马铃薯SoFtsH基因全长cDNA克隆与在干旱条件下表达研究

FtsH (Filamentation Temperature-Sensitive H)是一种ATP和Zn²⁺依赖型金属蛋白酶，广泛存在于原核生物和真核生物中，在真核生物中是多基因家族。FtsH具有ATP酶活性、蛋白水解活性和分子伴侣活性，参与多种胁迫反应。从抗旱马铃薯（Solanum tuberosum）二倍体品系H145中分离得到cDNA-AFLP差异片段,利用RACE技术克隆了SoFtsH cDNA全长序列, 并对其进行分析。结果表明, 该序列包含完整的开放阅读框，长为723 bp, 编码129个氨基酸。SoFtsH具有2个铁氧化还原蛋白结合位点，并存在信号肽序列、跨膜区域和Zn²⁺结合域。SoFtsH基因序列与GenBank数据库中的其他FtsH基因进行同源序列比对, 并构建系统进化树, 发现该基因与番茄、烟草、拟南芥等高等植物FtsH基因同源性达90%以上。半定量RT-PCR和Northern Blot杂交结果表明SoFtsH基因在干旱胁迫下叶片和根系里的表达量明显增加, 且在抗旱品系H145与干旱敏感品系H214中表达模式不同。说明SoFtsH基因在马铃薯抗旱中起作用。     

Potential of a Fusarium eumartii culture filtrate on the screening for wilting resistance in potato

Summary Fusarium solani f.sp. eumartii Carp. Snyder and Hansen (Fusarium eumartii) is a soil inhabitant that induces the so-called Potato Wilt and Stem End Rot disease. Prior to wilting, the pathogen induces peculiar small bronze spots on the leaflets. Failure to isolate F. eumartii from infected leaflets suggests the involvement of a toxin in the disease. The fungus was grown in liquid Richard's medium and thereafter a filtrate was obtained dialyzing (MW cutoff 12,000–14,000) and sterilizing the culture by filtration (0.22 m). Potato leaves treated with both the pathogen or the filtrate showed symptoms of bronze spots and significantly higher electrolyte leakage when compared to controls. Tomato leaves showed neither bronze spots nor electrolyte leakage after plant inoculation with the pathogen or with the filtrate treatment. Both, the absence of visible symptoms and the lack of electrolyte leakage in tomato could be associated to a certain degree of host specificity of the F. eumartii filtrate towards potato. The filtrate also induced symptoms similar to infections by F. eumartii in adult plants and in vitro plantlets of cultivars Huinkul MAG and Kennebec. Callus responses to the filtrate were related to responses of the cultivars to the pathogen in greenhouse. These results show the potential of the culture filtrate of F. eumartii for use in screening for wilting resistance.     

Flowering behaviour,male sterility and berry setting in tetraploid Solanum tuberosum germplasm

Summary Six hundred and seventy six accessions of cultivated potato (Solanum tuberosum ssp. tuberosum) from 25 countries, were studied for flowering and fruiting behaviour under long days (12–14 h). Flowering intensity ranged from dropping of floral buds just after initiation to profuse blooming. The majority (58.3%) of the accessions bloomed profusely, though 20.4% of the accessions did not bloom at all. Weeks to flowering ranged from 6 to 15 and the majority (66.5%) of the flowering accessions bloomed within 8 to 9 weeks after planting. Duration of flowering ranged from 1 to 10 weeks and the majority (68.1%) of the flowering accessions bloomed for 1 to 4 weeks only. Twentythree per cent of the flowering accessions were completely male sterile. Maximum male fertility was 90% only. No berry setting was observed in 31.8% of the flowering accessions. Only 54.3 per cent of the accessions were found to be fertile in all respects and could be used both as male and female parents. Premature bud abscission was the major cause of sterility. Peru was the best source of profuse-flowering genotypes, Poland was the best source of early flowering genotypes and Mexico was the best source of long duration flowering and good berry setting genotypes. The results suggested that flower bud formation; the growth and development of mature flowers; weeks to flowering and duration of flowering are independent characters controlled by different genes of quantitative nature. Berry setting and duration of flowering were closely associated (r=0.95). Genetic as well as environmental factors interfered with the developmental process leading to flower production and berry setting at different times in different genotypes. The practical implications of these results for true potato seed production are discussed.Publication No. 1298, CPRI, Shimla.     

Optimising potato breeding. II. A model for optimising single-stage and single-trait selection

Summary A model for optimising single-stage and single-trait selection is presented. The model is based on the expected selection response model, extended with parameters describing the nature of the environment and with variables allowing a manipulation of selection schemes. As an example, the model is used to optimize tuber yield selection in potato breeding.Estimated parameter values have an uncertainty, which may bias the model outcome. Sensitivity analysis shows that the sensitivity to unrealistic parameter values for optimal allocation is less than the sensitivity for the selection response.     

Inheritance of Resistance to Pseudomonas solanacearum E. F. Smith in Tetraploid Potato

Inheritance of bacterial wilt resistance in tetraploid potato was investigated in segregating progenies of parent clones with resistance derived from different specific sources and different types of adaptation. A race 1 and a race 3 isolate of Pseudomonas solanacearum were used to test the resistance under warm temperatures. Results obtained indicated partial dominance of resistance. Significant general and specific combining abilities showed that both additive and non-additive gene actions are important in conditioning resistance expression. There was evidence that epistasis is an important component of the non-additive gene action in the inheritance of resistance. Other aspects of the resistance and implications for breeding are discussed.     

