Number Of Adventitious Roots Research Articles

Vegetative propagation of Bagoadlau (Xanthosthemon philippinensis Merr.) using indolebutyric acid

The research investigated the vegetative propagation of Bagoadlau (Xanthosthemon philippinensis Merr.) stem cuttings using different concentrations of indolebutyric acid (IBA). Pretreated cuttings were planted in polyethylene bags and observed in a fully covered chamber for 45 days. The study employed a single trial of completely randomized design (CRD) with five treatments (500 ppm, 100 ppm, 1,500 ppm, and 2000 ppm), each replicated four times. Results indicated significant variations among treatment means in terms of percent shooting, shoot length, percent rooting, number and length of adventitious roots, and percent callusing. Notably, 500 ppm and 1,500 ppm demonstrated the highest outcomes in percent shooting, shoot length, percent survival, measurement of adventitious roots, count of roots, and percentage of rooting. In contrast, the survival percentage of T2 (500 ppm) displayed the highest rate and consistent performance compared to other treatments. Hence, the study recommends using 500 ppm and 1,500 ppm for effective rooting of Bagoadlau (Xanthosthemon philippinensis Merr.) stem cuttings. The successful propagation of native species like Bagoadlau is particularly relevant to ecosystem restoration efforts in regions marked by land degradation and mining activities. The study addresses several crucial aspects by successfully establishing Bagoadlau on such lands. This includes the restoration of native biodiversity, improved soil, and water quality through stabilizing soil, preventing erosion, and acting as a natural filtration system.

Adaptation of the Invasive Plant Sphagneticola trilobata to Flooding Stress by Hybridization with Native Relatives.

Hybridization is common between invasive and native species and may produce more adaptive hybrids. The hybrid (Sphagneticola × guangdongensis) of Sphagneticola trilobata (an invasive species) and S. calendulacea (a native species) was found in South China. In this study, S. trilobata, S. calendulacea, and Sphagneticola × guangdongensis were used as research materials to explore their adaptability to flooding stress. Under flooding stress, the ethylene content and the expression of key enzyme genes related to ethylene synthesis in Sphagneticola × guangdongensis and S. calendulacea were significantly higher than those in S. trilobata. A large number of adventitious roots and aerenchyma were generated in Sphagneticola × guangdongensis and S. calendulacea. The contents of reactive oxygen species and malondialdehyde in Sphagneticola × guangdongensis and S. calendulacea were lower than those in S. trilobata, and the leaves of S. trilobata were the most severely damaged under flooding stress. The results indicate that hybridization catalyzed the tolerance of Sphagneticola × guangdongensis to flooding stress, and the responses of Sphagneticola × guangdongensis to flooding stress were more similar to that of its native parent. This suggests that hybridization with native relatives is an important way for invasive species to overcome environmental pressure and achieve invasion.

Unraveling Key Factors for Hypoxia Tolerance in Contrasting Varieties of Cotton Rose by Comparative Morpho-physiological and Transcriptome Analysis.

The cotton rose (Hibiscus mutabilis) is a plant species commonly found in tropical and subtropical regions. It is remarkably resilient to waterlogging stress; however, the underlying mechanism behind this trait is yet unknown. This study used hypoxia-tolerant "Danbanhong" (DBH) and more hypoxia-sensitive "Yurui" (YR) genotypes and compared their morpho-physiological and transcriptional responses to hypoxic conditions. Notably, DBH had a higher number of adventitious roots (20.3) compared to YR (10.0), with longer adventitious roots in DBH (18.3 cm) than in YR (11.2 cm). Furthermore, the formation of aerenchyma was 3-fold greater in DBH compared to YR. Transcriptomic analysis revealed that DBH had more rapid transcriptional responses to hypoxia than YR. Identification of a greater number of differentially expressed genes (DEGs) for aerenchyma, adventitious root formation and development, and energy metabolism in DBH supported that DBH had better morphological and transcriptional adaptation than YR. DEG functional enrichment analysis indicated the involvement of variety-specific biological processes in adaption to hypoxia. Plant hormone signaling transduction, MAPK signaling pathway and carbon metabolism played more pronounced roles in DBH, whereas the ribosome genes were specifically induced in YR. These results show that effective multilevel coordination of adventitious root development and aerenchyma, in conjunction with plant hormone signaling and carbon metabolism, is required for increased hypoxia tolerance. This study provides new insights into the characterization of morpho-physiological and transcriptional responses to hypoxia in H. mutabilis, shedding light on the molecular mechanisms of its adaptation to hypoxic environments.

