SiMYB19 from Foxtail Millet (Setaria italica) Confers Transgenic Rice Tolerance to High Salt Stress in the Field

Salt stress is a major threat to crop quality and yield. Most experiments on salt stress-related genes have been conducted at the laboratory or greenhouse scale. Consequently, there is a lack of research demonstrating the merit of exploring these genes in field crops. Here, we found that the R2R3-MYB transcription factor SiMYB19 from foxtail millet is expressed mainly in the roots and is induced by various abiotic stressors such as salt, drought, low nitrogen, and abscisic acid. SiMYB19 is tentatively localized to the nucleus and activates transcription. It enhances salt tolerance in transgenic rice at the germination and seedling stages. SiMYB19 overexpression increased shoot height, grain yield, and salt tolerance in field- and salt pond-grown transgenic rice. SiMYB19 overexpression promotes abscisic acid (ABA) accumulation in transgenic rice and upregulates the ABA synthesis gene OsNCED3 and the ABA signal transduction pathway-related genes OsPK1 and OsABF2. Thus, SiMYB19 improves salt tolerance in transgenic rice by regulating ABA synthesis and signal transduction. Using rice heterologous expression analysis, the present study introduced a novel candidate gene for improving salt tolerance and increasing yield in crops grown in saline-alkali soil.

Root Morphology, Allometric Relations and Rhizosheath of Ancient and Modern Tetraploid Wheats (Triticum durum Desf.) in Response to Inoculation with Trichoderma harzianum T-22

Early root traits and allometrics of wheat are important for competition and use of resources. They are under-utilized in research and un-explored in many ancient wheats. This is especially true for the rhizosheath emerging from root-soil interactions. We investigated root morphology, root/shoot relations and the amount of rhizosheath of four tetrapoid wheat seedlings (30 days after emergence): the italian landrace Saragolle Lucana and modern varieties Creso, Simeto and Ciclope, and tested the hypothesis that inoculation with Trichoderma harzianum T-22 (T-22) enhances rhizosheath formation and affects wheat varieties differently. Overall growth of non-inoculated plants showed different patterns in wheat varieties, with Saragolle and Ciclope at the two extremes: Saragolle invests in shoot rather than root mass, and in the occupation of space with highest (p < 0.05) shoot height to the uppermost internode (5.02 cm) and length-to-mass shoot (97.8 cm g−1) and root (more than 140 m g−1) ratios. This may be interpreted as maximizing competition for light but also as a compensation for low shoot efficiency due to the lowest (p < 0.05) recorded values of optically-measured chlorophyll content index (22.8). Ciclope invests in biomass with highest shoot (0.06 g) and root (0.04 g) mass and a thicker root system (average diameter 0.34 mm vs. 0.29 in Saragolle) as well as a highest root/shoot ratio (0.95 g g−1 vs. 0.54 in Saragolle). Rhizosheath mass ranged between 22.14 times that of shoot mass in Ciclope and 43.40 in Saragolle (different for p < 0.05). Inoculation with Trichoderma increased the amount of rhizosheath from 9.4% in Ciclope to 36.1% in Simeto and modified root architecture in this variety more than in others. Ours are the first data on roots and seedling shoot traits of Saragolle Lucana and of Trichoderma inoculation effects on rhizosheath. This opens to new unreported interpretations of effects of Trichoderma inoculation on improving plant growth.

Vermicompost humates as a salinity mitigator in the germination of basil

ABSTRACT: This study determined the effect of vermicompost humates as salinity mitigator in germination and morphometric characteristics of basil varieties seedlings, tolerant and sensitive to salinity, subjected to vermicompost humates diluted 1/60 (v/v) and 0, 50 and 100 mM NaCl in a completely randomized design with four replications. The rate and percentage of germination, root length, shoot height, root and shoot fresh and dry-weight were measured. The varieties showed differential response, highlighting Napoletano as the most tolerant. Vermicompost humates showed biostimulant effects on variables evaluated, allowing that tolerant variety to improve germination and growth, and increasing the salinity tolerance of the sensitive variety.

Influence of Seed Source and Soil Contamination on Ecophysiological Responses of Lavandula pedunculata in Rehabilitation of Mining Areas

