Fodders, worth to be considered for biotechnological improvement
Nature has blessed Pakistan with fertile land, a large network of irrigation canals, and climate that is favourable to produce all types of food and non-food crops. Agriculture and livestock sector has a unique position in Pakistan's economy by contributing about 23 percent to GDP and 44 percent of total employment. . Agriculture contributes substantially to the economy in terms of food, employment and foreign exchange earnings and will continue to be a very important sector in future. Despite the importance of agriculture in the national economy, there is an ever-widening gap between food and feed supply and demand due to some serious constraints here only forages are discussed.
Forages include grasses and fodders being the rich source of carbohydrates and proteins respectively. Forage crops possess certain unique problems that are quite different from the food grain, and horticultural crops. Besides multiplicity of the crop species and their nature, the forage crops are usually area and region specific. The preference for forages varies from season to season and locality to locality. Non-commercial nature of the crops restricts the farming community to cultivate such crops. In most of the cases the degraded and marginal lands are usually utilized for forage production with minimum inputs in
term of fertilizers, water and human resource. All these factors presents some key challenges to the breeders to use modern technology for,
1. Generation of molecular maps in Berseem, cowpea, and grasses
2. Identification of molecular markers for important traits in fodder crops and their
molecular mapping, and QTL mapping of key agronomic traits
3. Understanding genetics, physiology and molecular biology of traits such as
apomixis and stress tolerance in fodders
4. Transformation for tolerance to stress and enhancement in quality parameters
5. Haploid production in polyploid fodders
6. Utilization of perennial grasses for biofuel production
7. Synteny and evolutionary relationships with model crops
And above all could be achieved through the application of biotechnology. In reality forage and grasses form the foundation for grassland agriculture and play important roles in animal production and environmental protection. Because forage production is generally a low-cash-input system, the most economical way to deliver advanced technology to farmers is through the genetic improvement of cultivars. Biotechnology offer certain benefits over conventional means of breeding like 1) mutations are utilized by breeders, integrated maps increase opportunities for indirect selection methods; 2) the ability to share genetic information between sexually isolated species should accelerate isolation of targeted genes; 3) the definition of crop gene pools should become broader and more precise for specific genes; 4) understanding of the biological basis of complex traits should improve by providing a common language for various branches of biology; 5) important genes may be localized by a variety of increasingly complementary methods for potential use in transgenesis projects; and 6) an element of objective hypothesis testing has become available for plant breeding.
Forage quality improvement, disease and pest resistance, tolerance to abiotic stresses, manipulation of growth and development, and the production of foreign proteins of industrial relevance represent current targets for molecular breeding of fodder crops. Due to their perennial growth habit and the ability to grow in marginal areas, some grass species can be considered form molecular farming, which is the production of biodegradable plastics, industrial enzymes, pharmaceuticals, vaccines and antibodies in transgenic plants. The use of transgenic grasses may provide a cost-effective way of phytoremediation for the control and removal of soil contaminants. Introduction substitution or addition of diverse genes from various organisms into crops and livestock has long been regarded as a promising way to ensure the continued productivity of agriculture Biotechnological approaches to improve forage quality include the modification of lignin to improve digestibility, manipulation of fructan metabolism to increase non-structural carbohydrate concentration, and the expression of rumen bypass proteins to enhance the supply of essential amino acids. Another aspect of quality improvement is the delay or inhibition of flowering in trangenic grasses by regulation of the expression of the meristem identity genes. The control of flowering in grasses may also offer a trangene containment system. Biotic and abiotic stresses are common features experienced by perennial forages. Disease resistance is an important trait. Genes and strategies for engineering disease resistance in transgenic plants has been developed over the last decade: chitinases, glucanases, plant defensins, phytoalexins, ribosome inactivating proteins, viral coat proteins, etc. Abiotic stresses such as drought and cold affect the growth of fodder crops. Transgenic expression of regulatory genes involved in stress responses has great potential for improving drought and cold tolerance in fodder crops. This is all made possible through the development of QTLs and PCR or non PCR based DNA markers like AFLP, RFLP, SSR, RAPD etc. Certain problems like in Berseem Narrow genetic base, Slow cell wall degradability, Enhanced longevity, Stem rot/root rot, in Lucerne weevil, Stress tolerance, Quality parameters, Transformation, in Pearl millet Abiotic stress tolerance (drought, frost), apomixes, Biotic stress tolerance (downy mildew, Intervarietal and interspecific ergot, smut), in Oats Stress tolerance (salinity & drought), Quality enhancement, in Sorghum Stress tolerance, Reduced HCN content, Enhancing stover quality are solved by Interspecific hybridization, use of polyploidy, mutation breeding Genetic engineering of cell wall proteins, Molecular mapping, RNA approach, Transformation, MAS etc.
Molecular markers offer prospects for better identifying superior individuals and enhancing selection efficiency. In order to make the molecular markers more effective and efficient for improvement of fodder crops, the following should be considered as priority:
(a) development of suitable high throughput PCR-based codominant markers (eg. SSRs, SNPs, etc.) in sufficient numbers,
(b) constructions of mapping populations from well characterized parents by using appropriate population structures so that each population segregates for the maximum number of genes for target traits, and
(c) development of effective and efficient phenotyping protocols for target traits so that precise phenotyping of a large number of segregating progeny would be feasible for QTL mapping.
Maximum progress in developing improved fodder cultivars will most likely occur through a multidisciplinary team approach involving plant breeders, molecular biologists, agronomists and animal scientists, among others. Biotechnology has the potential to make significant contributions to fodder crops improvement. Certain productive species may be engineered to make them a suitable source of bioenergy. With the development of current gene discovery methods, especially ESTs and microarrays, an increasing number of isolated genes will need to be functionally tested. Admittedly, current protocols for plant regeneration and transformation in grasses are time consuming, labourious and inefficient. There is a great need to drastically improve transformation efficiency and thus allow the production of large number of transgenic grasses in a relatively short time period.
MASOOMA NASEER CHEEMA, LECTURER
SAMMINA MAHMOOD STUDENT OF MSc(hons)AGRICULTURE
DEPARTMENT OF PLANT BREEDING AND GENETICS
Article Source: ArticlesBase.com