Crossability relationships among wild potato species with different ploidies and Endosperm Balance Numbers (EBN)

Three wild potato species with different ploidies and Endosperm Balance Numbers (EBN) were crossed in a complete diallel design and the development of the embryo and endosperm as well as the type of seeds produced were analyzed. The compatible crosses – intraspecific intra-EBN and interspecific intra-EBN – produced more than 89% plump seeds, whereas in the incompatible crosses – intraspecific inter-EBN and interspecific inter-EBN – more than 85% of the seeds were not as well developed or were shrunken. The histological analysis revealed that inviable seeds had less developed or collapsed endosperms and thicker endotheliums than viable ones. A gradation of crossabilities was observed among species. The self-compatible species Solanum acaule had good performance as a female but not as a male parent. Among the self-incompatible species, Solanum gourlayi was the best male parent but had a poor performance as a female, whereas Solanum commersonii had an intermediate behavior. Differences in crossabilities among genotypes within species were also observed. These results can not be solely explained by the EBN hypothesis. It is, therefore, suggested that the EBN may be part of a more complex system of interspecific barriers acting at the pre- and post-zygotic levels. This revised version was published online in July 2006 with corrections to the Cover Date.     

Large yield differences between reciprocal families of Solanum tuberosum

Summary A number of reports have indicated differences in reciprocal families of Solanum tuberosum when intergroup hybrids were studied. Questions have been raised concerning the potential magnitude, frequency, and genetic basis for such differences. In this study, exact reciprocal crosses were made using parents characterized by different maturities and having different cytoplasmic sources within Solanum tuberosum in order to substantiate previous claims of reciprocal differences and to clarify the nature of such differences.Field trials revealed reciprocal differences which were large and highly significant. Reciprocal yield differences of up to 115% were observed when parents of opposite maturities were used. In seven crosses, the higher-yielding reciprocal always had the higher-yielding parent as the maternal parent. Significant reciprocal differences for flowering and vine maturity were also observed between some families. The F₂ populations were generated for one set of reciprocals and the reciprocal differences in the F₂ generation seemed to be substantially reduced relative to the F₁ generation.It is concluded that the occurrence of large reciprocal differences seems to depend more upon having parents of opposite maturity than upon the taxonomic origin of the parent's cytoplasm. This, in conjunction with the reduced F₂ reciprocal differences, suggests that observed differences may be due to very persistent maternal effects or a type of dauermodification, rather than true cytoplasmic inheritance.Cooperative Investigation of U.S. Department of Agriculture, Science and Education Administration. Agricultural Research and the Wisconsin Agricultural Experiment Station.     

Competition between 2x and x pollen in styles of Solanum tuberosum determined by a quick in vivo method

Summary Pollen competition in vivo was studied by placing two pollen samples on one stigma and comparing the length of the tubes under a U.V. microscope. Comparisons involving pollen of Solanum tuberosum and S. phureja showed that 2x pollen grew faster than x pollen, both in 2x and x styles. Consequences for induction of dihaploids in S. tuberosum are discussed.     

Performance of Solanum habrochaites LA1777 introgression line hybrids for marketable tomato fruit yield in Asia

Wild relatives of the cultivated tomato (Solanum lycopersicum L.) are major sources of new genetic diversity for tomato improvement. Introgression lines (IL) are near-isogenic lines homozygous for one or several mapped wild DNA fragments in a common recurrent parent. A set of ILs developed by Cornell University from Solanum habrochaites accession LA1777 and recurrent parent E6203 has been made publicly available through the Tomato Genetics Resource Center of the University of California-Davis. Our objective was to identify LA1777 introgressions with potential to increase the marketable fruit yield of tomato grown in the tropics. A subset of ILs were each crossed to CLN2498E (resistant to bacterial wilt and some begomoviruses) to create IL hybrids (ILH). ILH, IL recurrent parent E6203, CLN2498E, and CLN2498E × E6203 (Hchk) were evaluated in replicated trials in Thailand, India, and Taiwan during two dry seasons. Highly significant effects for marketable fruit yield were detected in Thailand and Taiwan. ILH heterozygous for S. habrochaites segments at the bottom of chromosome 1 yielded about 20% than the Hchk at Thailand and Taiwan. Our results agree with previous results from Cornell University researchers who found a segment of S. habrochaites DNA located between TG158 and TG27 associated with increased total fruit yield in previous trials conducted in upper state New York. Yield improvement due to this S. habrochaites introgression can occur over a wide range of environments.     

Development of SCAR markers linked to the Ns locus in potato

A random amplified polymorphic DNA marker OPG17₄₅₀ linked to the Ns gene that confers resistance of potato to potato virus S (PVS), was used to develop sequence‐characterized amplified region (SCAR) markers. After cloning and sequencing of OPG17₄₅₀ new polymerase chain reaction (PCR) primers were designed to generate dominant (SCG17₃₂₁) and codominant (SCG17₄₄₈) markers. For SCG17₄₄₈, polymorphism between susceptible and resistant genotypes was recovered after digestion of the marker with the restriction enzyme Muni. In addition to the band corresponding to ‘susceptible’ allele that does not contain the Muni cleavage site, two bands of approximately 251 bp and 197 bp were observed in the resistant genotypes. The usefulness of these SCAR markers was verified in diploid potatoes possessing the Ns locus from clone G‐LKS 678147/60, and in tetraploid potatoes derived from G‐LKS 678147/60 and from clone MPI 65118/3.