胚挽救技术在植物育种中的应用

综述了胚挽救技术在植物远缘杂交、挽救发育不良或早期退化胚、培育三倍体及多倍体新种质方面的应用,分析了培养时期、培养基以及培养环境等因素对胚挽救效果的影响。     

佛坪自然保护区濒危野生动物救护案例启示

通过对佛坪国家自然保护区大熊猫、羚牛、金雕等3种濒危珍稀动物野外救护案例分析,提出了秦岭地区自然保护区濒危珍稀动物保护、救护方略。     

Breaking the crossability barriers between disomic tetraploid Solanum acaule and tetrasomic tetraploid S. tuberosum

Summary A combination of compatible second pollinations and embryo rescue was applied for systematic production of true tetraploid hybrids from crosses between disomic tetraploid Solanum acaule and tetrasomic tetraploid potato, S. tuberosum. Several genotypes of tetraploid potatoes were pollinated with S. acaule, and the compatible second pollinations were made on the following day, with a genotype of S. phureja, IvP 35 to promote fruit development. Embryo rescue was carried out in 21 families, 14 to 27 days after the first pollination. A total of eight plants were obtained from the embryo rescue and their chromosome numbers were counted in the root tips. Three of the eight plants were identified as tetraploid, and five others as diploid. Morphology, isozyme banding patterns, and pollen stainability, as well as potato spindle tuber viroid (PSTVd) resistance, indicated the hybrid nature of the three plants. This is the first report of successful tetraploid hybrid production between disomic tetraploid S. acaule (4x) and tetrasomic tetraploid potatoes. Seed set from the crosses between one of hybrids and diploid potatoes indicated workable levels of both male and female fertility for introgression of valuable genes from S. acaule into the cultivated potato gene pool. The methodology used may be applied to other disomic tetraploid tuber-bearing Solanum species and with some modifications also to distantly related solanaceous species and genera.     

Congruity backcrossing as a means of creating genetic variability in self pollinated crops: seed morphology of Phaseolus vulgaris L. and P. acutifolius A. Gray hybrids

Summary Seeds of early generations of three reciprocal congruity-backcross (CBC) pedigrees, developed by backcrossing Phaseolus vulgaris-P. acutifolius hybrids to each of the parent species in alternate generations, exhibited a preponderance of traits (size, shape, color, and pattern) of the cytoplasmic parent. The large size of Red Cloud (V₁), the P. vulgaris parent common to all of the pedigrees, dominated pedigrees with V₁ as the cytoplasmic parent, while the small size and rounded or square shapes of the tepary parents, wild P. acutifolius var. acutifolius PI 263590 or G400445 (A₁₉), wild P. acutifolius var. latifolius PI 406622 (A₁₀), or cultivated P. acutifolius var. latifolius Serowi PI 319443 (A₉), were the majority phenotypes when P. acutifolius was the cytoplasmic parent. Continuing through the second cycle of CBC, that is the second backcross with each of the parent species or the fourth backcross, began an amelioration of the apparent cytoplasmic effect on gene expression, as reciprocal pedigrees became more alike, usually with intermediate expression of parental traits or the appearance of new traits. The large seed size of V₁ was recovered in hybrids with P. acutifolius cytoplasm and the kidney shape of V₁ became rare in hybrids with P. vulgaris cytoplasm. Although the tepary-bean parents represented two subspecies and both cultivated and wild P. acutifolius, the three sets of reciprocal-hybrid pedigrees with P. vulgaris Red Cloud are surprisingly similar. It may be that the exotic parent used to develop a CBC pedigree should be selected more for combining ability in the interspecific cross than for specific economic traits. While the number of generations (six or more) required to produce fertile, intermediate CBC hybrids (that did not require embryo rescue) may preclude routine use of this method by practical plant breeders, the crossability of advanced hybrids with both parental species and the amount of variability apparent in advanced-hybrids progenies suggests that CBC would be valuable for maintaining exotic germplasm in immediately useful forms.     

Interspecific hybrids of Cyclamen persicum and C. graecum

Summary Interspecific crosses were made to introduce the disease resistance of Cyclamen graecum into C. persicum cultivars and the abortive hybrid embryos were rescued by ovule culture. Diploid and tetraploid cultivars of C. persicum (CPD, 2n=2x=48; CPT, 2n=4x=96) were the pistillate parents and wild form of C. graecum (CG, 2n=84) were the staminate parents. After pollination, crossed ovaries were periodically collected and examined using paraffin sections. Histological observations suggested that both hybrid ovules of CPD × CG and CPT × CG should be transferred to the culture medium 35 days after pollination. Based upon this observation, crossed ovaries were collected 35 days after pollination, then ovules with placenta were explanted on culture medium and cultured in the dark at 25°C. Plantlets were induced from ovules cultured in MS medium containing 3% sucrose and 10% coconut milk. The hybrids (2n=66) derived from CPD × CG failed to yield viable seeds by self-pollination, although they showed some pollen fertility. In contrast, the hybrids (2n=90) derived from CPT × CG showed high pollen fertility and yielded viable seeds by self-pollination. Furthermore, they were resistant to disease caused by Fusarium oxysporum f. sp. cyclaminis, Erwinia herbicola pv. cyclamenae and Pseudomonas marginalis pv. marginalis.Abbreviations CPD C. persicum diploid - CPT C. persicum tetraploid - CG C. graecum     

Interspecific hybridization between Cicer arietinum and C. pinnatifidum

An interspecific hybrid between Cicer arietinum cv. GL 769 and a wild species C. pinnatifidum was obtained after emasculation, pollination and application of growth regulators. Ovules were cultured and embryos were later dissected to obtain hybrid plants. These plants were albinos and morphologically resembled C. pinnatifidum. Shrivelled seeds were also obtained in 2% of the crosses, which on germination gave rise to albino plants. These plants did not survive beyond 20 days. The hybrid nature of these plants was confirmed by esterase isozyme studies. Hybrid shoots obtained from germinating embryos were cultured on modified ML-6 medium with BAP 2 mg/1, IAA 0.5 mg/1, where they turned green after 3–4 weeks. Transmission electron microscopy (TEM) studies on leaf sections from green hybrid shoots showed an improvement in the chloroplast structure, with better organized grana.