Hypocotyls Of Seedlings Research Articles

WRKY-ing in the light.

This article is a Commentary on Zhou et al. (2022), 235: 111–125.

Pre-sowing seed treatment of narrow-leafed lupin against anthracnose and other diseases

The results of laboratory and field studies of the effectiveness of the Tirada SK disinfectant (suspension concentrate) against anthracnose seed infection and other lupine diseases are presented.The work was carried out in 2018-2020 in the Bryansk region. The object of study is the seeds, seedlings and crops of the Vityaz narrow-leafed lupin. In laboratory conditions, the effectiveness of the Tirada SK disinfectant (tiram 400 g / l + difenoconazole 30 g / l) was studied in three application doses (1.0; 1.5; 2.0 l / t). The biological effectiveness was evaluated by the number of infested seedlings grown in paper-polyethylene rolls compared to the control (without dressing). High biological effectiveness (100%) against anthracnose was shown by doses of 1.5 and 2.0 l / t. The highest overall germination (99.6%) and the number of seeds with strong seedlings (90.4%) were noted in the variant with a dose of 1.5 l / t. At the same time, the length of roots and hypocotyl of seedlings increased significantly (LSD05 = 0.69 and LSD05 = 0.51) by 18.0 and 1.0%, respectively. The field experiment was carried out in four repetitions, the plot area was 34 m2. The seeding rate was 1.2 1.2 million viable seeds / ha. The soil of the plot is grey forest with the humus content of 2.7%. The predecessor is spring sown cereals. Seed dressing with Tirada disinfectant at a consumption rate of 1.5 l / t was applied one month before sowing. The effectiveness of the disinfectant was evaluated in comparison with the control. The average biological effectiveness of the disinfectant against anthracnose infection was 94.3%. By the shiny pod phase, the number of affected pods was 5.7%, compared to 26.4% in the control. Plant infestation by Fusarium (Fusarium spp.) was reduced from 18.7% in the control to 11.8% in the experiment and by Rhizoctonia (Rhizoctonia solani Kuhn.) from 9.8% to 2.8%. The spread of grey rot and white rot on pods has been reduced by a factor of 2.4 and 2.8, respectively. The seed germination increased significantly (LSD05 = 0.71) by 8.1% and the safety of productive plants at harvest increased by 35.3%. A significant (LSD05 = 0.041) increase in seed yield was 0.82 t/ha, with a cost recovery of 7.15 rubles.

Stress response of ABI5 to BR stress and its regulation on hypocotyls growth in Arabidopsis thaliana.

Abscisic acid-insensitive 5 (ABI5) is a basic leucine zipper (bZIP) transcription factor that is abundantly expressed in seeds. It plays a central role in regulating the abscisic acid (ABA) signal of seed germination and early seedling growth. Brassinosteroid (BR) is a new type of plant endogenous hormone, which has many physiological functions such as regulating plant growth and development and response to adversity stress. It has recently been discovered that under brassinolide stress, BIN2 (BRASSINOSTEROID INSENSITIVE2) and BES1 (BRI1-EMS-SUPPRESSOR 1) in the BR signaling pathway can inhibit the expression of ABI5 and promote Arabidopsis thaliana seed germination. In order to further explore the function of ABI5 under BR stress, this study analyzed the ABI5 expression characteristics during seed germination, identified Arabidopsis ABI5 gene deletion mutant abi5-1 and analyzed its function under BR stress, the results of which indicated that ABI5 was abundantly expressed in Arabidopsis dry seeds and responded to BR stress during germination. Under normal conditions, there was no significant difference between the hypocotyls of abi5-1 and wild-type seedlings; but under BR stress, the hypocotyls of abi5-1 seedlings were significantly longer than those of wild-type seedlings. These results reveal that ABI5 regulates the growth of Arabidopsis hypocotyls under BR stress, thereby providing a basis for in-depth understanding of the molecular mechanism of ABI5 regulation on plant development.