Adventitious root formation confers waterlogging tolerance in cowpea (Vigna unguiculata (L.) Walp.)

Crop adaptation to waterlogging stress necessitates alterations in their morpho-physiological and biochemical characteristics. Cowpeas, which serve as a dual-purpose legume crop (food and fodder), are sensitive to waterlogging stress, especially when exposed to extended periods of water stagnation during the early growth stage. In this study, we subjected five distinct and superior cowpea varieties to 10 days of waterlogging stress at the early seedling stage (V2, 15 days post emergence for 10 days) under controlled conditions. The aim was to comprehend the response of these varieties and identify the ideal trait for screening a large collection of cowpea genetic resources for waterlogging tolerance. We measured and analyzed changes in morpho-physiological and root parameters to gain a deeper understanding of the mechanism underlying waterlogging tolerance. The treatment (waterlogging and control), genotype, and their interactions had a significant impact on the most studied traits (p < 0.05). The results indicated a significant reduction in morpho-physiological parameters such as plant height, leaf area, leaf number, Normalized Difference Vegetation Index (NDVI), chlorophyll content, and chlorophyll fluorescence parameters under stress treatment than control conditions. However, root parameters like the number of adventitious roots (AR) and their length (ARL) significantly increased under waterlogging stress in tolerant cowpea varieties like DC15 and PL4. Correlation and PCA analyses further revealed a positive and significant association between cowpeas’ waterlogging tolerance and AR formation and its AR length. Therefore, the current study reveals that swift development of AR and ARL may serve as potential traits conferring waterlogging tolerance in cowpeas. Using suitable mapping populations, these traits could reveal genomic regions associated with waterlogging tolerance in cowpeas. The tolerant varieties and key traits identified in this study could be beneficial in breeding programs aimed at enhancing waterlogging tolerance in cowpeas.

Morphological and molecular response mechanisms of the root system of different Hemarthria compressa species to submergence stress.

The severity of flood disasters is increasing due to climate change, resulting in a significant reduction in the yield and quality of forage crops worldwide. This poses a serious threat to the development of agriculture and livestock. Hemarthria compressa is an important high-quality forage grass in southern China. In recent years, frequent flooding has caused varying degrees of impacts on H. compressa and their ecological environment. In this study, we evaluated differences in flooding tolerance between the root systems of the experimental materials GY (Guang Yi, flood-tolerant) and N1291 (N201801291, flood-sensitive). We measured their morphological indexes after 7 d, 14 d, and 21 d of submergence stress and sequenced their transcriptomes at 8 h and 24 h, with 0 h as the control. During submergence stress, the number of adventitious roots and root length of both GY and N1291 tended to increase, but the overall growth of GY was significantly higher than that of N1291. RNA-seq analysis revealed that 6046 and 7493 DEGs were identified in GY-8h and GY-24h, respectively, and 9198 and 4236 DEGs in N1291-8h and N1291-24h, respectively, compared with the control. The GO and KEGG enrichment analysis results indicated the GO terms mainly enriched among the DEGs were oxidation-reduction process, obsolete peroxidase reaction, and other antioxidant-related terms. The KEGG pathways that were most significantly enriched were phenylpropanoid biosynthesis, plant hormone signal transduction etc. The genes of transcription factor families, such as C2H2, bHLH and bZIP, were highly expressed in the H. compressa after submergence, which might be closely related to the submergence adaptive response mechanisms of H. compressa. This study provides basic data for analyzing the molecular and morphological mechanisms of H. compressa in response to submergence stress, and also provides theoretical support for the subsequent improvement of submergence tolerance traits of H. compressa.

