Effects of Elevated Temperature on Root System Development of Two Lupine Species

The aim of this study was to assess the effect of elevated temperature on the growth, morphology and spatial orientation of lupine roots at the initial stages of development and on the formation of lupine root architecture at later stages. Two lupine species were studied—the invasive Lupinus polyphyllus Lindl. and the non-invasive L. luteus L. The plants were grown in climate chambers under 25 °C and simulated warming at 30 °C conditions. The angle of root curvature towards the vector of gravity was measured at the 48th hour of growth, and during a 4-h period after 90° reorientation. Root biometrical, histological measurements were carried out on 7-day-old and 30-day-old plants. The elevation of 5 °C affected root formation of the two lupine species differently. The initial roots of L. polyphyllus were characterized by worse spatial orientation, reduced growth and reduced mitotic index of root apical meristem at 30 °C compared with 25 °C. The length of primary roots of 30-day-old lupines and the number of lateral roots decreased by 14% and 16%, respectively. More intense root development and formation were observed in non-invasive L. luteus at 30 °C. Our results provide important information on the effect of elevated temperature on the formation of root architecture in two lupine species and suggest that global warming may impact the invasiveness of these species.

OPTIMIZATION OF IN VITRO SELECTIVE MEDIA FOR SELECTING ANTHRACNOSIS-RESISTANT FLAX CELLS

Цель исследований – оптимизация селективных сред для проведения отбора in vitro каллусных клеток льна, устойчивых к культуральному фильтрату штаммов возбудителя антракноза и создание in vitro новых генотипов, устойчивых к болезни. В результате исследований уточнен состав культурального фильтрата штаммов антракноза. Выявлено, что токсичность культуральных фильтратов не зависела от вирулентности используемых штаммов – более токсичными оказались культуральные фильтраты штаммов 784 (сильновирулентного) и 780 (средневирулентного) (загнивание и отмирание первичных корешков на 5 сутки наблюдали у 67 – 88% проросших семян), менее токсичны – штаммы 793 (сильновирулентный) и 788 (слабовирулентный) (на 5 сутки загнивание и отмирание первичных корешков отмечено у 9 – 15% проросших семян). Установлено, что морфогенные очаги формировались активнее у генотипов, морфогенный каллус которых переносили на среду с аналогичной или более высокой концентрацией культурального фильтрата. Показано, что на 14 сутки во втором пассаже с большей частотой формировались морфогенные каллусы, почки и побеги при использовании в первом и втором пассажах селективной среды, содержащей культуральный фильтрат в концентрации 40 мл/л, или в первом пассаже – 40 мл/л, а во втором – 44 мл/л. Выделены генотипы, сохраняющие устойчивость к антракнозу в течение трёх поколений на уровне 50 – 60%: НО-78 х Ленок, HJI-103-2 х Ленок, НЛ-40-1 х Ленок, HЭ-38 х Росинка, НЭ-36 х Ленок, НЭ-17 х Ленок, HЭ-16-2 х Росинка. Research objective – optimization of selective media for in vitro selection of flax callus cells resistant to culture filtrate of anthracnose pathogen strains and in vitro creation of new disease-resistant genotypes. As a result of the research, the composition of the culture filtrate of anthracnose strains was clarified. It was revealed that the toxicity of cultural filtrates did not depend on the virulence of the strains used - cultural filtrates of strains 784 (highly virulent) and 780 (medium virulent) turned out to be more toxic (decay and death of primary roots on day 5 was observed in 67 - 88% of germinated seeds), less toxic - strains 793 (strongly virulent) and 788 (weakly virulent) (on the 5th day, decay and death of primary roots was noted in 9-15% of germinated seeds). It was found that morphogenic foci were formed more actively in genotypes, the morphogenic callus of which was transferred to a medium with a similar or higher concentration of the culture filtrate. It was shown that on the 14th day in the second passage, morphogenic callus, buds and shoots were formed with a greater frequency when using in the first and second passages a selective medium containing a culture filtrate at a concentration of 40 ml/l, or in the first passage - 40 ml/l, and in the second - 44 ml/l. Genotypes were identified that retain resistance to anthracnose for three generations at a level of 50 - 60%: NO-78 x Lenok, HJI-103-2 x Lenok, NL-40-1 x Lenok, NE-38 x Rosinka, NE-36 x Lenok, NE-17 x Lenok, NE-16-2 x Rosinka.

