Papaya, a prominent tropical fruit crop in India, is witnessing expanding cultivation across the country’s diverse agro-climatic zones. This growing popularity is due to its nutritional value, year-round production and economic significance. However, the availability of varieties with improved nutritional and fruit quality remains limited. The trial to investigate combining ability and heterosis for nutritional and eating-quality traits in papaya was conducted at the ICAR-Indian Agricultural Research Institute, New Delhi. The quality traits under study were total soluble solids (TSS), total phenolic content, total flavonoid content, antioxidant activity, β-carotene, lycopene, total carotenoids, fruit firmness, and shelf life. 6 inbred lines of papaya were crossed in a full diallel mating design to develop 30 F1 hybrids, including the reciprocal crosses. The per se mean performance and general combining ability led to the identification of the best parental lines, like P-9–12 for TSS, total carotenoids, β-carotene, lycopene, antioxidants, fruit firmness, and shelf-life, and P-9–5 for total phenolic and flavonoid content. The range of heterosis was low to moderate in papaya hybrids for the traits studied, except for total carotenoids and lycopene, where a high range of heterosis was recorded. The best performing hybrids and specific combiners like PN x P-7–2 for TSS, PS3 x P-7–9 and P-9–5 x PS3 for total phenolic content, P-9–12 x P-9–5 and P-7–2 x P-7–9 for total flavonoid content, PS3 x P-7–2 for antioxidant, P-7–2 x P-9–5 for lycopene, P-7–2 x PN for β-carotene, PS3 x P-7–9 for total carotenoids and P-7–2 x PS3 for fruit firmness and shelf life were identified. Hybrids exhibiting high SCA effects along with desirable mean performance may serve as promising candidates for future hybrid development programs. The study indicated the importance of both additive and non-additive gene action in governing quality and nutritional traits. It demonstrated substantial scope for developing nutritionally superior papaya hybrids with improved shelf life and consumer acceptability.
IntroductionGene-family identification and comparative analyses have largely relied on a single reference genome and therefore cannot capture presence/absence variation among genomes.MethodsThe glutathione S-transferase (GST) family was analysed computationally across 20 Arachis genomes, 16 allotetraploid and four from the diploid progenitor lineages, using orthologous gene groups (OGGs) as the unit of analysis. Gene structure, phylogeny, duplication, collinearity, Ka/Ks and expression in tissue and stress transcriptomes were compared among OGG categories.ResultsThe 1,436 GSTs carrying both canonical domains were assigned to 57 OGGs, comprising 18 core OGGs present in all 20 genomes and 39 dispensable OGGs (softcore, shell and line-specific). The family was structurally uniform, and its uniformity declined from the core to the shell OGGs. The OGGs fell into the Tau, Phi, Theta and Lambda subfamilies, 53 of the 57 belonging to Tau. WGD/segmental duplicates predominated in core and softcore OGGs, making up 65.2% of core genes, whereas tandem duplicates predominated among shell genes at 42.0%, and WGD/segmental duplicates made up a far larger share of the GSTs in the tetraploids than in the diploids. Core and softcore OGGs occupied syntenic positions shared with the progenitor diploids, about half of the cross-genome syntenic links connecting the A and B subgenomes. Among 23,399 within-OGG gene pairs, mean Ka/Ks was below 1 in 43 of the 46 OGGs for which it could be estimated, consistent with predominantly purifying selection; no pair with Ka/Ks above 1 departed significantly from neutrality, and neither Ka, Ks nor Ka/Ks differed between core and dispensable OGGs. Across 22 tissues of the cultivar NDH108, all 35 core genes were expressed, the nine silent genes belonged to softcore or shell OGGs, and the calyx was the most frequent tissue of peak expression. Under drought, cold or salt, 74 of the 84 NDH108 GSTs responded, at similar rates in core and dispensable OGGs.DiscussionAll results are computational and were not validated experimentally. The OGG-based analysis resolves variation in GST content and genomic organisation across the Arachis panel that a single reference genome does not capture, and the genes it highlights are candidates for experimental study.