Cинтетические укрытия вегетационных сооружений с интегрированным фотолюминофором в укоренении черенков туи западной

We have explored the effectiveness of using light-correcting covering materials for greenhouse structures when rooting the cuttings of various ornamental forms and varieties of the northern white-cedar (Thuja occidentalis L.). Two types of shelters have been tested: the modified spunbond at a density of 30 g/m2 with a photoluminescent phosphor integrated into its structure at a concentration of 0.8 % and the unmodified spunbond at the same density. Europeum-doped yttrium oxysulfide (Y2O2SEu) has been chosen as a photoluminescent phosphor. We have analyzed 11 varieties and forms of Thuja occidentalis L.: Rheingold, Mr. Bowling Ball, Woodwardii, Tiny Tim, Golden Smaragd, Mirjam, Golden Globe, Danica, Sunkist, Smaragd and Brabant. The response of the indicators of callusogenesis and rhizogenesis to the influence of a transformed light flux has been tested. A positive effect of the use of photoluminescent phosphors in rooting the stem cuttings of the northern white-cedar has been established. An increase in the indicators of regenerative ability and post-regenerative development of the root systems and the aboveground parts of the cuttings has been recorded, such as: the activity of callusogenesis, the number of adventitious roots formed, the length of the leading root, the total length of the root system, the height of the aboveground part and the diameter of the root collar. Callusogenesis has increased from 67.59 ± 2.05 % in the check to 76.81 ± 1.61 % when having integrated the photoluminescent phosphor. The number of adventitious roots formed has increased from 9.64 ± 0.43 to 11.44 ± 0.34 pcs., correspondingly. The total length of the root systems has increased from 64.56 ± 3.70 to 75.52 ± 2.77 cm, correspondingly. One-way analysis of variance confirmed the significance of the differences between the tested forms and varieties in each of the shelter options for most of the tested indicators. Two-way analysis of variance has revealed a significant effect of the positive impact of photoluminescent phosphors on callusogenesis, adventitious root formation, post-regenerative development of the root systems and the aboveground parts of the cuttings.

The Receptor Kinases DRUS1 and DRUS2 Behave Distinctly in Osmotic Stress Tolerance by Modulating the Root System Architecture via Auxin Signaling.

Receptor kinases DRUS1 (Dwarf and Runtish Spikelet1) and DRUS2 are orthologues of the renowned Arabidopsis thaliana gene FERONIA, which play redundant roles in rice growth and development. Whether the two duplicated genes perform distinct functions in response to environmental stress is largely unknown. Here, we found that osmotic stress (OS) and ABA increased DRUS1 expression while decreasing DRUS2. When subjected to osmotic stress, the increased DRUS1 in drus2 mutants suppresses the OsIAA repressors, resulting in a robust root system with an increased number of adventitious and lateral roots as well as elongated primary, adventitious, and lateral roots, conferring OS tolerance. In contrast, the decreased DRUS2 in drus1-1 mutants are not sufficient to suppress OsIAA repressors, leading to a feeble root system with fewer adventitious and lateral roots and hindering seminal root growth, rendering OS intolerance. All these findings offer valuable insights into the biological significance of the duplication of two homologous genes in rice, wherein, if one is impaired, the other one is able to continue auxin-signaling-mediated root growth and development to favor resilience to environmental stress, such as water shortage.

Differences of waterlogging tolerance in winter pulse crop between emergence and vegetative stages

AbstractPulse production is decreased when grown on waterlogged soil in rice‐based cropping. This study evaluated four pulse crops—grass pea, field pea, cowpea and lentil—to find out their responses to waterlogging (WL) stress at emergence and vegetative stages. The treatment levels at emergence were drained control, 4‐, 7‐ and 10‐day WL, while in the vegetative stage they were drained control, 6‐, 10‐ and 14‐day WL. In the emergence stage, %emergence was significantly reduced as WL duration increased. After 10‐day WL, emergence was reduced to 65% for grass pea, 30% for field pea, 5% for lentil and 7% for cowpea. At the vegetative stage, in both the WL and recovery phases, the WL treatment reduced plant height, tap root length, shoot and root dry mass compared to those in drained control with a significant difference in crops. In recovery as compared to the WL phase at 14‐day WL, the chlorophyll content was increased 15% in cowpea and 14% in grass pea but decreased in field pea (26%) and lentil (35%). Similarly, in the recovery phase at 14‐day WL, shoot relative growth rates (RGRs) of cowpea, grass pea, field pea and lentil were 20, 66, 10 and 5 mg plant−1 d−1; which were 66%, 70%, 8% and 14% of drained control, respectively. The RGR of root at 14‐day WL was also higher in cowpea and grass pea with the rate of 13.8 and 16 mg−1 plant−1 d−1, respectively; in sharp contrast to a reduction of −4.3 mg−1 plant−1 d−1 in field pea and −3.9 mg−1 plant−1 d−1 for lentil than drained control. Furthermore, the higher number of adventitious roots was found in cowpea (14) and grass (9) pea than in field pea (6) and lentil (4). Comparison between growth stages, grass pea was tolerant to WL in both stages. Cowpea was WL sensitive at emergence, but tolerant to vegetative stage. Field pea was moderately tolerant to emergence but was sensitive at vegetative stage. Lentil was sensitive at WL at both stages. These novel insights will allow the fitting of winter pulses to various cropping systems according to the perceived risk of WL at various growth stages.

Transcription Factor MdPLT1 Involved Adventitious Root Initiation in Apple Rootstocks

The induction of adventitious roots is a key factor restricting the vegetative propagation of apple dwarf rootstocks. PLETHORA (PLT) transcription factors are involved in the regulation of plant stem cell niche and adventitious root development. In this study, we identified the PLT1 gene in apples by bioinformatics and analyzed its evolutionary relationship. The MdPLT1 gene was cloned from M9-T337 to verify its subcellular localization and analyze its function in transgenic tobacco. The MdPLT1 protein contained two conserved AP2 domains which may be similar to those of poplar the PtrPLT2a and PtrPLT2b with 85% support. The CDS sequence of the MdPLT1 gene was 1638 bp, encoding 545 amino acids. The transcription factor MdPLT1 was localized in the nucleus. The number of adventitious roots of tobacco plants overexpressing MdPLT1 significantly increased. In the adventitious roots of MdPLT1-overexpressed plants, the expression levels of genes related to the NtPINs family and the NtYUCCAs family were significantly increased. The results showed that MdPLT1 positively regulated adventitious root formation. This study provided a theoretical basis for the establishment of the fast vegetative propagation of apple dwarf rootstocks.

A systematic review on the morphology structure, propagation characteristics, resistance physiology and exploitation and utilization of Nitraria tangutorum Bobrov.

Nitraria tangutorum Bobrov., belonging to the family Nitrariaceae, is a drought-tolerant and salt-loving plant and has drawn attention for its good economic and ecological value. As one of the main group species and dominant species in China's desert and semi-desert regions, N. tangutorum possesses superior tolerance to drought, high temperature, cold, barren, high salinity and alkalinity and wind and sand. Its root system is well developed, with many branches and a strong germination capacity. Once buried in sandy soil, N. tangutorum can quickly produce a large number of adventitious roots, forming new plants and continuously expanding the shrubs, forming fixed and semi-fixed shrub sand dunes. Sand dune shrubs can trap and fix a large amounts of quicksand, prevent desert expansion and erosion, and play an important role in maintaining regional ecosystem balance and improving ecological environmental quality. In addition, the phytochemical screening studies report that N. tangutorum contains an abundance of various compounds including flavonoids, alkaloids, phenolic acids and polysaccharides. These compounds confer a range of beneficial bioactivities such as antioxidant, anti-inflammatory, anti-tumor, anti-fatigue, liver protection, neuroprotection, cardiovascular protection, lowering blood lipid, regulating blood sugar level and immunoregulation. The fruits of N.tangutorum also contain vitamin C, amino acids, minerals and microelements. It has been traditionally used as a nutritional food source and in folk medicine to treat diseases of the spleen and stomach, abnormal menstruation, indigestion, and hyperlipidemia. N. tangutorum, as a wild plant with medicinal and edible homology, possesses remarkable economic and medicinal values. This detailed, comprehensive review gathers and presents all the information related to the morphological structure, propagation characteristics, resistance physiology and exploitation and utilization of N.tangutorum, providing a theoretical basis for the researchers to conduct future in-depth research on N.tangutorum.

Vanillin, a Newly Discovered Autotoxic Substance in Long-Term Potato Continuous Cropping Soil, Inhibits Plant Growth by Decreasing the Root Auxin Content and Reducing Adventitious Root Numbers.

Phenolic acids are known to reduce root biomass and hinder plant development, but it is unclear how they affect potato root traits. Over a 10 year field experiment, we found a negative correlation between the potato yield and continuous cropping years. The substantial reduction in adventitious root (AR) numbers was found to be primarily inhibited by soil vanillin accumulation. The study also found that vanillin had a more pronounced inhibitory effect on the potato yield than commonly reported ferulic acid and p-hydroxybenzoic acid. The decrease in yield was attributed to the reduction of root indole-3-acetic acid (IAA) content, which impeded the formation of AR. Exogenous IAA was found to increase the root IAA content and stimulate AR formation under vanillin stress, ultimately leading to an increase in the potato yield. This study provides valuable insights into potential strategies for the degradation of autotoxic substances and breeding of potato cultivars with enhanced resistance to autotoxicity.

