Identification of Heat Tolerant Cotton Lines Showing Genetic Variation in Cell Membrane Thermostability, Stomata, and Trichome Size and Its Effect on Yield and Fiber Quality Traits

Heat stress in cotton reduces its productivity. The development of heat-tolerant cotton varieties having resilience against changing climate is feasible. The purpose of this study was to probe the genetic variability in upland cotton for heat tolerance, the association of cell membrane thermostability (CMT), stomata, and trichome size with cotton adaptation to high temperature and effective breeding strategy to advance the valued traits. Relative cell injury percentage (RCI%) in studied genotypes ranged from 39 to 86%. Seventeen genotypes were found heat tolerant on the basis of low RCI%, heat susceptibility index (HSI<1), higher number of boll/plant, and seed cotton yield (SCY). Scanning electron microscopy (SEM) of heat-tolerant genotypes revealed the presence of different size of stomata (21.57 to 105.04 μm2) and trichomes (177 to 782.6 μm) on leaves of selected genotypes. The regression analysis showed a strong and negative association of RCI% and stomata size with SCY. However, no association was observed between the trichome size, yield, and fiber traits. On the overall location basis, a significant genotype × environment interaction was observed. All selected genotypes produced a higher SCY as compared with check varieties. But the stability analysis showed that the high yielding genotypes NIA-M-30, NIA-80, NIA-83, and CRIS-342 were also wide adaptive with unit regression (bi∼1) and non-significant deviation from the regression line (S2d∼0). The ability for the combination of some heat-tolerant genotypes was estimated by using the line × tester method among nine hybrids along with their 3 testers (i.e., male) and 3 lines (i.e., females). Genotypes, CRIS-342 and NIA-Perkh, were observed as best general combiners for SCY with a negative general combining ability effects for RCI%. Five hybrids showed a positive specific combining ability and heterotic effects for studied traits and also found lowest for HSI. RCI% and SCY/plant displayed higher estimates of heritability and genetic advance, indicating the heritability due to additive gene effects and chances of effective selection. The identified heat-tolerant and wide adaptive germplasm can be further advanced and utilized in cotton breeding programs for developing heat-tolerant cultivars. Selection criteria involving CMT and stomata size concluded to be an effective strategy for the screening of heat-tolerant cotton.

Liana functional assembly along the hydrological gradient in Central Amazonia

Soil hydrology, nutrient availability and forest disturbance determine the variation of tropical tree species composition locally. However, most habitat filtering is explained by tree species' hydraulic traits along the hydrological gradient. We asked whether these patterns apply to lianas. At the community level, we investigated: (i) whether the hydrological gradient, soil fertility and forest disturbance explain liana species composition; and (ii) whether differences in leaf and stem wood functional traits were linked to species composition along ecological gradients. We sampled liana species composition in 18 1-ha plots across a 64 km² landscape in Central Amazonia and measured ten leaves and stem wood traits across 115 liana species in 2,000 individuals. We correlated liana species composition summarized with PCoA with the functional composition summarized by PCA, considering the species mean values of traits at the plot level. We tested the relationship between ordination axes and the environmental gradients. Liana species composition was highly correlated with functional composition. Taxonomic (PCoA) and functional (PCA) composition were strongly associated with the hydrological gradient, with a slight impact of forest disturbance on functional composition. Species at valley areas had higher stomata size and higher proportions of self-supporting xylem than plateau. Differently, lianas on plateaus invest more in fast-growing leaves (higher SLA), although with a higher wood density. Our study reveals that lianas use different functional solutions in dealing with each end of the hydrological gradient and that the relationships between habitat preferences and traits explain lianas species distributions not straightforwardly as previously found for trees.

