Analysis of the response to heat and water-deficit stress in durum wheat introgression lines with segmental transfers from wild Thinopyrum species
Author(s)
Giovenali, Gloria
Date Issued
July 18, 2023
Type
Doctoral Thesis
Abstract
Severity and frequency of abiotic stress is increasing worldwide, posing a major threat to durum wheat (DW) production. DW is mainly grown in areas around the Mediterranean basin, which is considered a hotspot of climate change. Here, heat waves/high temperature peaks accompanied by water shortage conditions are predicted to become more recurring and intense, causing a number of negative effects on overall DW vigour and productivity. Given the importance of improving crop yields to achieve food security, and the restricted genetic basis of most crop species, including DW, identification of new tolerant genotypes is a major breeding target. The introgression of novel and genes/QTLs in still unexplored wild relatives into DW backgrounds represents a promising and sustainable strategy to improve the crop tolerance to abiotic stresses. In this thesis, the overall performance of a set of DW-Thinopyrum spp. near-isogenic recombinant lines (NIRLs), previously obtained via chromosome engineering, was tested under heat and/or water-limited stress conditions. The NIRLs included three primary types (R5, R112, R23) carriers (+) and non-carriers (−) of a differently sized Th. ponticum 7el1L segment on DW 7AL arm, and two corresponding secondary NIRLs (R69-9/R5, R69-9/R112), possessing a Th. elongatum 7EL segment distally inserted into the respective 7el1L ones. The genotypes were analysed under controlled conditions at two key phenological phases (seedlings at two-leaf stage and adult plants at anthesis) and their performance was evaluated based on morphological, physiological, biochemical and yield traits. Comparative analyses performed on NIRLs + vs. − allowed to associate different stress response mechanisms to the presence of specific alien chromatin introgressions, highlighting a number of physiological/biochemical and ultimately yield advantages expressed by given recombinant lines under stress conditions. The results of the experimental activities carried out at the seedling stage showed that the 23%-long Th. ponticum segment, common to R5+ and R69-9/R5+, conferred substantial advantages under stress conditions, mainly related to the maintenance of the superoxide dismutase activity under heat (H) and of RWC under water-deficit + heat (WH) conditions. The same chromosome segment turned out to be involved in proline increase in WH stressed flag leaves (stress applied at anthesis under control conditions) and in maintenance of chlorophyll content and grain weight across different water regimes in field conditions. The slightly longer 28%-long 7el1L segment, carried by R112+ and R69-9/R112+, was associated with several physiological advantages under H stress, the most evident being maintenance of a highly
efficient photosynthetic activity. Finally, the 7el1L segment specific to R23+, proved to harbor genes/QTLs for spike fertility expressed even under H and WH conditions. In summary, the evidence reported in this thesis largely substantiates the effectiveness of using wild germplasm, often adapted to stressful environments, as in the case of Thinopyrum species, to transfer useful tolerance attributes into important crops such as DW, thus improving their stress resilience and hence contributing to yield stability or even enhancement.
Additional information
Dottorato di ricerca in Scienze delle produzioni vegetali e animali
File(s)![Thumbnail Image]()
Name
ggiovenali_tesid.pdf
Size
18.9 MB
Format
Adobe PDF
Checksum (MD5)
8a8a3d501f2e2683f8dcf418b0fed5e1