Salinity Stress Alters Root Morphology and Root Hair Traits in Brassica napus

Plant roots show morphological plasticity and play a substantial role in tolerance to various edaphic stresses. The aim of this study was to explore salinity-induced morphogenic responses of root traits and root hairs of two rapeseed varieties, BARI Sarisha-8 and Binasarisha-5, at the reproductive stage and perceive the effects on their reproductive growth. The experiment was conducted in a hydroponic culture. Two treatments, 0 mM NaCl as control and 100 mM NaCl, were imposed 55 d after germination. Plants exposed to 100 mM NaCl for seven days displayed greater damage in the leaves, flowers, and siliquae compared to control. Length of root hairs on first-order and third-order lateral roots, density of root hairs on first-order lateral roots, and length of third-order lateral roots were significantly greater by 91%, 22%, 29%, and 48%, respectively, in the treated condition compared to the control. An increase in estimated root surface area by 20% under salt stress conditions indicated that the spontaneous responses of plants to uptake more water and nutrients allowed a plant to cope with stressful conditions. The results of this study suggest that any future stress breeding programs should consider plasticity of root traits intensively.

Download Full-text

Interactions between stress response, carbohydrate metabolism, and defense pathways modulate rootstock root-dependent fire blight susceptibility in apple (Malus × domestica)

10.21203/rs.2.10413/v1 ◽

2019 ◽

Author(s):

Jugpreet Singh ◽

Jack Fabrizio ◽

Elsa Desnoues ◽

Julliany Pereira Silva ◽

Wolfgang Busch ◽

...

Keyword(s):

Stress Response ◽

Carbohydrate Metabolism ◽

Fire Blight ◽

Expression Patterns ◽

Root Traits ◽

Root Surface ◽

Root Surface Area ◽

Protein Kinase Activity ◽

Root Mass ◽

Molecular Relationships

Abstract Background Although it is known that resistant rootstocks facilitate management of fire blight disease, incited by Erwinia amylovora (Burr.) Winslow et al., of apple scion cultivars, the role of rootstock root traits in providing systemic defense against E. amylovora is unclear. In this study, the hypothesis that rootstocks of higher root mass provide higher tolerance to fire blight infection in apples is tested. Several apple scion cultivars grafted onto a single rootstock genotype and non-grafted ‘M.7’ rootstocks of varying root mass are used to assess phenotypic and molecular relationships between root traits of rootstocks and fire blight susceptibility of apple scion cultivars. Results It is observed that different root traits display significant (p < 0.05) negative correlations with fire blight susceptibility. In fact, root surface area partially dictates differential levels of fire blight susceptibility of ‘M.7’ rootstocks. Furthermore, contrasting changes in gene expression patterns of diverse molecular pathways accompany observed differences in levels of root-driven fire blight susceptibility. It is noted that a singular co-expression gene network consisting of genes from defense, carbohydrate metabolism, protein kinase activity, oxidation-reduction, and stress response pathways modulates root-dependent fire blight susceptibility in apple. In particular, WRKY75 and UDP-glycotransferase are singled-out as hub genes deserving of further detailed analysis. Conclusions It is proposed that low root mass may incite resource-limiting conditions to activate carbohydrate metabolic pathways, which reciprocally interact with plant immune system genes to elicit differential levels of fire blight susceptibility.

Download Full-text

Plant Growth Regulator Effects on Germination and Root Traits of ‘Lambada’ and ‘Don Victor’ Onion Cultivars

HortScience ◽

10.21273/hortsci12473-17 ◽

2017 ◽

Vol 52 (12) ◽

pp. 1759-1764

Author(s):

Maria A. Macias-Leon ◽

Daniel I. Leskovar

Keyword(s):

