Genetic analyses of Oryza species by molecular markers for chloroplast genomes

Summary Relationships in a wide range of Oryza species (13 species) were analyzed using the large subunits (LS) of Fraction I protein (Rubisco) and the Bam HI restriction patterns of chloroplast DNA (ctDNA) as molecular markers. Four types of LS were detected by isoelectrofocusing with and without S-carboxymethylation. The close relation between AA and CCDD genome species was suggested by analyses of LS and ctDNA. Intraspecific variation in O. latifolia was detected at the levels of both LS and ctDNA. The LS of the BB, BBCC, and CC genomes and FF (O. brachyantha) were not distinguishable, although the native Rubisco of the latter was slightly different from those of the first three. It was also shown that O. australiensis, the only EE genome species, might have evolved differently than the other Oryza species.     

Competition between laboratory populations of green leafhoppers,Nephotettix spp. (Homoptera: Cicadellidae)

Intra- and interspecific competition between laboratory populations of four green leafhoppers, Nephotettix spp. was studied in the laboratory under three different temperature regimes of 24°C, 27°C and 30°C. For the single-species population of the three tropical species, the equilibrium density increased as the temperature increased. On the other hand, for the temperature species N. cincticeps, the highest equilibrium density was at the intermediate temperature and the lowest at high temperature. Interspecific interactions between two tropical (N. virescens vs. N. nigropictus), a tropical and a temperature (N. virescens vs. N. cincticeps) and a rice-feeding and a grass-inhabiting (N. virescens vs. N. malayanus) Nephotettix species were also studied in the laboratory at the three temperature regimes. Temperature differentially affected the outcome of competition between two Nephotettix species. Between N. virescens and N. nigropictus, the latter was more successful over the former at low and intermediate temperatures, while the former was more successful at high temperature. Between N. virescens and N. cincticeps, the temperate species inhibited the growth of the tropical species at low temperature while the tropical species inhibited the growth of the temperate species at high temperature. At intermediate temperature, the population of N. virescens persisted at a slightly higher density over the population of N. cincticeps. Between the rice-feeding N. virescens and the grass-inhabiting N. malayanus, regardless of temperature the population density of the latter was greatly reduced and later became extinct while the population of the former continued its growth. These consequences of competition between two Nephotettix species conformed fairly well to those predicted by theLotka-Volterra model using demographic parameters specified for each species.     

Genetic structure of Glycine canescens,a perennial relative of soybean

Summary Allozyme variation as detected by starch gel electrophoresis was used to assess the extent and spatial organization of genetic variation across the entire range of Glycine canescens sensu lato. Eleven enzyme systems were assayed in 116 accessions of this taxon and 102 alleles were detected at a total of 31 loci. Eighty-one percent of loci were polymorphic. Most of this variation occurred between and very little within accessions. Three major groupings were detected. These groupings (groups 1, 2, and 3) also differed with respect to mean seed size and their geographic distribution. A further ten accessions stood out from these distinct groups. These accessions were most closely related to group 3 but were variable among themselves. In general, they were collected from highly dissected terrain, often in the remote interior of the continent. A final group of 18 problematic accessions (group X), originally tentatively identified as G. canescens on morphological grounds, was shown to be isozymically distinct from this species and was reclassified as one form of the polytypic species G. clandestina.     

Molecular cloning and restriction enzyme analysis of a long repetitive DNA sequence in rice

Rice long repetitive DNA (9–20 kbp) reassociating at Cot 50 M.s was cloned in pBR325. Out of several recombinants (Cam^r Amp^r Tet^s), only a few were selected randomly for further characterization. The insert size in all these clones was 3–4 kbp. Restriction enzyme analysis showed the absence ofEcoRI andBclI sites, presence of a singlePstI andPvuII site and multiple sites forAluI in 3 clones namely pRLl, pRL7 and pRL10. TheBamHI-PstI fragment of about 0.4 kbp in the pRL7 insert DNA (pRL7-0.4 kbp) was subcloned in M13mpl8 and partially sequenced using Sanger’s dideoxynucleotide chain termination method. Dot matrix comparison of this sequence with rice rDNA sequences revealed low homology with the 25 S rDNA sequence of rice, however, hybridisation did not indicate any homology.     

Development of microsatellite markers and characterization of simple sequence length polymorphism (SSLP) in rice (Oryza sativa L.)

Microsatellite markers containing simple sequence repeats (SSR) are a valuable tool for genetic analysis. Our objective is to augment the existing RFLP map of rice with simple sequence length polymorphisms (SSLP). In this study, we describe 20 new microsatellite markers that have been assigned to positions along the rice chromosomes, characterized for their allelic diversity in cultivated and wild rice, and tested for amplification in distantly related species. Our results indicate that the genomic distribution of microsatellites in rice appears to be random, with no obvious bias for, or clustering in particular regions, that mapping results are identical in intersubspecific and interspecific populations, and that amplification in wild relatives ofOryza sativa is reliable in species most closely related to cultivated rice but becomes less successful as the genetic distance increases. Sequence analysis of SSLP alleles in three relatedindica varieties demonstrated the clustering of complex arrays of SSR motifs in a single 300-bp region with independent variation in each. Two microsatellite markers amplified multiple loci that were mapped onto independent rice chromosomes, suggesting the presence of duplicated regions within the rice genome. The availability of increasing numbers of mapped SSLP markers can be expected to increase the power and resolution of genome analysis in rice.     

