铁膜形成能力,其根表铁膜相对数量分别为480.58、382.66、364.05 mg Fe/(cm·株)。根表铁膜数量与根生物量、主根表面积、侧根表面积、根系表面积和根系体积均呈正相关;而根表铁膜相对数量与根生物量、根系表面积、侧根表面积及其所占比率呈正相关;但是,根表铁膜含量仅与侧根表面积所占比率呈正相关,根表铁膜厚度与这些根系特征参数均无相关性。根表铁膜的4个指标与根孔隙度之间均无相关性。因此,侧根表面积及其所占比率是影响根表铁膜的重要因子,可作为筛选具有较多根表铁膜的普通野生稻居群的关键依据。     

Genetic Analysis of Early Generation Stability in Rice

The mechanism of early generation stability （EGS） in rice was studied via genetic analysis. Three types of crosses were made, namely between EGS varieties, EGS and conventional rice variety, and conventional rice varieties. The genetic analysis was based on the stable lines in F2 population. The stable lines may appear from some combinations of EGS rice crossing with each other and EGS rice crossing with conventional varieties at different frequencies, but stable lines didn＇t appear in conventional varieties crossing with conventional varieties. Genetic analysis results indicated that the EGS phenomena should just exist in special rice materials, and the frequency of stable lines was closely related to the EGS traits of parents. The EGS traits were neither qualitative nor quantitative traits, and they were controlled by neither dominant genes nor recessive genes. The EGS traits might be inherited by F1 single plant, and the traits of F3 and F4 were corresponded to those of F2 population, i.e. F3 and F4 lines derived from non-segregating F2 showed uniform agronomic traits, and those from segregating F2.did not. The agronomic traits of EGS lines were consistent with those of F1 single plant. On the other hand, when EGS lines occurred, the segregating lines in Mendelian manner were also observed in all F2 population of the same combination. It was suggested that the reason why the stable strains occurred might be a special factor to control （open/close） gene at the beginning of cell division in zygote, resulting in closing mitosis and opening somatic reduction. The somatic reduction of zygote resulted in recombination and homozygosity forming in F1 single plant, and some lines with uniform agronomic traits were observed in some lines of F2 population.     

Screening of allelochemicals on barnyardgrass (Echinochloa crus-galli) and identification of potentially allelopathic compounds from rice (Oryza sativa) variety hull extracts

Experiments were conducted to screen 23 known allelochemicals, including sinapic acid, and an equimolar mixture of the chemicals for potential allelopathy on barnyardgrass (Echinochloa crus-galli var. oryzicola), and to identify allelochemical(s) from hull extracts from three rice (Oryza sativa L.) cultivars. In a bioassay, the inhibitory effect was increased as the concentration of allelochemicals increased from 10⁻⁵ to 10⁻³ M. Ferulic, p-hydroxybenzoic, p-coumaric, and m-coumaric acids were the most active compounds and caused the greatest effect on seed germination, germination rate, and total seedling dry weight reduction. p-hydroxybenzoic acid (10⁻³ M; pH 4.1) showed the greatest inhibitory effect on the same parameters. HPLC analysis using three rice cultivars, Janganbyeo, Baekambyeo, and Labelle, showed that the concentration and composition of potentially allelopathic compounds depended upon the cultivar. Hull extracts from the allelopathic cultivar Janganbyeo contained higher levels of p-hydroxybenzoic acid than did those of the non-allelopathic cultivars Labelle and Baekambyeo. Nine compounds, including p-hydroxybenzoic acid (4.29 mg/g) in Janganbyeo, seven compounds including m-coumaric (0.43 mg/g) in Labelle, and five compounds including p-hydroxybenzoic acid (0.36 mg/g) in Baekambyeo, were detected. Preliminary identification by HPLC analysis resulted in peaks with retention times near those of standards, including p-hydroxybenzoic acid that was confirmed with EI/MS. It is suggested that these compounds may be, at least, a key factor in rice allelopathy on barnyardgrass, and the information presented may contribute to the development of naturally occurring herbicides.     