In vitro induction and identification of polyploid Neolamarckia cadamba plants by colchicine treatment

Polyploidization has played a crucial role in plant breeding and crop improvement. However, studies on the polyploidization of tropical tree species are still very scarce in this region. This paper described the in vitro induction and identification of polyploid plants of Neolamarckia cadamba by colchicine treatment. N. cadamba belongs to the Rubiaceae family is a natural tetraploid plant with 44 chromosomes (2n = 4x = 44). Nodal segments were treated with colchicine (0.1%, 0.3% and 0.5%) for 24 h and 48 h before transferring to shoot regeneration medium. Flow cytometry (FCM) and chromosome count were employed to determine the ploidy level and chromosome number of the regenerants, respectively. Of 180 colchicine-treated nodal segments, 39, 14 and 22 were tetraploids, mixoploids and octoploids, respectively. The highest percentage of polyploidization (20% octoploids; 6.7% mixoploids) was observed after treated with 0.3% colchicine for 48 h. The DNA content of tetraploid (4C) and octoploid (8C) was 2.59 ± 0.09 pg and 5.35 ± 0.24 pg, respectively. Mixoploid plants are made up of mixed tetraploid and octoploid cells. Chromosome count confirmed that tetraploid cell has 44 chromosomes and colchicine-induced octoploid cell has 88 chromosomes. Both octoploids and mixoploids grew slower than tetraploids under in vitro conditions. Morphological characterizations showed that mixoploid and octoploid leaves had thicker leaf blades, thicker midrib, bigger stomata size, lower stomata density, higher SPAD value and smaller pith layer than tetraploids. This indicates that polyploidization has changed and resulted in traits that are predicted to increase photosynthetic capacity of N. cadamba. These novel polyploid plants could be valuable resources for advanced N. cadamba breeding programs to produce improved clones for planted forest development.

Morphological, Physiological, and Biochemical Responses of Zinnia to Drought Stress

Bedding plants in the nursery phase are often subject to drought stress because of the small volume of the containers and the hydraulic conductivity of organic substrates used. To analyse the morphological, physiological, and enzymatic responses of zinnia (Zinnia elegans L.) plants at different irrigation levels, four treatments were performed: irrigated at 100% (100% field capacity, FC); light deficit irrigation (75% FC), medium deficit irrigation (50% FC), and severe deficit irrigation (25% FC). The growth of zinnia was significantly influenced by drought stress treatments. Different morphological parameters (dry biomass, leaf number, root to shoot ratio (R/S)) were modified only in the more severe drought stress treatment (25% FC). The stomata density increased in 50% FC and 25% FC, while the stomata size was reduced in 25% FC. The net photosynthesis, stomatal conductance, and transpiration were reduced in 50% FC and 25% FC. The relative water content (RWC) was reduced in 25% FC. Severe drought stress (25% FC) increased proline content up to seven-fold. Catalase (CAT), peroxidase (GPX), and superoxide dismutase (SOD) activity significantly increased in 50% FC and 25% FC. Principal component analysis (PCA) showed that the morphological and physiological parameters were mostly associated with the 100% FC and 75% FC treatments of the biplot, whereas the stomata density, R/S ratio, and antioxidant enzymes (GPX, CAT) were associated with 50% FC, and proline and DPPH were associated with 25% FC, respectively.

Anatomical Characteristics of African Cherry (Prunus Africana) Medicinal Plant for its Accurate Taxonomic Identification

Background: The genus Prunus (Family Rosaceae) comprises over 400 plant species and exhibits vast biodiversity worldwide. Due to its wide distribution, its taxonomic classification is important. Anatomical characters are conserved and stable and thus can be used as an important tool in plant taxonomic characterization. Thus, this study aimed at examining and documenting P. africana leaf, stem, and seed anatomy using micrographs and photographs for possible use in identification, quality control, and phylogenetic studies of the species.Methods: P. africana leaves, stems, and seeds were fixed, dehydrated in ascending ethanol series (50–100 %), embedded in Technovit resin, and sectioned using a microtome for mounting histological slides for anatomical observation under a microscope and subsequent description.Results: The anatomical sections of a young stem revealed a cortex consisting of isodiametric parenchyma cells, druse crystals, primary vascular bundles, and pith. The mature stem bark consisted majorly of rhytidome with periderm densely arranged in multiple layers, a cluster of stone cells, and sclerenchyma. The sections of the leaf were hypostomatic with stomata size ranging between 18.90– (22.34)–26.90 × 15.41– (18.40)–21.22 μm. The leaf sections showed the presence of characteristic druse crystals, vascular bundles, and mesophyll layers. The pericarp showed the presence of epicarp, mesocarp, and endocarp with a thickness of approximately 350–400, 300–350, and 30–50 μm, respectively and a seed testa with a thickness of approximately 50–60 μm. Conclusion: The characteristic morphological and anatomical features observed in P. africana leaves, stems, and seeds in this study could provide useful data in taxonomical identification of this species.

