Primary Root Length Research Articles

Response of crop seed germination and primary root elongation to a binary mixture of diclofenac and naproxen.

Non-steroidal anti-inflammatory drugs, diclofenac (DCF) and naproxen (NPX), represent a group of environmental contaminants often detected in various water and soil samples. This work aimed to assess possible phytotoxic effects of DCF and NPX in concentrations 0.1, 1 and 10 mg/L, both individually and in binary mixtures, on the seed germination and primary root elongation of crops, monocots Allium porrum and Zea mays, and dicots Lactuca sativa and Pisum sativum. Results proved that the seed germination was affected by neither individual drugs nor their mixture. The response of primary root length in monocot and dicot species to the same treatment was different. The Inhibition index (%) comparing the root length of drug-treated plants to controls proved to be approximately 10% inhibition in the case of dicots lettuce and pea, and nearly 20% inhibition in monocot leek, but almost 20% stimulation in monocot maize. Assessment of the binary mixture effect confirmed neither synergistic nor antagonistic interaction of DCF and NPX on early plant development in the applied concentration range.

The Rolled Towel Method for Hormone Response Assays in Maize.

The rolled towel assay (RTA) is a soil-free method to evaluate juvenile phenotypes in crops such as maize and soybean. Here, we provide an updated RTA-based protocol to phenotype maize seedling responses to chemicals of interest. We exemplify the protocol with two synthetic auxin herbicides (2,4-dichlorophenoxyacetic acid and picloram), an auxin precursor (indole-3-butyric acid), and an auxin inhibitor (N-1-naphthylphthalamic acid), but the method can be used with other hormones or plant growth regulators that are soluble in growth media. We also include instructions on how to annotate root traits and analyze primary root length trait data. The protocol can be scaled up for use in genetic screens, preparing tissue for gene expression analyses, carrying out genome-wide association studies (GWASs), and quantitative trait locus (QTL) identification.

Germination of chief fire seeds cockscomb cultivar under saline stress conditions induced by sodium chloride

Cockscomb plant, Chief fire cultivar, is used as an ornamental, medicinal and non-conventional food plant (NCFP) and is cultivated from the north to the center-west of Brazil; however, these areas suffer from adverse environmental factors such as salinity stress. The objective of this study was to evaluate the seed germination performance and vigor of Celosia cristata L. var. Chief Fire seedlings exposed to salinity during the germination phase. To carry out the work, C. cristata seeds were sown in gerboxes conditioned to increasing doses of sodium chloride (NaCl), obtained by dissolving the salt in distilled water, obtaining electrical conductivities of 2.0; 4.0; 6.0 and 8.0 dS.m-1, constituting the treatments. An additional group was treated only with distilled water and was used as a control for the experiment. The experiment was conducted in a completely randomized design, with a total of five treatments and four replicates of 25 seeds. The parameters assessed were: first germination count, germination, germination speed index (GVI), mean germination time (MGT), length of aerial part and primary root. The data was submitted to analysis of variance and the means were compared using the Scott-Knott test at 5% significance. Based on the results obtained, it can be concluded that the conditions of salt stress induced by NaCl were not harmful to the germination of C. cristata, presenting itself as a species tolerant to water salinity during seed germination, since the variables analyzed showed no signs of deleterious effects as the salt concentration was increased.

Evaluating the suitability of Brazilian native species for riverbank stabilization and protection

In Brazil, soil and water bioengineering techniques have mainly been used for hydraulic stabilization, water course management and to re-establish the vegetation in fluvial environments. In these techniques plants are considered as an important structural component and their use requires adequate selection. The present study aimed to evaluate the root system and shoot development traits of the Allamanda cathartica L., Ludwigia elegans (Camb.) H. Hara and Sesbania virgata (Cav.) Pers species. The experiment was conducted in a greenhouse at the Laboratory of Soil Bioengineering at the Federal University of Santa Maria. The following variables were evaluated after 120 days: the survival rate, average height, average root collar diameter, average number and sum of shoot length per plant, average number of primary roots and the sum of primary root length, length of the largest root and root dry mass per plant. The percentage of fine roots and coarse roots and distribution of root dry mass percentage in soil depth were also evaluated. The results confirm the suitability of the L. elegans, S. virgata and A. cathartica species for riverbank stabilization and protection in soil and water bioengineering works.

