Investigating durum wheat-Thinopyrum spp. introgression lines differing for the LATERAL ROOT DENSITY gene under water-deficit stress
Author(s)
Date Issued
2024
Type
conferenceObject
Abstract
Drought is the major abiotic stress currently affecting plant growth and limiting crop production. Its effects on wheat yield depend on intensity, duration and the development stage at which plants face water limitation. To improve durum wheat (DW) tolerance to water scarcity, the introgression of short chromosome segments derived from wild germplasm, adapted to harsh and drought-prone environments, is a promising strategy. Here, the response to water deficit of two chromosomally engineered DW-Thinopyrum spp. nearisogenic recombinant lines (NIRLs) was evaluated. The NIRLs, carriers (+) and non-carriers (−) of different alien segments, included a primary type
(named R112+) with a Th. ponticum 7el1L segment at the 28%-long distal end of DW 7AL arm, and a secondary type (R69-9/R112+) with a Th. elongatum 7EL
segment distally inserted into the 7el1L one. Plants at three-leaf stage were subjected to water deficit and analysed at 3 time-points: day 0, before stress application, day 5 and day 10 upon stress application. In addition to shoot and root morphological traits, the expression of the LRD gene (LATERAL ROOT DENSITY) was evaluated in two developmental root zones, i.e. the differentiation (mature) zone and the terminal root end. Reduced expression of the LRD 7el1 allele under limited water was previously shown to confer bread wheat the ability to increase lateral root growth and to have a positive pleiotropic effect on grain size and number under optimal growth conditions. Here, LRD gene structure across Triticeae species was characterized and the Th. ponticum allele mapped onto the 23-28% proximal end of the 7el1L segment of the R112+ introgression, shared with the R69-
9/R112+ recombinant. The alien segment of R112+ showed significant positive effects under stress, maintaining root dry biomass accumulation and the correlated root-to-shoot (R/S) ratio (+31% vs. R112−). R112+ also showed a lower LRD expression than R112− in the root differentiation zone, under both control (−65%) and drought-stressed (−60%) conditions at the final time-point. On the other hand, a fairly constant level of LRD expression was observed in R69-9/R112+, despite its better root hydration under stress (+91% fresh root biomass), longer principal roots (+11%) and 59% higher R/S biomass at day 10 vs. its R69-9/R112− control. Further analyses will help clarifying the effects of 7el1L LRD on durum wheat root development and identifying other genes possibly involved.
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[2024]SIGA_DiRomana_et_al_LRD.pdf
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Checksum (MD5)
4bc19ea80efe17afa0abbce038121f61
Conference(s)
Annual Congress of Italian Society of Agricultural Genetics