Inheritance of tolerance to rice tungro bacilliform virus (RTBV) in rice (Oryza sativa L.)

Summary From a large number of rice varieties tested, no variety was identified as resistant to tungro bacilliform virus (RTBV). Only in Utri Merah was the RTBV multiplication restrictive, whereas other varieties such as Kataribhog and Pankhari 203 were identified as tolerant. These varieties were crossed with a susceptible variety. TN1, to study the inheritance of restrictive multiplication and tolerance to RTBV. After 3 weeks of inoculation with RTBV, F₁; F₂, and F₃ progenies were assessed by enzyme-linked immunosorbent assay (ELISA). The RTBV concentration in all F₁ populations was intermediate between parents. The frequency distribution of F₂ seedlings with various levels of RTBV concentration indicated that the RTBV tolerance is controlled by multiple genes. The RTBV concentrations in F₁ and F₂ progenies from the Utri Merah x TN1 cross revealed that restrictive multiplication of RTBV in Utri Merah is a polygenic character. The continuous variation observed in F₂ populations from crosses between tolerant varieties and Utri merah indicated no allelic relationships between tolerant and restrictive multiplication traits.Part of PhD thesis submitted by senior author to University of Kebangsaan Malaysia, Bangi     

野生稻和栽培稻的随机多态DNA(RAPD)分析

应用 RAPD方法对药用野生稻、普通野生稻、粳稻和籼稻进行基因组多态性分析。 1 2个随机引物共扩增出 1 3 2条 RAPD带 ,片段大小在 3 0 0～ 3 5 0 0 bp之间 ,其中有 1 0 6条表现出多态性 ,占总扩增片段的86.4%。根据遗传距离分析 ,用 UPGMA法构建了聚类树状图 ,结果表明 ,普通野生稻的遗传特性比药用野生稻更接近于栽培稻。     

Relationship between trace metal concentration and antioxidative activity of ancient rice bran (red and black rice) and a present-day rice bran (Koshihikari).

Antioxidative activity and polyphenol and trace metal content in bran from ancient rice varieties (red and black rice) and a present-day variety of rice (Koshihikari) were measured. The antioxidative properties of rice bran in terms of scavenging and quenching activity for reactive oxygen species (ROS), including superoxide anion radicals (*O(2)(-)), hydroxyl radicals (*OH), singlet oxygen ((1)O(2)) and lipid peroxide (LOO*), correlated well with polyphenol and trace metal content. In particular, the possibly that Mn content greatly contributes to the antioxidative properties of rice bran was revealed.     

Movement of Mexican rice borer (Lepidoptera: Crambidae) through the Texas rice belt

Pheromone-baited traps were used to monitor the movement of the Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), through the Texas rice belt from 2000 to 2005. Based on location of discovery in each county and year, the average rate of spread from 1980 to 2005 was 23 km/yr. From 2000 to 2005, the leading edge of the infestation has moved 16.5 km/yr toward Louisiana. The 1.8-fold increase (99% confidence interval) of the area occupied from 2000 to 2005 in the Texas rice belt indicates an expansion of the distribution of E. loftini. If movement continues to occur at similar rates, E. loftini will reach Louisiana by 2008.     

海南中南部地区旱稻(山兰稻)种质资源及保育模式

山兰稻是一类适应性很强的旱稻品种,对于开发节水性高产稻种具有重要意义。该研究调查了海南中南部地区山兰稻种质资源的组成,并选种5个山兰稻品种开展其农艺性状和生产性状的研究,以期了解山兰稻种质资源在该地区的分布及生产现状,并进一步为其保护模式提供理论基础。结果表明:调查共获得38份山兰稻种质资源,含25个品种,主要分布在保亭、琼中和五指山三个市县,在现有的品种中约有45.0%在种植利用。因此,山兰稻品种资源面临濒危,亟需保护;这25个品种可分为籼稻和粳稻2个类型,共聚成6个类群,不同区域间的种质资源具有亲缘性,其中3个独立聚集的品种有明显区域性分布的特征;5个品种容易种植,生产性状较一致,其全生育期约为138 d,与历史栽培记录时间一致,遗传特性稳定,单位产量为2.0~2.8t·hm-2,平均产量为2.4 t·hm-2。综上说明保护山兰稻品种的成本和技术难度不高,但其育种和栽培技术还需要进一步研究,种质资源的开发模式应结合生态保护、品种保育、社会需求等多角度进行综合考虑。     

Genetically modified (GM) rice versus non-GM rice: Pesticide use and yield

正Dear Editor,The economic benefits of genetically modified (GM) crops have been well-documented in the literature (Huang et al.,2002; Huang et al., 2005; Qiao, 2015; Qiao et al., 2016).Previous studies showed that the global economic gain that the GM crops had generated at the farm level approximated100 billion USD in 1996–2011 (Brookes and Barfoot, 2013).     

