水牛胎儿成纤维细胞转染外源基因的初步研究

研究了水牛胎儿成纤维细胞（buffalo fetal fibroblasts,BFF）转染外源基因后的细胞生物学特性。纯化含有绿色荧光蛋白（green fluorescent protein,GFP）和新霉素抗性基因的线性化载体,用脂质体法转染体外培养3代的BFF细胞,应用抗生素G418筛选2周后挑取转基因抗性细胞集落扩大培养。结果发现：经过G418筛选后细胞增殖活力下降,胰蛋白酶消化法共分离获得162个转基因水牛阳性细胞集落,转移到24孔板扩大培养后,132个（85．2％）细胞集落可以存活,转移到4孔板中后仅有52个（32．1％）细胞集落能继续生长,最终能在35mm培养皿中大量培养的只有15个（〈9．3％）。抗性细胞由梭形、成簇生长变为多角形、不规则形弥漫生长,立体感减弱,细胞生长速度减慢,活力下降。染色体核型异常率增加,10个抗性细胞集落核型正常率平均为61％,显著低于对照组86．7％（P〈0．01）。研究结果为建立和优化BFF细胞转染外源基因平台奠定了工作基础。     

Classification of Peruvian highland maize races using plant traits

The maize of Latin America, with its enormous diversity, has played an important role in the development of modern maize cultivars of the American continent. Peruvian highland maize shows a high degree of variation stemming from its history of cultivation by Andean farmers. Multivariate statistical methods for classifying accessions have become powerful tools for classifying genetic resources conservation and the formation of core subsets. This study has two objectives: (1) to use a numerical classification strategy for classifying eight Peruvian highland races of maize based on six vegetative traits evaluated in two years and (2) to compare this classification with the existing racial classification. The numerical classification maintained the main structure of the eight races, but reclassified parts of the races into new groups (Gi). The new groups are more separated and well defined with a decreasing accession within group × environment interaction. Most of the accessions from G1 are from Cusco Gigante, all of the accessions from G3 (except one) are from Confite Morocho, and all of the accessions from G7 are from Chullpi. Group G2 has four accessions from Huayleño and four accessions from Paro, whereas G4 has four accessions from Huayleño and five accessions from San Geronimo. Group G5 has accessions from four races, and G6 and G8 formed small groups with two and one accession each, respectively. These groups can be used for forming core subsets for the purpose of germplasm enhancement and assembling gene pools for further breeding.     

Additive gene action for resistance to Puccinia striiformis F.SP. Tritici in Triticum dicoccoides

Summary Seven single-plant selections of wild emmer, with temperature-sensitive minor-effect genes for stripe rust resistance, were intercrossed in eight combinations. The resulting progenies were studied for a possible additive gene action.The transgressive segregation towards resistance in F₂ observed in all the combinations indicates that additive gene action for resistance indeed occurs in wild emmer. The common occurrence of this phenomenon in random combinations suggests further that several minor-effect genes are involved.Following selection of the most resistant plants in F₂, a marked shift towards resistance was noted in F₃, which demonstrates a positive response to selection. In some instances, additive resistance selected for (in F₂) at the high temperature-profile was expressed (in F₃) also at the low temperature-profile. This kind of resistance, when utilized in breeding programmes, promises therefore to be effective over a range of temperatures.     

Resistance to the gall mite and American gooseberry mildew in black currants in relation to season of leafing out

Summary In black currant (Ribes nigrum) backcross progenies segregating for resistance to the gall mite, Cecidophyopsis ribis Westw. (gene Ce from Ribes grossularia L.), and to American gooseberry mildew, Sphaerotheca mors-uvae (Schw.) Berk. (gene Sph ₃from R. glutinosum), significant differences in season of leafing out occurred between the resistant and susceptible classes. The data are consistent with the hypothesis that two additive genes, Lf ₁and Lf ₂, controlled season of leafing out and that Ce and Sph ₃ were linked with Lf ₁.     

