Identifying population genetic structure (PGS) is crucial for breeding and conservation. Several clustering algorithms are available to identify the underlying PGS to be used with genetic data of maize genotypes. In this work, six methods to identify PGS from unlinked molecular marker data were compared using simulated and experimental data consisting of multilocus-biallelic genotypes. Datasets were delineated under different biological scenarios characterized by three levels of genetic divergence among populations (low, medium, and high

Drought severely affects soybean productivity, challenging breeding/management strategies to increase crop resilience. Hormone-based biostimulants like brassinosteroids (BRs) modulate growth/defence trade-off, mitigating yield losses; yet, natural molecule's low stability challenges the development of cost-effective and long-lasting analogues. Here, we investigated for the first time the effects of BR functional analogue DI-31 in soybean physiology under drought by assessing changes in growth, photosynthesis, water relations, antioxidant metabolism, nodulation, and nitrogen homeostasis. Moreover, DI-31 application frequencies' effects on crop cycle and commercial cultivar yield stabilisation under drought were assessed. A single foliar application of DI-31 favoured plant drought tolerance, preventing reductions in canopy development and enhancing plant performance and water use since the early stages of stress. The analogue also increased the antioxidant response, favouring nitrogen homeostasis maintenance and attenuating the nodular senescence. Moreover, foliar applications of DI-31 every 21 days enhanced the absolute yield by ~ 9% and reduced drought-induced yield losses by ~ 7% in four commercial cultivars, increasing their drought tolerance efficiency by ~ 12%. These findings demonstrated the practical value of DI-31 as an environmentally friendly alternative for integrative soybean resilience management under drought.

Sugarcane breeding programs incorporate foreign material to broaden the genetic base, expanding the gene pool. In South America, the Inter-university Network for the Development of the Sugarcane Industry (RIDESA) and Estación Experimental Agroindustrial Obispo Colombres (EEAOC) sugarcane breeding programs from Brazil and Argentina, respectively, have never exchanged materials. In that sense, the knowledge of the genetic diversity and population structure among sugarcane genotypes of both germplasm banks, determined in a reliable way through their molecular profiles, will provide valuable information to select the best parental accessions for crossing aimed at the efficient introgression of desirable alleles. For that, the aim was to determine the genetic diversity and population structure of 96 Saccharum commercial hybrids from RIDESA and EEAOC sugarcane breeding programs by using TRAP, SSR and markers related to disease resistance (e.g. Bru1 and G1). Genetic structure was determined through genetic similarity analysis, analysis of molecular variance (AMOVA), Multidimensional scaling (MDS), and a Bayesian method. Average PIC values were 0.25 and 0.26, Ho values were 0.24 and 0.28, and He values were 0.25 and 0.28, for TRAP and SSR primers, respectively. Genetic similarity, MDS, and analysis of structure revealed that Brazilian and Argentinean genotypes clustered in two groups clearly differentiated, whereas AMOVA suggested that there is more variability within programs than between them. Regarding Bru1 markers, Brazilian genotypes showed high frequency of haplotype 1 (71.4%) whereas Argentinean genotypes showed high frequency of haplotype 4 (80.8%); haplotypes 1 and 4 are indicated for the presence and absence of the brown rust resistance gene (Bru1), respectively. Respecting the G1 marker, most of the evaluated genotypes (60.4%) showed the presence of the fragment, in a similar proportion for genotypes of both programs. In conclusion, the exchange of materials, at least the most diverse genotypes, between RIDESA and EEAOC breeding programs will allow extending the genetic base of their germplasm banks, and the knowledge of genetic diversity will help breeders to better manage crosses, increasing the probability of obtaining more productive varieties.

Sweet potato, in Argentina, is affected by the “encrespamiento amarillo”, a viral disease in which seven viruses are involved, among them two potyvirus (sweet potato feathery mottle virus - SPFMV and sweet potato virus G - SPVG) and a crinivirus (sweet potato chlorotic stunt virus - SPCSV). This research aimed to study the interaction between SPFMV and SPVG with SPCSV in sweet potato. Two sweet potato cultivars (Gem and Arapey INIA) and Ipomoea setosa as an indicator susceptible plant were tested as single (SPFMV or SPVG), double (SPFMV + SPVG, SPFMV + SPCSV or SPVG + SPCSV) or triple (SPFMV + SPVG + SPCSV) grafts. Both potyviruses were purified and the viral concentrations in the plant tissues were quantified by the DAS-Elisa method. The viruses and their severities were evaluated at 7, 15, 21, 30 and 35 days post-inoculation. A synergistic effect was observed with the three viruses in the indicator plant. The viral concentration increase was 50 times for SPFMV (day 35) and two times for SPVG (day 21) in the Gem cultivar, and 1.89 times for SPFMV (day 35) and three times for SPVG (day 7) in the Arapey INIA. For multiple infections, the indicator plant and the Gem cultivar exhibited synergistic symptoms and increase in the viral titers, with a higher severity and variability of the symptoms. Co-infections such as SPFMV + SPVG showed characteristic potyvirus symptoms, without increasing the viral concentrations; triple co-infections exhibited viral complex symptoms, with increase in the potyvirus titers; and the symptoms were mild or imperceptible in the simple infections.