Activity profile of defence-related enzymes in rice genotypes (Oryza sativa L.) against rice blast (Magnaporthe oryzae)

The control and infected leaf samples of blast resistant and susceptible rice genotypes were evaluated for activities of defence-related enzymes viz., total phenol content, chitinase, phenylalanine ammonia lyase (PAL), β-glycosidase, antioxidative enzymes, superoxide dismutase, peroxidase and ascorbate peroxidase. The level of total phenol content and the activity profile of chitinase, PAL and β-glycosidase significantly increased in both blast-resistant and susceptible rice genotypes with comparatively higher level induction Tetep, NLR-20104 and Swarnadhan the blast-resistant genotypes. The antioxidative enzymes were comparatively higher in the leaf samples of blast-resistant genotypes recording highest increase in NLR-20104 and KJT-5. The constitutive levels of total phenols and activity of defence-related and antioxidative enzymes in the control leaf samples differed among the genotypes and were even higher in the two blast susceptible genotypes (EK-70 and Chimansal). However, the level of induction as evident from the activity profile differences between control and infected leaf samples suggests higher level of induction was more which is indicative of the induced defence response. The genotype recording maximum induction of defence-related and antioxidative enzymes activity could be useful criteria in screening for blast resistant genotype in rice.     

Antisense expression of a rice sucrose transporter OsSUT1 in rice (Oryza sativa L.).

We analyzed the function of a rice sucrose transporter, OsSUT1, by using antisense rice. There was no difference between antisense and wild-type plants in carbohydrate content and photosynthetic ability of the flag leaves in the vegetative growth stage, suggesting that OsSUT1 may not play an important role in carbon metabolism, at least in these materials.     

Comparative RFLP mapping of an allotetraploid wild rice species (Oryza latifolia) and cultivated rice (O. sativa)

The purpose of this study was to construct a comparative RFLP map of an allotetraploid wild rice species, Oryza latifolia, and to study the relationship between the CCDD genome of O. latifolia and the AA genome of O. sativa. A set of RFLP markers, which had been previously mapped to the AA genome of cultivated rice, were used to construct the comparative map. Fifty-eight F₂ progeny, which were derived from a single F₁ plant, were used for segregation analysis. The comparative RFLP map contains 149 DNA markers, including 145 genomic DNA markers from cultivated rice, 3 cDNA markers from oat, and one known gene (waxy, from maize). Segregation patterns reflected the allotetraploid ancestry of O. latifolia, and the CC and DD genomes were readily distinguished by most probes tested. There is a high degree of conservation between the CCDD genome of O. latifolia and the AA genome of O. sativa based on our data, but some inversions and translocations were noted.     

Structure of the rice glutaredoxin (thioltransferase) gene

We have isolated the gene encoding a glutaredoxin in rice (Oryza sativa L.) and determined the nucleotide (nt) sequence of about a 4.2 kb long. The cloned gene (gRASC8) was found to contain four exons interrupted by three introns. The first exon begins the ATG translation start codon and the four exons code for a protein composed of 112 amino acids. The tetrapeptide -Cys-Pro-Phe-Cys- [-Cys-Pro-Phe(Tyr)-Cys-] which constitutes an active site of Escherichia coli and mammalian glutaredoxins, was conserved. The nt sequence contained consensus TATA and CAAT boxes, and two polyadenylation signals. Southern blot analysis of rice genomic DNA suggests that there are two copies of the glutaredoxin genes in rice.     

杂草稻落粒粳的抗逆境特性研究

杂草稻落粒粳（Oryza sativa）发生在我国辽宁丹东.落粒粳植株明显高于当地大多数栽培品种,颖果呈中长型,成熟后容易掉粒;果壳稻草色或黄间黑灰色,小穗无芒或有芒,芒长4～12 cm;颖果千粒重235 g,种皮桔红色.落粒粳种子在13～38 ℃条件下的发芽率均大于88%,水层2.5～10 cm处理,落粒粳植株干重减少50%～69%.在幼苗期,落粒粳对无芒稗的各项影响因子均明显大于化感潜力品种I-kung-pao,表明落粒粳无化感作用.落粒粳可以忍耐0.5%的盐碱.     

Protein profile of rice (Oryza sativa) seeds

Seeds are the most important plant storage organ and play a central role in the life cycle of plants. Since little is known about the protein composition of rice (Oryza sativa) seeds, in this work we used proteomic methods to obtain a reference map of rice seed proteins and identify important molecules. Overall, 480 reproducible protein spots were detected by two-dimensional electrophoresis on pH 4–7 gels and 302 proteins were identified by MALDI-TOF MS and database searches. Together, these proteins represented 252 gene products and were classified into 12 functional categories, most of which were involved in metabolic pathways. Database searches combined with hydropathy plots and gene ontology analysis showed that most rice seed proteins were hydrophilic and were related to binding, catalytic, cellular or metabolic processes. These results expand our knowledge of the rice proteome and improve our understanding of the cellular biology of rice seeds.     

