Inheritance of resilience: genetic Mapping of transgenerational and intergenerational drought stress memory in wheat

Abstract

Drought stress is a critical challenge for global wheat production, threatening food security by reducing crop yields and quality. The ability of wheat to adapt to and survive under drought conditions is largely dependent on its genetic makeup. Therefore, understanding the genetic associations controlling the effects of intergenerational and transgenerational stress memory underlying drought exposure histories in a diverse collection of 111 wheat accessions using a genome-wide association study (GWAS) plays a significant role in sustaining yields. In this study, we conducted a comprehensive comparison between seeds from the second-generation group that were not subjected to drought stress (C1C2) and seeds from groups that experienced drought stress in one generation, either two generations prior (D1C2; transgenerational drought memory) or in the preceding generation (C1D2; intergenerational drought memory). Additionally, we analyzed seeds from the group exposed to drought stress in both generations (D1D2; combined drought memory). Our findings reveal that historical exposure to drought stress, irrespective of the specific generational context, led to significant alterations in several key plant characteristics, including spike length, the number of spikelets per spike, grain number per spike, grain weight per spike, thousand kernel weight, and levels of both enzymatic and non-enzymatic antioxidants. These results suggest that previous encounters with drought stress impart a lasting impact on the plant, potentially priming it for altered responses under future stress conditions. Using GWAS analysis, we identified highly significant associations and candidate genes associated with most of the traits evaluated, highlighting the genetic underpinnings that may drive these stress memory effects. Interestingly, the candidate gene TraesCS2A02G432800 on chromosome 2 A mapped as Leucine-rich repeat protein 1 (LRR) that harbors the variation of all the agronomical traits for the wheat genotypes that experienced drought stress over three generations. LRR proteins are involved in various physiological processes, including stress response, making them key players in the adaptation of wheat to drought stress. This research underscores the importance of understanding environmental stressors' transgenerational and intergenerational impact on crop performance, with potential implications for breeding and agricultural resilience.