Pre-fertilization barriers, crossability, meiotic abnormalities and phenotypic characterization of inter-specific hybrids among Brassica species
| dc.contributor.advisor | Pant, Usha | |
| dc.contributor.author | Joshi, Shikha | |
| dc.date.accessioned | 2019-02-02T05:52:42Z | |
| dc.date.available | 2019-02-02T05:52:42Z | |
| dc.date.issued | 2018-07 | |
| dc.description.abstract | Interspecific hybridization is an important driving force in plant evolution and speciation. But not all of the crosses are successful, the cross incompatibility in the interspecific hybridizations has impeded the development of hybrids. A number of pre- and post-fertilization barriers limit the diversity of different genomic combination. The present investigation was carried out with the aim to get an idea of the crossability relationship among the species of Brassica, to study the pre-fertilization barriers that limit the formation of interspecific hybrid, phenotypic characterization of the interspecific hybrids recovered and to study the meiotic abnormalities during microsporogenesis of the interspecific hybrid. The investigation consisted of five Brassica species viz; B. rapa, B. nigra, B. juncea, B. napus and B. carinata. Field trials were carried out at N.E Borlaug Crop Research Centre, Pantnagar in rabi seasons of the years 2015-2016, 2016-2017 and 2017-2018. All the laboratory experiments were carried out following all the standard procedures in Cytogenetics and Molecular Marker Laboratory of the department of Genetics and Plant Breeding. Highest seed set percent was recorded for B. juncea × B. napus (28.89%) and lowest seed set percent was recorded for B. rapa × B. rapa (2.0%). High seed set (> 20% - <30%) was recorded for B. napus × B. rapa, B.carinata × B. nigra. Moderate seed set percent (> 10 % - < 20 %) was observed for B. nigra × B. juncea, B. napus × B. carinata, B. nigra × B. rapa, B. napus × B. nigra, B. juncea × B. Rapa while low seed set (>1% - <10%) recorded for B. carinata × B. rapa, B. juncea × B. nigra, B. napus × B. juncea, B. juncea × B. carinata, B. carinata × B. napus, B. rapa × B. juncea, B. carinata × B. juncea. Other crosses failed to set seed. Crossability of amphidiploid × amphidiploid crosses was highest among all of the crosses made and was followed by amphidiploid × diploid crosses and diploid × diploid crosses. Amphidiploids performed better as female parents in crosses between amphidiploids and diploids. Prefertilization barriers includes pollen tube abnormalities exhibiting coiling and bending of the tube, emergence of two pollen tubes from a single pollen grain, zigzag pollen tubes, swelling of pollen tube at the tip, pollen tube growing in wrong direction, branched pollen tubes, hairpin shaped pollen tube etc. Nature of the pollen tubes were however not specific to a particular cross. Pre-fertilization barriers were more prevalent in diploid × diploid crosses. The pollen germination percent showed highly significant and positive correlation with mean pollen tube growth, and percent siliqua set and highly significant and negative correlation with pollen tube abnormality percent. A highly significant and positive correlation also existed between mean pollen tube growth and siliqua set percent and a highly significant and negative correlation existed between mean pollen tube growth and pollen tube abnormality percent. Pollen tube abnormality percent had a highly significant and negative correlation with all of the crossability parameters with lack of correspondence with seed set percent. Siliqua set percent was found in correspondence with percent seed set. The morphology of interspecific hybrids was intermediate between both of the parents with predominance of female in some characters whereas in few crosses viz; B. napus × B. juncea and B. napus × B. carinata morphology of the hybrids resembled the female parent. The meiotic irregularities in the microsporogenesis of interspecific hybrids showed improper alignment of chromosomes at metaphase I and II, laggard chromosomes were also observed at anaphase I and II, bridge-fragment configuration at anaphase I and II and micronuclei at telophase II. These irregularities were however not specific to a particular interspecific hybrid. This study will help the breeders in choosing the parents and to decide the direction of the interspecific cross during gene transfer in wide hybridization in order to create novel genetic variation for crop improvement. | en_US |
| dc.identifier.uri | http://krishikosh.egranth.ac.in/handle/1/5810093339 | |
| dc.keywords | fertilization, crosses, meiosis, chromosome aberrations, meiosis, phenotypic variation, characterization, interspecific hybridization, Brassica | en_US |
| dc.language.iso | en | en_US |
| dc.pages | 96 | en_US |
| dc.publisher | G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand) | en_US |
| dc.research.problem | Brassica | en_US |
| dc.sub | Genetics and Plant Breeding | en_US |
| dc.subject | null | en_US |
| dc.theme | Genetic Parameters | en_US |
| dc.these.type | M.Sc | en_US |
| dc.title | Pre-fertilization barriers, crossability, meiotic abnormalities and phenotypic characterization of inter-specific hybrids among Brassica species | en_US |
| dc.type | Thesis | en_US |