Durum wheat cultivation is increasingly threatened by viral diseases worldwide. Soil-borne cereal mosaic virus (SBCMV) and wheat spindle streak mosaic virus (WSSMV) cause significant crop losses in Europe. These viruses are transmitted through a soil-inhabiting vector, the plasmodiophoromycota Polymyxa graminis Led. There are very few methods available to eradicate P. graminis, whose resting spores survive in infested soil for decades, but they are either too expensive or not environmentally friendly. Therefore, it is crucial to develop resistant wheat varieties to mitigate the damage. For this purpose, more than 200 durum wheat genotypes, mostly landraces, were selected from the Global Durum Wheat Panel germplasm collection. Then, an experiment was conducted in a semi-controlled environment: the genotypes were sown in pots containing soil infested by P. graminis carrying SBCMV and WSSMV and maintained through the winter period. In early spring, visual assessment of viral symptomatology was performed. Subsequently, the viral loads of the two viruses in leaf tissues were determined through qRT-PCR analysis. The tested genotypes exhibited different responses to the two viruses: SBCMV showed very diversified viral loads among genotypes, whereas WSSMV infected all genotypes. We identified 23 genotypes, with low viral loads of both viruses and reduced symptoms, that could be of particular interest for breeders aiming at new resistant durum wheat varieties. A pilot GWAS allowed to identify genomic regions putatively associated to resistance to SBCMV or WSSMV, as well as possible candidate genes involved in these traits.

In an era characterized by rapidly changing and less-predictable weather conditions fueled by the climate crisis, understanding the mechanisms underlying local adaptation in plants is of paramount importance for the conservation of species. As the frequency and intensity of extreme precipitation events increase, so are the flooding events resulting from soil water saturation. The subsequent onset of hypoxic stress is one of the leading causes of crop damage and yield loss. By combining genomics and remote sensing data, it is now possible to probe natural plant populations that have evolved in different rainfall regimes and look for molecular adaptation to hypoxia. Here, using an environmental genome-wide association study (eGWAS) of 934 non-redundant georeferenced Arabidopsis ecotypes, we have identified functional variants of the gene MED25 BINDING RING-H2 PROTEIN 1 (MBR1). This gene encodes a ubiquitinprotein ligase that regulates MEDIATOR25 (MED25), part of a multiprotein complex that interacts with transcription factors that act as key drivers of the hypoxic response in Arabidopsis, namely the RELATED TO AP2 proteins RAP2.2 and RAP2.12. Through experimental validation, we show that natural variants of MBR1 have different effects on the stability of MED25 and, in turn, on hypoxia tolerance. This study also highlights the pivotal role of the MBR1/MED25 module in establishing a comprehensive hypoxic response. Our findings show that molecular candidates for plant environmental adaptation can be effectively mined from large datasets. This thus supports the need for integration of forward and reverse genetics with robust molecular physiology validation of outcomes.

The present study aimed to identify and characterize new sources of salt tolerance among 94 rice genotypes from varied geographic origins. The genotypes were divided into five groups based on their morphological characteristics at both vegetative and reproductive stages using salinity scores from the Standard Evaluation System (SES). The experiment was designed as per CRD (Completely Randomized Design) with two sets of salinity treatments for 8 dS/meter and 12 dS/meter, respectively compared with one non-salinized control set. Using a Soil Plant Analysis Development (SPAD) meter, assessments of the apparent chlorophyll content (greenness) of the genotypes were done to comprehend the mechanism underlying their salt tolerance. To evaluate molecular genetic diversity, a panel of 1 K RiCA SNP markers was employed. Utilizing TASSEL 5.0 software, 598 filtered SNPs were used for molecular analysis. Whole-genome association studies (GWAS) were also used to investigate panicle number per plant (pn, tiller number per plant (till), SPAD value (spad), sterility (percent) (str), plant height (ph) and panicle length (pl). It is noteworthy that these characteristics oversee conveying the visible signs of salt damage in rice. Based on genotype data, diversity analysis divided the germplasm groups into four distinct clusters (I, II, III and IV). For the traits studied, thirteen significant marker -trait associations were discovered. According to the phenotypic screening, seven genotypes namely Koijuri, Asha, Kajal, Kaliboro, Hanumanjata, Akundi and Dular, are highly tolerant to salinity stress. The greenness of these genotypes was found to be more stable over time, indicating that these genotypes are more resistant to stress. Regarding their tolerance levels, the GWAS analysis produced comparable results, supporting that salinity -tolerant genotypes having minor alleles in significant SNP positions showed more greenness during the stress period. The Manhattan plot demonstrated that at the designated significant SNP position, the highly tolerant genotypes shared common alleles. These genotypes could therefore be seen as important genomic resources for accelerating the development and release of rice varieties that are tolerant to salinity.