A Reliable Regeneration Method in Genome-Editable Bell Pepper ‘Dempsey’

A reliable regeneration technique is critical for the improvement of pepper traits in the genome editing era. Recently, we reported that peppers were successfully and specifically edited using CRISPR tools, CRISPR/Cas9 and CRISPR/Cas12a (LbCpf1). Although genome-editing tools can be applied to modify peppers at the cellular level, feasible pepper regeneration techniques have not been developed. Therefore, we studied a pepper regeneration protocol for Capsicum annuum L. ‘Dempsey’, a bell pepper species that has been proven to be genome-editable. Three explant types were used in this study, including the first leaves, cotyledons and hypocotyls of pepper seedlings. The shoot buds of the tested explants were produced using 8 mg/L 6-benzylaminopurine (BAP)- and 6 mg/L indole-3-acetic acid (IAA)-containing shoot induction medium (SIM). The first leaves of the ‘Dempsey’ seedlings showed an average shooting rate of 69.8%, whereas the hypocotyls and cotyledons had approximately 25.5% and 19.5% shooting rates, respectively. The regenerated ‘Dempsey’ plants exhibited no alterations in fruit and fertile seed phenotypes. Furthermore, the parent ‘Dempsey’ and progenies of the regenerants were cytogenetically stable with the same chromosome numbers (2n = 24). Therefore, this regeneration protocol enables the precise molecular breeding of ‘Dempsey’ peppers when coupled with CRISPR tools.

SOYBEANS SEED PRODUCTIVITY UNDER THE ACTION OF GROWTH STIMULATING DRUGS

Biostimulants are the kind of "doping", due to which crops gain great vitality for crop formation. Growth stimulating drugs make a positive effect on the soil microflora, they are rapidly transformed by soil microorganisms, plant cells. The aim of the work was to substantiate scientifically the use of stimulating growth regulators –Epin-extra, Agorostimulin, Rival, and Kornevin, as the elements of soybean growing technology;to identify their effect on biological characteristics and seed productivity of the crop. The research was conducted on soybean variety Millennium. Pre-sowing experimental treatments of seeds were carried out with aqueous solutions of Epin-extra (0,025 g l), Agorostimulin (1 ml/l), Rival (1 ml/l) and Kornevin (0,5 g/l), and control – with water. During the study laboratory germination and energy of germination of seeds, and also morphometric indicators of seedlings and roots were defined. It was found that the pre-sowing treatment of soybean seeds of Millennium variety with stimulant drugs – Epin-extra (0,025 g/l), Agorostimulin (1 ml/l), Rival (1 ml/l) and Cornevin (0,5 g/l) increased seed productivity. In all variants of the experiment, both germination energy and seed germination were increased. It was found that the most effective drugs for the increase of germination energy and seed germination of Millennium soybeans are Epin-extra (0,025 g/l) and Agorostimulin (1 ml/l). Under the action of plant growth stimulators, morphometric changes occurred in soybean seedlings. The drugs affected the length of the hypocotyls in seedlings of soybean culture. Under the use of Epin-extra (0,025 g/l) the length of hypocotyls increased by 18 %, under the action of Agorostimulin (1 ml/l) – by 32 %, under Cornevin (0,5 g/l) treatment - by 41 % and after the use of the drug Rival (1 ml/l) – by 85 %. Stimulators helped to lengthen the main root of soybean seedlings. The largest indicator of the length of the main root was found under the treatment of such drugs Riaval and Agorostimulin. It was found that all studied drugs contributed to the regrowth of lateral roots in soybean seedlings, but the best effect was observed under the usage of the drug Cornevin (0,5 g/l). The significant increase in the dry weight of Millennium soybean seedlings was revealed with the use of stimulating plant growth regulators. The increase of the dry weight of soybean seedlings was detected under the pre-sowing treatment of seeds with Cornevin (by 36 %), Agrostimulin (by 50 %), and Rival (by 88 %) in comparison to the control. Pre-sowing treatment of soybean seeds leads to the increase of dry weight of roots. The best effect on the increase of dry weight of roots was found under the use of drugs Cornevin and Agrostimulin. The use of Epin-extra and Rival also led to a positive result, but not as significant as after the use of two previous drugs that were given above.

