甘露醇预处理对大麦雄核发育的影响李文泽等:甘露醇预处理对大麦雄核发育的影响

研究了甘露醇预处理对大麦（Ｈｏｒｄｅｕｍ ｖｕｌｇａｒｅ Ｌ．）雄核发育的影响。结果发现,第一,甘露醇预处理比低温预处理和对照能明显地提高花粉存活频率,三者在接种后第８ 天分别为１９．０％ 、８．４％ 和６．６％ 。第二,甘露醇预处理能提高小孢子的质量,抑制淀粉积累,有利于小孢子分裂发育,使发育进度比低温预处理和对照提早２—３ ｄ,而对照和低温预处理的小孢子都不同程度出现淀粉积累,它对发育不利。第三,甘露醇预处理后小孢子的发育途径主要是Ｂ途径,Ａ途径较少。大多数小孢子的细胞核为二倍体,而低温预处理大多数小孢子的染色体数目较少,为单倍体     

Chloroplast and Mitochondrial DNA Variation in HORDEUM VULGARE and HORDEUM SPONTANEUM

A survey of restriction fragment polymorphism in Hordeum vulgare and Hordeum spontaneum was made using 17 and 16 hexanucleotide restriction endonucleases on chloroplast (cp) and mitochondrial (mt) DNA, respectively. The plant accessions originated from various places throughout the Fertile Cresent and Mediterranean. The types of changes in cpDNA consisted of nucleotide substitutions and insertions and deletions on the order of 100 base pairs. In contrast, mtDNA has most likely undergone larger insertions and deletions of up to 20 kilobase pairs in addition to rearrangements. Grouping of mtDNA fragment data showed that in some cases geographical affinities existed between the two species, whereas in others there were no clear affinities. Nucleotide diversity estimates derived from the restriction fragment data were used in a number of comparisons of variability. Comparisons of overall mtDNA variability (nucleotide diversity = 9.68 x 10^-4) with cpDNA variability (nucleotide diversity = 6.38 x 10^-4 ) indicated that the former are somewhat more variable. Furthermore, there was no indication that the wild H. spontaneum (cpDNA diversity = 5.57 x 10^-4; mtDNA diversity = 6.04 x 10 ^-4) was more variable than the land races of H. vulgare (cpDNA diversity = 5.88 x 10^-4; mtDNA diversity = 9.79 x 10^-4). In fact, on the basis of mtDNA diversity, H. vulgare was the more variable species. Comparison of organelle nucleotide diversity estimates with an estimate of nuclear nucleotide diversity derived from existing isozyme data provided evidence that both organelle genomes are evolving at a slower rate than the nuclear genome.     

大麦转基因座位结构的研究

利用质粒营救法获得基因枪法转化的4种转绿色荧光蛋白基因(green fluorescent protein,GFP)大麦的转基因座位序列,序列分析显示4种材料的转基因座位中均有完整栽体的串联重复现象,表明转基因整合是同源重组的结果.同时转基因座位中也存在不完整载体片段、基因组片段的混杂排列,说明转基因整合时也发生异常重组.微粒轰击的转基因整合是由异常重组和同源重组共同完成的.     

Mutation Rates, Population Sizes and Amounts of Electrophoretic Variation of Enzyme Loci in Natural Populations

A method is presented for estimating relative mutation rates or relative effective population sizes, under the hypothesis of adaptively neutral allelic variation. This method was applied to seven surveys of electrophoretic variation. It was observed that electrophoretic mutation rates so obtained follow the gamma distribution and, in Drosophila, are positively correlated with the molecular weights of the enzymes subunits. The variance in mutation rate is larger under the step-wise model of electrophoretic mutation than under the infinite-alleles model. Rates for the most variable loci may exceed rates for less variable loci by a factor of 500. For completely invariant loci, this factor may be as high as 4 X 10(4), an observation suggesting that these loci are subject to purifying selection. In contrast to mutation rates, effective population sizes may vary at the most by a factor of ten. These results support the hypothesis that differences in the amount of electrophoretic variability among polymorphic loci may reflect differences in the rate by which electrophoretically detectable variation is generated in population.     

