鲤鱼种间、种内杂交中杂种优势强度表现的某些规律的初步研究

从1986年至1990年于我所松浦试验场,用黑龙江野鲤、荷包红鲤、兴国红鲤、红镜鲤、散鳞镜鲤、德国镜鲤和柏氏鲤进行了种间、种内14个组合的杂交,系统观察了不同组合亲本和杂种F_1在鳞被、体色、体型、生长、成活率、抗寒力、抗病力和起捕率等8个性状的遗传传递规律及其杂种优势强度,结果是.(1)鲤鱼种内异源杂交几乎所有的杂交组合的杂种F_1都表现出生长优势和对环境抗性的增强,其大小随亲本的亲缘远近和鳞被、体色、体型等性状间的差异而不同。一般品系间杂交,杂种生长的优势率在10％左右;品种间杂交,单交种的生长优势率在15—30％,三杂交种的生长优势率在30％以上。在抗寒、抗病、成活率等抗性上,表现出受其中一个亲本的影响,且有明显的母本效应,并可遗传传递给杂种后代。鳞被、体色、体型的基因效应,对杂种的生长有明显的促进作用。(2)鲤鱼种间杂交几乎不表现杂种优势,其特点:是柏氏鲤和黑龙江野鲤两个野生种间杂交,成活率、抗寒力强烈的表现不亲和性;而柏氏鲤与家养种间的杂交,表现一定的亲和性。亲本和杂种F_1的鳞被、体色仍表现显隐性关系,而体型、抗寒、抗病、成活率、起捕率等受柏氏鲤种质的强烈影响。获得抗寒力的杂种,在第二代时抗寒力明显消失,说明基因转移和整合的不稳定性。用柏氏鲤与散鳞镜鲤杂交的杂种F_1与另一抗寒很强的杂种F_1(黑龙江野鲤♀×红镜鲤♂)的双杂交种F_1,抗寒明显增强。     

Relationship of wild and cultivated forms of <Emphasis Type="Italic">Pisum</Emphasis> L. as inferred from an analysis of three markers,of the plastid,mitochondrial and nuclear genomes

Eighty-nine accessions of wild and cultivated peas (12 Pisum fulvum Sibth. et Smith., 7 P. abyssinicum A. Br., 31 wild and 42 cultivated forms of P. sativum L.) were analysed for presence of the variants of three functionally unrelated polymorphic markers referring to different cellular genomes. The plastid gene rbcL either contains or not the recognition site for restriction endonuclease AspLEI (rbcL+ vs. rbcL−); the mitochondrial gene cox1 either contains or not the recognition site for restriction endonuclease PsiI (cox1+ vs. cox1−); the nuclear encoded seed albumin SCA is represented by slow (SCA^S) or fast (SCA^F) variant. Most of the accessions possessed either of two marker combinations: 24 had SCA^F cox1+ rbcL+ (combination A) and 49 accessions had SCA^S cox1− rbcL− (combination B), 16 accessions represented 5 of the rest 6 possible combinations. All accessions of P. fulvum and P. abyssinicum had combination A, the overwhelming majority of cultivated forms of P. sativum had combination B while wild representatives of P. sativum had both combinations A and B, as well as rare combinations. This pattern indicates that combination A is the ancestral state in the genus Pisum L., inherited by P. fulvum and P. abyssinicum, while combination B seems to have arisen in some lineage of wild P. sativum which rapidly fixed mutational transitions of the three markers studied, most probably via a bottleneck effect during the Pleistocene. Then this ‘lineage B’ spread over Mediterranean and also gave rise to cultivated forms of P. sativum. Rare combinations may have resulted from occasional crosses between ‘lineage A’ and ‘lineage B’ in nature or during cultivation, or represent intermediate evolutionary lineages. The latter explanation seems relevant for an Egyptian cultivated form ‘Pisum jomardii Schrank’ (SCA^F cox1− rbcL−) which is here given a subspecies rank. Wild representatives of P. sativum could be subdivided in two subspecies corresponding to ‘lineage A’ and ‘lineage B’ but all available subspecies names seem to belong to lineage B only. Presently all wild forms would better be considered within a fuzzy paraphyletic subspecies P. sativum subsp. elatius (Bieb.) Schmalh. s. l.     

Discrimination among subterranean clover (<Emphasis Type="Italic">Trifolium subterraneum</Emphasis> L. complex) genotypes using RAPD markers

RAPD markers were applied to subterranean clover aiming at: (i) assessing the genetic relationships among the subspecies subterraneum L., brachycalycinum Katzn. et Morley, yanninicum Katzn. et Morley, as their taxonomic status is still debated; (ii) verifying the adoption of RAPDs to supplement the common morphological markers used for cultivar identification and protection; (iii) assessing the possible genetic diversity in relation to the geographic origin. Eight primers were selected for genetic analysis of 18 genotypes: 10 subsp. yanninicum (five from Greece and five from Sardinia), six subsp. subterraneum (forming three pairs, each one difficult to distinguish by morphological markers), and two subsp. brachycalycinum. Cluster analysis, performed on the Jaccards coefficients of association computed across the eight primers, formed three groups of genotypes, corresponding to the three subspecies. The results supported at the DNA level previous inferences, made at cytological, karyological, and isoenzymatic levels, on the ongoing speciation process within the subterranean clover complex, although not warranting yet the full species rank to the three forms. The genotypes of subsp. yanninicum were genetically closer to those of subsp. subterraneum than either group was to the subsp. brachycalycinum genotypes. Within the subsp. yanninicum cluster, the Sardinian genotypes appeared fairly distinct from those from Greece, suggesting a possible, independent evolution going on in different centres of diversity of this subspecies. In two pairs of subsp. subterraneum genotypes, the members could be unequivocally distinguished, thus supporting the role of RAPD fingerprinting in cultivar identification. In the third pair, the two genotypes appeared to be the same, inadvertently duplicated within the germplasm collection.     

Aegilops tauschii: Genetic Variation in Iran

All the 79 Aegilops tauschii Coss. accessions of Iranian origin from Prof. Kihara’s collection were analyzed electrophoretically. Of 23 enzyme-encoding loci studied, 11 were polymorphic. In Iran Ae. tauschii is presented by ssp. tauschii and ssp. strangulata which distinctly differ genetically, morphologically and ecologically. Variation patterns of low polymorphic locus Aco2 and highly polymorphic Ep are similar in both subspecies. In contrast, variation of Acph1, Ak, Est2, Est5, Got1, Got2, Got3 and Lap is a set of diverse patterns which markedly differ between subspecies and natural regions also, implying that natural selection is involved.