Genome-Wide Association Mapping for Stomata and Yield Indices in Bread Wheat under Water Limited Conditions

Genome-wide association study (GWAS) was performed for stomata- and yield-related attributes with high-density Illumina 90 K Infinium SNP (single nucleotide polymorphism) array in bread wheat to determine genetic potential of germplasm for scarce water resources with sustainable yield potential. Major yield and stomata attributes were phenotyped on a panel of Pakistani and foreign accessions grown in non-stressed and water shortage environments during two seasons. Highly significant variations were shown among accessions in both conditions for examined characteristics. Water shortage conditions reduced the overall wheat yield and strong positive correlation existed among stomatal frequency, leaf venation and grain yield per plant. Population structure analyses based on 90,000 SNP data classified the accessions into four sub-populations which indicated the presence of genetic variability. Marker-trait association (MTA) analyses revealed that 422 significant SNPs at p ≤ 10−3, after crossing the false discovery rate (FDR) <0.05 threshold, were linked with examined attributes. Pleiotropic loci (wsnp_Ex_c8913_14881924 and Tdurum_contig10598_304) were associated with flag leaf area (FLA), stomata size (SS), stomata frequency (SF), leaf venation (LV), number of grain per spike (NGS) and grain yield per plant (GYP), which were located on chromosome 4B and 6B at the positions 173.63cM and 229.64cM, respectively, under water shortage conditions. Pleotropic loci wsnp_Ex_c24167_33416760, wsnp_Ex_c5412_9564046 and Tdurum_contig81797_369 on chromosomes 7A, 2A and 4B at the positions 148.26cM, 261.05cM and 173.63cM, respectively, were significantly linked with stomata and yield indices such as FLA, SS, SF, LV, NGS and GYP under normal and water shortage conditions. The current experiment not only validated several MTAs for studied indices reported in other studies but also discovered novel MTAs significant under water shortage environments. Associated and significant SNPs will be useful in discovering novel genes underpinning water shortage tolerance in bread wheat for producing high-yielding and drought tolerant wheat varieties to fulfill the wheat demand for growing populations.

Photosynthetic contribution and characteristics of cucumber stem and petiole

Background Photosynthesis of plant non-leaf blade green tissue has been studied in some plants, but the photosynthesis characteristics of stem and petiole are poorly understood. Cucurbitaceous plants are climbing plants, and have a large biomass of stem and petiole. Understanding the photosynthetic contribution of cucumber stem and petiole to growth and the underlying molecular mechanisms are important for the regulation of growth in cucumber production. Results Here, the photosynthetic capacity of cucumber stem and petiole were proved by 14CO2 uptake. The total carbon fixation of stem and petioles is around 4% to that of one leaf blade in cucumber seedling stage, while the proportion of carbon accumulated in stem and petioles redistributed to sink organs (root and growing point) is increased obviously under leaf less condition. Photosynthetic properties of cucumber stem and petiole were studied using a combination of electron microscopy, chlorophyll fluorescence imaging and isotope tracer to compare with leaf blade using two genotype of cucumber (dark green and light green stems). Compare with leaf blade, chlorophyll contents of cucumber stem and petiole are lower, and accompanying with lower chloroplast number, lower stoma number, but with higher thylakoid grana lamella number and larger stomata size. The total photosynthetic rate of stem and petiole is equivalent to 6 ~ 8% of one leaf blade, but the respiration rates were simiar in all the three tissues, which shown an almost 0 net photosynthetic rate in stems and petioles, and with lower non-photochemical quenching (NPQ). Transcriptome analysis showed that compared with leaf blade, there are significantly different gene expressions in photosynthesis, porphyrin and chlorophyll metabolism, photosynthetic antenna proteins and carbon fixation in stem and petiole. Although with lower Rubisco expression level in stem and petiole, Rubisco and PEPC enzyme activities were both higher in stem and petiole than in leaf blade, suggesting the photosynthetic and respiratory mechanisms in stem and petiole are different from those in leaf blade. Conclusions In this study, we confirmed the photosynthetic contribution to growth of cucumber stem and petiole, and shown their similar photosynthetic pattern in tissue anatomy, molecular biology and physiology.