Mining activities have turned many areas of the Iberian Pyrite Belt (IPB) into extreme environments with high concentrations of metal(loid)s. These harsh conditions can inhibit or reduce the colonization and/or development of most vegetation. However, some species or populations have developed ecophysiological responses to tolerate stress factors and contaminated soils. The main objectives of this study are: (i) to assess the differences in germination, growth, development and physiological behaviour against oxidative stress caused by metal(loid)s in Lavandula pedunculata (Mill.) Cav. from two different origins (a contaminated area in São Domingos mine, SE of Portugal and an uncontaminated area from Serra do Caldeirão, S of Portugal) under controlled conditions; and (ii) to assess whether it is possible to use this species for the rehabilitation of mine areas of the IPB. After germination, seedlings from São Domingos (LC) and Caldeirão (L) were planted in pots with a contaminated soil developed on gossan (CS) and in pots with an uncontaminated soil (US) under controlled conditions. Multielemental concentrations were determined in soils (total and available fractions) and plants (shoots and roots). Germination rate, shoot height, dry biomass and leaf area were determined, and pigments, glutathione, ascorbate and H2O2 contents were measured in plant shoots. Total concentrations of As, Cr, Cu, Pb and Sb in CS, and As in US exceed the intervention and maximum limits for ecosystem protection and human health. The main results showed that L. pedunculata, regardless of the seed origin, activated defence mechanisms against oxidative stress caused by high concentrations of metal(loid)s. Plants grown from seeds of both origins increased the production of AsA to preserve its reduction levels and kept the contents of GSH stable to maintain the cell’s redox state. Plants grown from seeds collected in non-contaminated areas showed a high capacity for adaptation to extreme conditions. This species showed a greater growth capacity when seeds from a contaminated area were sown in uncontaminated soils. Thus, L. pedunculata, mainly grown from seeds from contaminated areas, may be used in phytostabilization programmes in areas with soils with high contents of metal(loid)s.

Study on in vitro propagation of Sophora tonkinensis Gagnep through stem node culture

In the present study, authors propagated Sophora tonkinensisGagnep plants using stem nodal culture. The results indicated that on MS medium supplemented with 30 g/l sucrose, 5.5 g/l agar, 200 ml/l coconut water, 1 g/l activated charcoal, 0.75 mg/l TDZ shoots proliferated from stem segments have the best count and height of shoots. The most appropriate medium for multiplication of shoots was the MS medium supplemented with 30 g/l sucrose, 5.5 g/l agar, 200 ml/l coconut water, 1 g/l activated charcoal, 0.75 mg/l TDZ, 0.5 mg/l IBA, 2.0 g/l peptone, 30 g/l carrot puree, pH 5.5 with the results of 20.60 shoots/explant, shoot height of 3.75 cm and 4.6 leaves/shoot after 8 weeks of culture. Root formation of shoots carried out on the MS medium supplemented with 30 g/l sucrose, 5.5 g/l agar, 200 ml/l coconut water, 1 g/l activated charcoal, 1.0 mg/l αNAA gave the best result. In the nursery, a mixture of humus + coconut fiber powder (70:30 ratio) was regarded as the best substrate due to the high survival rate of plantlets (92%) and healthy plantlets (10.30 cm high with 7.2 leaves and 4.3 new roots/a plantlet) at 10 weeks after planting

Effect of analcite on cadmium phytoavailability and phytotoxity

The interactive effects of Cd and natural siliceous mineral analcite on Cd phytotoxicity and rate of accumulation in plant tissues have been analyzed. The test-plants of corn and hemp were grown in pots under controlled conditions of light, temperature, and soil moisture for 21 days in experiments modeling the following treatments: (1) without any amendments (control); (2) with the application of 0.1 % and 0.5 % (by weight) of CdSO4; (3) Cd salts (CdSO4) + analcite 0.1 g, 0.25 g, and 0.5 g per container. Test-plants performance was assessed by their growth characteristics (shoot height and root length), the content of photosynthetic pigments, macro- and micronutrients in leaves. The effect of Cd on maize and hemp plants inhibited their growth, chlorophyll biosynthesis in the leaves, led to a change in the balance of macro- and microelements, which leads to the accumulation of Cd in the tissues of shoots of both studied crops. Application of analcite partially compensated for the negative effects of Cd salts on the crop’s growth, chlorophyll content, and balance of nutrients and reduced Cd accumulation significantly in shoots.

Characterization of Root System Architecture Traits in Diverse Soybean Genotypes Using a Semi-Hydroponic System

Phenotypic variation and correlations among root traits form the basis for selecting and breeding soybean varieties with efficient access to water and nutrients and better adaptation to abiotic stresses. Therefore, it is important to develop a simple and consistent system to study root traits in soybean. In this study, we adopted the semi-hydroponic system to investigate the variability in root morphological traits of 171 soybean genotypes popularized in the Yangtze and Huaihe River regions, eastern China. Highly diverse phenotypes were observed: shoot height (18.7–86.7 cm per plant with a median of 52.3 cm); total root length (208–1663 cm per plant with a median of 885 cm); and root mass (dry weight) (19.4–251 mg per plant with a median of 124 mg). Both total root length and root mass exhibited significant positive correlation with shoot mass (p ≤ 0.05), indicating their relationship with plant growth and adaptation strategies. The nine selected traits contributed to one of the two principal components (eigenvalues > 1), accounting for 78.9% of the total genotypic variation. Agglomerative hierarchical clustering analysis separated the 171 genotypes into five major groups based on these root traits. Three selected genotypes with contrasting root systems were validated in soil-filled rhizoboxes (1.5 m deep) until maturity. Consistent ranking of the genotypes in some important root traits at various growth stages between the two experiments indicates the reliability of the semi-hydroponic system in phenotyping root trait variability at the early growth stage in soybean germplasms.

