Cowpea (Vigna unguiculata) is a tropical grain legume widely distributed in sub-Saharan Africa, Asia, Central and South America as well as parts of southern Europe and the United States (Singh et al., 2002). Domestication of cowpea is presumed to have occurred in Africa given the exclusive presence of wild cowpea (Steele, 1976) although knowledge about the general region or regions of origin and number of domestication events within Africa is fragmented (Ng and Padulosi, 1988; Coulibaly et al., 2002). It is very important, widely adapted, and versatile grain legume of high nutritional value. Cowpea is mainly produced and consumed in Africa, where it provides a major low-cost dietary protein for millions of smallholder farmers and consumers, who cannot afford high protein foods, such as fish and meat. The seed protein content is reported to range from 23-32% of seed weight and therefore is often referred to as a “poor man’s meat” (Diouf and Hilu, 2005). In many parts of West Africa, cowpea hay is also critical as livestock feed, especially during the dry season (Wests and Francis, 1982). Being a legume, cowpea is nitrogen-fixing (Sanginga, 2003) and fits perfectly in the traditional intercropping systems that are common in Africa, especially given its ability to tolerate shade. The total area under cowpea cultivation is more than 12.5 million hectares worldwide, with an annual production of around 4.5 million metric tons (Singh et al., 2002).
Table of Contents
1.0 Introduction
2.0 The Genotoxic Effect of Lead and Zinc on Cowpea
2.1 MATERIALS AND METHODS
3.0 Assessing the genetic diversity of cowpea [Vigna unguiculata (L.) Walp.] accessions from Sudan using simple sequence repeat (SSR) markers.
3.1 MATERIALS AND METHODS
3.1.1 Plant materials
3.1.2 DNA extraction
3.1.3 Microsatlite amplification
3.1.4 PCR analysis
Research Objectives and Core Themes
The primary objective of this research is to evaluate the genetic diversity of Sudanese cowpea germplasm and investigate the genotoxic impact of heavy metals on cowpea chromosomes to enhance crop productivity and breeding programs.
- Genotoxic assessment of lead and zinc on cowpea chromosomes.
- Genetic characterization of 245 Sudanese cowpea accessions.
- Application of Simple Sequence Repeat (SSR) markers for genotype discrimination.
- Establishment of a core germplasm collection for breeding in Sudan.
Excerpt from the Book
2.1 MATERIALS AND METHODS
Dry seeds of Cowpea (Vigna unguiculata) accessions: TVU 3788 were collected from the International Institute of Tropical Agriculture (I.I.T.A.), Ibadan. The metal salts used were lead nitrate and zinc nitrate. The metal salts were purchased from Labio Scientific, Mushin, Lagos. Seeds were spread uniformly in Petri dishes lined with filter paper. The Petri dishes were divided into three replicates and the seeds were divided into two sets of metal treatment (Pb and Zn). Equal volumes of the different concentrations of lead and zinc nitrate solutions (25, 50 and 100 mg/L) respectively were administered while the control group had distilled water. The seeds were allowed to germinate within the Petri dishes and were treated with the different concentrations of each of the metals and distilled water respectively at a temperature of 25 C for 5 days. Growing root tips which were brittle, translucent and gently tapering were selected from the three plants grown in the effluents of different concentration and from the control.
About 2-3 mm terminal root tips were cut off using a sharp blade and then placed on a clean glass slide and macerated with the aid of two dissecting needles and the remaining portion discarded. A drop of 1N Hydrochloric acid (HCL) was added to the root tip and left for 5 minutes; this softens the root tissue breaking up the middle lamellae. The excess acid was sucked up with a filter paper and the softened tissue was further macerated with
Summary of Chapters
1.0 Introduction: This chapter provides an overview of cowpea as a vital tropical grain legume, emphasizing its nutritional importance and the necessity for genetic characterization to improve production.
2.0 The Genotoxic Effect of Lead and Zinc on Cowpea: This section investigates the physiological impact of heavy metal exposure on cowpea chromosomes, detailing the methodology for root tip preparation and microscopic analysis.
2.1 MATERIALS AND METHODS: This chapter outlines the specific experimental procedures used to treat cowpea seeds with lead and zinc solutions and the subsequent preparation of samples for cytological examination.
3.0 Assessing the genetic diversity of cowpea [Vigna unguiculata (L.) Walp.] accessions from Sudan using simple sequence repeat (SSR) markers.: This chapter details a comprehensive study aimed at understanding the genetic variation and origin of Sudanese cowpea germplasm using molecular markers.
3.1 MATERIALS AND METHODS: This section describes the sourcing of plant materials and the standardized laboratory protocols for DNA extraction, marker amplification, and statistical analysis.
3.1.1 Plant materials: This subsection lists the collection details and sourcing of the cowpea accessions used for the genetic diversity study.
3.1.2 DNA extraction: This subsection details the laboratory protocol for extracting high-quality genomic DNA from young cowpea leaf tissue.
3.1.3 Microsatlite amplification: This subsection explains the PCR procedures, specific marker usage, and thermal cycling conditions applied to the cowpea samples.
3.1.4 PCR analysis: This subsection describes the fragment analysis and the software used to interpret the genetic structure of the studied cowpea genotypes.
Keywords
Cowpea, Vigna unguiculata, Genetic diversity, SSR markers, Sudanese germplasm, Genotoxic effect, Lead, Zinc, Mitotic index, Molecular breeding, Germplasm characterization, Plant science, Crop productivity, Agriculture.
Frequently Asked Questions
What is the primary focus of this publication?
The publication focuses on the genetic improvement and protection of cowpea, specifically through the analysis of genetic diversity in Sudanese accessions and the investigation of heavy metal genotoxicity.
What are the central thematic areas covered?
The work covers molecular plant genetics, the use of SSR markers for crop improvement, and cytological studies regarding the stress tolerance and genetic stability of cowpea.
What is the primary research goal?
The main goal is to characterize the genetic diversity of Sudanese cowpea to support breeding programs while identifying how environmental stresses, such as heavy metals, affect crop development.
Which scientific methods are employed?
The study employs SSR marker analysis for genetic diversity, Analysis of Molecular Variance (AMOVA), principal coordinate analysis (PCoA), and light microscopy for assessing mitotic indices in root tips.
What topics are discussed in the main body?
The main body details materials and methods for both the heavy metal treatment experiments and the large-scale genetic screening of cowpea accessions.
Which keywords best characterize this work?
Key terms include Cowpea, Vigna unguiculata, SSR markers, Genetic diversity, Sudanese germplasm, and Genotoxic effect.
How were the Sudanese cowpea accessions handled?
The accessions were sourced from various agro-ecological zones in Sudan, established as seedlings in a greenhouse, and then subjected to DNA extraction and SSR marker screening.
Why are SSR markers used in this study?
SSR markers are utilized because they are effective, single-locus markers with multiple alleles that allow for precise discrimination between different cowpea genotypes.
What did the genotoxicity experiment reveal about root tips?
The experiment involved treating root tips with lead and zinc nitrates to observe changes in mitotic stages and index, providing data on the crop's sensitivity to these specific pollutants.
- Quote paper
- Imiruaye Oghenetega (Author), 2020, Cowpea as a Genetic model Organism. Models in Experimental Genetics, Munich, GRIN Verlag, https://www.hausarbeiten.de/document/914607