An Evolutionary Reduction Principle for Mutation Rates at Multiple Loci

A model of mutation rate evolution for multiple loci under arbitrary selection is analyzed. Results are obtained using techniques from Karlin (Evolutionary Biology, vol. 14, pp. 61–204, 1982) that overcome the weak selection constraints needed for tractability in prior studies of multilocus event models.     

Uzu Mutation in Barley (Hordeum vulgare L.) Reduces the Leaf Unrolling Response to Brassinolide

A sensitive method to examine the brassinolide (BL) response of barley (Hordeum vulgare L.) using dark-grown leaf segments was established based on the known method for wheat. BL responses of 53 dwarf isogenic lines of barley were examined, and two lines were found having a uzu gene that doesn't respond significantly. These results indicate that uzu dwarfism may be caused by the non-responding character to BL.     

基于SSH技术的青稞低温诱导cDNA文库的构建(简报)

青稞（Hordeum vulgare L．var．nudum HK．f）．因其果实成熟后可从颖壳中脱落．所以又称裸大麦（hulless barley）．是一种禾本科作物,主要分布于青藏高原地区。由于海拔高,其生长环境的温度相对较低。在青稞生长期间．经常出现霜冻以及雪、雹等天气,夜间温度往往低于0℃,但青稞仍生长良好。因此．青稞具有较强的抗低温胁迫的遗传特性．是一个潜在的遗传资源库。研究开发这些抗低温相关基因及其调控机制将具有重要的理论和实践意义．     

Lysine Catabolism in Barley (Hordeum vulgare L.)

Lysine catabolism in seedlings of barley (Hordeum vulgare L. var. Emir) was studied by direct injection of the following tracers into the endosperm of the seedlings: aspartic acid-3-(14)C, 2-aminoadipic acid-1-(14)C, saccharopine-(14)C, 2,6-diaminopimelic acid-1-(7)-(14)C, and lysine-1-(14)C. Labeled saccharopine was formed only after the administration of either labeled 2,6-diaminopimelic acid or labeled lysine to the seedlings. The metabolic fate of the other tracers administered also supported a catabolic lysine pathway via saccharopine, and apparently proceeding by a reversal of some of the biosynthetic steps of the 2-aminoadipic acid pathway known from lysine biosynthesis in most fungi. Pipecolic acid seems not to be on the main pathway of l-lysine catabolism in barley seedlings.     

Fertilization of Barley (Hordeutn distichutn L.)

Fertilization of barley has been studied and photographically recorded. The pollen grain germinates almost immediately after attaching itself to the stigma, pollen tube reaches the embryo sac after 20–30 minutes (temperature 26°C). One of the sperms permeates immediately to the oosphere, the other joins polar nuclei migrating from the oosphere to antipodal cells after the discharge of pollen tube content. Fertilization of the polar nucleus occurs in most cases at the antipodal cells which have pronounced haustorial character. In triple fusion polar nuclei do not usually fuse prior to fertilization. However, some exceptions were noted: sometimes the fertilization takes place after the fusion of polar nuclei or during the fusion. Being slower, pre-mitotic fertilization of the egg cell could be studied in greater detail.     

Root-Tiller Interrelationships in Spring Barley (Hordeum distichum (L.) Lam.)

Root-tiller relations were investigated in spring barley grownin soil in deep pots. The total dry wt of the root system reachedits maximum 6 weeks from sowing, when the shoot weight was only50 per cent of its value at maturity. Seminal and nodal rootscomprised 40 and 60 per cent, respectively, of the total rootdry wt at maturity; the majority of the nodal root weight wasassociated with the main shoot. The main shoot had approximatelytwice as many nodal roots as either of the first two primarytillers (T1 and T2), and the primary and secondary tillers appearinglater were very poorly rooted. Some tillers, especially secondarytillers that died prematurely, produced no nodal roots. Theweight of the seminal roots and nodal roots attached to themain shoot continued to increase up to maturity but the drywt of nodal roots on tillers declined with time. This patternof growth was closely related to the pattern of ¹⁴C assimilateddistribution within the root system. A very small proportionof ¹⁴C assimilated by the main shoot and T1 and T2 was exported.The majority of the exported assimilate went to the seminalroot system and to nodal roots attached to the main shoot. Individualnodal and seminal roots seemed to have different roles in supplyingnutrients to the shoot system, with the former mainly providing³²P-phosphate to its tiller of origin and the latter generallysupplying the main shoot and primary tillers. Hordeum distichum. (L.) Lam., barley, root growth, nodal roots, seminal roots, tillering, assimilate distribution, ³²P-distribution     

