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Articles by S. Farooq
Total Records ( 8 ) for S. Farooq
  S. Farooq and F. Azam
  Not Available
  S. Farooq and F. Azam
  This paper describes the concept of agricultural biodiversity and its importance in present and future food security. Some facts and figures are being presented in order to apprise the reader about the state of agricultural biodiversity in this country and elsewhere. The term agricultural biodiversity has been elaborated at length with special reference to the type of biodiversity available in Pakistan. The importance of biodiversity has been discussed in relation to its role in value addition to commercial crops in the form of resistance against pests and diseases. Its contribution, to human foodstuff, removal of genetic vulnerability and food security has also been discussed in detail. How agro-biodiversity has been utilized in crop production programmes and how rapidly it is being eroded, has also been described. Emphasis has been made on the conservation (both in situ and ex situ) of sites rich in agro-biodiversity along with its characterization and utilization in order to enhance its present status and to create new biodiversity to meet the future demand of crop improvement especially for tolerance to abiotic stresses.
  F. Azam and S. Farooq
  One of the dramatic observations on response of plants to elevated CO2 is their enhanced tolerance to stresses like light, temperature, salinity and nutrients. High temperatures and light intensity (like that in Pakistan) have generally a depressing effect on growth of plants, especially those having C3 photosynthetic system. These plants have a lower optimum temperature for photosynthesis that is raised at elevated CO2 thereby protecting the plants from being over-heated. In addition, the photorespiratory activities of C3 plants at higher temperatures are curtailed in the presence of high CO2 concentrations, thereby helping the plants conserve C and energy. Low as well as high light intensities are reported to limit photosynthesis at ambient concentrations of CO2, while elevated CO2 levels have a mitigating effect. Elevated CO2 levels allow plants to live under light conditions insufficient to meet photosynthetic requirements, while under high light intensities photorespiratory activities are curtailed. Similarly, positive effect of elevated CO2 on plant performance under conditions of limited water availability (e.g., because of soil salinity, drought) has consistently been reported. It is believed that the on-going rise in air`s CO2 content will protect trees from debilitating water stress. The water stress may not necessarily be that of drought, excessive irrigation may have negative effect as well and is reported to be mitigated by elevated CO2. Plants growing under soil salinity stress have also been reported to benefit from elevated CO2. The benefit is reported to be derived from the availability of more solutes for osmoregulation by reducing the transpirational intake of salts or by improving RUBISCO activity. In C4 plants, elevated CO2 helps overcome the leakiness induced by salt stress. In addition, positive effect of elevated CO2 on root proliferation and root-induced microbiological and biochemical changes may help plants withstand salinity stress. One of the reasons for a more positive effect of elevated CO2 on plants under growth limiting conditions is the enhanced root proliferation. Thus at low level of N availability that would generally limit plant growth, elevated CO2 helps plants extract more N from soil by exploring a greater soil volume and stimulation of photosynthetic rates. This paper gives an overview of the available information on the subject vis-à-vis agroclimatic conditions prevailing in Pakistan.
  F. Azam and S. Farooq
  Symbiotic nitrogen fixation by legumes is the major natural process of adding nitrogen into the biosphere amounting to about 35 million tons annually. The process of nitrogen addition to the ecosystems and its further fate is such as to pose minimum threat to environmental cleanliness relative to N used as chemical fertilizers. Therefore, it has been of great interest not only to understand the basics of nitrogen fixation process but also to quantify the amount of N added to a system under different conditions. This is important in order to quickly screen the available germplasm for its potential of biological N2 fixation and to devise strategies for further improving the process under different ecological conditions. A critical evaluation of some common methods of studying N2 fixation in legumes is presented.
