Interspecific crosses

Beier DR, Dushkin H, Sussman DJ. Mapping genes in the mouse using single-strand conformation polymorphism analysis of recombinant inbred strains and interspecific crosses. Proc Natl Acad Sci USA 1992 89 9102-9106. 

Unilateral incompatibility is a phenomenon in which self-compatible species can be crossed as a female, but not as a male, to self-incompatible species (Abdalla and Hermsen, 1972). Pollen tubes fail to penetrate stylar tissue in self-incompatible (female) X self-compatible (male) crosses. Although most diploid Solarium species are self-incompatible, the Mexican species S. verrucosum is self-compatible. Dinu et al. (2005) found that S. verrucosum could be crossed as a female, but not as a male, to self-incompatible species. It is sometimes possible to find exceptional plants that do not exhibit unilateral incompatibility in self-incompatible X selfcompatible interspecific crosses (Pandey, 1962). The identification of such plants allows a breeder to overcome the unilateral incompatibility crossing barrier. For example, exceptional plants ( acceptors ) that accept S. verrucosum pollen and produce fertile hybrids have been reported (Eijlander et al., 2000). It is interesting that some acceptor plants will accept pollen... 

It is important to note that, while knowledge of EBN and 2n gamete production allows for successful cross prediction most of the time, there are exceptions. Sometimes intra-EBN crosses fail and, at other times, inter-EBN crosses succeed even without the presence of 2n gametes. EBN is only one component of a complex system of pre- and post-zygotic interspecific crossing barriers (Masuelli and Camadro, 1997 Chen et al., 2004). 

Miller, J.F. and Gulya, T.J., Inheritance of resistance to race 4 of downy mildew derived from interspecific crosses in sunflower, Crop Sci., 31, 40-43, 1991. 

Werck-Reichhart, D., Batard, Y., Kochs, G., Lesot, A., and Durst, F., Monospecific polyclonal antibodies directed against purified cinnamate 4-hydroxylase from Helianthus tuberosus immunopurification, immunoquantification, and interspecific cross-reactivity, Plant Physiol., 102, 1291-1298, 1993. 

Wide Occurrence of Interspecific Cross-Talking in the Streptomyces Community 297... 

Some Results Utilizing Interspecific Cross-Conditioning. It is well known that the phenomenon of conditioning is not species specific. This fact was ascertained first by Benbadis (21) and successively confirmed by other authors (11,28,29). 

The overall goal of the TGI is to sequence and annotate more than 90% of the open reading frames in the genome of cultivated tobacco, Nicotiana tabacum. Nicotiana tabacum is an amphiploid species (2n = 48) likely resulting from an interspecific cross between Nicotiana sylvestris (2n = 24) and Nicotiana tomentosiformis (2n = 24), and at approximately... 

Interspecific cell hybrids between human and murine cells do not express the rDNA genes of both genes. Interspecific crosses in plants and between Xenopus species have also shown a gene-specific dominance effect. This phenomenon is known as nucleolar dominance and, depending on the chromosomal organization of the hybrid, the rDNA of either one of the species is expressed (Reeder, 1985). These findings indicated that there are some aspects of rDNA transcription that are species specific. The incompatibility between different species has then been... 

Fig. 3. Polyunsaturated fatty acid distribution in a G. maxx G. soja 2 population. The Glycine max parent of this interspecific cross, N85-2122, carries the fap allele for low-palmitic acid. The Glycine soja parent, PI 366121, exhibits high polyunsaturated fatty acid composition. Experimental approach is outlined in Pantalone etal. (9).

In contrast, development of the oilseed and root forms of B. napus appears to be relatively recent. The Greeks and Romans knew of the 8. napus swede or rutabaga root crops however, reference to these forms does not appear in the ancient literature, and wild populations of B. napus have not been found (Prakash and Hinata, 1980). Because the species is the result of an interspecific cross between B. campestris and B. oleracea, it could only arise where the two parental species were growing in close proximity. Since the distribution of wild B. oleracea was confined to the Mediterranean area, it is generally agreed that B. napus originated in Southern Europe. 

It is only in relatively recent times that B. napus forms have been introduced to Japan, China, and the Indian subcontinent. In the Far East the B. napus form has been more productive than indigenous oilseed forms of B. campestris. Today, most of the rapeseed produced in China, Korea and Japan is harvested from B. napus type plants that have been bred from interspecific crosses between Introduced B. napus and older indigenous B. cam-... 

Fukuhara, N. (1989) Fertility in interspecific-crossing between hinoki Chamaecyparis obtusa Endl.) and Sawara (C. pisifera Endl.) and identification of the hybrids. Bulletin of the Forestry and Forest Products Research Institute, 354 1-38. 

Many plants form viable interspecific crosses. Often these are sterile, which results in seedless fruits. Seedless varieties must either be hybrids of seed-producing parents or propagated vegetatively. Sometimes breeders use colchicine to induce polyploidy, resulting in a sexually reproducing interspecific hybrid with a double chromosome complement. 

Most alkaloid genetics research has been performed on interspecific crosses. There are some disadvantages of such studies. While the parent plants are fertile and viable, the hybrid is usually sterile, and the development of most plants is abnormal however, occasional hybrids are viable and vigorous. Seeds are produced in some instances, but the ratio of developed seeds to the number of ovules produced is very low. Also, only a small percentage of the pollen grains is viable. To secure the large number... 

In interspecific crosses the segregation ratios can be so badly obscured by irregularities of gametogenesis that a proper evaluation of the results is impossible. Nevertheless, such results may yield data which can serve to confirm tracer experiments. 

In connection with this, the analysis of isozymes of interspecific crosses is demonstrative. In interspecies fish hybrids of Lepomis gulosus x (JL. microlophus the inhibition of one of the paternal esterases was observed concomitant with asynchronous gene activation (Fig. 43 Whitt et al., 1972). In Micropterus salmonides x < Lepomis cyanellus fish hybrids the expression of maternal glucoso-6-phosphate dehydrogenase and one of the liver esterases is inhibited (Whitt et al., 1973a,b). Some of the fractions of paternal esterases are not active in virilisX( D. littoralis hybrids (Korochkin et al., 1973 a). 

---