利用QTL-Seq定位粳稻整精米率QTL

[目的]稻米整精米率是加工品质的重要评价指标之一,其QTL定位将为提升稻米品质提供理论依据.[方法]通过两个粒型相近、整精米率差异极大的粳稻材料构建的F2分离群体为材料,利用QTL-Seq方法对分离群体中的高整精米率单株和低整精米率单株进行混池重测序以定位粳稻整精米率QTL位点.[结果]经过QTL-Seq分析发现在第8...     

Growth and colonization of a range of white clover cultivars strip-seeded into an upland perennial ryegrass sward

Seven cultivars of white clover (Trifolium repens L.) (Kent, S184, Huia, Menna, Donna, Alice and Nesta) and a commercial mixture, ‘Ensign’, were strip-seeded into an upland perennial rye-grass (Lolium perenne L.) sward in late June 1986. Swards were first grazed by sheep, either on 5/6 August (early) or on 19/20 August (late) and then every 14–21 days (frequently) or 28–42 days (infrequently) during 1986, followed by a common grazing regime in 1987. During April to mid-June 1988 the swards received either a moderate amount of nitrogen or none and were cut frequently or once only in mid-June. Growth of individual seedlings was assessed before and after grazing during 1986 and stolon accumulation and distribution and sward colonization were assessed during 1987 and 1988. All cultivars emerged rapidly and satisfactorily and there were no consistent significant differences in the overall dry matter accumulation per seedling during establishment. During the first autumn the proportion of the aboveground biomass removed during grazing was smallest in Kent (c. 20%) and largest in Nesta (c. 40%). Kent and S184 produced most leaves and stolons and the greatest length of stolons per seedling and per individual stolon, and Nesta and Alice the fewest leaves and stolons and shortest stolons. Seedlings grazed early had heavier and longer stolons than those grazed late; those grazed frequently had more leaves, stolons and growing points than those grazed infrequently, especially following early grazing. During 1987 Kent and S184 had consistently the largest number of stolon growing points, and weight and length of stolons per unit area; these two cultivars and Nesta also colonized the sward more rapidly than the other cultivars. All cultivars contributed substantially and similarly to herbage production in late September. There were no residual effects of the 1986 treatments after the summer of 1987. During 1988 additions of nitrogen fertilizer at 100 kg N ha^-1 or allowing the herbage to remain undefoliated between mid-April and mid-June both independently halved the number of stolon growing points per unit area; together they reduced it by 80%. Nitrogen also, on average, halved stolon weights but less so in Nesta, Alice and Huia and more so in all other cultivars. Infrequent defoliation greatly decreased stolon weights in Kent and S184 but had no significant effects on the other cultivars. Sward colonization was almost complete by June and entirely so by October for all cultivars in all treatments. Implications of the results for the after-management of strip-seeded white clover are discussed.     

西瓜品种‘黑皮’对瓜蚜的抗性遗传分析

采用单株蚜量比值法室内鉴定与RAPD、SCAR标记相结合的方法,系统开展了西瓜品种‘黑皮’对瓜蚜的抗性遗传分析。结果表明,以‘黑皮’和‘花绿’为亲本的杂交F₁代对瓜蚜表现为抗性,自交F₂代植株表型出现抗感性分离,抗蚜与感蚜植株分离比经χ²测验符合3∶1分离规律,并用筛选获得的RAPD标记WO4₆₀₀和SCAR标记WO4-S₅₃₀验证了4个抗蚜品种、4个感蚜品种和10个F₂抗蚜单株、10个F₂感蚜植株。结果以‘黑皮’为亲本的西瓜抗蚜性由单显性核基因控制且能稳定遗传,‘黑皮’‘绿美人’‘黑美人’和‘惠兰’品种对瓜蚜具有良好抗性,‘花绿’‘凤光’‘蕙宝’和‘甜美人’品种则易感蚜虫。     

Prediction criteria of promising F3 populations in durum wheat: A comparative study