多胚水稻ApⅢ（双13）的胚胎学观察

对多胚水稻（Ｏｒｙｚａ ｓａｔｉｖａ Ｌ．）ＡｐⅢ的大量成熟颖果、人工萌发的幼苗和开花后３～５ ｄ 的幼嫩颖果进行的整体解剖和显微制片观察表明：ＡｐⅢ的５０００粒成熟颖果中,８９．０％ 含单胚单苗,８．９％ 和１．２％分别含双胚双苗和三胚三苗;７００多粒幼嫩颖果中,９０．０％ ～９５．０％ 含单胚,５．０％ ～７．０％ 含双胚。因制片的数目有限,未见到含三胚的;在含单胚和多胚颖果中,胚均位于同一胚囊的珠孔端,未见到胚囊以外存在不定胚。根据上述结果,似可以认为ＡｐⅢ单粒颖果的双胚和三胚是由同一胚囊内的卵细胞和１或２个助细胞受精或不受精发育而来的     

水稻幼芽细胞生物膜上的赤霉素结合蛋白的结合特性

在水稻 (Oryza sativa)幼芽中存在膜结合的赤霉素结合蛋白 ,其与 GA3 结合的平衡解离常数(Kd)为 6.5× 1 0 -8mol/ L,总浓度为 0 .3 pmol· mg-1 蛋白质。结合蛋白与 GA3 结合活力在 0℃时比 2 5℃时高 1 4 0 %。它与 GA3 结合的最适 p H为 5。 GA3 与此结合蛋白的结合量随反应时间延长而增加 ,1 h达最大值 ,以后又逐渐下降。 IAA、ABA可与 GA3 竞争赤霉素结合蛋白。     

Structural characterization of a novel mono-sulfated gangliotriaosylceramide containing a 3-O-sulfatedN-acetylgalactosamine from rat kidney

A novel mono-sulfated glycosphingolipid based on the gangliotriaose core structure was isolated from rat kidney. The isolation procedure involved extraction of lipids with chloroform/methanol, mild alkaline methanolysis, column chromatographies with anion exchangers and silica beads. The structure was characterized by compositional analysis, FTIR spectroscopy, methylation analysis,¹H-NMR spectroscopy and negative-ion liquid secondary ion mass spectrometry (LSIMS) using the intact glycolipid and its desulfation product. The two dimensional chemical shift correlated spectroscopy provided information on the sugar sequence as well as anomeric configurations, and indicated the presence of a 3-O-sulfatedN-acetylgalactosamine within the molecule. Negative-ion LSIMS with high- and low-energy collision-induced dissociation defined the sugar sequence and ceramide composition, confirming the presence of a sulfatedN-acetylgalactosamine at the non-reducing terminus. From these results, the complete structure was proposed to be HSO₃-3GalNAc1-4Gal1-4Glc1-1Cer (Gg₃Cer III³-sulfate, SM2b). Abbreviations: Abbreviations for sulfated glycolipids [17] follow the modifications of the nomenclature system of Svennerholm for gangliosides [37], and the designation of the other glycosphingolipids follows the IUPAC-IUB recommendations [38]. Cer, ceramide; LacCer, lactosylceramide, Gal1-4Glc1-1Cer; Gg₃Cer, gangliotriaosylceramide, GalNAc1-4Gal1-4Glc1-1Cer; Gg₄Cer, gangliotetraosylceramide, Gal1-3GalNAc1-4Gal1-4Glc1-1Cer; iGb₄Cer, isoglobotetraosylceramide, GalNAc1-3Gal1-3Gal1-4Glc1-1Cer; Gb₄Cer, globotetraosylceramide, GalNAc1-3Gal1-4Gal1-4Glc1-1Cer; SM4s, galactosylceramide sulfate, GalCer I³-sulfate; SM3, lactosylceramide sulfate, LacCer II³-sulfate; SM2a, Gg₃Cer II³-sulfate; SM2b, Gg₃Cer III³-sulfate; SB2, Gg₃Cer II³,III³-bis-sulfate; SM1a, Gg₄Cer II³-sulfate; SM1b, Gg₄Cer IV³-sulfate; SB1a, Gg₄Cer II³,IV³-bissulfate; GLC, gas-liquid chromatography; GC-MS, gas chromatography-mass spectrometry; DQF, double quantum filtered; COSY, chemical-shift-correlated spectroscopy; LSIMS, liquid secondary ion mass spectrometry; CID, collision-induced dissociation; MS/MS, tandem mass spectrometry.