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21.
Comparison of phosphorus mobilization during monocarpic senescence in rice cultivars with sequential and non-sequential leaf senescence 总被引:1,自引:0,他引:1
The senescence pattern of the three uppermost leaves of four rice (Oryza sativa L.) cultivars viz. Ratna, Jaya, Masuri and Kalojira was analysed in terms of decline of chlorophyll and by measuring [32P]-phosphate retention and export from leaf to grains during the reproductive development. With the advancement of reproductive development, the cultivars Masuri and Kalojira showed a sequential mode of senescence, but the cultivars Ratna and Jaya showed a non-sequential mode of leaf senescence where the flag leaf senesced earlier than the older second leaf. Foliar spraying with benzyladenine (0.5 mM) significantly delayed, and abscisic acid (0.1 mM) accelerated, leaf senescence. In untreated control plants, the second leaf had the highest export of labelled phosphate among the leaves at the grain formation stage (0–7 days) in Masuri and Kalojira. This was compensated by the flag leaf at the grain development stage (7–14 days), whereas export of [32P]-phosphate was highest from the flag leaf of Ratna and Jaya at the grain development stage. Compared with the control, benzyladenine treatment caused higher retention of [32P]-phosphate in the leaves and also export to the grains, but abscisic acid treatment gave lower retention and export of [32P]-phosphate to the grains. The amount of [32P]-phosphate export from a mother to a daughter shoot developed in the axil of the second leaf of plants with the panicle removed, was less than that to panicles remaining on control plants of all cultivars. When the panicle had been excised, the greatest export of [32P]-phosphate took place from the second leaf to the daughter shoot in all cultivars. Excision of the panicle delayed leaf senescence as compared with intact controls and maintained an age-related leaf senescence pattern in all the four cultivars. The results presented here demonstrate that mobilization of phosphorus from leaf to grains, regardless of cultivar or age and position of the leaf, correlates well with the senescence of that leaf. 相似文献
22.
23.
P. Janardhan Reddy K. Vaidyanath 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1986,71(5):757-760
Summary The response of plant cells to salt stress was studied on embryo derived calli of rice (Oryza sativa L.) in order to identify cellular phenotypes associated with the stress. The feasability of selecting salt tolerant callus and its subsequent regeneration to plants was also studied. Callus was grown on agar-solidified media containing 0%, 1% and 2% (w/v) NaCl for 24 days. Parameters such as fresh weight, dry weight, soluble protein and proline content were measured. The callus growth decreased markedly with increasing NaCl concentration in the medium. The proline content was enhanced several fold in salt stressed calli. A prolonged exposure of callus to the salt environment led to discolouration and arrested growth in the majority of the calli and only a small number of callus cells maintained healthy and stable growth. These variants were subcultured every three weeks for a period of four months onto medium containing 1% NaCl to identify tolerant lines. At the end of the third cell passage, the tolerant calli were transferred to regeneration medium to regenerate plants. The regeneration frequency in the salt-selected lines was enhanced when compared to unselected lines. 相似文献
24.
When kinetin was applied to the source organ (flag leaf) of rice (Oryza sativa L. cv. Ratna), foliar senescence was delayed and grain yield per plant (as evidenced by grain weight, grain/straw weight ratio and 1,000 grain growth) was increased through the increase of sink activity (increase in dry weight of the grains/plant), duration of sink capacity as well as photosynthetic ability of the glumes (as determined by the chlorophyll content of the glumes of the developing grains). However, application of kinetin to the sink organs (fruits), promoted senescence of the source but increased the yield by increasing the sink capacity and 1,000 grain growth mostly at the earlier stage of reproductive development. Lower sterility percentage was associated with higher grain yield of the plant by kinetin treatments. ABA applied either to the source or the sink promoted leaf senescence and reduced the grain yield by reducing the sink activity, harvest index, sink capacity duration and increasing the sterility percentage. Thousand grain dry weight at harvest did not vary significantly amongst the treatments. It was concluded that nutrient drainage was associated with the correlative influence of fruit on the monocarpic senescence of rice plant and that a competetion for differential allocation of cytokinin and ABA in the source and sink organs initiates this senescence syndrome. 相似文献
25.
26.