  S. Farooq and F. Azam
  Plant breeding is a combination of principles and methods of changing the genetic constitution of a plant to make it more suitable for human needs. Conventional plant breeding has evolved with the passage of time from simple seed saving of the best harvest to the selection of seeds according to the laws of Mendel. With the advent of morphological and biochemical markers, the selection process has hastened and the scope of conventional plant breeding increased many folds during the recent years. However, the process that actually revolutionized the plant breeding in the 20th century was the realization that there exist a widespread polymorphism in natural populations, the degree of which can be assessed by sequencing or making restriction maps: an application of new tools of molecular biology. The first and the foremost molecular markers system i.e., restriction fragment length polymorphism (RFLP) was developed in early 1980. These are co-dominant markers and are available in unlimited number. Another breakthrough was the emergence of polymerase chain reaction (PCR) in 1990. With this technology, a new generation of DNA markers such as randomly amplified polymorphic DNA (RAPDs), sequence characterized amplified regions (SCARs), sequence tagged sites (STS), single polymorphic amplification test (SPLAT), variable number of tendom repeats (VNTRs), amplified fragment length polymorphism (AFLP), DNA amplification fingerprinting (DFA), single strand conformational polymorphism (SSCP), single nucleotide polymorphism (SNPs), micro-satellites or short tandem repeats (STRs), cDNA, DNA micro arrays and rDNA-ITS were introduced into the modern plant breeding systems. The concept of DNA based markers has increased our ability many folds, to follow minute regions of chromosome through opportunities such as map based cloning and Marker-assisted Plant (MAP) Breeding. In MAP breeding, the new ideas and concepts have been introduced which need to be understood thoroughly, before applying these ideas in practical breeding programmes particular in country like Pakistan where application of molecular biological approaches are still in its infancy. In order to achieve this objective, efforts were made to write a series of review articles in which concept of MAP breeding is being described thoroughly yet in a simple way so that student and researchers can build their understanding of plant molecular breeding and application of DNA based markers for the genetic dissection of qualitative and quantitative traits. In the present paper, concepts of MAP breeding and the type and characteristics of DNA markers is presented so that choice of the marker(s) can be made rational and for the defined purposes.
  S. Farooq and F. Azam
  Plant breeding in its primitive form is being practiced since the transition of human being from hunter/gatherers to settled agriculturist, approximately 10,000 thousand years ago. Without knowing genetics and its principal, it was used genetics to modify crops and their products. The selection of plants with best characteristics as source of next year seeds quickly resulted into domestication of crops that were distinct from their wild relative. Genetic modification (GM) has emerged against this historic background of breeding and selection and is thus, the extension of existing techniques and not something, which is unprecedented. In present paper, efforts have been made to review situation (s) that are responsible for the origin of genetically modified (transgenic) approaches to be used for crop improvement. The outcome of these approaches and the credibility of the resultant products along with their impact and significance on crop productivity in particular have also been reviewed. Impact of GM technology on the poor farmers in the developing countries with special reference to their needs and resources has been discussed in detail. The current status of genetically modified crops in the developed countries and also in the developing countries willing to adopt this technology albeit slowly has also been described along with their fears and concerns in order to provide the readers the choice to select this technology or otherwise according to their own needs and resources. The paper also provides information on the genetically modified products that can have significant impact in improving nutritional status of food generally consumed by millions of people living in the hart land of poverty that is South Asia and Sub-Saharan Africa.
  S. Farooq and F. Azam
  This paper describes some of the pre-requisites for applying molecular markers in plant breeding or crop improvement programmes. This includes, possible answers to some of the very pertinent questions regarding marker-assisted plant breeding. For example, I) how an effective marker system is to be selected, ii) how, when and where these expensive technologies can be used efficiently and iii) what particular problem would be solved just by using a particular marker system. The most commonly used marker systems including restriction fragment length polymorphism (RFLP), amplified fragment length polymorphism (AFLP), micro-satellite or simple sequence repeat (SSR) and random amplified polymorphic DNAs (RAPDs) have been described in detail. The advantages and disadvantages (if any) of these marker systems and their practical utilization in different areas of crop improvement programmes have been discussed. Different methods of integrating molecular markers in conventional plant breeding programmes have also been described in greater detail with special reference to varietal identification and germplasm characterization, marker-assisted selection for qualitative and quantitative traits and abiotic stress tolerance. It is suggested that in all these cases, cost-effective application of markers can best be achieved through collaboration with those who excel in this technology. This collaboration is also necessary in order to integrate the systems and technologies to deliver the product in minimum possible time and with minimum extra input/investment in terms of operational expenses.
  S. Farooq and F. Azam
  Some of the empirical results obtained through the use of RFLP, AFLP, SSR and RAPD markers in the areas of DNA fingerprinting, measurement of genetic distance and heterosis, marker-assisted selections and abiotic stress tolerance are being described. Various difficulties that a user can encounter during the ontogeny of marker`s application have also been discussed. Marker mediated varietal fingerprinting and germplasm characterization appeared most common and most pervasive application with AFLP and SSR markers. Being cost effective, easy to handle and devoid of any radioisotope requirement, SSR markers are considered as the most suitable and reliable system for DNA fingerprinting. Capturing heterosis appeared most difficult with very little success due to lack of a facile marker system that could unconditionally identify the heterotic groups, population and progenies. Marker-assisted selections for qualitative traits appeared most successful after DNA fingerprinting while for quantitative characters, major disease resistance genes and genes controlling QTL for abiotic stress tolerance, the success is limited. It is anticipated that application of markers will remain restricted in these areas till the allele-specific markers are available and the cost of marker analysis is reduced significantly.
 
 
 
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