The domain of unknown function 4005 (DUF4005) in an Arabidopsis IQD protein functions in microtubule binding

The dynamic responses of microtubules (MTs) to internal and external signals are modulated by a plethora of microtubule-associated proteins (MAPs). In higher plants, many plant-specific MAPs have emerged during evolution as advantageous to their sessile lifestyle. Some members of the IQ67 domain (IQD) protein family have been shown to be plant-specific MAPs. However, the mechanisms of interaction between IQD proteins and MTs remain elusive. Here we demonstrate that the domain of unknown function 4005 (DUF4005) of the Arabidopsis IQD family protein ABS6/AtIQD16 is a novel MT-binding domain. Cosedimentation assays showed that the DUF4005 domain binds directly to MTs in vitro. GFP-labeled DUF4005 also decorates all types of MT arrays tested in vivo. Furthermore, we showed that a conserved stretch of 15 amino acid residues within the DUF4005 domain, which shares sequence similarity with the C-terminal MT-binding domain of human MAP Kif18A, is required for the binding to MTs. Transgenic lines overexpressing the DUF4005 domain displayed a spectrum of developmental defects, including spiral growth and stunted growth at the organismal level. At the cellular level, DUF4005 overexpression caused defects in epidermal pavement cell and trichome morphogenesis, as well as abnormal anisotropic cell elongation in the hypocotyls of dark-grown seedlings. These data establish that the DUF4005 domain of ABS6/AtIQD16 is a new MT-binding domain, overexpression of which perturbs MT homeostasis in plants. Our findings provide new insights into the MT-binding mechanisms of plant IQD proteins.

Overexpression of GmGAMYB Accelerates the Transition to Flowering and Increases Plant Height in Soybean.

The flowering time and plant height of soybean are important agronomic characters, which control the adaptability and yield of soybean. R2R3 MYB transcription factor plays an important regulatory role in plant growth and development. In this study, soybean GmGAMYB gene of R2R3-MYB type was induced by long-days (LDs). GmGAMYB showed higher transcriptional levels in the flowers, leaves and pods of soybean. Overexpression of GmGAMYB in transgenic soybean showed earlier flowering time and maturity in LDs and short-days (SDs). GmGAMYB interacted with GmGBP1 and might promote flowering time by up-regulating the expression of GmFULc gene in soybean. Moreover, the expression level of GmGAMYB was also induced by gibberellins (GAs) and the plant height of GmGAMYB-ox plants was significantly increased, which was caused by the enlargement of internode cell in stem. Furthermore, GmGAMYB overexpression led to increased GA sensitivity in the hypocotyl of soybean seedlings compared with WT. GmGAMYB may be a positive regulator of GA response of promoting plant height by up-regulating the expression of GmGA20ox gene in soybean. Together, our studies preliminarily showed that the partial functions of GmGAMYB in regulating flowering time and GA pathway.

The CBL-Interacting Protein Kinase NtCIPK23 Positively Regulates Seed Germination and Early Seedling Development in Tobacco (Nicotiana tabacum L.).

CBL-interacting protein kinase (CIPK) family is a unique group of serine/threonine protein kinase family identified in plants. Among this family, AtCIPK23 and its homologs in some plants are taken as a notable group for their importance in ions transport and stress responses. However, there are limited reports on their roles in seedling growth and development, especially in Solanaceae plants. In this study, NtCIPK23, a homolog of AtCIPK23 was cloned from Nicotiana tabacum. Expression analysis showed that NtCIPK23 is mainly expressed in the radicle, hypocotyl, and cotyledons of young tobacco seedlings. The transcriptional level of NtCIPK23 changes rapidly and spatiotemporally during seed germination and early seedling growth. To study the biological function of NtCIPK23 at these stages, the overexpressing and CRISPR/Cas9-mediated knock-out (ntcipk23) tobacco lines were generated. Phenotype analysis indicated that knock-out of NtCIPK23 significantly delays seed germination and the appearance of green cotyledon of young tobacco seedling. Overexpression of NtCIPK23 promotes cotyledon expansion and hypocotyl elongation of young tobacco seedlings. The expression of NtCIPK23 in hypocotyl is strongly upregulated by darkness and inhibited under light, suggesting that a regulatory mechanism of light might underlie. Consistently, a more obvious difference in hypocotyl length among different tobacco materials was observed in the dark, compared to that under the light, indicating that the upregulation of NtCIPK23 contributes greatly to the hypocotyl elongation. Taken together, NtCIPK23 not only enhances tobacco seed germination, but also accelerate early seedling growth by promoting cotyledon greening rate, cotyledon expansion and hypocotyl elongation of young tobacco seedlings.