Response of Leaf Traits of Eastern Qinghai-Tibetan Broad-Leaved Woody Plants to Climatic Factors

Plant ecologists have long been interested in quantifying how leaf traits vary with climate factors, but there is a paucity of knowledge on these relationships given a large number of the relevant leaf traits and climate factors to be considered. We examined the responses of 11 leaf traits (including leaf morphology, stomatal structure and chemical properties) to eight common climate factors for 340 eastern Qinghai-Tibetan woody species. We showed temperature as the strongest predictor of leaf size and shape, stomatal size and form, and leaf nitrogen and phosphorus concentrations, implying the important role of local heat quantity in determining the variation in the cell- or organ-level leaf morphology and leaf biochemical properties. The effects of moisture-related climate factors (including precipitation and humidity) on leaf growth were mainly through variability in leaf traits (e.g., specific leaf area and stomatal density) related to plant water-use physiological processes. In contrast, sunshine hours affected mainly cell- and organ-level leaf size and shape, with plants developing small/narrow leaves and stomata to decrease leaf damage and water loss under prolonged solar radiation. Moreover, two sets of significant leaf trait-climate relationships, i.e., the leaf/stomata size traits co-varying with temperature, and the water use-related leaf traits co-varying with precipitation, were obtained when analyzing multi-trait relationships, suggesting these traits as good indicators of climate gradients. Our findings contributed evidence to enhance understanding of the regional patterns in leaf trait variation and its environmental determinants.

KAJIAN STRUKTUR ANATOMI DAN MORFOLOGI DAUN PLANLET PISANG KEPOK KUNING HASIL PEMBERIAN EKSTRAK UMBI KEMBANG SUNGSANG SECARA IN VITRO

Plantain is a fruit commodity that has a high level of market demand, but the yield is low. To overcome this problem, tissue culture techniques are used to increase plantlet production in a short time. Plantain have parthenocarpy character, high sterility, and different levels of ploidy. Tissue culture with the addition of flame lily tuber biomutagen containing colchicine was used as a strategy to overcome the above constraints because it was thought to increase the production of polyploid banana plantlets. Changes in the anatomical and morphological structures are indicators of polyploidy. The purpose of this study was to obtain information on changes in the anatomical and morphological structures of plantain leaves as a result of giving in vitro plantlet propagation media as an indicator of the formation of polyploidy. Plantlets were grown on tissue culture media supplemented with three treatments: 10% flame lily tuber extract, 0.1% pure colchicine, and without addition (control). The parameters observed were epidermal cell size, stomata size, stomata index, number and leaf area. Epidermal cell size, stomata size and stomatal index were analyzed using range values ​​and mean values. The number of leaves, and the average wide of leaf, is then shown in the form of a bar chart. The results showed that administration of flame lily tuber extract was able to increase epidermal cell size, stomata size, wide of a leaf, and able to reduce the stomata index and number of leaves.

The Plastid-Localized AtFtsHi3 Pseudo-Protease of Arabidopsis thaliana Has an Impact on Plant Growth and Drought Tolerance

While drought severely affects plant growth and crop production, the molecular mechanisms of the drought response of plants remain unclear. In this study, we demonstrated for the first time the effect of the pseudo-protease AtFtsHi3 of Arabidopsis thaliana on overall plant growth and in drought tolerance. An AtFTSHi3 knock-down mutant [ftshi3-1(kd)] displayed a pale-green phenotype with lower photosynthetic efficiency and Darwinian fitness compared to wild type (Wt). An observed delay in seed germination of ftshi3-1(kd) was attributed to overaccumulation of abscisic acid (ABA); ftshi3-1(kd) seedlings showed partial sensitivity to exogenous ABA. Being exposed to similar severity of soil drying, ftshi3-1(kd) was drought-tolerant up to 20 days after the last irrigation, while wild type plants wilted after 12 days. Leaves of ftshi3-1(kd) contained reduced stomata size, density, and a smaller stomatic aperture. During drought stress, ftshi3-1(kd) showed lowered stomatal conductance, increased intrinsic water-use efficiency (WUEi), and slower stress acclimation. Expression levels of ABA-responsive genes were higher in leaves of ftshi3-1(kd) than Wt; DREB1A, but not DREB2A, was significantly upregulated during drought. However, although ftshi3-1(kd) displayed a drought-tolerant phenotype in aboveground tissue, the root-associated bacterial community responded to drought.