Cytogenetic Studies of Some F1 Hybrids between Wild and Cultivated Taxa of Capsicum L.

Abstract

Summary Two F 1 hybrids one between wild C. annuum var glabrisculum and C. frutescens (H 1 ) and another between wild C. annuum var antigua and C. frutescens (H 2 ) were obtained. Cytogenetic analysis of F 1 hybrids showed that the parental genomes differ from each other by 2 or 1 translocations, 1 inversion and some minor structural alterations leading to reduced homologies between the respective parental genomes. Meiotic irregularities pollen and seed sterilities were higher in H 2 than in H 1 . Probable reasons for the differences in respect of their crossability relationships, chromosome pairing and fertilities in non-rearing of reciprocal hybrids are suggested. The role of chromosome structural changes in genome differentiation is suggested. Isolating mechanisms viz., hybrid inviability and hybrid weakness in the reciprocal cross and hybrid sterility in the F 1 hybrids are in operation. Key words Capsicum annuum L., C. frutescens L. interspecific hybrids, Cytogenetics.The genus Capsicum commonly known as chilli pepper, is a major crop and is almost cosmopolitan in distribution. The genus comprises of 5 domesticated and 20 wild species (Anonymous 1983). From the taxanomic standpoint interspecific relationships among them have not been well understood even today. Though cross compatibility relationships among some taxa of this genus have been reported by quite a few workers (Smith and Heiser 1951, Lippert et al. 1966, Ohta 1961, Pickersgill 1971, Venkateswara Rao and Yesoda Raj 1974, Egawa and Tanaka 1984, 1986, Aniel Kumar et al. 1987, 1988 these were mostly confined to the breeding behaviour of the F 1 hybrids. Information on cytogenetic analysis of species hybrids of apsicum is meager (Egawa and Tanaka 1984, Aniel Kumar et al. 1987, 1988. Further, information relating to the cytogenetic behaviour of F 1 hybrids between wild and cultivated species is very meager (Egawa and Tanaka 1984, Aniel Kumar et al. 1988). In view of this, the present study is taken up to elucidate cytogenetic relationships between 2 wild forms of C. annuum and a cultivated form of C. frutescens on the basis of meiotic chromosome pairing, behaviour and fertility of F 1 hybrids and the results are documented in the present communication. Materials and methodsSeeds of 2 wild varieties of C. annuum viz. var, glabrisculum, and var, antigua and cultivar Tabasco of C. frutescens were obtained from. E. Pochard, Monotofavet, Avignon, France. All the 3 accessions were selfed for several generations before these were employed in the hybridization programme. Reciprocal crosses have been attempted by controlled pollinations between each of the 2 varieties of C. annuum with C. frutescens. Hybrids were obtained between C. annuum var glabrisculum and C. frutescens, and C. annuum var antigua and C. frutescens and are referred to as H 1 , H 2 respectively in the text.Young flower buds of the parents and hybrids were fixed in acetic acid and alcohol mixture (1 : 3) and transferred to 70% alcohol after 24 h of fixation. Squashes were made in 2% aceto-

New Insights into Capsicum spp Relatedness and the Diversification Process of Capsicum annuum in Spain

“…The C. annuum complex contains C. annuum , C. chinense , C. frutescens , their wild relatives and C. galapagoense Hunziker. These species are integrated into a morphological continuum and they are potentially crossable with ease, although compatibility might be affected by the pollinated genotypes, the direction of crossing or even by the reciprocal 1/8 chromosome translocation event that differentiates C. annuum from its related species [7] – [9] . Many authors have argued that at least C. frutescens and C. chinense should be combined into one species [10] , [11] .…”

Genetic, embryonic and anatomical study of an interspecific cassava hybrid

“…Nassar (1978) explained that his type used in crosses is not a pure type and that it is different from M. oligantha Pax in leaf type and tuber formation, characters that are assumed to have been acquired from cassava by natural hybridization followed by subsequent introgressive crosses in the direction of M. oligantha. From a plant breeding viewpoint, this is an advantageous aspect in our program, since bivalent configuration usually indicates the parental degree between species and the probability of gene transfer between them (Kumar et al, 1988;Nassar, 2003b,c;Panda et al, 2004).…”

Cytogenetics, Embryology, and Stem Anatomy of a Cassava Interspecific Hybrid

“…Nassar explained (1978) his type used in crosses is not a pure type and it is different from M. oligantha pax in leaf type and tuber formation, characters which assumed to have beeen aquired from cassava by natural hybridization followed by subsequent introgressive crosses in direction of M. oligantha. From a plant breeding viewpoint this is an advantageous aspect in our program since bivalents configuration usually indicates the parental degree between species and the probability of gene transferring between them (Kumar et al 1988, Panda et al 2004.…”