Interspecific Derivatives Research Articles

Genetic diversity in advanced derivatives of Brassica interspecific hybrids

Genetic diversity among the 88 entries including eighty F4 derivatives i.e., 20 each selected from Brassica crosses viz., B. juncea × B. napus, B. juncea × B. rapa var. toria, B. juncea ×B. rapa var. yellowsarson and B. tournefortii × B. juncea, and eight parent genotypes was assessed through multivariate analysis (D2 statistic). Significant differences among the family groupsas well as within the family were recorded for all the 14 characters studied. The D2 analysis revealed enormous diversity among the interspecific cross derivatives. The genetic distances calculated among different Brassica species revealed that B. tournefortii had maximumdiversity with B. juncea followed by B. napus, B.rapa var. toria and B. rapa var. yellow sarson.Amongst interspecific crosses, maximum diversity was noticed indescendants of cross B. tournefortii × B. juncea followed byB. juncea × B. napus, B. juncea × B.rapa var. toria and the least in the cross B. juncea ×B. rapa var. yellow sarson. These results indicated that the derivatives selected from cross of diverse parents revealed greater diversity. The clustering pattern showed that many derivatives of the cross fell into the same cluster but in many cases in spite of common ancestry many descendants of the cross spread over different clusters. The characters, namely, plant height, secondary branches per plant, days to flowering and1000-seed weight were contributed maximum towards genetic divergence.

Resistance to Meloidogyne javanica in wild Arachis species

The root-knot nematode, Meloidogyne javanica Race 3 is an important nematode parasite of groundnut. Greenhouse evaluation of 184 accessions of 33 wild Arachis spp. five interspecific derivatives, 18 groundnut cultivars for root damage (galls formed by nematode) and nematode reproduction demonstrated that resistance to the nematode is available in the genepool of wild Arachis spp. Seven accessions, ICG 8952 (Arachis helodes), ICC 13211 (A. sylvestris), ICG 13224 (A. kretscmeri), ICG 13231 (Arachis sp.), ICG 14862 (A. kuhlmannii), ICG 14868 (A. stenosperma), and ICG 14915 (A. sylvestris) were highly resistant to nematode reproduction and root damage. There was no gall and eggmass formation on any plant of these accessions. Thirty-three accessions were resistant and 14 were moderately resistant. All the tested accessions of A. monticola, A. benensis, A. ipaensis, A. hoehnei, A. kempff-mercadoi, A. valida, A. chiquitana, A. rigonii, A. vallsii, A. dardani, A. paraguariensis, A. triseminata, interspecific derivatives, and groundnut cultivars were susceptible. The possible use of resistance sources in the breeding program is discussed.

S-related protein can be recombined with self-compatibility in interspecific derivatives ofLycopersicon

S-related protein can be recombined with self-compatibility in interspecific derivatives ofLycopersicon

S-related protein can be recombined with self-compatibility in interspecific derivatives ofLycopersicon

Stylar proteins involved in the self-incompatible (SI) response of Lycopersicon hirsutum have been identified and mapped to the locus that controls SI (S locus). L. esculentum, a self-compatible (SC) species of cultivated tomato, does not display these proteins. Hybrids between SC L. esculentum and SI L. hirsutum are self-sterile despite these individuals bearing pollen containing the S allele of L. esculentum. In progeny derived from backcrossing the hybrids to L. esculentum, there was a strong correlation between the presence of the S allele from L. hirsutum and self-infertility. However, this relationship was uncoupled in a number of backcross (BC) progeny. The SI response appeared to be nonexistent in two self-fertile BC individuals that were heterozygous for the S allele of L. hirsutum, based on Mendelian segregation of a tightly linked DNA marker, CD15, in selfed progeny. Among these progeny self-fertile individuals that were homozygous for the L. hirsutum allele of the linked marker were also determined to be homozygous for an S-related proteins are not sufficient to elicit a self-incompatible response in L. esculentum and that there is a mutation(s) in L. esculentum somewhere other than the S locus that leads to self-compatibility.

Comparative studies of isozymes in Oryza sativa, O. minuta, and their interspecific derivatives: evidence for homoeology and recombination

Enzyme electrophoresis was used to compare the isozyme phenotypes of Oryza sativa, IR31917 (AA genome), and two O. minuta accessions (Om 101089 and Om101141; BBCC genome) for ten enzyme systems. Between the two species, two systems were monomorphic (isocitrate dehydrogenase and alcohol dehydrogenase) and eight were polymorphic (shikimate dehydrogenase, phosphogluconate dehydrogenase, phosphoglucose isomerase, malate dehydrogenase, glutamate oxaloacetate transaminase, esterase, aminopeptidase, and endopeptidase). Polymorphism between O. minuta accessions was detected for shikimate dehydrogenase and glutamate oxaloacetate. As expected, the quaternary structure of the O. minuta isozymes was comparable to that of O. sativa. Possible allelic relationships with known O. sativa alleles and their genomic designation are discussed. Combined with chromosome data, the interspecific variation was exploited to monitor the relative genetic contribution of the two parents in the IR31917/Om101141 F1 hybrids and recurrent (IR31917) backcross progenies. The isozyme content of F1 hybrid reflected its triploid nature (ABC genome composition), while that of the backcross progenies paralleled the duplication of the A genome and the gradual loss of O. minuta chromosomes during the backcrossing process. Evidence is provided for a degree of homoeology between the A, B, and C genomes, and for introgression from O. minuta into O. sativa.

Experimental Studies on the Nature of Species. VI. Interspecific Hybrid Derivatives between Facultatively Apomictic Species of Bluegrasses and their Responses to Contrasting Environments.

Experimental Studies on the Nature of Species. VI. Interspecific Hybrid Derivatives between Facultatively Apomictic Species of Bluegrasses and their Responses to Contrasting Environments.

Chromosome numbers of the genusCalamagrostis in Japan

Chromosome counts for 783 collection ofCalamagrostis in Japan are reported. These include the first record forC. tashiroi and the reports of new cytotypes inC. stricta, C. hakonensis andC. longiseta. The geographical distribution of different cytotypes ofC. langsdorffii andC. hakonensis is outlined. Counts are also reported for a number of “intermediates” which are supposed to be interspecific hybrids or hybrid derivatives. A summary of chromosome counts for JapaneseCalamagrostis so far recorded is tabulated. No diploid plants with 2n=14 chromosomes are found. The tetraploid taxa, which are plentiful and seem to have adaptively radiated in Japan, jack any sign suggestive of their recent origin from the diploids. It is suggested that plant with 2n=28 (4X in the traditional sense) may be regarded as semidiploid and having that behavior, and that speciation ofCalamagrostis in Japan has occurred principally at this chromosome level. Speciation by means of amphiploidy may have been scarce. It is also suggested that hybridization and polyploidy have greatly contributed to the formation of complicated internal structure of various species.

THE EFFECT OF INTERSPECIFIC HYBRIDIZATION ON CERTAIN GENETIC RATIOS IN SWEET CLOVER

In crosses involving derivatives of interspecific crosses of (Melilotus alba × Melilotus dentata) and (M. officinalis × M. alba) with pure Melilotus alba, irregular ratios were shown to be common. Previous studies using pure M. alba have indicated simple Mendelian inheritances for many of the characters studied herein. However, when interspecific derivatives are involved, some plants give F2 families that do not fit any Mendelian ratio. Data are presented indicating that in segregations where the deficiency occurs it is always in the genotype that has contributed the gene from the non-recurrent species. Investigations carried out in this study are designed to determine possible causes for these "blurred" ratios.