Soybean gene GmMLP34 regulates Arabidopsis negative response to high temperature stress

The functions of major latex proteins (MLPs) in plant defense and stress responses have been widely documented; however, their roles in HT stress response in soybeans have not been elucidated. This study investigated the role of GmMLP34, a member of the major latex protein (MLP) family, in the response of soybeans to HT stress. Transcriptome analysis of HT-resistant (JD21) and HT-sensitive (HD14) soybean leaves under HT stress (43.40 ± 1.70 °C) and field conditions revealed differential expression of GmMLP34. Further examination across different HT-resistant varieties showed that GmMLP34 was down-regulated in the leaves of 6 HT-resistant varieties (85.7 %) and up-regulated in the leaves of 6 HT-sensitive varieties (85.7 %) under the HT treatment (45 °C for 3 h). The results of this study indicate that ectopic expression of the GmMLP34 gene in Arabidopsis led to a significant decrease in the survival rate of seedling when compared to the wild type (WT) under HT stress conditions of 37/28 °C (day/night) for 5 d, Moreover, the results indicated a significant decrease in primary root length and lateral root number under 45 °C/3 h HT stress followed by 12 h room temperature recovery. Additionally, the levels of abscisic acid (ABA), and flavonoids, and the activity of the peroxidase (POD) enzyme in the antioxidant system was decreased, while the activity of the superoxide dismutase (SOD) enzyme increased in GmMLP34-overexpressing transgenic Arabidopsis thaliana. The expression levels of the HT-response genes AtCHS1 and AtCHI2-A, were significantly down-regulated, whereas that of AtGBP1 was significantly up-regulated. These results suggest that GmMLP34 negatively regulates the response of Arabidopsis thaliana to HT stress by modulating flavonoid synthesis, hormone synthesis, and the antioxidant enzyme system. These findings provide theoretical information for the genetic improvement of HT tolerance in soybean and contribute to the understanding of the molecular mechanisms underlying plant responses to abiotic stress.

Respuesta morfológica de plántulas de maíz nativo (Zea mays L.) a ambientes contrastantes de nitrógeno

Nitrogen plays a vital role in plant metabolism, influencing growth and development, particularly in crops like maize (Zea mays L.). This study aimed to evaluate the morphological response of maize seedlings to different nitrogen levels. The design was a completely randomized factorial arrangement of 4 x 2, involving four maize cultivars and two nitrogen levels.The variety Sb 302 Berentsen and three native varieties originating from Tecamachalco, Puebla, Mexico were studied. For a period of 14, 21, 28 and 35 days, seedlings were grown in nutrient solution with 10 % and 100 % nitrogen levels under hydroponic conditions. The results revealed significant variability in seedling morphology, particularly in root architecture and dry weight, between the 10 % and 100 % nitrogen treatments. High coefficients of variation were observed in the lengths of crown and seminal roots, alongside significant correlations between root and seedling dry weights at both nitrogen levels. Additionally, a strong correlation was found between root length and number under the 10 % nitrogen treatment. The results highlight the critical role of nitrogen in maize seedling development and the interaction between nitrogen concentration and maize variety, particularly in primary root length. The study improves understanding of nitrogen's role in optimizing maize growth and suggests strategies to enhance nitrogen use efficiency across different maize varieties. Keywords: cereals, nitrogen use efficiency, root architecture, native varieties.

Developmental responses of roots to limited phosphate availability: research progress and application in cereals.

Phosphorus (P), an essential macronutrient, is crucial for plant growth and development. However, available inorganic phosphate (Pi) is often scarce in soil, and its limited mobility exacerbates P deficiency in plants. Plants have developed complex mechanisms to adapt to Pi-limited soils. The root, the primary interface of the plant with soil, plays an essential role in plant adaptation to Pi-limited soil environments. Root system architecture significantly influences Pi acquisition via the dynamic modulation of primary root and/or crown root length, lateral root proliferation and length, root hair development, and root growth angle in response to Pi availability. This review focuses on the physiological, anatomical, and molecular mechanisms underpinning changes in root development in response to Pi starvation in cereals, mainly focusing on the model monocot plant rice (Oryza sativa). We also review recent efforts to modify root architecture to enhance P uptake efficiency in crops and propose future research directions aimed at the genetic improvement of Pi uptake and use efficiency in crops based on root system architecture.