Seed Germination ◽

Plant Growth ◽

Synergistic Effects ◽

Field Performance ◽

Root Traits ◽

Root Surface ◽

Root Diameter ◽

Root Surface Area ◽

Relative Growth ◽

Relative Growth Rates

Onions (Allium cepa L.) are easily outcompeted by weeds because of slow germination and relative growth rates. Therefore, high percentage of seed germination and root vigor are important traits to improve field performance. The effects of exogenous plant growth regulators (PGRs), 2-chloroethylphosphonic acid (ethephon, Eth), indole-3-acetic acid (IAA), trans-zeatin (tZ), and 1-aminocyclopropane-1-carboxylic acid (ACC) were evaluated on the germination and root growth of ‘Don Victor’ (yellow) and ‘Lambada’ (red) onion seedlings. Seeds were soaked for 10 hours in hormonal solutions and water (hydro-priming). Seed germination improved with Eth (30 and 100 μm), Eth (100 μm) + IAA (10 μm), and IAA (3 μm) treatments. Root surface area (RSA) increased in response to Eth at 30 and 100 μm, Eth + IAA, and 3 μm IAA. Root length (RL) and root diameter (RD) were enhanced by 1 μm tZ and 100 μm ACC. Eth reduced RL and RD, whereas IAA showed no effects. A subsequent experiment evaluated synergistic effects of different PGRs. Treatment of seeds with ACC (250 μm) + tZ (0.5 μm) and ACC (250 μm) + tZ (0.5 μm) + Eth (20 μm) enhanced RL and RD. RSA was unaffected by ACC + tZ + Eth. The results suggest that exogenous PGRs could be useful to enhance germination, RL, and RSA of onion seedlings.

Download Full-text

Stand morphology of Townsville lucerne (Stylosanthes humilis) : Seasonal growth and root development

Australian Journal of Experimental Agriculture ◽

10.1071/ea9680533 ◽

1968 ◽

Vol 8 (34) ◽

pp. 533 ◽

Cited By ~ 19

Author(s):

BWR Torssell ◽

JE Begg ◽

CW Rose ◽

GF Byrne

Keyword(s):

Root Length ◽

Lateral Roots ◽

Heavy Rain ◽

Root Surface ◽

Root Surface Area ◽

General Description ◽

Seasonal Growth ◽

Wet Season ◽

Average Growth ◽

Stylosanthes Humilis

This paper describes the seasonal growth and morphology of a four-year-old pasture of Townsville lucerne (Stylosanthes humilis) used in a detailed microenvironmental study conducted at Katherine, N.T., during the 1966-67 wet season. Rapid germination and penetration of the tap root followed an early storm rain of 38 mm at the end of September, and most of the seedlings survived the next seven weeks without rain. A second germination followed heavy rain at the end of November, and by the end of December the main development of lateral roots commenced and the rate of shoot development increased. The highest average growth rate, 31 g/m2/day for the period March 31-April 14, was after the last rain of the season and preceded by ten weeks of above average rainfall. Growth continued for a further two weeks while the roots continued to deplete available soil water. During the main period of growth, approximately 80 per cent of root length and 70 per cent of root surface area was in the top 30 cm of soil. The density of root length varied very little below 30 cm. Growth and development are discussed in relation to grass competition and drought adaptation, and fitted to a general description of the life cycle of Townsville lucerne under northern Australian conditions.

Download Full-text

Root hair specification and its growth in response to nutrients

Notulae Botanicae Horti Agrobotanici Cluj-Napoca ◽

10.15835/nbha49212258 ◽

2021 ◽

Vol 49 (2) ◽

pp. 12258

Author(s):

Xian HUANG ◽

Tianzhi GONG ◽

Mei LI ◽

Cenghong HU ◽

Dejian ZHANG ◽

...

Keyword(s):

Root Hair ◽

Reverse Genetics ◽

Current Knowledge ◽

Plant Root ◽

Root Hairs ◽

Root Surface ◽

Root Surface Area ◽

Root Hair Development ◽

Hair Development ◽

Calcium Iron

Plant root hairs are cylindrical tubular projections from root epidermal cells. They increase the root surface area, which is important for the acquisition of water and nutrients, microbe interactions, and plant anchorage. The root hair specification, the effect of root hairs on nutrient acquisition and the mechanisms of nutrients (calcium, iron, magnesium, nitrogen, phosphorus, and potassium) that affect root hair development and growth were reviewed. The gene regulatory network on root hair specification in the plant kingdom was highlighted. More work is needed to clone the genes of additional root hair mutants and elucidate their roles, as well as undertaking reverse genetics and mutant complementation studies to add to the current knowledge of the signaling networks, which are involved in root hair development and growth regulated by nutrients.