Manganese distribution in the Mn-hyperaccumulator Grevillea meisneri from New Caledonia

New Caledonian endemic Mn-hyperaccumulator Grevillea meisneri is useful species for the preparation of ecocatalysts, which contain Mn–Ca oxides that are very difficult to synthesize under laboratory conditions. Mechanisms leading to their formation in the ecocatalysts are unknown. Comparing tissue-level microdistribution of these two elements could provide clues. We studied tissue-level distribution of Mn, Ca, and other elements in different tissues of G. meisneri using micro-X-Ray Fluorescence-spectroscopy (μXRF), and the speciation of Mn by micro-X-ray Absorption Near Edge Structure (µXANES), comparing nursery-grown plants transplanted into the site, and similar-sized plants growing naturally on the site. Mirroring patterns in other Grevillea species, Mn concentrations were highest in leaf epidermal tissues, in cortex and vascular tissues of stems and primary roots, and in phloem and pericycle–endodermis of parent cluster roots. Strong positive Mn/Ca correlations were observed in every tissue of G. meisneri where Mn was the most concentrated. Mn foliar speciation confirmed what was already reported for G. exul, with strong evidence for carboxylate counter-ions. The co-localization of Ca and Mn in the same tissues of G. meisneri might in some way facilitate the formation of mixed Ca–Mn oxides upon preparation of Eco-CaMnOx ecocatalysts from this plant. Grevillea meisneri has been successfully used in rehabilitation of degraded mining sites in New Caledonia, and in supplying biomass for production of ecocatalysts. We showed that transplanted nursery-grown seedlings accumulate as much Mn as do spontaneous plants, and sequester Mn in the same tissues, demonstrating the feasibility of large-scale transplantation programs for generating Mn-rich biomass.

Effect of sucker weight and seedling site on the growth of sago seedlings (Metroxylon sago Rottb.) in Papua

This study aims to obtain sucker weight and appropriate seedling site as a source of sago seeds by using seedling techniques in polybags to improve seed quality on sago cultivation. The experiment used a factorial design arranged in a randomized block design with three replications. Factor A, namely sucker weight, consisted of <999 g, 1000-1499 g, 1500-1999 g and > 2000 g. Factor B is the seedling site, consisting of laying seeds in the field, greenhouse and paranet of 60%. The results of the study showed that there was no interaction between the sucker weight combined with the seedling site, but the sucker weight had a significant effect on the number of rachis and the number of primary roots per plant and the percentage of life seedlings. Higher rachis growth was 3.8 obtained from medium-sized sucker weights (1000-1499 g and 1500-1999 g) and the highest number of primary roots was 41.3. It is obtained at sucker weights of 1000-1499 g. Meanwhile, the higher percentage of seedling survival was obtained at medium to large sucker weights of 66.3-71.0%. Thus, multiplication of sago seeds using medium-sized sucker on polybag media is highly suggested.

Comparative phenotypic and transcriptomic analyses unravel conserved and distinct mechanisms underlying shade avoidance syndrome in Brassicaceae vegetables

Background Plants grown under shade are exposed to low red/far-red ratio, thereby triggering an array of altered phenotypes called shade avoidance syndrome (SAS). Shade negatively influences plant growth, leading to a reduction in agricultural productivity. Understanding of SAS is crucial for sustainable agricultural practices, especially for high-density indoor farming. Brassicaceae vegetables are widely consumed around the world and are commonly cultivated in indoor farms. However, our understanding of SAS in Brassicaceae vegetables and their genome-wide transcriptional regulatory networks are still largely unexplored. Results Shade induced common signs of SAS, including hypocotyl elongation and reduced carotenoids/anthocyanins biosynthesis, in two different Brassicaceae species: Brassica rapa (Choy Sum and Pak Choy) and Brassica oleracea (Kai Lan). Phenotype-assisted transcriptome analysis identified a set of genes induced by shade in these species, many of which were related to auxin biosynthesis and signaling [e.g. YUCCA8 (YUC8), YUC9, and INDOLE-3-ACETIC ACID INDUCIBLE (IAAs)] and other phytohormones signaling pathways including brassinosteroids and ethylene. The genes functioning in plant defense (e.g. MYB29 and JASMONATE-ZIM-DOMAIN PROTEIN 9) as well as in biosynthesis of anthocyanins and glucosinolates were repressed upon shade. Besides, each species also exhibited distinct SAS phenotypes. Shade strongly reduced primary roots and elongated petioles of B. oleracea, Kai Lan. However, these SAS phenotypes were not clearly recognized in B. rapa, Choy Sum and Pak Choy. Some auxin signaling genes (e.g. AUXIN RESPONSE FACTOR 19, IAA10, and IAA20) were specifically induced in B. oleracea, while homologs in B. rapa were not up-regulated under shade. Contrastingly, shade-exposed B. rapa vegetables triggered the ethylene signaling pathway earlier than B. oleracea, Kai Lan. Interestingly, shade induced the transcript levels of LONG HYPOCOTYL IN FAR-RED 1 (HFR1) homolog in only Pak Choy as B. rapa. As HFR1 is a key negative regulator of SAS in Arabidopsis, our finding suggests that Pak Choy HFR1 homolog may also function in conferring higher shade tolerance in this variety. Conclusions Our study shows that two Brassicaceae species not only share a conserved SAS mechanism but also exhibit distinct responses to shade, which will provide comprehensive information to develop new shade-tolerant cultivars that are suitable for high-density indoor farms.

