Landraces and Crop Genetic Improvement

Abstract

Landraces are repository of gene pool that enrich biodiversity and maintain and stabilize ecosystem in a sustainable way to make it functional. Cultivation of traditional crops in different regions of the world, aside maintaining biodiversity in agriculture, also avails humanity of regulatory services such as nutrient cycling, carbon sequestration, control of soil erosion, reduction of greenhouse gas emission and control of hydrological processes. However, man through over-exploitation of some plant species with utter neglect to some other either deliberately or otherwise through modern agricultural systems that promote cultivation of a few high-input and high-yielding crop species caused disaffection to biodiversity with consequences of reduction in its regulatory services. In this chapter, different landraces of crops are examined, their usefulness in the maintenance of genetic diversity is explored, and implications of their depletion are discussed.

Genome-Wide Association Studies Detect Multiple QTLs for Productivity in Mesoamerican Diversity Panel of Common Bean Under Drought Stress

“…Somehow, the genetic diversity within these traditional germplasms gives the necessary plasticity to support an adaptive response to environmental variation, providing an advantage over improved varieties (Mercer and Perales, 2010;Dwivedi et al, 2016). This reinforces the fact that landraces remain a vital resource for contemporary plant breeding and demand permanent conservation and knowledge of their genetic variability (Villa et al, 2005;Azeez et al, 2018). Regarding the Ouro Negro cultivar, from Honduras, which has black grains and a normal cultivation cycle (80-100 days; Amaro et al, 2015), in addition to standing out for disease resistance (Valentini et al, 2017), it also has high capacity to fix nitrogen (Da Silva et al, 2017), combining a number of attributes for plant breeding.…”

“…A more comprehensive pattern was observed for M3 ( n = 116; H E = 0.198), mainly formed by landraces (95%) representative of all Brazilian regions, which is an evidence that these accessions still retain much of their identity, a resource that remains to be better exploited by breeders in strategically planned breeding programs ( Cortés et al, 2013 ). The common bean has been broadly adapted to the Brazilian territory ( Burle et al, 2010 ), having a significant genetic value that cannot be neglected ( Azeez et al, 2018 ). The greater between-accessions variation (≥74%) was observed, thus evidencing that the germplasm groups analyzed are not genetically homogeneous.…”

Retracted: Dissection of soybean populations according to selection signatures based on whole-genome sequences

“…Domestication and geographical dispersion across diverse environments have generated a number of landrace soybeans with locally adapted characteristics, and modern breeding efforts based mainly on these landraces have developed a variety of improved soybeans with artificially adapted characteristics [104, 105]. These processes, accompanied by conscious and unconscious selections, have led to genome-wide divergence and stratification of the soybean population [8, 13].…”

Whole Genome Scan Reveals Molecular Signatures of Divergence and Selection Related to Important Traits in Durum Wheat Germplasm

“…Most Italian landraces were indigenous, cultivated in specific areas of Southern Italy (mainly in Sicily and Sardinia and to a lesser extent in Apulia, Campania, and Basilicata). They were the results of natural selection over a long period of time and/or of unconscious selection by farmers (Azeez et al, 2018). The continue exchange of seeds among farmers and the introduction of exotic LR from North Africa and West Asia contributed to the maintenance of a large genetic base within local varieties (see Figure 3).…”