Inheritance of Partial Resistance to Isolate VdLs17 of Verticillium dahliae Within Lactuca spp.

Lettuce (Lactuca sativa L.) production is greatly threatened by Verticillium wilt, which is caused by three pathogenic races (races 1, 2, and 3) of the soilborne fungus Verticillium dahliae. Race 1 is predominant, and resistant varieties that provide full protection against it are commercially available. However, heavily relying on race 1-resistant cultivars could shift the population towards resistance-breaking isolates and impact the durability of plant resistance. This study determined the inheritance of partial resistance to isolate VdLs17 of V. dahliae within Lactuca spp. using 258 F2:3 progeny generated from a cross between two partially resistant accessions, 11G99 (L. serriola) and PI 171674 (L. sativa). Eight experiments were performed under greenhouse and growth room conditions across 3 years using a randomized complete block design, and segregation analysis was conducted to determine the inheritance pattern. The results indicate that partial resistance to isolate VdLs17 of V. dahliae is conditioned by a two-major-gene genetic model with additive-dominance-epistatic effects. Transgressive segregants were infrequent but observed in both directions, indicating that favorable and adverse alleles are dispersed in both parents. Combining favorable alleles of these two partially resistant parents appears to be challenging because of epistatic effects and a significant role of environment in disease severity. The probability of capturing favorable additive genes could be maximized by generating and evaluating a large population and making selections at late generations. This study provides valuable insights into the inheritance pattern of partial resistance to isolate VdLs17 of V. dahliae that will be helpful in designing efficient breeding strategies in lettuce.[Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Furan-based Chalcone Annihilates the Multi-Drug-Resistant Pseudomonas aeruginosa and Protects Zebra Fish Against its Infection.

The emergence of carbapenem-resistant Pseudomonas aeruginosa, a multi-drug-resistant bacteria, is becoming a serious public health concern. This bacterium infects immunocompromised patients and has a high fatality rate. Both naturally and synthetically produced chalcones are known to have a wide array of biological activities. The antibacterial properties of synthetically produced chalcone were studied against P. aeruginosa. In vitro, study of the compound (chalcone derivative named DKO1), also known as (2E)-1-(5-methylfuran-2-yl)-3-(4-nitrophenyl) prop-2-en-1-one, had substantial antibacterial and biofilm disruptive action. DKO1 effectively shielded against P. aeruginosa-induced inflammation, oxidative stress, lipid peroxidation, and apoptosis in zebrafish larvae. In adult zebrafish, the treatment enhanced the chances of survivability and reduced the sickness-like behaviors. Gene expression, biochemical analysis, and histopathology studies found that proinflammatory cytokines (TNF-α, IL-1ß, IL-6, iNOS) were down regulated; antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT) levels increased, and histoarchitecture was restored in zebrafish. The data indicate that DKO1 is an effective antibacterial agent against P. aeruginosa demonstrated both in vitro and in vivo.

Mapping quantitative trait loci for biomass yield and yield-related traits in lowland switchgrass (Panicum virgatum L.) multiple populations.

Switchgrass can be used as an alternative source for bioenergy production. Many breeding programs focus on the genetic improvement of switchgrass for increasing biomass yield. Quantitative trait loci (QTL) mapping can help to discover marker-trait associations and accelerate the breeding process through marker-assisted selection. To identify significant QTL, this study mapped 7 hybrid populations and one combined of 2 hybrid populations (30-96 F1s) derived from Alamo and Kanlow genotypes. The populations were evaluated for biomass yield, plant height, and crown size in a simulated-sward plot with 2 replications at 2 locations in Tennessee from 2019 to 2021. The populations showed significant genetic variation for the evaluated traits and exhibited transgressive segregation. The 17,251 single nucleotide polymorphisms (SNPs) generated through genotyping-by-sequencing (GBS) were used to construct a linkage map using a fast algorithm for multiple outbred families. The linkage map spanned 1,941 cM with an average interval of 0.11 cM between SNPs. The QTL analysis was performed on evaluated traits for each and across environments (year and location) that identified 5 QTL for biomass yield (logarithm of the odds, LOD 3.12-4.34), 4 QTL for plant height (LOD 3.01-5.64), and 7 QTL for crown size (LOD 3.0-4.46) (P ≤ 0.05). The major QTL for biomass yield, plant height, and crown size resided on chromosomes 8N, 6N, and 8K explained phenotypic variations of 5.6, 5.1, and 6.6%, respectively. SNPs linked to QTL could be incorporated into marker-assisted breeding to maximize the selection gain in switchgrass breeding.

Identification of QTL Associated with Regrowth Vigor Using the Nested Association Mapping Population in Switchgrass.

Switchgrass (Panicum virgatum L.) is a warm-season perennial grass species that is utilized as forage for livestock and biofuel feedstock. The stability of biomass yield and regrowth vigor under changing harvest frequency would help manage potential fluctuations in the feedstock market and would provide a continuous supply of quality forage for livestock. This study was conducted to (i) assess the genetic variation and (ii) identify the quantitative trait loci (QTL) associated with regrowth vigor after multiple cuttings in lowland switchgrass. A nested association mapping (NAM) population comprising 2000 pseudo F2 progenies was genotyped with single nucleotide polymorphism (SNP) markers derived from exome-capture sequencing and was evaluated for regrowth vigor in 2017 and 2018. The results showed significant variation among the NAM families in terms of regrowth vigor (p < 0.05). A total of 10 QTL were detected on 6 chromosomes: 1B, 5A, 5B, 6B, 7B, and 8A, explaining the phenotypic variation by up to 4.7%. The additive genetic effects of an individual QTL ranged from -0.13 to 0.26. No single QTL showed a markedly large effect, suggesting complex genetics underlying regrowth vigor in switchgrass. The homologs of candidate genes that play a variety of roles in developmental processes, including plant hormonal signal transduction, nucleotide biosynthesis, secondary metabolism, senescence, and responses to both biotic and abiotic stresses, were identified in the vicinity of QTL.