Cymbopogon is an important genus of family Poaceae, cultivated mainly for its essential oils which possess high medicinal and economical value. Several cultivars of Cymbopogon species are available for commercial cultivation in India and identification of these cultivars was conceded by means of morphological markers and essential oil constitution. Since these parameters are highly influenced by environmental factors, in most of the cases, it is difficult to identify Cymbopogon cultivars. In the present study, Random amplified polymorphic DNA (RAPD) and Inter-simple sequence repeat (ISSR) markers were employed to discriminate nine leading varieties of Cymbopogon since prior genomic information is lacking or very little in the genus. Ninety RAPD and 70 ISSR primers were used which generated 63 and 69 % polymorphic amplicons, respectively. Similarity in the pattern of UPGMA-derived dendrogram of RAPD and ISSR analysis revealed the reliability of the markers chosen for the study. Varietal/cultivar-specific markers generated from the study could be utilised for varietal/cultivar authentication, thus monitoring the quality of the essential oil production in Cymbopogon. These markers can also be utilised for the IPR protection of the cultivars. Moreover, the study provides molecular marker tool kit in both random and simple sequence repeats for diverse molecular research in the same or related genera.
CYMBOPOGON: is an important member of grass family Poaceae, cultivated for essential oils which have greater medicinal and industrial value. Taxonomic identification of Cymbopogon species is determined mainly by morphological markers, odour of essential oils and concentration of bioactive compounds present in the oil matrices which are highly influenced by environment. Authenticated molecular marker based taxonomical identification is also lacking in the genus; hence effort was made to evaluate potential DNA barcode loci in six commercially important Cymbopogon species for their individual discrimination and authentication at the species level. Four widely used DNA barcoding regions viz., ITS 1 & ITS 2 spacers, matK, psbA-trnH and rbcL were taken for the study. Gene sequences of the same or related genera of the concerned loci were mined from NCBI domain and primers were designed and validated for barcode loci amplification. Out of the four loci studied, sequences from matK and ITS spacer loci revealed 0.46% and 5.64% nucleotide sequence diversity, respectively whereas the other two loci i.e., psbA-trnH and rbcL showed 100% sequence homology. The newly developed primers can be used for barcode loci amplification in the genus Cymbopogon. The identified Single Nucleotide Polymorphisms from the studied sequences may be used as barcodes for the six Cymbopogon species. The information generated can also be utilized for barcode development of the genus by including more number of Cymbopgon species in future.
Psyllium (Plantago ovata Forsk.) is an important medicinal species cultivated throughout the semi‐arid areas in India. The seed coat, commercially known as psyllium husk, is used as a laxative for treating irritation of gastro‐intestinal tract and relieving constipation. There is an urgent need to enhance its productivity to make the crop more profitable. Artificial crossing is difficult in the species because of its small‐sized sessile florets that are compactly arranged on a soft inflorescence axis. Male sterility has been reported in the species; however, no conclusive studies have been conducted to reveal the inheritance, mode of action, and cytogenetic basis of male sterility. Hence, the purpose of this study was to determine (a) the histological and cytogenetic bases of anther development and microsporogenesis in male‐sterile and fertile plant types and (b) the genetic basis of male sterility. The study revealed that male sterility in psyllium was not attributable to meiotic abnormality or to tetrad abnormalities, but it was attributable to premature degradation of the tapetum layer, which subsequently causes the microspore degeneration, resulting in nonproduction of pollen grains. Male sterility was controlled by a single recessive gene, which was found to be stable across years and hence can easily be bred into any psyllium genotypes of breeders’ choice. Newly developed male‐sterility‐maintainer line can be used to generate new sets of male‐sterile lines for hybrid seed production or harnessing hybrid vigor in the field.
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