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

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.

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Root system traits impact early fire blight susceptibility in apple (Malus × domestica)

10.21203/rs.2.10413/v2 ◽

2019 ◽

Author(s):

Jugpreet Singh ◽

Jack Fabrizio ◽

Elsa Desnoues ◽

Julliany Pereira Silva ◽

Wolfgang Busch ◽

...

Keyword(s):

Fire Blight ◽

Expression Patterns ◽

Root Traits ◽

Root Surface ◽

Root Surface Area ◽

Protein Kinase Activity ◽

Oxidation Reduction ◽

Molecular Relationships ◽

Blight Disease ◽

Root Vigor

Abstract Background Although it is known that resistant rootstocks facilitate management of fire blight disease, incited by Erwinia amylovora, 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 vigor provide higher tolerance to fire blight infection in apples is tested. Several apple scion genotypes grafted onto a single rootstock genotype and non-grafted ‘M.7’ rootstocks of varying root vigor 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.

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Root system traits impact early fire blight susceptibility in apple (Malus × domestica)

BMC Plant Biology ◽

10.1186/s12870-019-2202-3 ◽

2019 ◽

Vol 19 (1) ◽

Cited By ~ 1

Author(s):

Jugpreet Singh ◽

Jack Fabrizio ◽

Elsa Desnoues ◽

Julliany Pereira Silva ◽

Wolfgang Busch ◽

...

Keyword(s):

Fire Blight ◽

Expression Patterns ◽

Root Traits ◽

Root Surface ◽

Root Surface Area ◽

Protein Kinase Activity ◽

Oxidation Reduction ◽

Molecular Relationships ◽

Blight Disease ◽

Root Vigor

Abstract Background Although it is known that resistant rootstocks facilitate management of fire blight disease, incited by Erwinia amylovora, 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 vigor provide higher tolerance to fire blight infection in apples is tested. Several apple scion genotypes grafted onto a single rootstock genotype and non-grafted ‘M.7’ rootstocks of varying root vigor 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.

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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.

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Root morphological characteristics of host species having distinct mycorrhizal dependency

Canadian Journal of Botany ◽

10.1139/b91-089 ◽

1991 ◽

Vol 69 (3) ◽

pp. 671-676 ◽

Cited By ~ 50

Author(s):

A. Manjunath ◽

M. Habte

Keyword(s):

Root Hair ◽

Morphological Characteristics ◽

Root Surface ◽

P Uptake ◽

Root Diameter ◽

Root Surface Area ◽

Root Mass ◽

Hair Length ◽

Mycorrhizal Dependency ◽

Root Characteristics

Greenhouse and growth chamber investigations were undertaken using selected Leucaena and Sesbania species to determine the extent to which root morphological characteristics and rhizosphere acid production could explain differences in mycorrhizal dependency of host plants. Compared with the moderately to very highly mycorrhizal-dependent Leucaena species, the marginally to moderately dependent Sesbania species were characterized by higher root mass, higher root density, higher root surface area, higher root length, smaller root diameter, higher percentage of root hair incidence, higher shoot to root ratio, and higher total P uptake. The two groups of species were not consistently different from each other with respect to mycorrhizal colonization level, root hair diameter, root hair length, P uptake per unit root surface area, and acid production in agar media. A stepwise regression model in which mycorrhizal dependency (MD) was used as the dependent variable and root characteristics as independent variables suggested that root mass, root hair length, root diameter, root density, and root hair incidence were important determinants of MD, with root mass accounting for 65.5% of the variability. The results suggest that differences in the mycorrhizal dependency of host species can be largely predicted from root characteristics data. Key words: Brassica, Leucaena, Sesbania, P uptake, root hair, root mass.

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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.

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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.

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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.

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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.

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Targeting Low-Phytate Soybean Genotypes Without Compromising Desirable Phosphorus-Acquisition Traits

Frontiers in Genetics ◽

10.3389/fgene.2020.574547 ◽

2020 ◽

Vol 11 ◽

Author(s):

Mireadili Kuerban ◽

Wenfeng Jiao ◽

Jiayin Pang ◽

Jingying Jing ◽

Li-Juan Qiu ◽

...

Keyword(s):

Genotypic Variation ◽

Root Traits ◽

Dry Weight ◽

Root Surface ◽

Root Surface Area ◽

Soil P ◽

P Acquisition ◽

P Concentration ◽

Soybean Genotypes ◽

Food And Feed

Phytate-phosphorus (P) in food and feed is not efficiently utilized by humans and non-ruminant livestock, potentially contributing to high losses of P to the environment. Crops with high P-acquisition efficiency can access soil P effectively. It remains elusive whether crop genotypes with high P-acquisition efficiency can also have low seed phytate concentrations. A core collection of 256 soybean [Glycine max (L.) Merr.] genotypes from China with diverse genetic background were grown in the same environment and seeds were sampled to screen for seed phytate-P concentration. Some of these genotypes were also grown in a low-P soil in the glasshouse to measure root morphological and physiological traits related to P acquisition. Large genotypic variation was found in seed phytate-P concentration (0.69–5.49 mg P g–1 dry weight), total root length, root surface area, rhizosheath carboxylates, and acid phosphatase activity in rhizosheath soil. Geographically, seed phytate-P concentration was the highest for the genotypes from Hainan Province, whereas it was the lowest for the genotypes from Inner Mongolia. Seed phytate-P concentration showed no correlation with any desirable root traits associated with enhanced P acquisition. Two genotypes (Siliyuan and Diliuhuangdou-2) with both low phytate concentrations and highly desirable P-acquisition traits were identified. This is the first study to show that some soybean genotypes have extremely low seed phytate concentrations, combined with important root traits for efficient P acquisition, offering material for breeding genotypes with low seed phytate-P concentrations.

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Above- and below-ground effects of aspen clonal regeneration and succession to conifers

Canadian Journal of Forest Research ◽

10.1139/x01-001 ◽

2001 ◽

Vol 31 (5) ◽

pp. 739-745 ◽

Cited By ~ 40

Author(s):

Wayne D Shepperd ◽

Dale L Bartos ◽

Stephen A Mata

Keyword(s):

Populus Tremuloides ◽

Basal Area ◽

Root Surface ◽

Root Surface Area ◽

National Forest ◽

Root Mass ◽

Mixed Stands ◽

Area Growth ◽

Below Ground ◽

Ground Effects

Above- and below-ground characteristics were measured and compared for six sets of paired trembling aspen (Populus tremuloides Michx.) clones on the Fishlake National Forest in central Utah. Three self-regenerating clones were compared with three non-regenerating clones and three pure aspen stands were compared with three mixed aspen-conifer stands. Regenerating clones had dense understories of younger aspen stems, which were not present in non-regenerating clones. Regenerating clones also had greater numbers of roots and greater total root surface area than non-regenerating clones. Aboveground biomass and growth of the aspen in mixed stands was less than that of pure stands. A corresponding difference in aspen root mass was not apparent, indicating that the decline of aspen in mixed stands had not yet affected the root system. Conifer height and basal area growth rates were clearly greater than those of aspen, suggesting that aspen will eventually disappear from these forests in the absence of stand-reinitiating disturbances.

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