Gallic acid regulates primary root elongation via modulating auxin transport and signal transduction.

Gallic acid is an important secondary metabolite in plants, with great value in medicine, food, and chemical industry. However, whether and how this widely existing natural polyphenolic compound affects the growth and development of plants themselves remains elusive. In this study, we revealed that exogenous application of gallic acid has a dual effect on the elongation of primary root in Arabidopsis. While lower concentrations of gallic acid slightly stimulate primary root growth, excessive gallic acid profoundly reduces primary root length and root meristem size in a dose-dependent manner, probably via suppressing cell division in root meristem as indicated by CYCB1;1::GUS. Moreover, as suggested by the DR5::GFP line analysis and confirmed by the LC-MS assay, auxin contents in root tips were dramatically decreased upon excessive gallic acid treatment. Additional application of IAA partially rescued the shortened primary root and root meristem upon excessive gallic acid treatment, suggesting that auxin is required for excessive gallic acid-caused root growth inhibition. Then, we further revealed that excessive gallic acid down-regulated the expression of auxin transporters PIN1, PIN2, PIN3, and PIN7, and triple mutant pin1 pin3 pin7 exhibited a reduced sensitivity to gallic acid treatment. Meanwhile, excessive gallic acid decreased the degradation of AXR3/IAA17 protein as revealed by HS::AXR3NT-GUS reporter line. Auxin signaling mutant tir1 afb2 afb3 and axr3-3 were also less sensitive to excessive gallic acid treatment in terms of primary root length and root meristem size. Taken together, these findings suggested that excessive gallic acid inhibits primary root growth by modulating auxin transport and signaling in Arabidopsis.

Role of SbNRT1.1B in cadmium accumulation is attributed to nitrate uptake and glutathione-dependent phytochelatins biosynthesis

Phytoremediation of cadmium (Cd)-polluted soil by using sweet sorghum displays a tremendous potential as it is a fast-growing, high biomass and Cd tolerant energy plant. Previous study has demonstrated SbNRT1.1B expression change is in accordance with enhanced Cd accumulation by external nitrate supply in sweet sorghum. Nevertheless, underlying mechanism of SbNRT1.1B response to Cd stress is still elusive. SbNRT1.1B exhibited a positive response to Cd stress in sweet sorghum. Overexpressing SbNRT1.1B increased primary root length, shoot fresh weight, nitrate and chlorophyll concentrations compared with Col-0 under Cd stress, while complementary SbNRT1.1B rescued these decreased values in mutant chl1–5. Cd concentrations in overexpressing SbNRT1.1B, complementary SbNRT1.1B and Col-0 lines were 3.2–4.1, 2.5–3.1 and 1.2–2.1 folds of that in chl1–5. Consistent with Cd concentrations, non-protein thiol (NPT), reduced glutathione (GSH) and phytochelatins (PCs) concentrations as well as the related genes expression levels showed the same trends under Cd stress. GSH biosynthesis inhibitor failed to reverse the patterns of GSH-dependent PCs concentrations changes in different lines, suggesting that SbNRT1.1B plays an upstream role in GSH-dependent PCs biosynthesis under Cd treatment. Altogether, SbNRT1.1B enhances nitrate concentrations contributing to increased chlorophyll concentrations and GSH-dependent PCs metabolites biosynthesis, thereby improving growth and Cd concentrations in plants.

Hydrogen sulphide alleviates root growth inhibition induced by phosphate starvation.

Phosphorus (P) has crucial roles in plant growth and development. Hydrogen sulphide (H2S) has multiple functions in plants, particularly having the ability to promote tolerance to a variety of adversity stresses. However, it is unclear whether H2S has a function when plants suffer Pi-deficiency stress. DES1, encoding L-cysteine desulfhydrase1, is a crucial source of H2S in Arabidopsis thaliana by catalysing the substrate L-cysteine. Under phosphate starvation, the des1 mutant had a significantly shorter primary root length than the wild-type Col-0, and exogenous application of H2S donor NaHS could compensate for the root growth-sensitive phenotype. In contrast, the transgenic lines DES1ox overexpressing DES1 exhibited less sensitivity to phosphate starvation in terms of longer roots compared to the Col-0. These results demonstrate that H2S is involved in the regulation of Arabidopsis root growth under phosphate starvation. Moreover, using quantitative real-time polymerase chain reaction experiments to analyse the changes in genes induced by phosphate starvation in des1 mutant and Col-0, we screened to find that the expression of the Sulfoquinovosyl diacylglycerol 1 (SQD1) gene was significantly downregulated in the des1 mutant. Consistently, exogenous H2S significantly promoted SQD1 expression levels in roots of Col-0. Taken together, we demonstrate that DES1-mediated H2S participates in alleviating root growth inhibition by promoting the expression of SQD1 under Pi starvation.

