Priyanka Siwach

Molecular investigations on grain filling rate under terminal heat stress in bread wheat ( Triticum aestivum L.)

Grain yield under post anthesis high temperature stress is largely influenced by grain filling rate (GFR). To investigate molecular basis of this trait, a set of 111 recombinant inbred lines (RILs) derived from Raj 4014, a heat sensitive genotype and WH 730, heat tolerant cultivar was phenotyped during 2009-2010 and 2010-2011 crop seasons, under field conditions. The difference in GFR (dGFR) between the timely and late sown conditions was used as a phenotypic parameter to find association with molecular markers, as parental lines exhibited significant difference for this trait. The mapping population showed clear-cut segregation pattern for differences in GFR between timely and late sown conditions. About 75% of the progenies showed no difference while 25% showed significant difference in GFR under high temperature stress created by late sown condition. To study the association of this trait with the markers, the parental lines were screened with 300 simple sequence repeat (SSR) microsatellite markers out of which 15% (45) were polymorphic between parental lines. These polymorphic markers were utilized for genotyping a subset, comprising of 43 RILs that had clear contrasting variation for dGFR. Regression analysis revealed significant association of dGFR of RILs with two markers viz., Xbarc04 and Xgwm314 with coefficients of determination (R2) values of 0.10 and 0.06, respectively. Keywords : Grain filling rate (GFR), simple sequence repeat (SSR), heat tolerance, wheat African Journal of Biotechnology Vol. 12(28), pp. 4439-4445

Hairy Root Cultures of Medicinal Trees: A Viable Alternative for Commercial Production of High-Value Secondary Metabolites

Since the last two decades, a lot of attention has been given to the development of ‘hairy root’ system as potential source of desired secondary metabolites. To date, hairy root cultures have been developed for more than 100 medicinal plant species, including plants of various habits, habitat and belonging to different threat status also. Forest trees form a potential group among medicinal plants with some like Taxus spp. and Cinchona spp., yielding invaluable therapeutic molecules to the modern drug sector. The high-value secondary metabolites in trees are generally synthesized during the later stage of the life cycle and are produced in very less amount, making the development of stable in vitro source mandatory for commercial production of their metabolites. Hairy root systems have not been developed for many important tree species. Since the discovery of Agrobacterium rhizogenes as pathogenic bacteria causing hairy root disease, tremendous development towards establishment of hairy root system as biochemical factory has taken place. Diverse strategies can be developed to improve the yield so as to produce desired metabolites at large-scale and in eco-friendly conditions. Research inputs from metabolomics have facilitated the development of new strategies to manipulate the biosynthetic pathways while bioreactor design has allowed the scaling up of the hairy root systems. This chapter highlights the existing status of hairy root system for various medicinal trees and outlines different strategies in this direction.

Recent Updates on Molecular Biotechnological Intervention in Isabgol

Isabgol is a very important native medicinal plant and export commodity of India, which is the largest producer. At this stage, it becomes very important to study the genetic diversity within isabgol gene pool for proper maintenance, conservation, validation, and effective utilization. There are rare reports of DNA fingerprinting of Plantago ovata genotypes for determining genetic diversity or varietal identification. In this chapter, we discuss about the role of DNA markers especially random amplified polymorphic DNA (RAPD) and inter-simple sequence repeats (ISSRs) for genetic diversity study for useful crops by taking isabgol as a case study. No other reports of recent markers are available for isabgol. Genetic variation in Plantago species is of prime significance for focusing on the constructive breeding of improved varieties/cultivars with added value and durable resistance against diseases.

Advances in Computational Tools for Plant microRNA Identification

Continuous development in biotechnological techniques has led to major breakthrough discoveries in life sciences, one of which is the finding of a particular class of small RNA molecules known as microRNAs (miRNA). miRNAs have been found to regulate various biological activities in all life forms. Though plant miRNAs were discovered later than animal miRNAs, these have been found to reveal remarkable importance in gene regulation during plant development as well as toward responding to any stimuli. Unraveling the entire mystery of these small molecules is the first step to gaining a better understanding of their function. Initially, miRNAs were identified largely by experimental techniques like forward genetic screening, cloning, and microarray, but these techniques were expensive, more time-consuming, and unable to reveal poorly expressed RNA molecules. Advances in computational tools, made during the last decade, have done wonders in miRNA research work. Many novel miRNAs were discovered using these approaches in plant systems, though confirmation requires experimental validation. In this chapter, an effort has been made to understand the characteristic features of plant miRNA compared to animal miRNAs and to review the recent advances in various computational tools made for identification of plant miRNAs.