First Report of Globisporangium ultimum Causing Constriction on Hypocotyl of Beta vulgaris in North Dakota, USA

Sugar beet (Beta vulgaris) sowing to post-harvest is continuously encountered with wide range of soil-borne pathogens including Rhizoctonia, Fusarium, Aphanomyces, Rhizopus, Pythium, Talaromyces, Clonostachys, and Geotrichum. These evident to cause substantial qualitative and quantitative losses. In May/2019, dark brown to black irregular water-soaked lesions were observed near the soil-line (constriction of hypocotyl) on sugar beet seedlings in Prosper (46.9630° N, 97.0198° W), North Dakota (Figure 1). Approximately 2-5% of disease incidence was recorded. Small pieces (10 mm²) of symptomatic root tissues were cut from the margins between infected and healthy tissue, and disinfected with 10% sodium hypochlorite for 1 min, rinsed three times with autoclaved water, and then placed on Corn Meal Agar (CMA) amended with pimaricin-vancomycin- Pentachloronitrobenzene (PCNB) [1] for incubation at 20°C in the dark for 5 days. Subsequently, single hyphal tips were transferred to Water Ager (WA) (Figure 2). In total, 8 isolates were developed from diseased beets. Isolates were developed light fungal biomass on WA in 14 days. Microscopically, hyphal swelling and globular or lemon shaped sporangia were present (Figure 3). Based on macroscopic and microscopic characteristics, the fungus was speculated to be Oomycetes genus [2]. Determining the species, genomic DNAs of 8-isolates were used for Polymerase Chain Reaction (PCR) using ITS- 6 and ITS-7 primer. PCR amplicons were cleaned with E.Z.N.A ®Cycle Pure Kit, OMEGA, and 8 samples were sent for Sanger sequencing to GenScript (Piscataway, NJ) [3]. The sequences were identical, and standard nucleotide blast search showed 99% sequence identity to Globisporangium ultimum (Genbank accessions: MK794771.1). The nucleotide sequence was deposited in Genbank (MN086365.1). Phyto-pathogenicity testing was performed with 2-week old sugar beet susceptible cultivar which was inoculated with a 2-week old WA culture (5 mm² mycelial cut). This plug/mycelial cut was placed at a 1/2-inch depth close to seedlings in each plastic pot (27 x 13 x 13 cm, T.O. Plastics, Inc.; Clearwater, MN, USA) which was filled with vermiculite and perlite mixer (PRO-MIX FLX) amended with osmocote (N-P-K:15-9-12) fertilizer (Scotts Company; Marysville, OH). The pots were arranged in completely randomized design. The study was done twice with four replicates and 10 plants per replicate. One week of post-inoculation, 40% of the inoculated plants developed similar damping-off symptoms as discussed above (Figure 4), whereas mock-inoculated plants were healthy. Pathogen re-isolated from the infected hypocotyl tissue and was further confirmed morphologically and molecularly, fulfilled Koch’s postulates. Globisporangium species complex were previously reported to cause damping-off on aleppo pine (Pinus halepensis Mill) in Australia, Africa, Mediterranean, rootcrown rot of pepper (Capsicum annuum) in Turkey and alfalfa [4- 7]. To our best knowledge, this is the first report of Globisporangium ultimum causing constriction on hypocotyl of sugar beet seedlings in North Dakota, USA.

The Role of a New Compound Micronutrient Multifunctional Fertilizer against Verticillium dahliae on Cotton.

Verticillium dahliae Kleb., the causal pathogen of vascular wilt, can seriously reduce the yield and quality of many crops, including cotton (Gossypium hirsutum). To control the harm caused by V. dahliae, considering the environmental pollution of chemical fungicides and their residues, the strategy of plant nutrition regulation is becoming increasingly important as an eco-friendly method for disease control. A new compound micronutrient fertilizer (CMF) found in our previous study could reduce the damage of cotton Verticillium wilt and increase yield. However, there is little information about the mode of action of CMF to control this disease. In the present study, we evaluated the role of CMF against V. dahliae and its mechanism of action in vitro and in vivo. In the laboratory tests, we observed that CMF could inhibit hyphal growth, microsclerotia germination, and reduce sporulation of V. dahliae. Further studies revealed that the biomass of V. dahliae in the root and hypocotyl of cotton seedlings treated with CMF were significantly reduced compared with the control, and these results could explain the decline in the disease index of cotton Verticillium wilt. Furthermore, those key genes involved in the phenylpropanoid metabolism pathway, resistance-related genes defense, and nitric oxide signaling pathway were induced in cotton root and hypocotyl tissue when treated with CMF. These results suggest that CMF is a multifaceted micronutrient fertilizer with roles in inhibiting the growth, development, and pathogenicity of V. dahliae and promoting cotton growth.