Salt stress mitigation and improvement in fruit nutritional characteristics of tomato plants: New opportunities from the exploitation of a halotorelant Agrobacterium strain

Soil salinity is considered one of the most limiting factors in large agricultural areas, and tomato (Solanum lycopersicum L.) is highly sensitive to this abiotic stress, which exacerbates under drought. The use of halotolerant PGPR is a promising strategy to enhance tomato tolerance and productivity in saline soils. The present study tested the capability of the recently discovered bacterial strain PVr_9 to increase tolerance to salinity in tomato plants in vitro, greenhouse and open field conditions. When inoculated with PVr_9, in vitro seedlings showed a significant increase in primary root length, number of secondary roots and fresh weight both in absence of stress and when exposed to 150 mM NaCl. In plants exposed to salt treatment, PVr_9 upregulated the salt tolerance genes SOS1 and NHX1, and the enzyme prolyl aminopeptidase involved in proline metabolism. Proteins associated with resistance against pathogens were also upregulated by PVr_9 in absence of salt stress. In greenhouse, PVr_9-inoculated tomato plants treated for 1-week with 150 mM NaCl showed a significant increase in shoot fresh biomass, chlorophyll, proline content, and APX activity. Tomato fruits from PVr_9 inoculated plants, exposed in the field to salt stress during the flowering stage, showed higher levels of carotenoids, lycopene, and l-ascorbic acid, as well as an increased antioxidant capacity compared to fruits of uninoculated plants. These results indicate PVr_9 as a potential biostimulant in tomato for better tackling soil salinization in a context of climate change and expansion of coastal salinity, while there is large scope for the improvement of the nutritional characteristics of tomato fruits.

Production and evaluation of new microbic strains on zucchini (Cucurbita pepo L.) plants and control of Powdery mildew and Cladosporiosis

Research objective: The main objective of this article is to report the results obtained from the use of new microbial strains on vegetable plants. In particular, the article will deal with two important topics: i) the study of the effect of microorganisms on the biomass of vegetable plants; ii) the possible control of mortality due to diseases such as powdery mildew and Cladosporiosis. The information reported in this research work can support the design of cropping systems in which agricultural sustainability is fundamental due to the presence of microorganisms with biostimulating activity and as a possible alternative to synthetic plant protection products. Materials and Methods: The plants were grown in pots under controlled conditions; 30 seedlings per thesis, divided into 3 replications of 10 plants each, were planted in early February 2024. The plants used in the trial were Cucurbita pepo L.. The six experimental groups in cultivation were: i) group without microorganisms, irrigated with water and previously fertilised substrate; ii) group with Paecilomyces lilacinus, irrigated with water and previously fertilised substrate, (4.5 x 106 spores/ml), 5ml of product sprayed per kg of substrate; iii) group with Azospirillum sp., irrigated with water and previously fertilised substrate, (4 x 108 spores/g), 1g of mixed product per kg of substrate; iv) group with Glomus sp., irrigated with water and previously fertilised substrate, (3 x 109 spores/g), 1g of mixed product per kg of substrate; v) group with Trichoderma viride, irrigated with water and previously fertilised substrate, (3.6 x 108 spores/ml), 5ml of product sprayed per kg of substrate; vi) group with mix Bacillus subtilis, Pseudomonas sp. and Trichoderma viride, irrigated with water and previously fertilised substrate, (2.3 x 108 spores/ml) 5 ml of product sprayed per kg of substrate. On 5 June 2024, plant height, number of leaves, total leaf area per plant (mm2), primary root length (mm), biomass of the aerial and root system, number and weight of fruits, flowers number and the number of plants dead from powdery mildew and cladosporiosis attacks were recorded. Results and Discussion: The experiment showed that the use of of different types of probiotic and plant defence microorganisms can indeed significantly improve the vegetative and root growth of Cucurbita pepo L.. All treatments showed a significant improvement over the untreated control for the agronomic parameters analysed. The Bacillus subtilis, Pseudomonas sp. and Trichoderma viride treatment with a mix of microorganisms was significantly the best in terms of increasing vegetative and root biomass. Improvements were also found in plant height, number of leaves, leaf area and root length. In addition, significant effects were found on the number of flowers and fruits as well as fruit weight. The trial also revealed the significant effect of the products on the control of powdery mildew and Cladosporiosis, in which case the product PL (Paecilomyces lilacinus) was the best on the two diseases. Conclusions: Experiments have shown that the use of microorganisms can significantly improve the growth, vegetative and root biomass of Cucurbita pepo L.. The treatment also offers increased resistance to mortality that can occur in nursery cultivation. A variety of horticultural and ornamental species have already been tested with microorganisms in previous trials, which highlight other interesting and innovative aspects of the use of microorganisms. Due to the importance of using microbial inoculums in plants, the new agricultural experiments are extremely important as they may allow the development of new products for organic and sustainable farming systems and lead to better results.

