Triticeae Genomics and Genetics, 2024, Vol.15, No.3, 152-161 http://cropscipublisher.com/index.php/tgg 153 The primary objective of this study is to provide a comprehensive overview of the current state of research on the utilization of exotic germplasm for wheat improvement. Specifically, this study aims to highlight the importance of genetic diversity in wheat breeding programs, discuss the role of exotic germplasm in enhancing various wheat traits, summarize the challenges and opportunities associated with the use of exotic germplasm, and provide insights into the latest technological advancements that facilitate the exploitation of exotic genetic variation. By addressing these objectives, this study seeks to underscore the potential of exotic germplasm in developing high-yielding, stress-resistant, and nutritionally superior wheat varieties, thereby improving the quality and yield of wheat and contributing to global food security. 2 Overview of Exotic Germplasm 2.1 Definition and sources of exotic germplasm Exotic germplasm refers to genetic material from plant species or varieties that are not commonly used in current breeding programs. These sources often include wild relatives, landraces, and other underutilized species that possess unique genetic traits not found in modern cultivars. For instance, Aegilops tauschii, a wild relative of wheat, has been utilized to introduce genetic variations into wheat, enriching the germplasm pool with novel traits (Zhou et al., 2021). Similarly, wild emmer wheat has been explored for its potential to improve heat stress tolerance in wheat (Balla et al., 2022). 2.2 Historical use of exotic germplasm in wheat breeding Historically, exotic germplasm has played a crucial role in wheat breeding by providing genetic diversity necessary for the development of new varieties with improved traits. For example, the development of the Australian Bread Wheat Nested Association Mapping (NAM) population involved crossing diverse exotic parents with elite Australian varieties to incorporate genetic diversity and dissect complex traits (Chidzanga et al., 2021) (Figure 1). Additionally, the introgression of Aegilops tauschii into wheat has been a significant step in overcoming the narrow genetic base of the wheat D genome, thereby enhancing its breeding potential (Zhou et al., 2021). The use of landraces, such as those from the A.E. Watkins collection, has also been instrumental in identifying unique loci for climate resilience and other desirable traits (Cheng et al., 2023). Figure 1 Characteristics of the NAM exotic parents (Adapted from Chidzanga et al., 2021) Image caption: (a) Phylogenetic trees illustrating the diversity within the panel from which the diverse exotic parents of the Nested Association Mapping (NAM) population were selected. The NAM parents are specifically highlighted within the phylogenetic tree, showcasing their genetic diversity; (b) Geographical distribution of the NAM exotic parents, mapped to highlight the diverse origins and spread of these genetic resources across different regions (Adapted from Chidzanga et al., 2021)
RkJQdWJsaXNoZXIy MjQ4ODYzNQ==