Publications of NIPGR Scientists

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Author: search.filters.author.Sharma, VishakhaSubject: search.filters.subject.Compound stipule

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    Interaction between cochleata and stipule-reduced mutations results in exstipulate hypertrophied leaves in Pisum sativum L.
    (NISCAIR-CSIR, India, 2013) Kumar, Arvind; Sharma, Vishakha; Kumar, Sushil
    In the wild type P. sativum, each of the adult plant stem nodes, bears a pair of sessile foliaceous stipules and a petiolated unipinnately compound leaf of 4 to 6 leaflets and 7-9 tendrils. The stipule-reduced (st) and cochleata (coch) single null mutants and coch st double null mutant differ fom the wild type in respectively having sessile stipules of much reduced size, petiolated simple and/or compound leaf-like stipules and no stipules. It is also known that coch leaves are somewhat bigger than st and wild type leaves. Here, pleiotropic phenotype of coch st double mutant was investigated. The morphologies of stipules and leaf were quantified in the field grown plants and microcultured shoots, latter in the presence and absence of gibberellic acid and N-1-naphthylphthalamic acid. The observations showed that as compared to the corresponding plants or shoots of COCH ST (WT) genotype, (a) coch st plants bore leaves in which all the organs were hypertrophied; (b) full complement of leaflets and 3-5 tendrils were formed on leaf; (c) the microcultured coch st shoots were taller despite lower number of nodes, and (d) they also produced leaves in which all the organs were bigger and the ratio of leaflets/tendrils was higher. It was concluded that in coch st double mutant (a) ST function is essential for stipule primordium differentiation, in the absence of COCH function and (b) absence of negative feedback loops between simple stipules and compound leaf for metabolite utilization allows hypertrophied growth in leaves.
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    Organ-wise homologies of stipule, leaf and inflorescence between Pisum sativum genetic variants, Delonix regia and Caesalpinia bonduc indicate parallel evolution of morphogenetic regulation
    (Springer, 2012) Sharma, Vishakha; Tripathi, Bhumi Nath; Kumar, Sushil
    Plants of the garden pea Pisum sativum an annual Papilionaceae species which have a mutation in the COCHLEATA (COCH) gene bear compound stipules of leaf morphology and secondary inflorescences in which flowers are borne in axils of bracteoles on an inflorescence stem. In the wild-type P. sativum stipules are simple foliaceous and flowers are non-bracteolated. Mutants of the coch phenotype are not known in any other plant species. The COCH gene of P. sativum is not yet sequenced. Therefore whether or not the COCH gene is present in species other than P. sativum remains unknown. Based on the principle of parallel evolution, it is thought that there may be leguminous species that possess the coch phenotype. In search of coch species, the Leguminosae flora of Delhi was surveyed for species that demonstrate compound stipules and bracteolated inflorescences. Out of 124 reported in the Leguminosae flora of Delhi, only the perennial Caesalpinioideae tree species Delonix regia and the shrubby vine species Caesalpinia bonduc were observed to have features of the coch mutants of P. sativum. Since the traits of simple foliaceous stipules and bracteoleless secondary inflorescences of wild-type P. sativum are common to many species among more than 19,400 species of family Leguminosae, it is hypothesized that the COCH gene may be as common as the ubiquitously present LEAFY gene (orthologue of UNIFOLIATA gene of P. sativum) in angiosperms.