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Subject: search.filters.subject.Apomixis

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    Transcriptome analysis of differentially expressed genes during embryosac development in apomeiotic non parthenogenetic interspecific hybrid of Pennisetum glaucum
    (Springer, 2012) Sahu, Pranav Pankaj; Gupta, Sarika; Malaviya, D. R.; Roy, Ajoy Kumar; Kaushal, Pankaj; Prasad, Manoj
    Apomixis results in the production of genetically uniform progeny, derived from the fertilization independent development (parthenogenesis) of an unreduced egg cell (apomeiosis). To identify genes involved in the apomeiosis, a comparative transcriptome analysis of differentially expressed genes during embryo sac (ES) development in a sexual Pennisetum glaucum (genotype 81A1) and its apomeiotic (aposporic) non-parthenogenetic interspecific hybrid (BC1GO) was investigated. BC1GO exhibited the partitioned apomeiosis component, whereby the second apomixis component viz., parthenogenesis was completely lacking. A total of 96 non-redundant transcripts were recovered using suppression subtractive hybridization and classified into 11 different categories according to their putative functions. Amongst the identified transcripts, many of them belonged to unknown function (40%) followed by those involved in protein metabolism, stress response, pollen/ovule/embryo development, and translation/protein modification process. A data search of transcriptional profiling in other apomictic species revealed that 75% of the differentially expressed transcripts have not been reported in previous studies. By macroarray analysis, we identified differential expression pattern of 96 transcripts, 45 (47%) of which showed ≥2-fold induction in apomeiotic BC1GO. Further, the obtained results were validated by quantitative real-time polymerase chain reaction to have a comparative expression profiling of eight selected up-regulated transcripts (≥2.5-fold) between BC1GO and 81A1 at different phases of ovule development. In silico mapping demonstrated that 13 transcripts were located onto rice chromosome 2, region syntenic with the apospory locus as reported in Brachiaria brizantha and Paspalum notatum. The expression patterns of these transcripts showed a significant difference at differentiating megaspore mother cell and gametogenesis stages thereby suggesting their involvement in floral development during apomeiotic (Panicum-type aposporous) ES development.
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    Apomixis revisited
    (Indian Academy of Sciences, 2006) Kumar, Sushil
    The discussions recently published in Current Science, as reviews on apomixis in higher plants, by Kaushal et al. and Bhat et al., are valuable contributions for generating new ideas in this agriculturally important area. Besides describing the characteristics of the various forms of apomixis, the authors1,2 have also attempted to identify techniques that can be used to observe the occurrence of apomixis, and features to be present in model systems, as also approaches that should be employed in these to understand the biology of apomixis in molecular terms. The authors have reached the conclusion that, to unravel the enigma of apomixis (formation of seeds having maternal genotype without fertilization), detailed knowledge of the molecular biology of plant reproductive process is a prerequisite for its apomictic manipulation. They have advised that new experimentation on apomixis be directed in Arabidopsis and rice plants and it be designed to reveal the regulation of meiosis, endosperm development and parthenogenetic or apomictic embryo development. They have opined that knowledge-based deregulation of the key regulatory step(s) of the above-mentioned plant processes might help engineer apomixis in these systems. The conclusion is unquestionable.