[Show abstract][Hide abstract] ABSTRACT: Five accessions of Dipcadi erythraeum, a rare and endemic, bulbous medicinal plant of Thar desert in India, were collected from different districts of Rajasthan (India) to study the intra-specific genetic variation existing in their natural populations. To resolve species specific cytogenetical mechanism leading to evolution of D. erythraeum, mitotic and meiotic analyses were carried out. The karyotypes of various accessions of D. erythraeum were precisely resolved into ten distinct homologous pairs, not into groups of chromosomes. A striking feature observed meiotically is that bivalents are the most frequent association, while multivalent associations were completely absent in any of the PMCs presently analyzed. Almost diploid like behavior of chromosomes has been the hallmark of the PMCs investigated presently. Overall cytogenetical mechanism underlying the speciation and evolution indicates the probable amphidiploid origin of D. erythraeum.
Caryologia: International Journal of Cytology, Cytosystematics and Cytogenetics. 02/2014; 64(1):75-83.
[Show abstract][Hide abstract] ABSTRACT: Prosopis cineraria (Mimosaceae) is an important tree of agro-forestry and ethano- botanical importance with multipurpose utility as wood yielding, fodder, food and medicinal uses. Some remarkable features are observed in the form of phenotypic variation in various popula- tions inhabiting different regions of the Indian desert. To asses these variations male meiotic studies were con- ducted in ten different accessions collected from four proviences of Rajasthan, India. Analysis of data on chro- mosome associations, chiasma frequency and their dis- tributions pattern concluded that the somatic chromo- some number of P. cineraria is 2n = 2x = 28. The com- plete absence of accessory chromosomes (B) and percent- age of pollen stainability indicates an over all genomic stability in P. cineraria. Numerical changes like aneu- ploidy might have played an important role in origin and adoptation of P. cineraria against all the odds of the climatic condition of the Indian desert.
[Show abstract][Hide abstract] ABSTRACT: Prosopis cineraria, an important multipurpose tree and vital component of the otherwise fragile ecosystem of arid and semiarid regions of India.
It is highly drought tolerant and sprouts profusely during the extreme dry summer months when most other trees are leafless.
P. cineraria is known to exhibit comparable genetic variations at intra-specific and inter-population levels reflected through morphological
and cytogenetical diversity in regions, where this plant grows naturally. In the present study, single primer amplification
reaction (SPAR) methods have been used for determination of diversity at DNA level in 30 accessions of P. cineraria collected from different districts of Rajasthan. The analyses include the use of six minisatellite core sequence primers
for direct amplification of minisatellite DNA (DAMD), eight inter simple sequence repeats (ISSR) and 20 arbitrary primed decamer
sequences for random amplification (RAPD) reactions. Upon analysis of the data generated, all the three SPAR methods, either
independently and/or in combination, revealed wide range of genetic variation among accessions. Comparison of matrix of individual
SPAR method using MxComp component of NTSYS-pc 2.02K software proving that analysis of natural genetic variation using combination
of SPAR methods particularly ISSR and DAMD, rather than an isolated approach, is very effective. Such an approach also yields
better information and reflection of the relatedness and affinities at intra-species and inter-population levels. Therefore,
it is opined that in order to reveal the intrinsic intra-specific variation, SPAR approaches involving more than one DNA marker
may reveal more authentic genetic variation in tropical tree species like P. cineraria.