IntroductionSoil acidification poses a growing threat to forest seedling establishment, yet the physiological responses and tolerance limits of many multipurpose woody species under increasing acidity remain poorly understood. Idesia polycarpa Maxim. is an emerging woody oil tree with high ecological and economic value, but its physiological responses to root-zone acidification are largely unknown. MethodsWe subjected one-year-old I. polycarpa seedlings to 50 d of root-zone irrigation with acidified solutions at pH 5.5, 4.5, and 3.5, with deionized water as the control, and monitored visible injury, photosynthetic pigments, malondialdehyde (MDA), osmotic adjustment substances, and the activities of peroxidase (POD) and superoxide dismutase (SOD). ResultsVisible injury increased with both acidity and exposure duration, and the cumulative injury index reached 85.00% under pH 3.5, 40.00% under pH 4.5, and 16.67% under pH 5.5 after 50 d, while CK remained at 0%. Under pH 3.5, photosynthetic pigment contents showed pronounced temporal fluctuations, with marked reductions at 20 and 50 d and partial recovery during the intermediate stages. MDA content also exhibited a non-monotonic response, with significantly higher values under pH 3.5 at several middle and late sampling times. Soluble sugar, proline, and soluble protein showed stage- and treatment-dependent changes rather than continuous accumulation or decline. POD activity under pH 3.5 reached approximately 3.55-fold the CK value at 10 d and subsequently declined, whereas SOD activity fluctuated markedly among treatments and sampling times. Correlation analysis revealed coordinated variation among photosynthetic pigments, MDA, osmotic adjustment substances, and the two measured antioxidant enzymes, but these associations do not establish causal relationships. DiscussionOverall, seedlings under pH 5.5 and pH 4.5 showed partial physiological adjustment, whereas pH 3.5 was associated with substantially greater visible injury and physiological disturbance. The contrasting responses between the pH 4.5 and pH 3.5 irrigation treatments suggest a potential physiological tolerance boundary within this tested acidity interval under the present controlled conditions, rather than a statistically defined biological breakpoint.
IntroductionMountain habitats feature steep environmental gradients that shape specific vegetation diversity and soil heterogeneity. However, how plants coordinated aboveground and belowground reproductive strategies under varying resource availability remained poorly understood.MethodsWe quantified the belowground bud bank, functional traits, and phylogenetic structures to elucidate plant resource allocation strategies governing community assembly in mountain grasslands of northern China. Six habitat types (SubAlpine Meadow, Forest-Edge Meadow, Floodplain Meadow, Hillside Steppe, Dry Steppe and Sandy Steppe) were selected based on resource availability along the elevation.Results1) Subalpine Meadow exhibited the highest density and diversity. Floodplain Meadow and Dry Steppe had higher ramet density but lower diversity. Bud densities and diversities in the Subalpine, Floodplain and Hillside Steppe were higher than those in other low-elevation habitats; 2) None of the bud bank density, plant height and abundance showed strongly phylogenetic signals. The NTI, NRI were positively related with B/V density, while they were negatively correlated with height and B/V diversity indices; 3) Soil resources distinctly regulated aboveground and belowground populations: Total nitrogen, porosity and soil moisture were negatively correlated with diversities but positively with densities, acting as constraints on the density-diversity trade-off. Importantly, soil organic carbon specifically promoted belowground bud diversity, while total potassium drove aboveground ramet diversity.ConclusionOur results revealed that deterministic processes (niche theory) governed community assembly in the Saihanwula mountain grassland. The aboveground and belowground populations in mountain grasslands were governed by distinct ecological processes and soil resources. Interspecific competition and environmental filtering drove aboveground community assembly, whereas resource availability constrained the belowground bud bank. Our findings provided significant insights for predicting the renewal and recovery potential of plants under global changes.
Palmer amaranth is one of the most troublesome and economically important weeds in soybean production, with widespread occurrence of glyphosate-resistant (GR) populations. This study aimed to map and classify GR Palmer amaranth using UAV-based multispectral imagery and evaluate the effects of herbicide programs [preemergence (PRE) only, postemergence (POST) only, and PRE followed by (fb) POST] on Palmer amaranth coverage (early- and late-season) in soybean field in central Louisiana in 2025. A multispectral drone was used to map GR Palmer amaranth, and images were processed into orthomosaic using Pix4DFields and georeferenced in ArcGIS Pro. Weed classification was performed using pixel-based and object-based approaches implemented in ENVI and Orfeo Toolbox (OTB) within QGIS, employing Random Forest (RF), Multilayer Perceptron (MLP), and Support Vector Machine (SVM) algorithms. Both classification methods exhibited high performance, with RF achieving the highest overall accuracy (99%). UAV-based assessments provided a spatiotemporally efficient method for early-season Palmer amaranth mapping and late-season evaluation of residual weed activity following herbicide applications. UAV-derived Palmer amaranth coverage showed moderate positive correlation with the ground-truth weed density. Herbicide programs significantly reduced UAV-derived Palmer amaranth coverage during early-season (P = 0.0004) and late-season (P = 0.0223) assessments. Among the evaluated programs, PRE fb POST resulted in the greatest reduction in weed coverage (4.3%), compared with PRE only (9.2%) and POST-only (8.8%) programs. In conclusion, integrating UAV-based multispectral imagery with machine learning algorithms, particularly RF, offers a promising, automated approach for classification of GR Palmer amaranth and evaluating herbicide program effectiveness across different crop growth stages.
