Small "Nested" Introgressions from Wild Thinopyrum Species, Conferring Effective Resistance to Fusarium Diseases, Positively Impact Durum Wheat Yield Potential.

Ljiljana Kuzmanović,Carla Ceoloni,Francesco Rossini,Roberto Ruggeri,Gloria Giovenali

doi:10.3390/plants10030579

Abstract

Today wheat cultivation is facing rapidly changing climate scenarios and yield instability, aggravated by the spreading of severe diseases such as Fusarium head blight (FHB) and Fusarium crown rot (FCR). To obtain productive genotypes resilient to stress pressure, smart breeding approaches must be envisaged, including the exploitation of wild relatives. Here we report on the assessment of the breeding potential of six durum wheat-Thinopyrum spp. recombinant lines (RLs) obtained through chromosome engineering. They are characterized by having 23% or 28% of their 7AL chromosome arm replaced by a “nested” alien segment, composed of homoeologous group 7 chromosome fractions from Th. ponticum and Th. elongatum (=7el1L + 7EL) or from different Th. ponticum accessions (=7el1L + 7el2L). In addition to the 7el1L genes Lr19 + Yp (leaf rust resistance, and yellow pigment content, respectively), these recombinant lines (RLs) possess a highly effective QTL for resistance to FHB and FCR within their 7el2L or 7EL portion. The RLs, their null segregants and well-adapted and productive durum wheat cultivars were evaluated for 16 yield-related traits over two seasons under rainfed and irrigated conditions. The absence of yield penalties and excellent genetic stability of RLs was revealed in the presence of all the alien segment combinations. Both 7el2L and 7EL stacked introgressions had positive impacts on source and sink yield traits, as well as on the overall performance of RLs in conditions of reduced water availability. The four “nested” RLs tested in 2020 were among the top five yielders, overall representing good candidates to be employed in breeding programs to enhance crop security and safety.

Highlights

Durum wheat (Triticum durum Desf., 2n = 4x = 28, genomes AB) is cultivated on only 8% of the global land surface planted to wheat [1,2], yet it is a strategic crop for countries across diversified world areas, primarily in the Mediterranean Basin [3,4]
The R216+ recombinant (R5 derivative) showed to be disadvantaged versus its R216- control in the cooler and rainier 2019 for grain number/spike (GNS), grain number/spikelet (GNSP) and grain yield/spike (GYS) (15% to 20% reduction; Figure 4), which indicates more investment by the plants in biomass than in grains
Grain yield/plant (GY), grain yield/plant; TILN, tiller number/plant; GN, grain number/plant; TGW, 1000-grain weight; GYS, grain yield/spike; SPN, spikelet No./spike; GNS, grain No./spike; GNSP, grain No./spikelet; SFI, spike fertility index.; sr, spike row; sp, spaced plants; letters in each column correspond to the ranking of Tukey test at 0.05 level for Genotype effect; ** and ***, significance at p < 0.01 and 0.001, respectively

Summary

Introduction

Climate changes contributed to modify the durum wheat conventional distribution areas and to increase the differential response of genotypes to environments by 49% since the mid-1980 s [10], and exposed the crop to unfamiliar pathogens [11,12]. This is the case for fungal pathogens of the Fusarium genus, responsible for some of the most threatening diseases of wheat and other cereals, namely Fusarium head blight (FHB) and Fusarium crown rot (FCR). Intended for human consumption, the durum wheat crop greatly suffers, besides yield and quality reduction, the safety problems associated with health-dangerous Fusarium mycotoxins, such as deoxynivalenol [17]

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Conclusion