Molecular evolution of the Pi-ta gene resistant to rice blast in wild rice (Oryza rufipogon)

Rice blast disease resistance to the fungal pathogen Magnaporthe grisea is triggered by a physical interaction between the protein products of the host R (resistance) gene, Pi-ta, and the pathogen Avr (avirulence) gene, AVR-pita. The genotype variation and resistant/susceptible phenotype at the Pi-ta locus of wild rice (Oryza rufipogon), the ancestor of cultivated rice (O. sativa), was surveyed in 36 locations worldwide to study the molecular evolution and functional adaptation of the Pi-ta gene. The low nucleotide polymorphism of the Pi-ta gene of O. rufipogon was similar to that of O. sativa, but greatly differed from what has been reported for other O. rufipogon genes. The haplotypes can be subdivided into two divergent haplogroups named H1 and H2. H1 is derived from H2, with nearly no variation and at a low frequency. H2 is common and is the ancestral form. The leucine-rich repeat (LRR) domain has a high pi(non)/pi(syn) ratio, and the low polymorphism of the Pi-ta gene might have primarily been caused by recurrent selective sweep and constraint by other putative physiological functions. Meanwhile, we provide data to show that the amino acid Ala-918 of H1 in the LRR domain has a close relationship with the resistant phenotype. H1 might have recently arisen during rice domestication and may be associated with the scenario of a blast pathogen-host shift from Italian millet to rice.     

粳稻穗角与稻米品质的相关性及稻米品质遗传分析

测定了粳稻直立穗品种丙8979与弯曲穗品种C堡杂交组合的P1、P2及其重组自交系349个株系的穗角和10个稻米品质性状, 分析了穗角与稻米品质性状之间的相关性, 并运用主基因+多基因混合遗传模型, 对稻米品质10个性状进行了遗传分析。结果表明,穗角与糙米率、整精米率、垩白粒率、垩白度、糊化温度、胶稠度和直链淀粉含量均无显著相关; 与精米率呈显著正相关(r=0.124*); 与粒长和长宽比均呈极显著正相关(相关系数分别为0.470**和0.241**)。糙米率、精米率和直链淀粉含量均受2对主基因+多基因控制, 2对主基因具有累加作用和加性×加性的上位性作用; 整精米率、粒长、长宽比和胶稠度受2对加性-上位性主基因+多基因控制;垩白粒率、垩白度和糊化温度均受3对加性-上位性主基因+多基因控制。糙米率、精米率、整精米率、垩白粒率、垩白度和糊化温度6个品质性状以主基因遗传为主,粒长、长宽比、胶稠度和直链淀粉含量4个性状以多基因遗传为主。     

水稻穗期大螟危害习性初步观察

于2009年常规中稻的蜡熟前期、中期和黄熟期、枯熟期,分别取样观察大螟Sesamia inferens Walker的钻蛀危害习性。结果发现:单株螟害的蛀孔数一般为2～3个,多的达5个,而且表现白穗株>枯穗株>虫伤株。螟害株的蛀孔部位随着稻穗趋向成熟和大螟虫龄的增大,逐渐由稻株的中上部节间向中下部节间转移。其中,白穗株与枯穗株有70%以上的蛀孔分别分布于稻株由上向下的第1～3与3～5节间上;在水稻的这4个生长时期中,虫伤株有90%左右的蛀孔分别分布于稻株由上向下的第1～3、1～4和2～5、3～5节间上,全株虫量有85%以上依次分布于第1～3、2～4和3～5、3～5节间上,单株虫量4个时期最高分别为18、6、3、2头,同一节间内的4个时期最高虫量分别为12、5、1、1头;单个节间有多头螟虫时,80%以上为1～3龄幼虫。随着稻穗趋向成熟,白穗株和枯穗株上的虫量均逐渐下降,而虫伤株上的虫量则相对稳定或有上升的趋势;至枯熟期后,虫伤株的有虫株率和有虫孔率均稳定在30%以上。     

Expression of snowdrop lectin (GNA) in transgenic rice plants confers resistance to rice brown planthopper

