Molecular distinction and population structure of Indian mustard [Brassica juncea (L.) Czern.]

Genetic Resources and Crop Evolution - Rapeseed-mustard is one of the most important oilseed crops and providing a major source of edible oil in the world besides having other economic importance...     

Understanding Tecomella undulata: an endangered pharmaceutically important timber species of hot arid regions

Tecomella undulata (Sm.) Seem. (family Bignoniaceae) is an economically and pharmaceutically important small tree of arid regions of India, Pakistan and Arabia. It is well known as ‘Desert teak’ or ‘Marwar teak’ being the main source of timber amongst the tree species of desert region of Rajasthan, India. T. undulata has occupied a reputed position of having valuable medicinal properties in both folk and classical streams of indigenous medicinal systems. Plant is well-known for its wide range of therapeutic activities like hepatoprotective, antibacterial, antimicrobial, antifungal and anti-termite, immunomodulatory, anticancer, cytotoxic, analgesic, anti-inflammatory, anti-obesity, etc. Rohitakarishta, an ayurvedic drug obtained from T. undulata, is the classical compound which is being prescribed in liver and spleen diseases, oedema and anaemia. This well accepted agroforestry tree of the arid regions is heading towards extinction due to its increasing demand in timber and pharmacological industries coupled with negligible conservation efforts. This species has now been designated as “threatened” in Rajasthan, India. Susceptibility to many pathogens and pests is one of the major problems and detrimental factor in successful establishment and growth of this tree. Conventionally, it is propagated through seeds; however, natural regeneration of plants is poor due to air dispersal of seeds to remote areas, extreme environmental conditions during seed dispersal, improper harvest and storage of seeds, and short seed viability. The tree is very slow growing and suitable vegetative propagation methods are not available for its rapid multiplication. Alternatively, attempts have been made to propagate this tree through in vitro approaches; however, it also has many limitations including difficulties in culture establishment, slow growth, low rooting rates as well as field establishment rates. Moreover, little information is available regarding genetic diversity in this species using morphological and molecular markers. Efforts to undertake breeding programs for improvement of T. undulata have not been initiated yet. Some literature is available regarding cytology, role in agroforestry and silviculture, association with vesicular arbuscular mycorrhiza and application of biotechnological tools in T. undulata, however, an exponential increase in research publications on identification of bioactive constituents and verification of pharmacological effects has been recorded in the recent past. In this communication, we emphasize the research progress made in T. undulata on various aspects and suggest some future directions of research.     

Assessing phenotypic,biochemical, and molecular diversity in coriander (<Emphasis Type="Italic">Coriandrum sativum</Emphasis> L.) germplasm

Our goals for this research were to elucidate phenotypic and biochemical diversity in coriander (Coriandrum sativum L.) populations maintained at the North Central Regional Plant Introduction Station in Ames, IA, and examine relationships between amplified fragment length polymorphism (AFLP) markers and patterns of phenotypic and biochemical diversity. Phenotypic and biochemical traits were evaluated, and analyses of variance and mean comparisons were performed on the resulting data sets. Euclidean distances from phenotypic (PD) and biochemical (BD) data were estimated, and modified Rogers’ distances (RD) were estimated for 80 polymorphic AFLP markers. These data were subjected to cluster analyses (CA) and principal components analyses (PCA), to reveal patterns among populations, and to analyses of molecular variance (AMOVA) for grouping patterns from PD and BD by using the 80 polymorphic AFLP markers. Resulting phenotypic, biochemical, and molecular distance matrices were also compared by applying Mantel tests. Our results describe significant differences among populations for all the phenotypic traits, and dendrograms obtained from PD and BD revealed complex phenetic patterns, as did groups from PCA. The primary seed essential oils and nearly all fatty-acid components were identified and their abundance measured; the primary chemical constituents of corresponding PCA groups are described herein. Molecular evidence supported phenotypic and biochemical subgroups. However, variation attributed among subgroups and groups was very low (∼4–6%), while variation among populations within groups was intermediate (∼24–26%), and that within populations was large (∼69–70%), reflecting weak differentiation among subgroups and groups, which was confirmed by values for fixation indices. Phenotypic subgroups described in this study differed somewhat from previous infraspecific classifications. Weak correlations were found between the phenotypic and biochemical matrices and between the biochemical and AFLP matrices. No correlation was found between the phenotypic and AFLP matrices. These results may be related to coriander’s phenotypic plasticity, its wide range in lifecycle duration, its predominantly allogamous reproductive biology, a human-selection process focused on special traits that may be controlled by few genes, and the widespread trade of coriander seeds as a spice, which may result in dynamic, poorly differentiated molecular variation, even when phenotypic and biochemical differentiation is easily documented. The U. S. Government’s right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged.