Browsing by Author "Preethi, P."

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    Application of RAPD markers in hybrid verification in coconut
    (2014) Rajesh, M.K.; Jerard, B.A.; Preethi, P.; Regi Jacob Thomas; Anitha Karun
    Coconut palms are classified into two major types, viz., ‘talls’ and ‘dwarfs’, which mainly differ in their pollination behavior of cross- and self-pollination, respectively. Due to this difference, getting true-to-type progenies of desirable tall and dwarf cultivars has always been a challenge. The conventional practice of selection of seedlings based solely on morphological traits often results in selection of out-crossed seedlings and undesirable off-types. In the present investigation, RAPD markers for the tall/dwarf trait were identified in coconut using a bulked DNA approach. Screening of tall and dwarf palm bulk DNA with 200 primers revealed a RAPD primer OPBA3 which was able to clearly differentiate both the tall and dwarf bulks. For validation, the primer was used to screen individual tall and dwarf coconut palms representing different geographic regions. The primer was also used to screen the parents and validate hybrids of Dwarf x Tall crosses.
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    Authentication of coconut hybrids using RAPD analysis
    (2012-11) Rajesh, M.K.; Preethi, P.; Jerard, B.A.; Regi Jacob Thomas; Anitha Karun
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    Development of a RAPD-derived SCAR marker associated with tall-type palm trait in coconut
    (2013) Rajesh, M.K.; Jerard, B.A.; Preethi, P.; Regi Jacob Thomas; Fayas, T.P.; Rachana, K.E.; Anitha Karun
    Coconut palms are classified into two major types, viz. talls and dwarfs, based on plant stature. The selection of coconut seedlings in the nursery, presently relying solely on morphological markers, often results in selection of out-crossed seedlings. Hence, identification of molecular markers for distinguishing tall/dwarf character at an early stage of growth assumes importance. In the present investigation, a RAPD marker for tall-type palm trait was identified using a pooled DNA approach. Screening of tall and dwarf palm bulked DNA with 200 decamer primers revealed a primer OPA09, producing a unique band of around 260 bp exclusively in tall accessions. The primer was used for screening and validation in individual tall and dwarf coconut accessions representing different geographic regions. The band was present in all the tall accessions, but absent in the dwarfs. Furthermore, sequence characterized amplified region (SCAR) primers were designed from the unique RAPD amplicon. The primers produced a specific 260-bp amplicon in tall accessions, but not in dwarf accessions. The SCAR marker was utilized in assessing the purity of hybrid seedlings of D×T (Dwarf×Tall) cross. The results pave the way for ensuring genuineness/quality of hybrid seedlings of coconut.
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    Estimation of out-crossing rates in populations of West Coast Tall cultivar of coconut using microsatellite markers
    (2014-12) Rajesh, M.K.; Rijith, J.; Shafeeq Rahman; Preethi, P.; Rachana, K.E.; Sajini, K.K.; Anitha Karun
    Understanding of mating system of a plant species has fundamental importance for formulation of genetic conservation strategies and breeding programmes. The pattern of gene flow, via pollen, has a profound influence on the genetic structure within a population. Various genetic parameters, obtained from molecular marker studies, can be used to assess estimates of mating system. The aim of this study was to estimate the rate of outcrossing in West Coast Tall (WCT) cultivar of coconut, which is predominant in India, using microsatellite simple sequence repeats (SSR). Two WCT mother palms and their 88 progenies, collected as embryos for five months, were screened using 15 highly polymorphic microsatellite primers. The mating parameters were estimated using mixed mating model (MLTR software) and the extents of similarity between the mother palms and their progenies were analyzed using the NTSYS software. The percentage similarity between the mother palm and its progenies, as deduced using microsatellite data, ranged from 55 to 74 per cent. The progenies were also analyzed using a RAPD primer capable of distinguishing Tall and Dwarf palms. All the progenies were found to possess the Tall-type marker indicating that the pollen was derived from Tall palms in all the cases. The results revealed the WCT cultivar to be pre-dominantly out-crossing and indicated that proper sampling and indicated that proper sampling and breeding strategies are required to sustain the high genetic diversity found.
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    Role of Ozone in Post-Harvest Disinfection and Processing of Horticultural Crops: A Review
    (2022) Vijay Rakesh Reddy, S; Sudhakar Rao, D.V; Sharma, R. R.; Preethi, P.; Pandiselvam, R.