Studying the length of the hypocotyl of cucumber seedlings

Relevance . Study the selection material of cucumber on the basis of the hypocotyl length, as well as to assess the stability of this feature depending on the year of research and the timing of sowing. Material and methods . Studies were conducted on the selection samplesof the laboratory cucumber breeding and seed production of Cucurbitaceae of FSBSI Federal Scientific Vegetable Center in 2019 and 2020 in terms of seedling branches winter greenhouse type "Richelle". Cucumber seedlings were grown without artificial illumination. Measurement of the length of the subfamily knee was performed at the stages of expanded cotyledons and the formation of the first true leaf. Results . The length of the hypocotyl varied in the phase of expanded cotyledons – from 3 to 8 cm, in the phase of the first real leaf – from 6 to 18 cm. It was found that at the early stages of development, in the phase of expanded cotyledons, it is effective to reject plants with a hypocotyl length ≥5 cm. This will allow you to get rid of unwanted samples at the early stages of growing seedlings or to conduct selection within populations. The final assessment of the breeding material for lodging stability should be carried out in the phase of the first true leaf, since the most intensive growth of the hypocotyl was observed in the interphase period "expanded cotyledons – the first true leaf". During this period, it is possible to select non-lodging samples in a group that was characterized by an average hypocotyl (3.7-4.0 cm) for the expanded cotyledon phase. In breeding samples, depending on the year of research, the difference in the length of the hypocotyl in the phase of expanded cotyledons was 0.1-0.8 cm. All this indicates the stability of this feature and, accordingly, the possibility of selecting forms with the necessary parameters. A comparative study of cucumber seedlings of different sowing periods (1.5 months difference) revealed the samples most sensitive to low light. Promising samples were selected with a short hypocotyl in the phase of expanded cotyledons (< 5 cm), which are of interest for breeding for seedling resistance to lodging.

Salicylic acid regulates adventitious root formation via competitive inhibition of the auxin conjugation enzyme CsGH3.5 in cucumber hypocotyls.

Exogenous SA treatment at appropriate concentrations promotes adventitious root formation in cucumber hypocotyls, via competitive inhibiting the IAA-Asp synthetase activity of CsGH3.5, and increasing the local free IAA level. Adventitious root formation is critical for the cutting propagation of horticultural plants. Indole-3-acetic acid (IAA) has been shown to play a central role in regulating this process, while for salicylic acid (SA), its exact effects and regulatory mechanism have not been elucidated. In this study, we showed that exogenous SA treatment at the concentrations of both 50 and 100µM promoted adventitious root formation at the base of the hypocotyl of cucumber seedlings. At these concentrations, SA could induce the expression of CYCLIN and Cyclin-dependent Kinase (CDK) genes during adventitious rooting. IAA was shown to be involved in SA-induced adventitious root formation in cucumber hypocotyls. Exposure to exogenous SA led to a slight increase in the free IAA content, and pre-treatment with the auxin transport inhibitor 1-naphthylphthalamic acid (NPA) almost completely abolished the inducible effects of SA on adventitious root number. SA-induced IAA accumulation was also associated with the enhanced expression of Gretchen Hagen3.5 (CsGH3.5). The in vitro enzymatic assay indicated that CsGH3.5 has both IAA- and SA-amido synthetase activity and prefers aspartate (Asp) as the amino acid conjugate. The Asp concentration dictated the functional activity of CsGH3.5 on IAA. Both affinity and catalytic efficiency (Kcat/Km) increased when the Asp concentration increased from 0.3 to 1mM. In contrast, CsGH3.5 showed equal catalytic efficiency for SA at low and high Asp concentrations. Furthermore, SA functioned as a competitive inhibitor of the IAA-Asp synthetase activity of CsGH3.5. During adventitious formation, SA application indeed repressed the IAA-Asp levels in the rooting zone. These data show that SA plays an inducible role in adventitious root formation in cucumber through competitive inhibition of the auxin conjugation enzyme CsGH3.5. SA reduces the IAA conjugate levels, thereby increasing the local free IAA level and ultimately enhancing adventitious root formation.

