Plants

Climate change is altering temperature and precipitation regimes in Argentina, with potential consequences for regeneration and persistence of forest tree species, emphasizing the importance of ex situ seed conservation. We evaluated interannual variation in seed traits, desiccation tolerance, storage behavior, and longevity of Cedrela balansae C. DC. and C. fissilis Vell. (Meliaceae), two endangered native species of subtropical rainforests in Argentina. Both species produced desiccation-tolerant seeds, independently of collection year, seed traits, or climatic conditions. Depending on the species, seed traits and longevity varied across years and showed strong relationships with temperature and precipitation, particularly during seed development. Cedrela balansae seeds are medium-lived seeds and have high longevity under standard seed banking conditions, suggesting strong potential for long-term ex situ conservation. Cedrela fissilis seeds are short-lived seeds and have high sensitivity to the storage environment. Correlations among climatic variables and seed traits and longevity parameters suggest that future warming and drying environments may shorten the window for germination and seedling establishment, with species-specific responses depending on climatic conditions during seed development. These results highlight the importance of climate effects in determining seed traits and seed longevity and emphasize the role of seed banking as a critical conservation strategy under climate change.

Soybean root rot, caused by diverse soil-borne pathogens, is a major constraint on production worldwide, with yield losses ranging from 10 to 60% under epidemic conditions. Symptomatic plants were collected from three locations in Harbin, Heilongjiang Province, China, and 23 fungal isolates were recovered using standard tissue isolation procedures. Integrated morphological characterization and rDNA-ITS sequencing identified these isolates as three Fusarium species: F. oxysporum (18 isolates, 78%), F. equiseti (3 isolates, 13%), and F. brachygibbosum (2 isolates, 9%). Pathogenicity assays following Koch’s postulates confirmed F. oxysporum as the predominant and most aggressive pathogen in this region. To identify resistance resources, 200 soybean germplasm accessions adapted to Northeast China were screened using an etiolated seedling hypocotyl inoculation method with Fusarium oxysporum isolate A3 (DSI = 68.5) as the test pathogen. Disease severity indices exhibited a continuous distribution (mean = 52.84, range = 0–100), suggesting quantitative inheritance. Accessions were classified as highly resistant (13, 6.5%), resistant (40, 20%), moderately susceptible (67, 33.5%), susceptible (43, 21.5%), or highly susceptible (37, 18.5%). To explore potential molecular mechanisms underlying resistance, RT-qPCR analysis was performed on two extreme genotypes—a highly resistant line (H9477F5, DSI = 15.3) and a highly susceptible line (HN91, DSI = 88.7) at 1, 3, and 5 days post-inoculation. The resistant line maintained consistently higher expression of positive regulators GmFER and GmSOD1, with GmFER reaching 15.89-fold induction at day 3. Conversely, expression of negative regulators GmJAZ1 and GmTAP1 remained lower in the resistant line, with susceptible plants showing 5.62-fold higher GmJAZ1 expression at day 3. These findings provide characterized pathogen isolates, resistant germplasm resources (53 accessions with HR or R classifications), and preliminary molecular insights that may inform breeding strategies for improving root rot resistance in Northeast China.

In the present study, the yield, chemical composition, and biological activities of Lavandula angustifolia flower essential oil (LAFEO) and leaves (LALEO) under different shade nets (pearl, red, blue) with 40% shading index compared with non-shading (control-open field) plants were investigated. The essential oil (EO) was isolated using a Clevenger-type hydrodistillation and the chemical composition of isolated EO was determined by GC/MS and GC/FID analyses. The antioxidant activity was determined using the DPPH and FRAP assay. The highest EO yield was recorded in flowers from plants grown under pearl shade nets (4.62 mL/100 g p.m.) and in leaves under red nets (0.99 mL/100 g p.m.). The lowest EO content occurred in plant leaves (0.50 mL/100 g p.m.) and flowers (3.17 mL/100 g p.m.) from non-shaded (control) plants. The composition of lavender EO depended on both plant part and light conditions. Among the 47–59 identified compounds in LAFEO, the major constituents were 1,8-cineole (27.4–32.2%), linalool (24.7–27.3%), borneol (18.0–21.9%), and camphor (7.5–8.6%). In LALEO, 55–65 compounds were identified, with 1,8-cineole (30.4–39.8%), borneol (21.9–26.5%), camphor (11.3–13.9%), and linalool (6.0–8.6%) as the dominant constituents. Flower samples from non-shaded (control) plants showed moderate antioxidant activity, with EC₅₀ values decreasing over time, indicating the highest activity among treatments tested. Conversely, plant leaves under pearl nets showed the lowest activity among samples, with an EC₅₀ value of 42.40 mg/mL at 120 min, still within the moderate antioxidant activity range. LALEO showed higher FRAP values than flower oils, confirming a stronger reducing capacity. The highest activity was found in plant leaves under red nets (0.72 mg EFe²⁺/g) and in non-shaded plants (0.68 mg EFe²⁺/g), while the lowest occurred in flower samples from red (0.28 mg EFe²⁺/g) and pearl nets (0.33 mg EFe²⁺/g). Unlike the FRAP results, the DPPH assay showed relatively higher activity in flowers compared to leaves, though all samples exhibited moderate antioxidant capacity. Shading significantly increased essential oil yield; however, the effects of different color nets on essential oil quality require further investigation, although preliminary results indicate a potential reduction in undesirable constituents.