Auxin and Target of Rapamycin Spatiotemporally Regulate Root Organogenesis

The programs associated with embryonic roots (ERs), primary roots (PRs), lateral roots (LRs), and adventitious roots (ARs) play crucial roles in the growth and development of roots in plants. The root functions are involved in diverse processes such as water and nutrient absorption and their utilization, the storage of photosynthetic products, and stress tolerance. Hormones and signaling pathways play regulatory roles during root development. Among these, auxin is the most important hormone regulating root development. The target of rapamycin (TOR) signaling pathway has also been shown to play a key role in root developmental programs. In this article, the milestones and influential progress of studying crosstalk between auxin and TOR during the development of ERs, PRs, LRs and ARs, as well as their functional implications in root morphogenesis, development, and architecture, are systematically summarized and discussed.

Change the condition of spring wheat when adding bacterial-humic preparation to herbicides

The authors studied the effect of the bacterial-humic preparation AFG-b containing the spore-forming bacteria Bacillus subtilis and Bacillus amyloliquefaciens in a production experiment in the northern forest-steppe of the Novosibirsk Priob’ye region. The preparation was used on midearly spring wheat, which forms grain at the level of valuable wheat. The drug was used as an antistressant together with herbicides against dicotyledonous and monocotyledonous plants. The tank mixture used was metsulfuron-methyl, fenoxaprop-P-ethyl with the antidote cloquintoset-mexyl and 2-ethyl hexyl ester of 2,4-D with florasulam. The bacterial-humic preparation AFG-b is known to level out herbicide stress in wheat and improve plant health. It improves the condition of leaf cell membranes by preventing the escape of electrolytes from the cells. On the roots of plants one month after applying the antistressant, the authors observed a 1.5-2 times reduction in the development and prevalence of root rot of fusarium-helminthosporiosis etiology. The authors also marked the most pronounced phytosanitary effect of the preparation’s bacteria, which are antagonists of phytopatho- gens for plants’ primary roots and epicotyl. An increase in plant productivity manifests the anti-stress and growth-stimulating effect of AFG-b. During the growing season of 2020, the bio preparation combined with herbicides provided a reliable increase of 40.2% of the grain of spring wheat and improved its quality by enhancing the protein and gluten content. Under 2019 conditions, AFG-b increased grain yield relative to herbicides by about 8% and did not affect grain quality. Application of AFG-b as an anti-stressant is not accompanied by improvement of seed quality of the new crop. It does not improve its phytosanitary status in infestation by phytopathogens Bipolaris sorokiniana, Fusarium sp., Alternaria, Stagonospora nodorum, Penicillium and Aspergillus relative to herbicides alone.