High-Efficiency Agrobacterium rhizogenes-Mediated Transgenic Hairy Root Induction of Lens culinaris

Previous efforts to transform lentil have been considerably hampered by the crop’s recalcitrant nature, giving rise to particularly low transformation and regeneration frequencies. This study aimed at optimizing an Agrobacterium rhizogenes-mediated transformation protocol for the generation of composite lentil plantlets, comprised of transgenic hairy roots and wild-type shoots. Transformation was performed by inoculating the cut hypocotyl of young lentil seedlings, while optimization involved the use of different bacterial strains, namely R1000, K599 and Arqua, and protocols differing in media composition with respect to the presence of acetosyringone and MES. Composite plantlets had a transgenic hairy root system characterized by an increased number of hairy roots at the hypocotyl proximal region, occasionally showing plagiotropic growth. Overall findings underline that transformation frequencies are subject to the bacterial strain, media composition as well as their combined effect. Among strains tested, R1000 proved to be the most capable of hairy root formation, while the presence of both acetosyringone and MES in inoculation and culture media yielded considerably higher transformation rates. The transgenic nature of hairy roots was demonstrated by the Ri T-DNA-mediated transfer of the rolB2 gene and the simultaneous absence of the virCD sequence of A. rhizogenes. Our findings provide strong evidence that A. rhizogenes-mediated transformation may be employed as a suitable approach for generating composite seedlings in lentil, a species whose recalcitrance severely hampers all efforts addressed to transformation and whole plant regeneration procedures. To the best of our knowledge, this is the first report on the development of a non-laborious and time-efficient protocol for the generation of transgenic hairy roots in lentil, thus providing an amenable platform for root biology and gene expression studies in the context of improving traits related to biotic and abiotic stress tolerance.

Plântulas de gergelim cv. BRS seda sob aplicação de água salinizada

O gergelim é uma importante cultura oleaginosa e alimentícia, bem adaptada às condições da região semiárida, na qual o problema da salinidade é comum. Assim, objetivou-se com este estudo avaliar a germinação e o crescimento das plântulas de gergelim submetidas ao estresse salino. Os tratamentos foram arranjados em delineamento inteiramente casualizado, aplicando cinco tratamentos, sendo os níveis de sais correspondente ás condutividades elétricas da água (0,6; 1,2; 1,8; 2,4 e 3,0 dS m-1) na cultivar de gergelim BRS seda, distribuídos em quatro repetições, totalizando 20 unidades experimentais. As variáveis analisadas foram à porcentagem, a primeira contagem, o índice de velocidade, o tempo médio de germinação, e as variáveis de crescimento das plântulas: comprimento total da plântula, do hipocótilo, da radícula primária, vigor e a massa fresca total da parte área e da radícula primária. Os resultados obtidos denotam que o aumento da salinidade na água ocasiona redução na germinação e no crescimento inicial das plântulas de gergelim. No se recomienda usar agua con concentraciones de sal de 1.2 dS m-1 en el establecimiento de la variedad de seda BRS.

Effects of glyphosate on germination, photosynthesis and chloroplast morphology in tomato

The adverse effects of glyphosate herbicide on plants are well recognised, however, potential hormetic effects have not been well studied. This study aimed to use tomato as a model organism to explore the potential hormetic effects of glyphosate in water (0–30 mg L−1) and in compost soil (0–30 mg kg−1). The growth-promoting effects of glyphosate at concentrations of 0.03–1 mg L−1 in water or 0.03–1 mg kg−1 in compost were demonstrated in tomato for the first time. These hormetic effects were manifest as increased hypocotyl and radicle growth of seedlings germinated on paper towel soaked in glyphosate solution and also in crops which had been sprayed with glyphosate. Increased rates of photosynthesis (up to 2-fold) were observed in 4-week old crops when seeds were sown in compost amended with glyphosate and also when leaves were sprayed with glyphosate. The examination of chloroplast morphology using transmission electron microscopy revealed that the hormetic effects were associated with elongation of chloroplasts, possibly due to lateral expansion of thylakoid grana.

