铝对水稻幼苗的生理影响

以水稻幼苗为材料研究了铝的植物毒性。将不同浓度的 AlCl 加入培养液,对幼苗处理30天。10ppm 以上的铝明显抑制水稻幼苗根和地上部分的生长。5.0ppm 以上铝可引起毒害症状。铝对根的毒害作用大于对地上部分的作用。铝主要积累在根部,少部分转移到地上部分。5.0ppm 以上的铝对叶绿体 Hill 反应和光合磷酸化作用以及根线粒体呼吸和氧化磷酸化作用均有较明显抑制作用。钙对铝的此种抑制作用有一定拮抗作用。     

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.     

内源植物激素与光敏核不育水稻农垦58S育性的关系

采用气相色谱－质谱联用选择离子检测（ＧＣ－ＭＳ－ＳＩＭ）技术,定性、定量分析了光敏核不育水稻农垦５８Ｓ（Ｏｒｙｚａ ｓａｔｉｖａ Ｌ． ｓｕｂｓｐ． ｊａｐｏｎｉｃａ）及对照品种“农垦５８”在长（ＬＤ）、短（ＳＤ）日照处理下,不同发育时期顶端全展叶片中内源ＩＡＡ、ＡＢＡ 和生殖器官中内源ＩＡＡ、ＡＢＡ、ＧＡ１、ＧＡ４ 的含量变化。实验结果表明：在ＬＤ 处理下,农垦５８Ｓ雌雄蕊形成期的叶片和花粉母细胞形成期的幼穗中ＩＡＡ 相继发生亏缺;农垦５８Ｓ－ＬＤ花粉母细胞形成期、单核期和扬花期,生殖器官中内源ＡＢＡ 均低于农垦５８Ｓ－ＳＤ 的含量,“农垦５８”则与此相反;扬花期不育花药中内源ＧＡ１ 和ＧＡ４ 含量剧减。据此认为：生殖器官中早期ＩＡＡ 的亏损、ＡＢＡ 含量剧减伴随着抗逆性能的减弱及ＧＡＳ的不足共同导致了农垦５８Ｓ的雄性败育     

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。     

Inter-varietal differences in xylem exudate composition and growth under contrasting forms of N supply in cucumber

Variations in the inorganic and organic composition of xylem exudate, growth and N content under contrasting forms of N supply in three cucumber cultivars (Hyclos, Medusa and Victory) were studied in glasshouse conditions. The plants were grown hydroponically with two NO₃ ^-:NH₄ ⁺ ratios (100:0 and 60:40).The xylem sap of Medusa grown with both N sources displayed an increase of organic N and carboxylate concentrations and a decrease of cations, inorganic anions and carbohydrates compared with that of those grown with NO₃ ^- alone, showing a higher growth and N content in tissues and thus better utilization of N supplied as NO₃ ^- and NH₄ ⁺. Mixed N nutrition in Hyclos caused the greatest amounts of NO₃ ^- and NH₄ ⁺ in xylem sap, lower root weight and N levels in the leaves, while its root was unable to generate an adequate supply of organic N compounds. Despite the levels of cations, inorganic and organic anions were reduced by the NH₄ ⁺ supplied to Victory, the ionic balance in the xylem sap, growth and N content remained similar to that of those supplied with NO₃ ^- alone. Finally, the cucumber cultivars studied here, responded differently to the form of N supplied, it may partly be due to their ability of assimilating N in the roots and partly to the form in which the N is translocated to the shoot.     

Microsatellite DNA markers for rice chromosomes

We found 369 complete microsatellites, of which (CGG/GCC)_n was the most frequent, in 11 798 rice sequences in the database. Of these microsatellites, 35 out of 45 could be successfully converted into microsatellite DNA markers using sequence information in their flanking regions. Thus, the time and labor used to develop new microsatellite DNA markers could be saved by using these published sequences. Twenty eight polymorphic markers between Asominori (japonica) and IR24 (indica) have been correctly mapped on the rice genome and microsatellites appear to be randomly distributed in the rice chromosomes. Integration of these markers with the published microsatellite DNA markers showed that about 35% of the rice chromosomes were covered by the 56 microsatellite DNA markers. These microsatellites were hypervariable and were easily to assay by PCR; they were distributed to all chromosomes and therefore, one can easily select plants carrying desired chromosome regions using these microsatellite DNA markers. Thus, microsatellite maps should aid the development of new breeds of rice saving time, labor, and money.