Wild Relatives of Maize, Rice, Cotton, and Soybean: Treasure Troves for Tolerance to Biotic and Abiotic Stresses

Abstract

Global food demand is expected to nearly double by 2050 due to an increase in the world's population. The Green Revolution has played a key role in the past century by increasing agricultural productivity worldwide, however, limited availability and continued depletion of natural resources such as arable land and water will continue to pose a serious challenge for global food security in the coming decades. High yielding varieties with proven tolerance to biotic and abiotic stresses, superior nutritional profiles, and the ability to adapt to the changing environment are needed for continued agricultural sustainability. The narrow genetic base of modern cultivars is becoming a major bottleneck for crop improvement efforts and, therefore, the use of crop wild relatives (CWRs) is a promising approach to enhance genetic diversity of cultivated crops. This article provides a review of the efforts to date on the exploration of CWRs as a source of tolerance to multiple biotic and abiotic stresses in four global crops of importance; maize, rice, cotton, and soybean. In addition to the overview of the repertoire and geographical spread of CWRs in each of the respective crops, we have provided a comprehensive discussion on the morphological and/or genetic basis of the traits along with some examples, when available, of the research in the transfer of traits from CWRs to cultivated varieties. The emergence of modern molecular and genomic technologies has not only accelerated the pace of dissecting the genetics underlying the traits found in CWRs, but also enabled rapid and efficient trait transfer and genome manipulation. The potential and promise of these technologies has also been highlighted in this review.

Plant adaptation to climate change—Where are we?

“…For example, Henry (2019) highlighted several recently identified wild rice species with most divergent genotypes in northern Australia containing novel alleles for various important traits, which could enhance the capacity of cultivated rice to tolerate climate change. During the past decade, dozens of review/ perspectives have been published to highlight the potential and importance of crop wild relatives in meeting global challenges (e.g., Brozynska et al, 2016;Zhang et al, 2017Zhang et al, , 2019Mammadov et al, 2018;Fernie & Yan, 2019;Henry, 2019). Nevertheless, few climate-adaptive casual genes identified in CWR have been applied to the development of crops that can withstand climate change.…”

Evaluation of rice wild relatives as a source of traits for adaptation to iron toxicity and enhanced grain quality

“…Crop wild relatives (CWR) are widely regarded as a rich source of genetic variation for the improvement of domesticated crops, which can be tapped more effectively than ever before due to the progress in CWR genomics [1,2]. Rice is one of the most important cereal crops in the world in terms of annual production and provides the staple food for around half of the a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 (ferrous Fe) [23,24].…”

Polyploid Gene Expression and Regulation in Polysomic Polyploids

“…54% of monocot crops are polyploids, while 40% of them are wild species [20] [21]. However, wild relatives have potentially advantageous gene pools, determining biotic stress resistance and abiotic stress tolerance (in corn, cotton, rice, and soybean) [22] or attractive traits (in potatoes [23] [24]). Current strategies for domestication and breeding of wild relatives may reduce the hereditary diversity of all crops [25].…”