Transcriptome analysis reveals ZmERF055 contributes to waterlogging tolerance in sweetcorn

Waterlogging is a major disaster damaging crop production. However, most sweetcorn cultivars are not tolerant to waterlogging, which severely threatens their production. In order to understand the genetic mechanisms underlying waterlogging tolerance in sweetcorn, this study conducted a comprehensive investigation of sweetcorn waterlogging tolerance at the levels of physiology, biochemistry, and transcriptome in two sweetcorn CSSLs (chromosome segment substitution lines), D120 and D81. We found that D120 showed increased plant height, root length, root area, adventitious root numbers, antioxidant enzyme activities, and aerenchyma area ratio compared to D81. The transcriptome results showed that 2492 and 2351 differentially expressed genes (DEGs) were obtained at 4 h and 8 h of waterlogging treatment, respectively. Genes involved in reactive oxygen species (ROS) homeostasis, photosynthesis, and alcohol fermentation are sensitive in the waterlogging tolerant genotype D120, resulting in enhanced ROS scavenging ability, adventitious roots, and aerenchyma formation. Additionally, ethylene-, auxin-, and ABA-related genes exhibited different responses to waterlogging stress in sweetcorn. We integrated transcriptome and differential chromosomal fragments data and identified that ZmERF055 on chromosome 9 was directly involved in waterlogging stress. ZmERF055-overexpressing plants consistently exhibited significantly increased waterlogging tolerance and ROS homeostasis in Arabidopsis. These results offer a network of plant hormone signaling, ROS homeostasis, and energy metabolism co-modulating waterlogging tolerance in sweetcorn. Additionally, the findings support ZmERF055 as a potential ideal target gene in crop breeding to improve plant waterlogging tolerance.

Growth Responses and Adventitious Root Formation of Cucumber Hybrid Lines in a Waterlogged Condition

Cucumber (Cucumis sativus L.) F1 hybrids are grown commercially in open-field or greenhouse conditions. Hybrids are well adapted to these settings due to directed breeding. In protected cultivation systems, a small rhizosphere volume and intensive, continuous fertigation predispose the roots to waterlogging (WL) conditions and potentially to hypoxia. However, high productivity is expected and achieved under these conditions. The aim of this study was to identify traits that play a role in this surprising behavior. Initial observations revealed the presence of a significantly higher number of adventitious roots (ARs) in three greenhouse (7–14) vs. three open-field cultivars (less than two) grown under normal conditions. Further on, two contrasting representative hybrids typically grown in open-field and in greenhouse conditions were subjected to WL stress. Declining oxygen levels in the media and increased alcohol dehydrogenase activity (ADH) in the roots were experienced during the WL treatment in both hybrids, with anaerobic metabolism triggered less intensively (~4-fold less ADH activity) in the greenhouse-type ‘Oitol’. The induction characteristics of cysteine oxidase (CysOx) genes, key components of the hypoxia sensing pathway, were used to confirm the hypoxic stress experienced by the roots. The lower extent of upregulation in CysOx genes expression agreed with the milder level of hypoxic stress in the roots of ‘Oitol’ than in ‘Joker’. The more efficient induction of AR formation with a ~50% increase upon waterlogging stress was found to be a prominent trait in ‘Oitol’, apparently helping root internal aeration and mitigating hypoxia. The shoot growth of neither hybrid was set back by hypoxic root conditions. ‘Joker’ plants maintained the same growth rate as that of the control, while the growth of ‘Oitol’ accelerated when its root system was flooded with nutrient solution. Acclimation processes to hypoxia were proposed to explain the lack of growth retardation in both varieties. This corresponded well with a general abundance of AR development in greenhouse-type (slicing) cucumbers that are typically cultivated in soilless systems.