Survival of cultured cells and somatic embryos of Asparagus officinalis cryopreserved by vitrification 总被引:2,自引:0,他引:2
Cultured cells and somatic embryos derived from the mesophyll tissue of asparagus (Asparagus officinalis L.) were cryopreserved by vitrification. The vitrification solution (PVS) contains (w/v) 22% glycerol, 15% ethylene glycol, 15% propylene glycol and 7% DMSO in Murashige-Skoog medium enriched with 0.5M sorbitol. After initial cryoprotection with sorbitol supplemented MS medium containing 12% ethylene glycol, cells or embryos were exposed stepwise to 85% PVS at 0°C. They were loaded into 0.5 ml transparent straws, and were then plunged directly into liquid nitrogen. After rapid warming, PVS was removed and diluted stepwise. The highest survivals of vitrified cells and embryos were about 65 and 50%, respectively. Surviving embryos developed into plantlets.Abbreviations DMSO
dimetyl sulfoxide
- PVS
vitrification solution
- LN
liquid nitrogen
- DSC
differential scanning calorimeter
- MS
Murashige-Skoog salt medium
- NAA
naphthalene acetic acid
- BA
6-benzyladenine 相似文献
27.
A. R. Yeo M. E. Yeo S. A. Flowers T. J. Flowers 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1990,79(3):377-384
Summary Phenotypic resistance of salinity is expressed as the ability to survive and grow in a salinised medium. Some subjective measure of overall performance has normally been used in plant breeding programmes aimed at increasing salinity resistance, not only to evaluate progeny, but to select parents. Salinity resistance has, at least implicitly, been treated as a single trait. Physiological studies of rice suggest that a range of characteristics (such as low shoot sodium concentration, compartmentation of salt in older rather than younger leaves, tolerance to salt within leaves and plant vigour) would increase the ability of the plant to cope with salinity. We describe the screening of a large number of rice genotypes for overall performance (using an objective measure based on survival) and for the aforementioned physiological traits. There was wide variation in all the characters studied, but only vigour was strongly correlated with survival. Shoot sodium concentration, which a priori is expected to be important, accounted for only a small proportion of the variability in the survival of salinity. Tissue tolerance (the cellular component of resistance reflecting the ability to compartmentalise salt within leaves) revealed a fivefold range between genotypes in the tolerance of their leaves to salt, but this was not correlated positively with survival. On the basis of such (lack of) correlation, these traits would be rejected in normal plant breeding practice, but we discuss the fallacies involved in attempting correlation between individual traits and the overall performance of a salt-sensitive species in saline conditions. We conclude that whilst overall performance (survival) can be used to evaluate the salt resistance of a genotype, it is not the basis on which parents should be selected to construct a complex character through breeding. It was the norm for varieties which had one good characteristic affecting salt resistance to be unexceptional or poor in the others. This constitutes experimental evidence that the potential for salt resistance present in the rice genome has not been realised in genotypes currently extant. The results are discussed in relation to the use of physiological traits in plant breeding, with particular reference to environmental stresses that do not affect a significant part of a species' ecological range. 相似文献
28.
Development of microsatellite markers and characterization of simple sequence length polymorphism (SSLP) in rice (Oryza sativa L.) 总被引:26,自引:0,他引:26
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. 相似文献
29.
中国普通野生稻遗传分化的RAPD研究 总被引:18,自引:0,他引:18
多数学者已认定亚洲栽培稻(OryzasativaL.)的祖先是普通野生稻(O.rufipogon)。然而栽培稻的籼、粳分化是发生在驯化之前还是在驯化之后,也即普通野生稻是否存在籼、粳分化的问题,是十几年来稻作起源研究中争论的热点之一。Second[1]用多个同工酶位点的分析结果得出结论,普通野生稻在驯化为栽培稻之前就已经发生了籼、粳分化,即有籼型普通野生稻和粳型普通野生稻之分。Morishima和Gadrinab[2]用24个形态和生理性状及12个同工酶位点和杂交亲合力等方法证明普通野生稻没有发… 相似文献
30.
从水稻同源三倍体中鉴定出无融合生殖种质TAR 总被引:14,自引:0,他引:14
水稻杂种优势的成功应用使水稻单产提高了20%,这主要得益于70年代初细胞质雄性不育系的发现和利用。但传统的三系法杂交水稻必须做到不育系、保持系、恢复系“三系”配套,选育程序和杂交种子生产环节较复杂,以致培育目标组合的周期长、效率低、推广环节多,同时种子成本高、价格贵[1]。80年代光敏核不育水稻以其“一系两用、配组自由”等优越性大有取代三系杂交水稻的趋势。但是,光敏核不育特性同时又受温度的调控,加之育性波动等缺陷使两系杂交水稻的研究和利用受到严重制约[2]。80年代后期,科技工作者开始探索利用无融合生殖固定水稻杂种优… 相似文献