The efficient induction of tetraploid plants via adventitious shoots in Antirrhinum majus L. by in vitro seed treatment with amiprophos-methyl

Tetraploid plants of Antirrhinum majus L. were obtained from the seeds of the F1 variety ‘Maryland True Pink’ by amiprophos-methyl (APM) treatment and subsequent in vitro culture. Seeds were treated with 0, 10 and 20 mgl−1 APM for 1, 3, or 7 d (day) with or without osmopriming. Overall, the seedlings established from the seeds treated with 10 or 20 mgl−1 APM for 3–7 d exhibited malformation with rudimentary roots and swollen hypocotyls that eventually produced adventitious shoots. The highest adventitious shoot formation frequency reached 71.6% in non-primed seeds treated with 10 mgl−1 APM for 7 d; this decreased to 54.4% in osmoprimed seeds that received the same APM treatment. The plantlets from the adventitious shoots were identified as tetraploids at frequencies of 51.4% and 90.4%, respectively. Tetraploid frequency increased with higher concentration and/or longer duration of APM treatment and ranged from 0 to 65.9% in the non-primed seeds and 10.3% to 100% in the osmoprimed seeds. Osmopriming of seeds accelerated the induction of tetraploids by APM treatment at the same concentration and duration by 10.3–39.0%, except in the case of treatment with 20 mgl−1 APM for 3 d treatment. In the osmoprimed seeds treated with 20 mgl−1 APM for 7 d, all the plantlets from the adventitious shoots were revealed to be tetraploids. This study revealed that APM has dual effects, namely the inhibitory effect on the growth of seedlings and the stimulatory effect on the induction of adventitious shoots on the hypocotyl of seedlings. APM induced adventitious shoots on the hypocotyl of seedling by seed treatment and the induced-adventitious shoots were identified to be tetraploids. Osmopriming accelerated the frequency of tetraploid induction.

Development of a systemic crop signalling system for automated real-time plant care in vegetable crops

Vegetable crop productivity is susceptible to damage from weed competition, with early season weeds a control priority to prevent significant yield loss. There is an urgent need for a reliable robotic sensing system that can work well in a variety of crops to achieve universal weed/crop differentiation, which would facilitate further development in robotic technologies for farming and bring economic benefits to vegetable production. The aim of this study was to develop a novel technique to create a machine-readable crop plant using a systemic crop signalling compound applied to seeds or transplants. The protocols for the crop signalling method and its detection are described. Rhodamine B (Rh–B) was selected as the signalling compound in this study, because it could be used as a fluorescent tracer, had a unique optical appearance in plants, and had the necessary properties to allow systemic behaviour in vegetable seedlings. The Rh–B tracer was applied to snap bean and the systemic behaviour analysed with a fluorescent macroscope. The uptake of Rh–B varied among treatment methods. The Rh–B uptake through the seed coat of snap beans was found mainly in the seedling hypocotyls. The results for root uptake showed that Rh–B could be more readily transported to the whole plant through the root system as compared to the application to seeds. The midvein and secondary veins of bean leaves showed stronger Rh–B fluorescence than other regions of the leaf. Higher concentrations of Rh–B resulted in greater absorption by the plant. Although the crop signalling compound could follow both seed and root pathways for plant uptake, the uptake based on the root pathway had greater capacity than that of the seed pathway. The use of Rh–B provided a systemic crop signalling compound was discussed on further research and field tested to have application to enhance weed/crop differentiation by automated weeders in vegetable crops. The systemic crop signalling system successfully created a machine-readable signal on vegetable crops, and appeared to be non-destructive, cost effective, efficient and accurate for performing automatic plant care tasks.