Download Full-text

Complete root specimen of plants grown in soil-filled root box: sampling, measuring, and staining method

Plant Methods ◽

10.1186/s13007-021-00798-3 ◽

2021 ◽

Vol 17 (1) ◽

Author(s):

Takuya Koyama ◽

Shun Murakami ◽

Toshihiko Karasawa ◽

Masato Ejiri ◽

Katsuhiro Shiono

Keyword(s):

Root System ◽

Surface Area ◽

Visual Information ◽

Physiological Function ◽

Physiological Activity ◽

Root Traits ◽

Arbuscular Mycorrhizal ◽

Spatial Arrangement ◽

Root Surface ◽

Root Surface Area

Abstract Background Detailed datasets containing root system and its architecture in soil are required to improve understanding of resource capture by roots. However, most of the root study methods have paid little attention to make and preserve whole root specimens. This study introduces root system sampling equipment that makes the entire root specimen with minimum impairment and without displacement of the spatial arrangement of the root system in root boxes. The objectives are to assess: whether the equipment can rapidly sample the entire root system; whether root surface area is measurable from a scanned digital image of the root specimen; and whether staining of the entire root specimens would provide multidimensional visual information on the interaction between soil and physiological function of root system architecture (RSA). For validation, we examined the root response of two soybean cultivars to arbuscular mycorrhizal (AM) inoculation and the effect of waterlogging stress on the physiological activity of buckwheat RSA. Results The root boxes allowed soybean and buckwheat plants to grow uniformly across the replications. Both species showed significant differences between cultivars and/or among treatments in shoot and root traits. The equipment enabled to sample the whole-root specimens of soybean and buckwheat, where the tips of the fine roots were alive (diameter < 0.2 mm). Also, the whole root specimens of soybean were made in about 7 min. The root surface area calculated from the scanned soybean specimens showed a significant correlation with that calculated from the roots spread out in water (a common method). Staining of the soybean root specimens enabled us to observe the localized root proliferation induced by AM colonization. Moreover, staining of the buckwheat root specimens made it possible to examine the respiratory activity of each root at different depths. Conclusions The present method realized: fast and accurate production of the whole root specimen and precise calculation of the specimens’ root surface area. Moreover, staining of the root specimens enabled analyzing the interaction between soil and physiological function of RSA. The evaluation of root traits, using our methods, will contribute to developing agronomic management and breeding program for sustainable food production.

Download Full-text

Lateral Root Traits of Taxodium Hybrid ‘Zhongshanshan 406’ in Response to Drought Stress

HortScience ◽

10.21273/hortsci12387-17 ◽

2018 ◽

Vol 53 (4) ◽

pp. 547-551

Author(s):

Qin Shi ◽

Yunlong Yin ◽

Zhiquan Wang ◽

Wencai Fan ◽

Jinbo Guo ◽

...

Keyword(s):

Drought Stress ◽

Surface Area ◽

Root Length ◽

Lateral Root ◽

Plant Root ◽

Lateral Roots ◽

Specific Root Length ◽

Root Traits ◽

Root Tip ◽

Root Surface Area

Roots are vital organs for resource uptake. However, the knowledge regarding the extent by which responses in roots influence plant resistance is still poorly known. In this study, we examined the morphological and physiological responses of lateral roots of Taxodium hybrid ‘Zhongshanshan 406’ (Taxodium mucronatum♀ and Taxodium distichum♂, T. 406) to 8 (DS-8) and 12 days (DS-12) drought. Control plants (CK-8 and CK-12) were well-watered throughout the experiment. Results indicated that drought resulted in significantly decreased root length, surface area, volume, and biomass and a relatively high death rate of roots (>2 mm). Specific root length (SRL) and specific root surface area (SRA) of drought-stressed T. 406 plants were reduced to enhance resource uptake. Meanwhile, root relative water content (RWC) of T. 406 plants in CK-12 treatment was 5.81 times of those in DS-12 treatment. Under drought stress and root superoxide dismutase and ascorbic acid (ASA) activities, proline and hydrogen peroxide (H2O2) contents consistently increased to benefit the elimination of O2−. At the ultrastructural level, the organelle structure of T. 406 plant root tip was visibly damaged because of dehydration. The nucleus swelled and then exhibited uncommon features of disorganization and disruption. In short, our results provided substantial information about lateral root traits of T. 406 plants in response to drought stress, which is crucial to improve the drought resistance of Taxodium hybrid in the future breeding.