The U1 small nuclear RNA enhances drought tolerance in Arabidopsis.

Alternative splicing (AS) is an important post-transcriptional regulatory mechanism that improves plant tolerance to drought stress by modulating gene expression and generating proteome diversity. The interaction between the 5' end of U1 small nuclear RNA (U1 snRNA) and the conserved 5' splice site of precursor messenger RNA (pre-mRNA) is pivotal for U1 snRNP involvement in AS. However, the roles of U1 snRNA in drought stress responses remain unclear. This study provides a comprehensive analysis of AtU1 snRNA in Arabidopsis (Arabidopsis thaliana), revealing its high conservation at the 5' end and a distinctive four-leaf clover structure. AtU1 snRNA is localized in the nucleus and expressed in various tissues, with prominent expression in young floral buds, flowers, and siliques. Overexpression of AtU1 snRNA confers enhanced abiotic stress tolerance, as evidenced in seedlings by longer seedling primary root length, increased fresh weight, and a higher greening rate compared to the wild type. Mature AtU1 snRNA overexpressor plants exhibit higher survival rates and lower water loss rates under drought stress, accompanied by a significant decrease in H2O2 and increase in proline. This study also provides evidence of altered expression levels of drought-related genes in AtU1 snRNA overexpressor or genome-edited lines, reinforcing the crucial role of AtU1 snRNA in drought stress responses. Furthermore, the overexpression of AtU1 snRNA influences the splicing of downstream target genes, with a notable impact on SPEECHLESS (SPCH), a gene associated with stomatal development, potentially explaining the observed decrease in stomatal aperture and density. These findings elucidate the critical role of U1 snRNA as an AS regulator in enhancing drought stress tolerance in plants, contributing to a deeper understanding of the AS pathway in drought tolerance and increasing awareness of the molecular network governing drought tolerance in plants.

Effects of Mulching Materials on Growth and Yield of Brinjal

Brinjal; a valuable vegetable, is susceptible to weeds and moisture stress that can hinder growth and yield. Mulching might be a good option to control weeds and moisture to enhance growth and yield. So, an experiment was conducted with five treatments viz. black silver coated mulch (BSCM; 100 gauge), black polythene mulch (BPM; 300 gauge), straw mulch (8 t ha-1), corrugated fiber box mulch (CFBM), and an unmulch group replicated for four times in randomized complete block design at Horticulture Research Station, Pokhara in 2022. Results revealed that BSCM showed the highest marketable yield (23.78 t ha-1) which was statistically similar to straw mulch (20.44 t ha-1) and BPM (19.64 t ha-1) and the lowest (12.1 t ha-1) was observed in the unmulch (12.1 t ha-1). Plant height (134.1 cm), primary root length (40.95 cm), and secondary root numbers (23.25) were observed significantly higher in BPM which was statistically similar (p>0.05) with BSCM and straw mulch. The number of branches (7.325), the fruit length (23.2 cm), and fruit diameter (2.5 cm) were found higher in BSCM. Findings suggested that applying different types of mulching materials can effectively enhance the growth and yield of brinjal.