Breeding maize lines for complete and partial resistance to maize streak virus (MSV)

Summary S₁ to S₅ inbred lines, derived from a maize population bred for its overall resistance to three tropical viruses, were screened for resistance to maize streak virus (MSV) by artificial plant infection using viruliferous leafhoppers. Symptoms were rated and intra-line frequency distributions studied for all pedigree inbred lines. Mortality due to MSV was very low among these inbreds. Symptoms appeared later, developed slower and were less severe than in the susceptible control hybrid. Results of a study of 500 S₁ and 93 S₂ lines suggested that resistance is under genetic control via a system involving loci with major genes (with dominance for resistance) controlling high to complete resistance, associated with a genetic system involving loci with minor genes controlling partial resistance. Lines expressing complete resistance to MSV were developed from 5 cycles of inbreeding and selection. The relevance of such complete and partial resistance is discussed.Abbreviations MRPS Mean Rating for Plants exhibiting Symptoms     

不同杉木种源在贵州省适生栽培区高生长及稳定性分析

杉木在我国有广泛的分市区。以北纬21°41′至北纬34°03′,东经101°45′至东经121°53′之间的广阔亚热带区域都有杉木的自然分布。由于长期的自然条件和漫长的自然选择影响,必然产生了对各种生态因子要求各异的群体,这些不同群体如在分布区内不同生态区进行交流,很有可能会产生各种各样的适应程度表现。 我国目前杉木引种已很普遍。选择生长量高且具有稳定增产效益的引种对象,已是人们日益关心的问题。本文对贵州省已有栽培的来自全国各地共64个种源在贵州省不同栽培地点稳定性进行分析,结合差异分析,为贵州省不同地区的杉木种子调拨区划提供数量化依据。     

Distribution and allelic expressivity of genes for hybrid necrosis in some elite winter and spring wheat ecotypes

The distribution and allelic expressivity of hybrid necrosis genes (Ne ₁ and Ne ₂) were studied in 21 winter (mostly exotic) and 43 spring type elite wheat genotypes, by crossing them with two known testers, C 306 (Ne ₁-carrier) and HD 2380 (Ne ₂-carrier).Ne ₁ gene was present in one north-west Himalayan winter wheat landrace, Shoure Local, but absent in the other winter as well as spring wheats. Ne ₂ gene was prevalent to a much lower extent in the exotic winter wheat germplasm (31.57%) as compared to the recently developed Indian and Mexican spring wheat semidwarfs (69.80%). This may suggest that breeders have tried to preclude hybrid necrosis by selecting for non-carrier genotypes in the development of exotic winter wheats in contrast to the situation in spring wheats. Based on the degree of expression of hybrid necrosis genes in the F₁ hybrids, the carrier genotypes were characterized with respect to the allelic strength of the hybrid necrosis genes. The 27 non-carrier genotypes of the two ecotypes identified in the present study have a greater potential use in future hybridization programmes so as to overcome the problem of hybrid necrosis. This revised version was published online in July 2006 with corrections to the Cover Date.     

Interrelationships among height,lodging and yield in determinate and indeterminate soybeans

Summary Seventy-three determinate and 93 indeterminate random F₉ lines from a cross between determinate and indeterminate soybean [Glycine max (L.) Merr.] parents were evaluated for seed yield, mature plant height, and lodging. Regression analyses indicated that among the determinate lines, seed yield increased by 350 kg/ha and lodging score increased by 0.008 for every 10 cm increase in plant height. Among indeterminate lines seed yield increased by 112 kg/ha and lodging score by 0.3 for every 10 cm increase in plant height. The highest yielding indeterminate lines were tall and very susceptible to lodging. The tall determinate lines had the best combination of high seed yield and excellent lodging resistance.Cooperative Investigations of the Science and Education Administration, U.S. Department of Agriculture and the Purdue University Agricultural Experiment Station.     

The effect of major dwarfing genes on yield potential in spring wheats

Summary A composite convergent cross of 16 spring wheat parents produced a set of unselected progeny lines among which the major dwarfing genes, Rht1, Rht2 and Rht3, were distributed against a common random genetic background. Random subsets of these lines were grown under irrigation and optimal conditions in 4 experiments with replicated bordered plots in southern New South Wales in order to measure the dwarfing gene effect on yield potential. The dwarfing gene composition of each line was determined by test crossing and seedling responsiveness to gibberellic acid.Lodging was negligible in the two experiments in 1982. While present in the two in 1983, it was not strongly associated with yield. Grain yield levels were appropriately high (mean 5.9 t/ha). In all but 1 experiment the Rht1+Rht2 dwarf genotypes gave highest yields while the Rht3 group yielded on average 3% lower, Rht2 9% lower, Rht1 11% lower, and the non-dwarf or tall group yielded 24% lower. These yield differences were positively associated with harvest index, kernels per m² and kernels per spike, but negatively associated with mature plant height. Even within major dwarfing gene classes, grain yield was significantly and negatively associated with height.