ROLE OF VENTILATION, CALCIUM AND BORON ON SHOOT TIP NECROSIS AND HYPERHYDRICITY REDUCTION OF IN VITRO ROORSTOOCKS OF PISTACIO ‘BADAMI’ ȘI ‘UCB1’

Shoot tip necrosis (STN) is one of the main physiological disorders in the micropropagation of pistachios. In the current study, the effects of CaNO3.4H2O at 196 mg/L and 291 mg/L, H3BO3 at 196 mg/L and 291 mg/L, and CaCl2.2H2O at 2,980 mg/L on STN and hyperhydricity reduction of Pistacia vera L., ‘Badami’ and ‘UCB1’ rootstocks were assessed, compared to the MS standard medium containing 3% sucrose, 0.7% agar supplemented with benzyladenine (BA) (1.5 mg/L), indole butyric acid (IBA) (0.1 mg/L). For ventilation parameter, filter container vessels with a 50-µm microporous polypropylene membrane (Pardis®) were used. Based on the results, an increase in calcium chloride content of the MS standard medium prevented hyperhydricity in the UCB1 rootstock, whereas it increased STN, yellow leaves, decreasing the multiplication of shoots in the ‘Badami’ rootstock. The results also showed that increasing boric acid from 196 mg/L up to 291 mg/L decreased STN in the UCB1 rootstock and increased this disorder by 37% in the ‘Badami’ rootstock. Ventilation showed no significantly reducing effect on the percentage of STN in the regenerated shoots of the ‘Badami’ rootstock, whilst it decreased the STN of the ‘UCB1’ rootstock to the lowest percentage. For the ‘Badami’ rootstock, CaNO3.4H2O at 196 mg/L led to the highest proliferation rate, shoot height, shoot diameter, and leaf number, but for the ‘UCB1’ rootstock, an increase in the concentration of CaNO3.4H2O up to 291 mg/L under ventilated conditions resulted in an increase in proliferation, shoot height, and shoot diameter.

Effects of Inorganic, Organic and Bio-Organic Fertilizer on Growth, Rhizosphere Soil Microflora and Soil Function Sustainability in Chrysanthemum Monoculture

The production of chrysanthemums is severely hampered by Fusarium wilt, which is exacerbated by monoculture. In this study, the role of inorganic plant nutrition fertilizer (IPN), organic fertilizer (OF) and bio-organic fertilizer (BOF) in avoiding monoculture-related production constraints was evaluated. We conducted a series of greenhouse experiments and studied the growth of chrysanthemum and changes in rhizosphere soil microflora and function. BOF application reduced the incidence of Fusarium wilt by 82.8% and increased the chrysanthemum shoot height and flower ray floret number by 31.4% and 26.1%, respectively. High-throughput Illumina HiSeq2500 sequencing results indicated that BOF and OF treatments increased the values of α-diversity indices of bacteria and fungi. In addition, significant alterations in microbe community structures were found in response to IPN, OF or BOF application. Among the major genera detected after BOF treatments, the levels of Fusarium and Glycomyces decreased while Cladosporium, arbuscular mycorrhizal and endophyte groups increased. In particular, the abundance of Mariniflexile had a positive relationship (R = 0.693, p < 0.05) with the incidence of Fusarium wilt, while Cladosporium showed a significant negative relationship (R = −0.586, p < 0.05). Interestingly, an analysis of microbiomes based on 16S rRNA sequences revealed that the functions of signal transduction, bacterial secretion system, oxidative phosphorylation and the metabolism of carbohydrate, nitrogen and amino acids all increased in both BOF and OF treatments. The results suggested that BOF could be effective for chrysanthemum monoculture soil restoration, potentially by altering the microbial community structures and functions, which affect the physiological and morphological attributes of chrysanthemum in monoculture.

Vermicompost Leachate, Seaweed Extract and Smoke-Water Alleviate Drought Stress in Cowpea By Influencing Phytochemicals, Compatible Solutes and Photosynthetic Pigments

Drought is a major constraint for agricultural production worldwide and is likely to become aggravated by global warming. It can induce land degradation, exorbitant food prices and menace livelihoods. Approaches for retaining optimal yield, especially in rainfed staple crops such as cowpea (Vigna unguiculata) are paramount. Biostimulants; vermicompost leachate (VCL), seaweed extract [Kelpak® (KEL)] and smoke-water (SW) have exhibited effective amelioration for plants under abiotic stresses, however, research on cowpea remains scarce. Therefore, this study aimed to investigate the effects of seed priming of cowpea with VCL, KEL and SW on the growth, photosynthesis and biochemical levels in cowpea cultivated under three watering regimes. SW treatment amplified growth variables (i.e., foliage, shoot height, root length and number of flowers) of water-stressed cowpeas. KEL- and VCL-treated seeds significantly augmented shoot and nodules production by 2 and 4-fold respectively, compared to the control. Leaf carbohydrates and photosynthetic pigments in KEL- and SW-treated plants increased considerably under severe water deficits, while leaf proteins decreased by more than 3-fold. The biostimulants also lowered phenolic and flavonoid concentrations. Increasing and decreasing levels of soluble sugars, proteins, photosynthetic pigments, phenolics and flavonoids indicate stress alleviation and osmotic adjustment to water deficits. These biostimulants are a suitable alternative to improve soil fertility, growth, and yield of staple crops under water stress conditions.