Phosphoinositides in Barley (Hordeum vulgare L.) Aleurone Tissue

[3H]Inositol labeling of barley (Hordeum vulgare L. cv Himalaya) aleurone layers and analysis of phospholipids by deacylation revealed the presence of phosphatidylinositol (PtdIns), PtdIns3P, and PtdIns4P but not PtdInsP2 species. In contrast to an earlier report (P.P.N. Murthy, G. Pliska-Matyshak, L.M. Keranen, P. Lam, H.H. Mueller, N. Bhuvarahamurthy [1992] Plant Physiol 98: 1498-1501) systematic chemical degradation of PtdIns revealed no evidence of a second isomer of PtdIns. Evidence of the widespread occurrence of 3-phosphorylated PtdIns within the plant kingdom is presented.     

Apoplast Acidification in Growing Barley (Hordeum vulgare L.) Leaves

Apoplast acidification associated with growth is well documented in roots, coleoptiles, and internodes but not in leaves. In the present study, advantage was taken of the high cuticle permeability in the elongation zone of barley leaves to measure apoplast pH and growth in response to application of test reagents. The role of the plasma membrane H⁺-ATPase (PM-H⁺-ATPase) and K⁺ in this process was of particular interest. pH microelectrodes and an in vitro gel system with bromocresol purple as pH indicator were used to monitor apoplast pH. Growth was measured in parallel or in separate experiments using a linear variable differential transformer. Test reagents that blocked (vanadate) or stimulated (fusicoccin) PM-H⁺-ATPase or that reduced (Cs⁺, tetraethylammonium) K⁺ uptake were applied. Apoplast pH was lower in growing than in nongrowing leaf tissue and increased in the elongation zone with increasing apoplast K⁺. Vanadate increased apoplast pH and reduced growth, whereas fusicoccin caused the opposite effects. It is concluded that barley leaves exhibit acid-growth-type mechanisms in that apoplast pH is lower in elongating leaf tissue. Both growth and apoplast pH depend on the activity of the PM-H⁺-ATPase and K⁺ transport processes. However, not all of the growth displayed by leaves is dependent on a lower apoplast pH in the elongation zone; up to 50 % of growth is retained when apoplast pH in the elongation zone increases to a value observed in mature tissue.     

Correlation between Photoinhibition Sensitivity and the Rates and Relative Extents of Xanthophyll Cycle De-epoxidation in Chlorina Mutants of Barley (Hordeum vulgare L.)

We compared photoinhibition sensitivity to high irradiance (HI) in wild-type barley (wt) and both its chlorina f ₁₀₄-nuclear gene mutant, that restricts chlorophyll (Chl) a and Chl b synthesis, and its f ₂-nuclear gene mutant, that inhibits all Chl b synthesis. Both F_v/F_m and _PS2 decreased more significantly in f ₂ than f ₁₀₄ and wt with duration of HI exposure. Chl degraded more rapidly in the f ₂ than in either f ₁₀₄ or wt. Most sensitivity to photoinhibition was exhibited for f ₂, whereas there was little difference in response to HI between the f ₁₀₄ and wt. The highest de-epoxidation (DES) value at every time point of exposure to HI was measured for f ₂, whereas the wt had the lowest value among the three strains. There were two lifetime components resolved for the conversion of violaxanthin (V) to zeaxanthin plus antheraxanthin (Z + A). The most rapid lifetime was around 6 min and the slower lifetime was >140 min, in both the mutants and wt. However, the wt and f ₁₀₄ both displayed larger amplitudes of both de-epoxidation lifetimes than f ₂. The difference between the final de-epoxidation state (DES = [Z + A]/[V + A + Z]) in the light compared to the dark expressed as DES for wt, f ₁₀₄, and f ₂ was 0.630, 0.623, and 0.420, respectively. The slow lifetime component and overall larger DES in the wt and f ₁₀₄ correlated with more photoprotection, as indicated by relatively higher F_v/F_m and _PS2, compared to the f ₂. Hence the photoprotection against photoinhibition has no relationship with the absolute DES value, but there is a strong relationship with de-epoxidation rate and relative extent or DES.