Plants

This study aimed to evaluate the effect of selenium concentrations in mitigating salt stress on the physiology, growth, and yield of okra plants irrigated with brackish water. Treatments consisted of four irrigation water salinity levels (ECw: 0.4, 1.3, 2.2, and 3.1 dS m⁻¹) combined with four selenium concentrations (0, 5, 10, and 15 mg L⁻¹), arranged in a randomized block design in a 4 × 4 factorial scheme, with three replicates and one plant per plot. Increasing irrigation water salinity from 0.4 dS m⁻¹ reduced relative water content, gas exchange, initial chlorophyll a fluorescence, plant growth, and production of okra, while increasing the percentage of electrolyte leakage. Irrigation Water salinity levels above 0.4 dS m⁻¹ impaired plant water status, gas exchange, growth, chlorophyll a fluorescence, yield, and water-use efficiency, while increasing electrolyte leakage. Salinity above 1.0 dS m⁻¹ also inhibited photosynthetic pigment synthesis. Selenium did not mitigate salinity-induced reductions in chlorophyll and carotenoids. However, foliar Se at 8.6–15 mg L⁻¹ enhanced gas exchange, chlorophyll a fluorescence, growth, and fruit yield under salinity up to 3.1 dS m⁻¹. These results support Se induced attenuation of salinity stress, warranting further mechanistic studies.

Cryopreservation is vital for conserving the elite germplasm of the hybrid poplar Populus davidiana × P. tremuloides, which is difficult to propagate conventionally. This study established optimized vitrification and encapsulation–vitrification protocols, achieving high regeneration rates of 85.91% and 79.70%, respectively, with confirmed genetic stability. The process induced oxidative stress, altering markers (MDA, H₂O₂) and antioxidant enzyme activities (SOD, POD, CAT). Integrated transcriptomic and metabolomic analysis of key steps—preculture/loading (DLA) and osmotic dehydration (DLB)—revealed extensive stress-responsive reprogramming. A central finding was the robust activation of the flavonoid biosynthesis pathway during DLB, marked by upregulation of key genes (PAL, CHS) and accumulation of flavonols (e.g., quercetin). This response was linked to hormone signaling and antioxidant systems, forming a coordinated defense network. Our multi-omics findings demonstrate that successful cryopreservation relies on an adaptive response where flavonoid biosynthesis plays a critical role in conferring oxidative stress tolerance, providing a theoretical basis for improving woody plant cryopreservation.

Nitrogen (N) is essential for maize (Zea mays L.) productivity, yet its acquisition is limited by the low N uptake efficiency of current varieties. Root cortical aerenchyma (RCA) formation provides a carbon-saving strategy that enhances soil exploration and N acquisition by reducing the metabolic cost of root tissue. However, the genetic basis of RCA formation remains poorly characterized. This study employed an association panel of 295 maize inbred lines to dissect the genetic architecture of RCA formation under low nitrogen (LN) stress. Phenotypic analysis demonstrated that LN stress significantly induced RCA area (RCAA) and proportion (RCAP), with responses ranging from −0.31 to 1.16 mm² for RCAA and −11.34% to 40.18% for RCAP. The non-stiff stalk (NSS) subpopulation exhibited 29.19% higher RCAA under LN than the stiff stalk subgroup. Genome-wide association analysis detected a total of 560 significant SNPs and 810 candidate genes associated with RCA-related traits. Transcriptomic profiling further identified 537 differentially expressed genes between inbred lines with contrasting RCA phenotypes. Integrated GWAS and transcriptomic analysis pinpointed 12 co-localized candidates, subsequently refined to four core genes (GRMZM2G033570, GRMZM2G052422, GRMZM2G080603, and GRMZM2G472266), which were implicated in ethylene signaling and stress-responsive root development. Favorable haplotypes of three genes were predominantly distributed in the NSS (25.64–56.00%) and tropical/subtropical (20.51–46.67%) subpopulations. These findings elucidate the genetic basis of LN-responsive RCA formation and provide fundamental resources for marker-assisted breeding of N-efficient maize.