OPTIMIZATION OF Talinum paniculatum Gaertn. ROOT INDUCTION AND THE EFFECT OF PHOSPHATE CONCENTRATIONS AND AMMONIUM:NITRATE RATIO ON BIOMASS OF ADVENTITIOUS ROOTS IN IN VITRO CULTURE

Java ginseng (Talinum paniculatum Gaertn.) is a medicinal plant, the roots of which are commonly used in traditional medicine. In its natural habitat, the roots grow very slowly, requiring two to three years to produce 100 g of roots per plant. Plant tissue culture could therefore provide an alternative means of accelerating root growth. This research aimed to optimize root induction and determine the effect of phosphate (KH2PO4) concentration and the ratio between ammonium and nitrate (ammonium:nitrate) on the biomass of Java ginseng adventitious roots in in vitro culture. Stem and leaf were used as explants and various combinations and concentrations of IBA and BAP, kinetin, and TDZ were used as growth regulators. Leaf explants were grown in Murashige and Skoog (MS) media supplemented with IBA 2 mg/L and various concentrations of phosphate (170; 212.5; 255; 297.5; 340; 382.5; 425; 467.5; 510 mg/L) and various ammonium:nitrate ratios (21:19 mM as the control, 0:30 mM, 10:20 mM, 15:15 mM, 20:10 mM, 30:0 mM). Cultures were maintained for 6 weeks. The observed parameters were fresh weight, dry weight, the duration of root formation, and the number and length of adventitious roots. The data were analyzed using Analysis of Variance. The results showed that the concentration of phosphate and the ammonium:nitrate ratio significantly influenced the amount, length, fresh weight, and dry weight of Java ginseng adventitious root. The highest fresh weight (37.47 mg) and dry weight (5.53 mg) were achieved in the treatment of double phosphate concentration (KH2PO4 340 mg/L), while an ammonium:nitrate ratio of 10:20 mM was the optimum treatment to produce the highest biomass (fresh weight 73.6 mg and dry weight 8.2 mg).

Overexpression of OsPIN9 Impairs Chilling Tolerance via Disturbing ROS Homeostasis in Rice.

The auxin efflux transporter PIN-FORMED (PIN) family is one of the major protein families that facilitates polar auxin transport in plants. Here, we report that overexpression of OsPIN9 leads to altered plant architecture and chilling tolerance in rice. The expression profile analysis indicated that OsPIN9 was gradually suppressed by chilling stress. The shoot height and adventitious root number of OsPIN9-overexpressing (OE) plants were significantly reduced at the seedling stage. The roots of OE plants were more tolerant to N-1-naphthylphthalamic acid (NPA) treatment than WT plants, indicating the disturbance of auxin homeostasis in OE lines. The chilling tolerance assay showed that the survival rate of OE plants was markedly lower than that of wild-type (WT) plants. Consistently, more dead cells, increased electrolyte leakage, and increased malondialdehyde (MDA) content were observed in OE plants compared to those in WT plants under chilling conditions. Notably, OE plants accumulated more hydrogen peroxide (H2O2) and less superoxide anion radicals (O2-) than WT plants under chilling conditions. In contrast, catalase (CAT) and superoxide dismutase (SOD) activities in OE lines decreased significantly compared to those in WT plants at the early chilling stage, implying that the impaired chilling tolerance of transgenic plants is probably attributed to the sharp induction of H2O2 and the delayed induction of antioxidant enzyme activities at this stage. In addition, several OsRboh genes, which play a crucial role in ROS production under abiotic stress, showed an obvious increase after chilling stress in OE plants compared to that in WT plants, which probably at least in part contributes to the production of ROS under chilling stress in OE plants. Together, our results reveal that OsPIN9 plays a vital role in regulating plant architecture and, more importantly, is involved in regulating rice chilling tolerance by influencing auxin and ROS homeostasis.