Salt stress alters root meristem definition, vascular differentiation and metabolome in Sorghum bicolor (L.) genotypes

Knowledge on salt tolerance requires further investigation, particularly in plants of agro-food interest. Sorghum is a potentially useful plant because it is a emerging food species that combines high levels of salt tolerance with interesting nutritional characteristics. In sorghum different genotypes respond differently to saline stress and the early events characterizing the salt stress tolerance are not yet fully understood. Moreover, the number of salt resistant genotypes needs to be extended. The genotypes Bianca and Tonkawa are two possible candidates for extending sorghum cultivation to soils characterized by high levels of salinity. The root is the first organ that responds to soil conditions, especially during the initial stages of plant developmental. The research aim was to analyse the root system responses to salt stress (NaCl) of Bianca and Tonkawa genotypes to identify the morpho-functional and metabolic changes that occur during the initial stages of the root system development and to use them as discriminating parameters for assessing the different plant’s susceptibility to the salt. The results showed that salt stress negatively affected many morphological and cyto-histological root parameters, from seed germination to root system establishment. The salt altered the root meristem organization and quiescent centre (QC) definition, but similarly in both genotypes. By contrast, it reduced primary root (PR) length and induced a more extended oxidative stress in the adventitious roots (ARs) and lateral root primordia (LRPs) of Tonkawa in comparison with Bianca. The stele area and the number of protoxylem and phloem elements in the ARs were more reduced in 150 mM NaCl-treated Tonkawa seedlings in comparison with those of Bianca. Moreover, the salt enhanced lignin deposition in protoxylem, early metaxylem and endodermis and changed the root metabolic profiles significantly increasing the levels of leucine, isoleucine, alanine, proline, trigonelline, allantoin and glutamine in Bianca compared to Tonkawa. Altogether, specific morpho-anatomical and metabolic differences between the genotypes were identified as discriminating markers of genotype salt susceptibility.

Multiomics Analyses Reveal MsC3H29 Positively Regulates Flavonoid Biosynthesis to Improve Drought Resistance of Autotetraploid Cultivated Alfalfa (Medicago sativa L.).

Alfalfa (Medicago sativa subsp. sativa), the "queen of forage," is the most important perennial legume, with high productivity and an excellent nutritional profile. Medicago sativa subsp. falcata is a subspecies of the alfalfa complex and exhibits better drought tolerance. However, drought stress significantly hampers their development and yield. The molecular mechanisms underlying the aboveground and underground tissues of sativa and falcata responding to drought stress remain obscure. Here, we performed a comprehensive comparative analysis of the physiological and transcriptomic responses of sativa and falcata under drought stress. The results showed that photosynthesis was inhibited, and antioxidant enzymes were activated under drought stress. MsC3H29, a CCCH-type zinc finger protein, was identified as a hub gene through weighted gene coexpression network analysis (WGCNA) and was significantly induced by drought in underground tissue. The MsC3H29 protein was localized in the nucleus. Overexpression (OE) of MsC3H29 can increase the primary root length and fresh weight of transgenic alfalfa hairy roots, while RNA interference (RNAi) decreases them under drought stress. The 2',7'-dichlorodihydrofluorescein diacetate (H2DCFDA) staining revealed that MsC3H29 promoted drought tolerance of alfalfa hairy roots through decreasing ROS accumulation. The targeted metabolome analysis showed that the overexpression of MsC3H29 resulted in higher levels of accumulation for flavonoid monomers, including vicenin, daidzein, apigenin, isorhamnetin, quercetin, and tricin, in transgenic alfalfa hairy roots before and after drought stress, while RNAi led to a reduction. Our study provided a key candidate gene for molecular breeding to improve drought resistance in alfalfa.

CsABCG11.2 mediates theanine uptake to alleviate cadmium toxicity in tea plants (Camellia sinensis)

Theanine (Thea) is a unique metabolite in tea plants, but its physiological functions remain elusive. A low soil pH increases cadmium (Cd) availability, affecting the quality of tea plant products. In this study, we found that Thea reversed the Cd-induced reduction in free amino acid (FAA) and caffeine (CAF) in the young tea leaves, as well as the down-regulation in the expression of nitrate transporters CsNRT1.2 and CsNRT2.5, and genes responsible for the nitrogen (N) assimilation. We demonstrated that Thea could alleviate Cd-induced oxidative stresses and enhance photosynthesis. Moreover, an ATP-binding cassette (ABC) transporter, CsABCG11.2, could uptake distinct Cd substrates and the five major amino acids in tea plants. Heterologous expression of CsABCG11.2 in yeast indicated a competitive absorption between Cd and Thea in a concentration-dependent pattern. CsABCG11.2-overexpressing Arabidopsis plants exhibited increased sensitivity to Cd due to enhanced Cd concentration, accumulation in the shoots, and reduction in the primary root length. Exogenous application of Thea at environmentally regular levels attenuated the adverse effects of Cd-induced growth inhibition and chlorosis in CsABCG11.2-overexpressing Arabidopsis plants. Knockdown of CsABCG11.2 tea plants significantly lowered Cd levels in young shoots. Our results suggest that Thea plays beneficial roles in alleviating Cd stress directly or indirectly by modulating CsABCG11.2-mediated Cd uptake and translocation within plants.

