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Subject: Agricultural Biotechnology × Author: Harmanpreet Kaur × End date: 2022 × Type: Thesis × Thesis Type: Ph.D ×
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    Identification and characterization of genes for regular and irregular bearing in mango (Mangifera indica L.)
    (Punjab Agricultural University, 2022) Harmanpreet Kaur; Sidhu, Gurupkar Singh
    The mango, known as the "King of Fruits," is a member of the Anacardiaceae family and is the most important fruit crop grown in India because of its exquisite flavour. Flowering is a crucial phenophase, since it directly impacts the production. Mango flowering, however, is a complicated phenomenon. Typically, it bears a large crop in one year (on year) and produces little to nothing in the following year (off year). The gene expression analysis for flowering genes in regular (Amrapali and Neelum) and irregular (Dashehari) bearing cultivars was done using RNA-Seq. Illumina technology was used to sequence the cDNA libraries made from the leaves, shoot apex, and inflorescence tissues of Dashehari, Amrapali, and Neelum. For Dashehari, Amrapali, and Neelum, paired-end high-quality clean reads of 117 Mb, 74 Mb, and 24 Mb, respectively, were obtained. Dashehari's de novo assembly generated 67,915 transcripts, 25,776 trinity genes, and N50 value of 1,981. The transcripts were annotated using BLAST2GO and PfamScan, and the biological process, molecular function, and cellular component functional categories of GO were used to group the genes. Major pathways include the sucrose and starch metabolism, tryptophan biosynthesis, trehalose biosynthesis, and phenylpropanoid biosynthesis were found by KEGG and Plant Reactome analyses. From the FLOR-ID flowering database, ortholog transcripts were found using reciprocal blast, and 85 genes relevant to flowering were found. In this study, more genes were found to be up-regulated in leaves of Dashehari bearing tree than in non-bearing tree, in inflorescence than in leaf and apex, and in Amrapali than Dashehari among varieties. In particular, genes associated with photoperiod (CO, GI, FTIP1 and FT), vernalization (FRI4 and VIN3), the circadian clock (LHY1, TIC and PRR7), age (TOPLESS and SPL15), and the hormonal pathway (BR1, EIN3, T6P and GA20OX) were identified. Using qRT-PCR, we validated 18 flowering-related genes for regular and irregular bearing in the three genotypes. All the genes demonstrated greater expression values in leaves of Dashehari bearing tree as compared to non-bearing tree and in Amrapali, which is congruent with the expression values revealed from the transcriptome data. These results will help in the discovery of regulatory regions and factors implicated for regularity in mango fruit bearing, and they will establish the foundation for understanding the cellular and molecular mechanisms involved in regular and irregular bearing fruit varieties.