Thumbnail Image

Thesis

Browse

20191
Reset filters
Subject: Genetics and Plant Breeding × Author: Agrawal, Neha × End date: 2019 × Start date: 2018 ×
Reset filters

Search Results

Now showing 1 - 1 of 1
  • Thumbnail Image
    ThesisItemOpen Access
    Disruption and delineation of the Brassica fruticulosa introgressions in Brassica juncea (l.) coss
    (Punjab Agricultural University, Ludhiana, 2019) Agrawal, Neha; Banga, S. S.
    Three B. juncea - B. fruticulosa introgression lines (ILs) AD-64, AD-101 and AD-104, carrying resistance against mustard aphid, were investigated using cytogenetic and genome sequence analysis to physically map the introgressed chromatin fragments into B. juncea genome. For the cytogenetic characterization of lines, four sets of massive oligo probes were developed for the first time in Brassicas. These probes allowed identification of all chromosomes of recipient B. juncea. Subsequently, these probes were used together with B. fruticulosa genomic probe to physically map introgressed segments using modified genomic in situ protocol. Multicolour in situ analysis led to identification of introgressed segments on chromosomes A05, B02, B03 and B04 in the distal regions in ILs AD 104 and AD-64. IL-101 revealed the introgressions on the same set of chromosomes with an additional introgressed segment on chromosome A01 at sub terminal to intercalary position. Introgressions on A01, B02, B03 and B04 were validated through bioinformatic analysis of whole genome sequences from these ILs, B. juncea and B. fruticulosa. We also attempted to disrupt these introgressions through gamma irradiation. A carefully selected set of 35 M3 progenies (out of 160 M3, developed following gamma irradiations (200 kR) were phenotypically characterized for aphid resistance and agronomic traits. These progenies showed varied levels of resistance to mustard aphid under screen house conditions coupled with early flowering, short stature and improved seed and pod size. Bioinformatic analysis confirmed post irradiation, breakdown of large alien chromosome fragments in several progenies. Phylogenetic analysis of 35 M3 lines along with their parental lines and three B. juncea cultivars allowed identification of many progenies that became genetically closer to cultivated B. juncea as compared to the parental ILs. Few of these were resistant to mustard aphid as well. Progenies N-31, N-36, N-38, N-78, N-65 of IL AD-64 were considered most important in that respect.