ROOTING OF JUVENILE CUTTINGS OF Pinus patula Schiede ex Schltdl. et Cham. HEDGES

Pinus patula Schiede ex Schltdl. et Cham. is endemic to Mexico and is used in both reforestation programs and in the timber industry due to its fast growth, wood quality, and easy handling. With the advance in genetic breeding programs, there is a need to massively propagate new plants from cuttings. One of the main challenges for this purpose is to know the effect of the age of the mother plant (hedge) on the rooting of cuttings. The younger the plant, the greater the rooting is expected to be. Three ontological ages of P. patula mother plants were compared (7, 10, and 13 months). The experimental design was in complete random blocks, with four replications and 25 cuttings per experimental unit. The response variables were evaluated 20 weeks after the experiment was established. No significant differences were observed in the rooting of the three ages evaluated (67.3 to 81 %), nor in the quality of the root (number and length of primary roots, percentage of plants with secondary roots). The results point out an advantage for the propagation of Pinus cuttings since the mother plants at those ages are capable of generating juvenile cuttings that are adequate to obtain percentages of rooting of over 75 %.

The RALF2-FERONIA-MYB63 module orchestrates growth and defense in tomato roots.

Plant secreted peptides RAPID ALKALINISATION FACTORs (RALFs), which act through the receptor FERONIA (FER), play important roles in plant growth. However, it remains unclear whether and how RALF-FER contributes to the trade-off of plant growth-defense. Here, we used a variety of techniques such as CRISPR/Cas9, protein-protein interaction and transcriptional regulation methods to investigate the role of RALF2 and its receptor FER in regulating lignin deposition, root growth, and defense against Fusarium oxysporum f. sp. lycopersici (Fol) in tomato (Solanum lycopersicum). The ralf2 and fer mutants show reduced primary root length, elevated lignin accumulation, and enhanced resistance against Fol than the wild-type. FER interacts with and phosphorylates MYB63 to promote its degradation. MYB63 serves as an activator of lignin deposition by regulating the transcription of dirigent protein gene DIR19. Mutation of DIR19 suppresses lignin accumulation, and reverses the short root phenotype and Fol resistance in ralf2 or fer mutant. Collectively, our results demonstrate that the RALF2-FER-MYB63 module fine-tunes root growth and resistance against Fol through regulating the deposition of lignin in tomato roots. The study sheds new light on how plants maintain the growth-defense balance via RALF-FER.

Genome-Wide Association Study Identifies Quantitative Trait Loci and Candidate Genes Involved in Deep-Sowing Tolerance in Maize (Zea mays L.).

Deep sowing is an efficient strategy for maize to ensure the seedling emergence rate under adverse conditions such as drought or low temperatures. However, the genetic basis of deep-sowing tolerance-related traits in maize remains largely unknown. In this study, we performed a genome-wide association study on traits related to deep-sowing tolerance, including mesocotyl length (ML), coleoptile length (CL), plumule length (PL), shoot length (SL), and primary root length (PRL), using 255 maize inbred lines grown in three different environments. We identified 23, 6, 4, and 4 quantitative trait loci (QTLs) associated with ML, CL, PL, and SL, respectively. By analyzing candidate genes within these QTLs, we found a γ-tubulin-containing complex protein, ZmGCP2, which was significantly associated with ML, PL, and SL. Loss of function of ZmGCP2 resulted in decreased PL, possibly by affecting the cell elongation, thus affecting SL. Additionally, we identified superior haplotypes and allelic variations of ZmGCP2 with a longer PL and SL, which may be useful for breeding varieties with deep-sowing tolerance to improve maize cultivation.