Wheat Type One Protein Phosphatase Participates in the Brassinosteroid Control of Root Growth via Activation of BES1

Brassinosteroids (BRs) play key roles in diverse plant growth processes through a complex signaling pathway. Components orchestrating the BR signaling pathway include receptors such as kinases, transcription factors, protein kinases and phosphatases. The proper functioning of the receptor kinase BRI1 and the transcription factors BES1/BZR1 depends on their dephosphorylation by type 2A protein phosphatases (PP2A). In this work, we report that an additional phosphatase family, type one protein phosphatases (PP1), contributes to the regulation of the BR signaling pathway. Co-immunoprecipitation and BiFC experiments performed in Arabidopsis plants overexpressing durum wheat TdPP1 showed that TdPP1 interacts with dephosphorylated BES1, but not with the BRI1 receptor. Higher levels of dephosphorylated, active BES1 were observed in these transgenic lines upon BR treatment, indicating that TdPP1 modifies the BR signaling pathway by activating BES1. Moreover, ectopic expression of durum wheat TdPP1 lead to an enhanced growth of primary roots in comparison to wild-type plants in presence of BR. This phenotype corroborates with a down-regulation of the BR-regulated genes CPD and DWF4. These data suggest a role of PP1 in fine-tuning BR-driven responses, most likely via the control of the phosphorylation status of BES1.

Overexpression of a Novel ERF-X-Type Transcription Factor, OsERF106MZ, Reduces Shoot Growth and Tolerance to Salinity Stress in Rice

Transcription factors (TFs) such as ethylene-responsive factors (ERFs) are important for regulating plant growth, development, and responses to abiotic stress. Notably, more than half of the rice ERF-X group members, including ethylene-responsive factor 106 (OsERF106), are abiotic stress-responsive genes. However, their regulatory roles in abiotic stress responses remain poorly understood. OsERF106, a salinity-induced gene of unknown function, is annotated differently in RAP-DB and MSU RGAP. In this study, we isolated a novel (i.e., previously unannotated) OsERF106 gene, designated OsERF106MZ (GenBank accession No. MZ561461), and investigated its role in regulating growth and the response to salinity stress in rice. OsERF106MZ is expressed in germinating seeds, primary roots, and developing flowers. Overexpression of OsERF106MZ led to retardation of growth, relatively high levels of both malondialdehyde (MDA) and reactive oxygen species (ROS), reduced catalase (CAT) activity, and overaccumulation of both sodium (Na+) and potassium (K+) ions in transgenic rice shoots. Additionally, the expression of OsHKT1.3 was downregulated in the shoots of transgenic seedlings grown under both normal and NaCl-treated conditions, while the expression of OsAKT1 was upregulated in the same tissues grown under NaCl-treated conditions. Further microarray and qPCR analyses indicated that the expression of several abiotic stress-responsive genes such as OsABI5 and OsSRO1c was also altered in the shoots of transgenic rice grown under either normal or NaCl-treated conditions. The novel transcription factor OsERF106MZ negatively regulates shoot growth and salinity tolerance in rice through the disruption of ion homeostasis and modulation of stress-responsive gene expression.

Trichoderma atroviride LZ42 Releases Volatile Organic Compounds Promoting Plant Growth and Resisting Fusarium wilt Disease in Tomatoes

The promotion of plant growth and suppression of plant disease using beneficial microorganisms is considered an alternative to the application of chemical fertilizers or pesticides in the field. In this study, a coconut-scented antagonistic Trichoderma strain LZ42, previously isolated from Genoderma lucidum-cultivated soil, was investigated for biostimulatory and biocontrol functions in tomato seedlings. Morphological and phylogenetic analyses suggested that strain LZ42 is closely related to T. atroviride. Tomato plants showed increased aerial and root dry weights in greenhouse trials after treatment with T. atroviride LZ42 formulated in talc, indicating the biostimulatory function of this fungus. T. atroviride LZ42 effectively suppressed Fusarium wilt disease in tomato seedlings, with an 82.69% control efficiency, which is similar to that of fungicide treatment. The volatile organic compounds (VOCs) emitted by T. atroviride LZ42 were found to affect the primary root growth direction and promote the root growth of tomato seedlings in root Y-tube olfactometer assays. The fungal VOCs from T. atroviride LZ42 were observed to significantly inhibit F. oxysporum in a sandwiched Petri dish assay. SPME-GC-MS analysis revealed several VOCs emitted by T. atroviride LZ42; the dominant compound was tentatively identified as 6-pentyl-2H-pyran-2-one (6-PP). 6-PP exhibited a stronger ability to influence the direction of the primary roots of tomato seedlings but not the length of the primary roots. The inhibitory effect of 6-PP on F. oxysporum was the highest among the tested pure VOCs, showing a 50% effective concentration (EC50) of 5.76 &mu;L mL-1 headspace. In conclusion, T. atroviride LZ42, which emits VOCs with multiple functions, is a promising agent for the biostimulation of vegetable plants and integrated management of Fusarium wilt disease.