ALLELOPATIC COMPATIBILITY OF COMMON BEAN AND COMPANION CROPS

Purpose. To investigate the allelopathic compatibility of common bean seeds and companion crops, to establish interaction patterns using water extracts from seeds and other plant parts of common bean and companion crops. Methods. Laboratory, statistical. Results. Biotest: interaction of germinating seeds of bean and companion crops in Petri dishes. Biologically active substances from winter and spring triticale seeds (the bean seeds/seeds of companion crops ratio was 1:10) negatively affected bean seedlings, which was seen from all parameters under investigation: hypocotyl length (with the root included), length of the longest adventitious root, the adventitious root number, and true leaf length (with epicotyl included). At a ratio of 1:5, winter triticale-induced inhibition of hypocotyl growth was enhanced up to 38 %, while, on the contrary, spring triticale had a neutral effect on this parameter. A stimulating effect (106 %) of spring triticale seeds on the true bean leaf length (with epicotyl) was noted. For winter and spring triticale in a ratio of 1:1 (compared to the control – without seeds of companion crops), inhibition of the growth of the hypocotyl with the root by 21 % and the true leaf with the epicotyl by 10–9 %, respectively, is observed. Biotest: germination of bean seeds in a water extract from whole seeds of bean and companion crops in Petri dishes. Water extract from spring triticale seeds in a ratio of 1:2 had the greatest stimulating effect on the tap root and the first leaf lengths; winter triticale extract in a ratio of 1:4 had the greatest effect on the adventitious root an epicotyl lengths; bean extract in a ratio of 1:2 had the greatest effect on the epicotyl length. Biotest: germination of bean seeds in a water extract from vegetative mass, roots and post-harvest residues of bean and companion crops in Petri dishes. Water extracts from roots of bean, winter and spring triticale weakly inhibited the main bean root elongation. A neutral allelopathic effect on the bean seed germination was exerted by extract from post-harvest residues of spring triticale. A water extract from top parts of bean had a negative allelopathic effect on germinating bean seeds, indicating self-incompatibility of this crop. Conclusions. The laboratory tests showed that biologically active substances from seeds of both winter triticale and spring triticale at a ratio of 1:10 were toxic for bean ssedlings. Combined germination of bean and spring triticale seeds at a ratio of 1:5 had a more positive effect compared to other ratios of seeds of companion crops, and combined germination of bean seeds with spring and winter triticale seeds at a ratio of 1:1 demonstrated very similar parameters of germinating bean seeds. It was found that water extracts from bean and spring triticale in a ratio of 1:2 and from bean and winter triticale (1:4) had a clear allelopathic effect on the bean parameters. Water extracts from winter triticale (1:1) and spring triticale (1:4) were more toxic to bean seedlings. Water extracts from roots of bean, winter and spring triticale weakly inhibited the main bean root elongation. A water extract from the aboveground parts of bean had a negative allelopathic effect on the germinating seeds of bean, indicating self-incompatibility of this crop. A neutral allelopathic effect on the germination of bean seeds was exerted by extract from post-harvest residues of spring triticale. Combined germination of seeds of bean and companion crops in the laboratory allows for assessments of peculiarities of seed germination and mutual influence of components as early as at the initial stage, for selection of crops for growing in heterogeneous fields aimed at forming a highly productive agrophytocenosis.

Waterlogging Effects in Adventitious Roots, Tillering and Yield of Bread Wheat Germplasm

In the context of climate changes, expected increases in intensity, frequency, and unpredictability of waterlogging events will aggravate wheat yield losses, currently estimated to range between 20-50%. Wheat production must fulfill ca. 20% of the population’s energy and protein requirements. Evaluating germplasm with different backgrounds may reveal variability for waterlogging tolerance, allowing a better selection of genotypes with desirable traits for wheat breeding programs. In this work, the effect of waterlogging on adventitious root emission, tiller survival and yield was evaluated. Five studied germplasm groups (Portuguese Landraces; Varieties with introduced Italian germplasm; Post-Green Revolution varieties with introduced CYMMIT germplasm; Advanced Lines from the Portuguese Cereal Breeding Program; Australian varieties) were studied. Groups exhibited intra and intervariability in all parameters in response to waterlogging imposed in climatized growth chambers. After 14 days of waterlogging, the number of adventitious roots ranged from 0 to 7.6 plant-1, with 4 Portuguese Landraces depicting the highest number. The number of living tillers at the end of the stress was highly variable, ranging from reductions of 100% to increases up to 35%. At harvest, the number of productive tillers significantly differed among genotypes, with reductions reaching 100% in some cases and increases up to 138% in others. The existence of variability and the identification of key traits underlying waterlogging tolerance will contribute to develop more adapted wheat plants and to improve wheat yield.

Genome-wide identification of LBD transcription factors in apple and the function of MdLBD16a in adventitious rooting and callus development

The plant-specific LBD transcription factors play crucial roles in plant growth and development. In this study, 67 MdLBDs were identified in apple by whole genome bioinformatics analysis. According to gene structure and phylogenetic analysis, the MdLBD gene family was divided into Class I (57) and Class II (10). Due to whole genome duplication, the number of LBD genes in apple was much greater than in other plants in the Rosaceae family. The LBD29/LBD16 locus was conserved in the Rosaceae plants, but with different orientations. Many cis-acting regulatory elements relative to plant growth and development and responses to the environment, growth regulators and abiotic/biotic stressors were enriched in the MdLBD promoters. Some MdLBDs showed organ-specific expression. MdLBD16a was significantly up-regulated during adventitious root formation, peaking seven days after auxin treatment. MdLBD16a was localized in the nucleus. Overexpression of MdLBD16a in tomato increased the number of adventitious roots. Auxin promoted callus growth in MdLBD16a-overexpressing callus. MdLBD16a played dual roles in root primordium formation and callus development. We propose that plants with the LBD29/LBD16 locus have adventitious root and lateral root development that depend on the LBD29/LBD16 network. These comprehensive analyses of these MdLBDs provided valuable resources for further functional study in apple and other species.