Snowdrop lectin ( Galanthus nivalis agglutinin; GNA) has been shown previously to be toxic towards rice brown planthopper ( Nilaparvata lugens ; BPH) when administered in artificial diet. BPH feeds by phloem abstraction, and causes ‘hopper burn’, as well as being an important virus vector. To evaluate the potential of the gna gene to confer resistance towards BPH, transgenic rice ( Oryza sativa L.) plants were produced, containing the gna gene in constructs where its expression was driven by a phloem-specific promoter (from the rice sucrose synthase RSs1 gene) and by a constitutive promoter (from the maize ubiquitin ubi1 gene). PCR and Southern analyses on DNA from these plants confirmed their transgenic status, and that the transgenes were transmitted to progeny after self-fertilization. Western blot analyses revealed expression of GNA at levels of up to 2.0% of total protein in some of the transgenic plants. GNA expression driven by the RSs1 promoter was tissue-specific, as shown by immunohistochemical localization of the protein in the non-lignified vascular tissue of transgenic plants. Insect bioassays and feeding studies showed that GNA expressed in the transgenic rice plants decreased survival and overall fecundity (production of offspring) of the insects, retarded insect development, and had a deterrent effect on BPH feeding. gna is the first transgene to exhibit insecticidal activity towards sap-sucking insects in an important cereal crop plant.     

Resistance of transgenic rice events (rbcS:cry1Ac) against three lepidopteran rice pests

The transgenic rice expressing cry1Ac gene, which is linked to the rice rbcS promoter and its transit peptide sequence (tp), was highly resistant against all instars of Cnaphalocrocis medinalis (Guenetée) (Lepidoptera: Crambidae). In this study, we evaluated the larval mortality, behavior change, and field occurrence of three main rice pests, C. medinalis, Naranga aenescens (Moore) (Lepidoptera: Noctuidae), and Parnara guttata (Bremer & Grey) (Lepidoptera: Hesperiidae) in T4 generations of three Bt rice events (rbcS3:cry1Ac; 608102, 608104 and 608107) and non-Bt rice. All of the three Bt rice events were resistant to C. medinalis which showed significantly higher mortality for all instars compared to non-Bt rice. The resistance of Bt rice events against the larvae decreased gradually as the larvae developed. However, the survived larvae which ingested Bt rice events died eventually without further development. The resistance of three Bt rice events was investigated in the pot test, which was conducted with 3rd instars of C. medinalis, N. aenescens, and P. guttata, showed mortalities of over 70%. In behavioral assay, C. medinalis fed on the Bt rice events showed feeding avoidance and less leaf rolling behavior compared to that of the larvae fed on non-Bt rice. A 2-yr field survey conducted with larvae of C. medinalis and P. guttata also showed that the three Bt rice events significantly had lower damaged on leaves compared to that of non-Bt rice. Overall, the three Bt rice events were highly resistant to the larvae of lepidopteran target rice pests.     

The polyembryo gene (OsPE) in rice

T-DNA insertional mutagenesis is one of the most important approaches for gene discovery and cloning. A fertile polyembryo mutant generated by T-DNA/Ds insertion in Oryza sativa, cv. Basmati 370 showed twin or triple seedlings at a frequency of 15–20%. T-DNA insertion was confirmed by 950 bp hpt gene amplification in the promoter region of the candidate gene. The annotated protein corresponding to the OsPE candidate gene has been reported as a hypothetical protein in O. sativa. OsPE gene lacked functional homologs in other species. No OsPE paralog was found in rice. No conserved domains were found in the protein coded by OsPE. RT-PCR showed the expression of OsPE gene in Basmati 370 shoots. Full-length OsPE gene was cloned in Basmati 370. The combined use of Southern blot, genome walking, TAIL-PCR, RT-PCR techniques, and bioinformatics led to the identification of a candidate gene controlling the multiple embryos in rice. There is gain of function, i.e., multiple embryos in the seeds in the knockout mutant OsPE whereas its wild-type allele strictly controls single embryo per seed. The seeds with multiple embryos are distributed at random in the rice mutant panicle. The origin of multiple embryos, whether apomictic, zygotic or both is under investigation.     

Characteristics of resistance in rice to rice hoja blanca virus (RHBV) and its vector, Tagosodes orizicolus (Muir)

This paper characterises resistance to rice hoja blanca virus (RHBV) which is transmitted by the planthopper Tagosodes orizicolus (Muir). Resistance is expressed as decreased proportion of plants infected compared to susceptible lines, although severity of symptom expression is similar in both types. This resistance is not due to differences in vector feeding behaviour. Vectors reared eight generations on resistant plants showed no increased ability to transmit to resistant lines or decreased ability to transmit to susceptible ones. Longevity of vectors was similar when reared either on virus-resistant or susceptible plants. Incubation period of the virus in resistant plants are significantly longer than in susceptible plants. Resistance increased with plant age in resistant and susceptible cultivars. Increased virus dosage, as determined by increased number of viru-liferous vectors per inoculated plant, caused an increase in transmission to both resistant and susceptible cultivars. However, the ranking of resistant and susceptible remained the same across the experimental range of dosage and plant age. It is concluded that the resistance studied is to virus infection and there is little risk of “breakdown” occurring as a result of genetic or behavioural changes in the vector population. This will permit the use of economic thresholds to planthopper feeding damage with little risk of RHBV epidemic outbreak.