Chapters authored
Wild Progenitor and Landraces Led Genetic Gain in the Modern-Day Maize (Zea mays L.)
Maize (Zea mays ssp. mays) originated from Mexico and Central America and grew worldwide for food, feed and industrial products components. It possesses ten chromosomes with a genome size of 2.3 gigabases. Teosinte (Z. mays ssp. parviglumis) is the probable progenitor of the modern-day maize. The maize domestication favored standing gain of function and regulatory variations acquired the convergent phenotypes. The genomic loci teosinte branched 1 (tb1) and teosinte glume architecture 1 (tga1) played a central role in transforming teosinte to modern-day maize. Under domestication and crop improvement, only 2% (~1200) genes were undergone selection, out of ~60000 genes. Around ~98% of the genes have not experienced selection; there is enormous variation present in the diverse inbred lines that can be potentially utilized to identify QTLs and crop improvement through plant breeding. The genomic resources of wild relatives and landraces harbor the unexplored genes/alleles for biotic/abiotic tolerance, productivity and nutritional quality. The human-made evolution led to the transformation of wild relatives/landraces to the modern-day maize. This chapter summarized the maize’s wild relatives/landraces and the genetic gain over time in biotic/abiotic, productivity, and nutritional quality traits.
Part of the book: Landraces
Pathogenesis-Related Proteins and Their Transgenic Expression for Developing Disease-Resistant Crops: Strategies Progress and Challenges
Various pathogenic microorganisms (such as fungi, bacteria, viruses and nematodes) affect plant viability and productivity. However, plants combat these pathogens by inducing their defense mechanism to sustain their fitness. The aggregation of pathogenesis-related (PR) proteins in response to invading pathogens is a crucial component of a plant’s self-defense mechanism. PR proteins induce innate resistance in plants through fungal cell wall disintegration, membrane permeabilization, transcriptional suppression, and ribosome inactivation. Earlier studies have demonstrated their crucial role in determining resistance against phytopathogens, making them a promising candidate for developing disease-resistant crop varieties. Plant genetic engineering is a potential approach for developing disease-resistant transgenic crops by employing several PR genes (thaumatin, osmotin-like proteins, chitinases, glucanases, defensins, thionins, oxalate oxidase, oxalate oxidases like proteins/germin-like proteins and LTPs). Furthermore, the overexpression of PR proteins enhances the resistance against phytopathogens. As a result, this chapter gives an overview of PR proteins, including their classification, functional characterization, signaling pathways, mode of action and role in defense against various phytopathogens. It also highlights genetic engineering advances in utilizing these genes singly or synergistically against various phytopathogens to impart disease resistance. Various challenges faced with the products of transgenic technology and synergistic expression of different groups of PR proteins were also discussed.
Part of the book: Case Studies of Breeding Strategies in Major Plant Species