Effective selection of parental material and promising segregating populations is an essential requirement for breeding success. There are many contradictive reports about the best parent selection criterion for the development of promising crosses. For the clarification of this problem field experiments were conducted for four consecutive years to compare the effectiveness of six criteria for the prediction of the most promising F₃ populations in durum wheat (Triticum durum L.): the mid-parent value, the F₁, the F₂, the (F₁ + F₂)/2, and the genetic distance among the parents as it is calculated using the SSR and RAPD molecular markers. During the first growing season (2003–2004) nine commercial cultivars of durum wheat and four landraces were crossed. The following growing season (2004–2005), 17 crosses (F₁ generation) were evaluated under low plant density (1.15 plants m⁻²) in a replicated (R-21) honeycomb design. During the third growing season (2005–2006), the four highest yielding crosses, one cross with an intermediate yield, and the three crosses with the lowest yield (F₂ generation) were evaluated under low plant density in a R-9 honeycomb design. Finally, in the fourth growing season (2006–2007) progeny of the aforementioned eight crosses (F₃ generation) and the ten parents were evaluated in a randomized complete block design in two locations. Furthermore, the genetic distance among the parents was determined using the SSR and RAPD molecular markers. It was observed that the three F₃ populations with the lowest yielding ability were the ones with the lowest mid-parental value. In addition, one of the two top F₃ populations was second in the rank according to the mid-parental value. Furthermore, the two top F₃ populations were also the highest yielding in the F₁ and F₂ generations. On the contrary, none of these crosses were predicted by the genetic distance as it was calculated using the SSR and RAPD molecular markers. It was concluded that parental pairs with high mid-parental value and high combined yield (F₁ + F₂)/2 obtained after evaluation of their F₁ and F₂ at low plant density was the most effective way to predict promising F₃ populations.     

Resistance of wild rices, Oryza spp., to the brown planthopper, Nilaparvata lugens (Stål) (Homoptera: Delphacidae)

Of the 128 wild rices screened, 83 accessions were resistant to the brown planthopper Nilaparvata lugens (Stål). Resistant accessions were non-preferred and significantly more individuals settled on susceptible TN1 plants than on resistant ones. The quantity of food ingested and assimilated by N. lugens on resistant accessions was less than on susceptible TN1. N. lugens caged on resistant accessions had slow nymphal development, reduced longevity and low fecundity. Two wild rice species, Oryza officinalis and O. punctata, reduced the percentage hatchability of N. lugens eggs. A significant reduction in population growth was observed on resistant accessions compared with susceptible TN1.     

Plant density and self-thinning affect yield and quality of fibre hemp (Cannabis sativa L.)

To ascertain the reasons for the high plant mortality in fibre-hemp (Cannabis sativa L.) crops in the Netherlands changes in biomass yield, plant mortality and plant morphology were investigated in a hemp cultivar grown at initial densities of 10, 30, 90 and 270 plants m⁻². At 90 plants m⁻² this cultivar was compared with a high bast-fibre cultivar and a late-flowering cultivar. Rate of canopy establishment and early growth rate increased with increasing plant density. At 90 and 270 plants m⁻², plants died as a result of self-thinning. Self-thinning was associated with a reduced crop growth rate. In self-thinning stands, dry biomass (B, g m⁻²) was related to density of surviving plants (D, m⁻²) as log B = 3.81 − 0.304 log D. At the same crop growth rate, the rate at which plants died from self-thinning was higher in hemp than in other herbaceous dicots. The proportion of stem in the total dry matter increased with increasing plant density. Stem yield was maximum at 90 plants m⁻². Stem quality improved with increasing density as the bark content in the stem increased, but self-thinning reduced the bark content in the stem. Optimum plant density was close to that resulting after self-thinning. In hemp the relationship between yield and optimum plant density is approximated by the equation of its self-thinning line. The late-flowering cultivar yielded more than the other two cultivars because it grew faster during the latter part of the growing season.     

水稻穗顶部小穗退化突变体paa1-2的表型与等位基因序列分析

水稻穗顶部小穗退化在水稻生产中普遍存在,严重影响了水稻产量。本文对水稻穗顶部小穗退化突变体paa1-2进行表型观察,同时测序分析突变体paa1-2中已报道的TUTOU1和PAA1基因序列。结果表明,突变体paa1-2穗顶部退化表型是在幼穗发育6期后产生的。突变体paa1-2和野生型的TUTOU1基因序列一致,然而其PAA1基因存在突变,在第1512~1515 bp处存在4个碱基缺失,导致基因移码突变并使得蛋白翻译提前终止,PAA1-2可能是已报道PAA1基因的新等位突变基因。     

Yield Traits and Associated Marker Segregation in Elite Introgression Lines Derived from O. sativa × O. nivara