Seed germination and seedling emergence of four tree species of southern China in response to acid rain

Acid rain has become a major concern due to increasing atmospheric pollution, particularly in China. We investigated whether acid rain inhibits the germination of seeds and subsequent emergence of seedling of four tree species from southern China: Cunninghamia lanceolata, Fokienia hodginisi, Pinus massoniana and Phoebe zhennan by simulating acid rain with pH of 2.5, 3.5, 4.5 and 5.5. We hypothesized that the inhibitory effect of acid rain on germination of seeds and emergence of seedling varies between species and the degree of acidity. A solution of 1 N H2SO4 and 1 N HNO3 in the ratio of 10–1 was prepared and diluted to four pH levels, and seeds were supplied with solutions of these pH values and distilled water as control and tested for germination in a controlled growth chamber. The results revealed that simulated acid rain of pH 2.5 adversely affected the germination capacity of F. hodginisi and P. zhennan; while all acid solutions significantly increased germination of P. Massoniana; but had no effect on germination of C. Lanceolata seeds. Strong acid solution (pH of 2.5) adversely affected elongation of radicle and hypocotyl as well as fresh and dry weights of radicle and hypocotyl of tender seedlings. The result demonstrated that seedling emergence is more sensitive than seed germination to simulated acid rain, and germination of conifer species are less sensitive than broad leaved species to simulated acid rain. As a whole, acid rain of pH of 3.5 is the threshold level and acid rain below this value will have a detrimental effect on seed germination and seedling emergence.

The biocontrol agent Streptomyces pactum increases Pseudomonas koreensis populations in the rhizosphere by enhancing chemotaxis and biofilm formation

Beneficial microbes can be used as biocontrol agents against soil-borne plant diseases. In addition to controlling plant pathogens and promoting plant growth, an introduced biocontrol agent can cause shifts in the indigenous microbial community structure in the rhizosphere. However, it remains unclear how biocontrol agents affect the distribution of rhizosphere microbial populations and whether population changes of particular dominant microbes in turn contribute to the role of the biocontrol agent in disease control and plant growth promotion. Our previous studies indicated that introduction of Streptomyces pactum Act12 (a multifunctional biocontrol agent) could affect rhizosphere micro-ecology and, particularly, increase the population of Pseudomonas koreensis GS (a dominant indigenous bacterium) in the rhizosphere of ginseng plants. Here we evaluated the potential effects of P. koreensis GS in disease control and plant growth promotion via in vitro antagonism and tomato seedling growth tests. We found that P. koreensis GS had no antagonistic effect on six common fungal pathogens. However, seed priming with cell-free culture filtrate of strain GS considerably promoted hypocotyl and radicle growth of tomato seedlings while increasing expression of expansin genes in seedling leaves compared with controls. Then, we explored the molecular mechanisms underpinning the population increase of P. koreensis GS based on its growth and transcriptome changes. We found that adding broth culture, cell-free filtrate, or spore powder of S. pactum Act12 did not significantly affect P. koreensis GS growth in solid agar, liquid broth, or autoclaved soil, respectively. However, RNA sequencing revealed upregulation of genes related to organic acid metabolic processes, reactive oxygen species metabolic processes, bacterial chemotaxis, and flagellar assembly in P. koreensis GS after treatment with S. pactum Act12 cell-free filtrate. S. pactum Act12 treatment improved the swimming motility of, and biofilm formation by, P. koreensis GS, thereby enhancing its ability to colonize the rhizosphere of tomato seedlings. These results indicate that introduction of S. pactum Act12 can enhance rhizosphere colonization and competition by P. koreensis GS via the promotion of biofilm formation, nutrient utilization, and environmental adaptation. The resulting increase in the P. koreensis population may directly contribute to the role of S. pactum Act12 in promoting plant growth.

Effect of biostimulants on soybean seedlings

The aim of this study was to analyze the effect of biostimulants on the morphological characteristics of soybean seedlings. The testing was conducted in the laboratory of the Faculty of Biofarming in Bačka Topola. The experimental material included three soybean varieties ('Galina', 'Sava' and 'Rubin') selected at the Institute of Field and Vegetable Crops in Novi Sad. The study lasted for two years, 2015-2016, and identical biostimulant treatments were applied in both years. In order to determine the effect of biostimulants on soybean seedling root, hypocotyl and weight, the following commercial biostimulants were applied: EM Aktiv, Terra Green Hobby, Slavol and Bioplant Flora. In addition to the single application of biostimulants, two combinations of Slavol + Bioplant Flora and Slavol + Bioplant Flora + Epin Extra + Slavol S were used as treatments. EM Aktiv showed the greatest effect on root growth. The root was on average 12% longer than the control. Slavol S had the greatest influence on seedling hypocotyl and weight. The increase was 8.24% and 5.15%, respectively, compared with the control.