Download Full-text

Integrating GWAS and Gene Expression Analysis Identifies Candidate Genes for Root Morphology Traits in Maize at the Seedling Stage

Genes ◽

10.3390/genes10100773 ◽

2019 ◽

Vol 10 (10) ◽

pp. 773 ◽

Cited By ~ 1

Author(s):

Wang ◽

Wei ◽

Li ◽

Wang ◽

Ge ◽

...

Keyword(s):

Root System ◽

Candidate Genes ◽

Root Development ◽

Root Length ◽

Root Traits ◽

Root Surface ◽

Root Surface Area ◽

Phenotypic Variance ◽

Potential Candidate ◽

Short Root

Root system plays an essential role in water and nutrient acquisition in plants. Understanding the genetic basis of root development will be beneficial for breeding new cultivars with efficient root system to enhance resource use efficiency in maize. Here, the natural variation of 13 root and 3 shoot traits was evaluated in 297 maize inbred lines and genome-wide association mapping was conducted to identify SNPs associated with target traits. All measured traits exhibited 2.02- to 21.36-fold variations. A total of 34 quantitative trait loci (QTLs) were detected for 13 traits, and each individual QTL explained 5.7% to 15.9% of the phenotypic variance. Three pleiotropic QTLs involving five root traits were identified; SNP_2_104416607 was associated with lateral root length (LRL), root surface area (RA), root length between 0 and 0.5mm in diameter (RL005), and total root length (TRL); SNP_2_184016997 was associated with RV and RA, and SNP_4_168917747 was associated with LRL, RA and TRL. The expression levels of candidate genes in root QTLs were evaluated by RNA-seq among three long-root lines and three short-root lines. A total of five genes that showed differential expression between the long- and short-root lines were identified as promising candidate genes for the target traits. These QTLs and the potential candidate genes are important source data to understand root development and genetic improvement of root traits in maize.

Download Full-text

Covariation in root traits of Leymus chinensis in response to grazing in steppe rangeland

The Rangeland Journal ◽

10.1071/rj18099 ◽

2019 ◽

Vol 41 (4) ◽

pp. 313

Author(s):

Wei Xiaoting ◽

Zhong Mengying ◽

Liu Yuehua ◽

Wu Ruixin ◽

Shao Xinqing

Keyword(s):

Root Length ◽

Topological Structure ◽

Grazing Intensity ◽

Root Traits ◽

Root Surface ◽

Leymus Chinensis ◽

Root Surface Area ◽

Total Root Length ◽

Grazing Season ◽

Heavy Grazing

Root traits are closely related to nutrient absorption and resource competition and can even influence plant recovery and community succession. Grazing can influence root traits directly through trampling and foraging, or indirectly by changing soil characteristics. In the present study, a grazing experiment that involved combinations of grazing season (from June to September) and intensity (rest, moderate and heavy) was conducted in steppe rangeland, Inner Mongolia, China to investigate how the root traits of Leymus chinensis respond to different grazing regimes in the case of aboveground miniaturisation after long-term overgrazing. Root traits such as root length, root surface area, specific root length, root tissue density, root links (unbranched parts of a root connecting either a tip and a branching point or two branching points) and root topological structure were scanned and analysed using Win-RHIZO image analysis software. The results showed that the size of L. chinensis plants was reduced in response to overgrazing, typically by a smaller plant height, total root length, root surface area, root volume, number of tips and number of links. However, root diameter and link length, branching angle and topological structure (herringbone or dichotomous) were unaffected by grazing. Most root traits showed strong correlations under moderate grazing intensity, but not under heavy grazing, indicating that grazing changed the relationships among root traits. Relationships between plant height and root traits (total root length and number of links) shifted from positive to negative as grazing intensity increased, and the trade-off between aboveground and belowground traits was an important adaptive strategy of L. chinensis under heavy grazing. Decreasing grazing intensity in the late grazing season could benefit plant recovery, and a rest in the early grazing season would mitigate root and shoot damage.