Introgression lines (ILs) derived from interspecific crosses are a source of new genetic variability. A total of 55 ILs derived from two crosses Swarna × O. nivara IRGC81848 (population A) and Swarna × O. nivara IRGC81832 (population B) were characterized for yield and yield-related traits/QTLs. Segregation of 103 simple sequence repeat (SSR) markers associated with yield-related QTLs was studied. Population A showed an average of 12.6% homozygous O. nivara alleles and population B showed 10.6%. Interestingly, three SSR markers, RM223, RM128 and RM517, showed conspicuous pattern of segregation. The distribution of parental alleles at three loci RM223, RM128 and RM517 linked to yield-related traits was unique. These markers flanked to several yield-related QTLs. RM223, flanking to qyld8.3, was heterozygous in almost all the 55 ILs except in IL10-3S and IL131S. RM128 on chromosome 1 and RM517 on chromosome 3 were mutually exclusive in 46 out of 55 ILs. These 46 ILs showed either of the marker allele RM128 or RM517 from O. nivara but not both. IL166S had both RM128 and RM517 from O. nivara and the other ILs showed homozygous Swarna allele at RM517 except IL65S. Population structure assigned the 55 ILs to three sub-populations based on their genomic diversity. IL65S, IL166S, IL248S, IL7K and IL250K showed high yields in multi-location trials, and IL248S was released for cultivation as DRRDhan 40.     

Levels of resistance of rice cultivars and the weed Leersia hexandra L. to Nephotettix malayanus Ishihara et Kawase and N. virescens (Distant)

Studies on the mechanisms of resistance of some rice cultivars and the weed, Leersia hexandra, to Nephotettix malayanus indicated low survival and popu;ation growth of the insect on resistant cultivars. Tests on feeding behaviour indicated that more feeding punctures were made on resistant than on susceptible cultivars. The amount of honeydew excreted was not related to the levels of resistance. Honeydew excreted on resistant cultivars was acidic (pH 5·08–6·92) and on susceptible L. hexandra, basic (pH 7·56). On the basis of the quality of honeydew excreted, N. malayanus was considered to be predominantly a xylem feeder. A test on the serial transmission of the rice tungro virus (RTV) showed that N. malayanus transmitted the virus for only one day after feeding acquisition. N. virescens was a more efficient vector of RTV than N. malayanus. N. malayanus prefers to feed on L. hexandra rather than on the rice cultivars tested.     

Breeding for perennial growth and fertility in an Oryza sativa/O. longistaminata population

The development of perennial cultivars (CVs) of upland rice would give farmers a new tool to reduce soil erosion from hilly fields, thereby mitigating a problem of regional concern in Southeast Asia. Oryza longistaminata is an undomesticated, perennial, rhizomatous relative of domesticated Asian rice (Oryza sativa). Using five sets of 4 × 2 factorial mating designs, we crossed rhizomatous interspecific genotypes (IGs) from an intermated O. sativa/O. longistaminata population with male-fertile IG selections from the intermated population, and with O. sativa CVs. Parents and progeny were planted in an upland field at IRRI using a randomized complete block design and evaluated for rhizome expression, survival after 1 year, vigor of the survivors, and yield. For the IG parents, rhizome expression was variable and penetrance of most genotypes was incomplete, but genotypes that demonstrated the potential for moderate rhizome expression had high penetrance (89% average). The CV parents yielded 11.0 g/plant on average but none produced rhizomes or survived 1 year. The IG parents averaged yields of 3.1 g/plant, 57% rhizomatous and 36% survival. The IG/IG progeny averaged yields of 4.2 g/plant, 32% rhizomatous and 37% survival. The IG/CV progeny averaged yields of 6.0 g/plant, 18% rhizomatous and 16% survival. Nine IG/IG progeny and six IG/CV progeny were rhizomatous, perennial, and yielded at least 5 g/plant, and five of these yielded more than 10 g/plant. For the IG parents and IG/IG progeny, rhizome presence and expression were positively associated with survival and vigor of the survivors. General combining ability effects were significant for percent survival and yield but not percent rhizomatous. Specific combining ability effects were significant for percent rhizomatous, percent survival and yield. By selecting female parents for long rhizomes and male parents for fertility, considerable gains in rhizome expression, survival and yield were made. The development of perennial upland rice CVs should be feasible via introgression of genes from O. longistaminata.