Variabilidad en caracteres vinculados a la implantación en poblaciones espontáneas de Stapfochloa berroi (Arechav.) P. M. Peterson de la Pampa Deprimida

Stapfochloa berroi is a spring-summer growing perennial grass, native to South America, which in the Pampa Deprimida (Buenos Aires, Argentina) is a key species due to its forage value and adaptation to environments that are restrictive (sodic soils, low organic matter content, waterlogging, drought) for other forage species. The reincorporation of selected native germplasm would be important both for increasing livestock productivity and for maintaining and/or recovering biodiversity in these agroecosystems. The objective was to analyze the variability in traits linked to the success of implantation in two spontaneous populations of S. berroi from the steppes of the halophyte of the Pampa Deprimida. Seed germination was evaluated and individual seed weight was recorded for both populations. Subsequently, seeds with their individual weights identified were sown in seedling trays with limiting substrate (low alkaline soil) and with nonlimiting substrate (horizon A from a typical Argiudol soil) in a greenhouse. The emergency was evaluated for 30 days. After 54 days, for each individual, the following traits were determined: height, total plant length and length of the longest adventitious root, number of adventitious roots, number of unfolded green leaves and number of tillers. The percentage of germination and cumulative emergence and an index of emergence speed were calculated, and aerial, root and total dry weight were determined. The variability found in key traits for establishment between S. berroi populations (e.g., germination, emergence), but mainly within populations (e.g., aerial, root and total dry weight) would be promising for an initial selection phase.

Nitric oxide promotes adventitious root formation in cucumber under cadmium stress through improving antioxidant system, regulating glycolysis pathway and polyamine homeostasis.

Cadmium (Cd) as a potentially toxic heavy metal that not only pollutes the environment but also interferes with plant growth. Nitric oxide (NO) regulates plant growth and development as well as abiotic stress response. However, the mechanism underpinning NO-induced adventitious root development under Cd stress remains unclear. In this study, cucumber (Cucumis sativus 'Xinchun No. 4') was used as the experimental material to investigate the effect of NO on the development of adventitious roots in cucumber under Cd stress. Our results revealed that, as compared to Cd stress, 10 μM SNP (a NO donor) could considerably increase the number and length of adventitious roots by 127.9% and 289.3%, respectively. Simultaneously, exogenous SNP significantly increased the level of endogenous NO in cucumber explants under Cd stress. Our results revealed that supplementation of Cd with SNP significantly increased endogenous NO content by 65.6% compared with Cd treatment at 48 h. Furthermore, our study indicated that SNP treatment could improve the antioxidant capacity of cucumber explants under Cd stress by up-regulating the gene expression level of antioxidant enzymes, as well as reducing the levels of malondialdehyde (MDA), hydrogen peroxide (H2O2) and superoxide anion ( ) to alleviate oxidative damage and membrane lipid peroxidation. Application of NO resulted in a decrease of the , MDA, and H2O2 level by 39.6%, 31.4% and 60.8% as compared to Cd-alone treatment, respectively. Besides that, SNP treatment significantly increased the expression level of related genes involved in glycolysis processes and polyamine homeostasis. However, application of NO scavenger 2-(4-carboxy -2-phenyl)-4, 4, 5, 5-tetramethy limidazoline -1-oxyl -3-oxide (cPTIO) and the inhibitor tungstate significantly reversed the positive role of NO in promoting the adventitious root formation under Cd stress. These results suggest that exogenous NO can increase the level of endogenous NO, improve antioxidation ability, promote glycolysis pathway and polyamine homeostasis to enhance the occurrence of adventitious roots in cucumber under Cd stress. In summary, NO can effectively alleviate the damage of Cd stress and significantly promote the development of adventitious root of cucumber under Cd stress.