Download Full-text

Phenotypic Diversity for Root Traits and Identification of Superior Germplasm for Root Breeding in Watermelon

HortScience ◽

10.21273/hortsci15093-20 ◽

2020 ◽

Vol 55 (8) ◽

pp. 1272-1279

Author(s):

Dennis N. Katuuramu ◽

W. Patrick Wechter ◽

Marcellus L. Washington ◽

Matthew Horry ◽

Matthew A. Cutulle ◽

...

Keyword(s):

Root System ◽

Surface Area ◽

Root Length ◽

Root Traits ◽

Root Surface ◽

Root Diameter ◽

Root Surface Area ◽

Total Root Length ◽

Root Volume ◽

Diverse Range

Root traits are an important component for productive plant performance. Roots offer immediate absorptive surfaces for water and nutrient acquisition and are thus critical to crop growth and response to biotic and abiotic stresses. In addition, roots can provide the first line of defense against soilborne pathogens. Watermelon crop performance is often challenged by inclement weather and environmental factors. A resilient root system can support the watermelon crop’s performance across a diverse range of production conditions. In this study, 335 four-day-old watermelon (Citrullus spp.) seedlings were evaluated for total root length, average root diameter, total root surface area, and total root volume. Total root length varied from 8.78 to 181 cm (20.6-fold variation), total surface area varied from 2 to 35.5 cm2, and average root diameter and total root volume had an 8- and 29.5-fold variation, respectively. Genotypes PI 195927 (Citrullus colocynthis) and PI 674448 (Citrullus amarus) had the largest total root length values. Accessions PI 674448 and PI 494817 (C. amarus) had the largest total root surface area means. Watermelon cultivars (Citrullus lanatus) had a relatively smaller root system and significantly fewer fibrous roots when compared with the roots of the other Citrullus spp. Positive genetic correlations were identified among total root length, total root surface area, and total root volume. This genetic information will be useful in future breeding efforts to select for multiple root architecture traits in watermelon. Germplasm identified in this study that exhibit superior root traits can be used as parental choices to improve watermelon for root traits.

Download Full-text

Physiological and morphological aspects of interactions between Rhizobium meliloti and alfalfa (Medicago sativa) in association with Azospirillum brasilense

Canadian Journal of Microbiology ◽

10.1139/m93-088 ◽

1993 ◽

Vol 39 (6) ◽

pp. 610-615 ◽

Cited By ~ 41

Author(s):

R. Itzigsohn ◽

Y. Kapulnik ◽

Y. Okon ◽

A. Dovrat

Keyword(s):

Medicago Sativa ◽

Rhizobium Meliloti ◽

Combined Treatment ◽

Root Hairs ◽

Background Level ◽

Root Surface ◽

Root Surface Area ◽

Main Root ◽

Nodule Number ◽

Infection Threads

In a 50-L pot experiment with Medicago sativa grown under nonsterile conditions, a combined treatment of Azospirillum and Rhizobium was measured against soil inoculated with Rhizobium or Azospirillum alone or a control with a low background level of autochthonous rhizobia. The combined treatment significantly increased the shoot length and weight at 6 weeks and the regrowth shoot weight at 14 weeks when compared with the treatment with Rhizobium alone. In 1.5-L pots in which gnotobiotic conditions were maintained, the combined treatment led to more nodules on the main root at intermediate Rhizobium concentrations, and a greater root surface area at intermediate and high Rhizobium concentrations after 2 weeks but not after 4 weeks. In pouch-grown seedlings, plants were inoculated with either Rhizobium alone or in combination with Azospirillum or applied together with a flavonoid, luteolin (a nodulation gene inducer), or with a cytokinin, benzyl adenine. Luteolin had similar effects to those of Azospirillum in increasing the main root nodule number and the total nodule number. With Fahraeus slides, a significant increase was observed in the number of root hairs and the root diameter in the presence of Azospirillum as compared with the control and Rhizobium alone. There was no increase in the total number of infection threads; however, the combined treatment caused a significant decrease in the percentage of infected root hairs.Key words: Rhizobium, Azospirillum, Medicago, flavonoid, inoculation.

Download Full-text