Nuclear and Cytoplasmic Diversity in Manifestation of Disease Control and Genepool Conservation for Sustainable Crop Productivity

Abstract

ABSTRACT Genetic diversity is important for success of crop improvement. Its utilization has facilitated enhanced ability to produce, locate, and access desirable genes. This paper presents a thorough discussion of the ideas and strategies for conservation of cytoplasmic and nuclear heterogeneity in crop plants. It is focused that maintenance of greater genetic diversity in field condition may provide an in-built natural protection to crop vulnerability to pathogens vis-a-vis genepool conservation for sustainable productivity. Several examples with the manifestation of genetic relationship between plant reproductive systems and planting of mixtures of varieties or species possessing nuclear and cytoplasmic diversity providing better option for sustainable yield improvement have been elaborated. Intergenomic interaction-complementation between genes for morpho-economic traits (e.g., QTL, quantitative trait loci) endowed in both nuclear genome and cytoplasmic organellar genomes (mitochondrial and chloroplastic) seem to play greater role for enhanced productivity while strengthening conservation of heterodiversity and biodiversity in crop plants. Conservation and maintenance of overall heterogeneity for both nuclear and organellar genomes have been conceived as possible solutions to combat vulnerability of monocultured crops to pests and diseases. Genetic diversity and divergence require assessment for two sets of attributes. The first relates to marker diversity between individual copies of genes and second for variation for adaptation. The differences should be detected at the DNA level, for a sample of homologous sequences representative of various classes of sequences (nuclear, organellar, structural, regulatory, spacer). The point has been made that deliberately produced heterodiversity for desirable traits in crop population in field cultivation has much to offer for both enhanced and sustainable yield production, especially in regard to the control of biomass and harvest index (grain yield) damages owing to vulnerability for insect, pest and pathogen led disease attacks.