The Israeli–Palestinian wheat landraces collection: restoration and characterization of lost genetic diversity

Abstract

BACKGROUNDFor over a century, genetic diversity of wheat worldwide was eroded by continual selection for high yields and industrial demands. Wheat landraces cultivated in Israel and Palestine demonstrate high genetic diversity and a potentially wide repertoire of adaptive alleles. While most Israeli‐Palestinian wheat landraces were lost in the transition to ‘Green Revolution’ semi‐dwarf varieties, some germplasm collections made at the beginning of the 20th century survived in gene banks and private collections worldwide. However, fragmentation and poor conservation place this unique genetic resource at a high risk of genetic erosion. Herein, we describe a long‐term initiative to restore, conserve, and characterize a collection of Israeli and Palestinian wheat landraces (IPLR).RESULTSWe report on (i) the IPLR construction (n = 932), (ii) the historical and agronomic context to this collection, (iii) the characterization and assessment of the IPLR's genetic diversity, and (iv) a data comparison from two distinct subcollections within IPLR: a collection made by N. Vavilov in 1926 (IPLR‐VIR) and a later one (1979–1981) made by Y. Mattatia (IPLR‐M). Though conducted in the same eco‐geographic space, these two collections were subjected to considerably different conservation pathways. IPLR‐M, which underwent only one propagation cycle, demonstrated marked genetic and phenotypic variability (within and between accessions) in comparison with IPLR‐VIR, which had been regularly regenerated over ∼90 years.CONCLUSIONWe postulate that long‐term ex situ conservation involving human and genotype × environment selection may significantly reduce accession heterogeneity and allelic diversity. Results are further discussed in a broader context of pre‐breeding and conservation. © 2019 Society of Chemical Industry

Importance of Landraces in Cereal Breeding for Stress Tolerance

“…In other cases, landraces were maintained as inbred lines, and analysis on very large collections became possible. These analyses were often focused on panels of landraces with a specific geographical origin, as in the case of durum or common wheat landraces from Ethiopia [ 38 , 39 ], Sicily [ 40 ], Morocco [ 41 ], Iran [ 42 ], Palestine and Israel [ 43 ], Pakistan [ 44 ], Turkey [ 45 ] and Mexico [ 46 ]; barley from Nepal [ 47 ], the Canary Islands [ 48 ], Tunisia [ 49 , 50 ] and Jordan [ 51 ]; oat from Poland [ 52 ] and Spain [ 53 ]; rice from Pakistan [ 54 ] and India [ 55 ] and millets from Senegal [ 56 ] and China [ 57 , 58 ]. If focusing on specific geographic areas has the advantage of exploring within a range of genotypes well adapted to that environment, examining wider collections opens the possibility of investigating the genetic relationship across landraces spread around the world, and having a more precise estimation of the genetic diversity within the group of landraces and with respect to advanced breeding lines or modern cultivars.…”

“…The use of high-throughput markers allowed, in particular, the collection of more precise information on decay of linkage disequilibrium in landrace panels, which showed a higher resolution compared to commercial cultivars, for their use in association mapping analysis [ 51 , 73 ]. Moreover, the availability of a large number of markers with a good coverage of the genome is important to identify rare and private alleles, which are present only in a defined group of genotypes [ 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 ]. This kind of knowledge is very important for breeding, as landraces can be chosen not only based on their diversity per se, but also for specific alleles of interest in a particular breeding program.…”

The INCREASE project: Intelligent Collections of food‐legume genetic resources for European agrofood systems

“…Genomics data will be used to: (i) reveal accessions with mismatching passport information and potentially correct those, and to reduce duplicated accessions and redundancy as in the barley ( Hordeum vulgare ) IPK collection (Milner et al., 2019 ); (ii) define core collections capturing a high diversity of the total collection to be in‐depth phenotypically and genotypically characterized (Milner et al., 2019 ; Wambugu et al., 2018 ); (iii) identify unique germplasm that needs particular attention in conservation (Gowda et al., 2013 ); and (iv) strictly monitor the multiplication of accessions (Mascher et al., 2019 ). Finally, advanced molecular methods will be applied to assess the levels and values of heterogeneity in germplasm accessions and in populations conserved on‐farm (Frankin et al., 2020 ; Gouda et al., 2020 ). Genomics data will be used to sample highly variable sets of accessions for target genes associated with traits of interest.…”

Evolution and origin of bread wheat

“…Biodiversity conservation in seeds banks and in situ protection are thus essential. Conservation of landraces is mostly taking place in seeds banks, with notable efforts to characterize them genetically ( Kilian et al, 2011 , 2021 ; Cavanagh et al, 2013 ; Dempewolf et al, 2017 ; Frankin et al, 2020 ) and to maintain their culture, in situ in farmer’s fields, for niche markets ( Negri, 2003 ). In situ conservation of wild wheat is much more limited.…”