The effect of source-sink manipulations on biomass partitioning and grain yield in durum wheat in the presence of Thinopyrum ponticum introgressions
Author(s)
Date Issued
2024
Type
conferenceObject
Abstract
Wheat is the most cultivated cereal worldwide and plays a fundamental role in the human diet, implying the need to maintain the stability of its yields in the context of climate change. Grain yield is a complex trait, resulting from the balance between the activity of photosynthetic organs called "source", which provide assimilates, and the assimilate storage capacity of the “sink” organs during maturation (i.e. grain number and weight). We have focused on the characterisation of shoot biomass partitioning and its effect on yield in three durum wheat-Thinopyrum ponticum (a wild wheat relative) recombinant lines (named R5+, R112+ and R23+) obtained via chromosome engineering. To assess the effects of the presence of each alien introgression on wheat chromosome 7A (spanning 23%,
28% and 40% of its long arm, respectively) on the source-sink relationships, three treatments were applied on shoots after anthesis in
field conditions during the 2020-21 and 2021-22 seasons: defoliation (DEF), ear shading (EAR) and degraining (DEG). The results showed the three recombinants to have different regulation mechanisms of the source-sink balance, in association with different amounts of Th. ponticum chromatin. Differences in biomass partitioning between alien segment-carrier and noncarrier sib lines were mostly evident under the limitation of ear photosynthesis (EAR). The R5+ recombinant was the most stable, as it did not alter the biomass partitioning, due to the ability to compensate for the lack of a given source (DEF, EAR) from other organs to maintain yield. In the presence of its alien segment, the R112+ line was found to allocate more biomass in the culm (+15%) and less in the ear (-10%) and grains (-19%). The poor efficiency of R112+ in transferring reserves from culm and other organs into grains was particularly evident under conditions of low
water availability and high temperatures of the 2021-22 season. In contrast, the alien segment of R23+ recombinant caused more biomass to be allocated in the ear (15%) and grains (up to 44%) and less in the culm (-15%) under all conditions tested, especially the unfavourable ones of the 2021-22 season and the EAR treatment. This was in line with the observed 51% higher efficiency in dry matter translocation from stem to ear of the R23+ recombinant vs its control. For the first time, it was possible to associate the presence of genetic factors in the chromatin portion of Th. ponticum exclusive to R23+ (28-40% 7AL) with greater efficiency of translocation of assimilates to grains. The new knowledge obtained confirms wild wheat relatives to be a rich source of useful genes also for complex traits and contributes to a better understanding of the complex source-sink interaction in wheat and related species.
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