Abscisic Acid Mediates Drought-Enhanced Rhizosheath Formation in Tomato

The rhizosheath, commonly defined as soil adhering to the root surface, may confer drought tolerance in various crop species by enhancing access to water and nutrients under drying stress conditions. Since the role of phytohormones in establishing this trait remains largely unexplored, we investigated the role of ABA in rhizosheath formation of wild-type (WT) and ABA-deficient (notabilis, not) tomatoes. Both genotypes had similar rhizosheath weight, root length, and root ABA concentration in well-watered soil. Drying stress treatment decreased root length similarly in both genotypes, but substantially increased root ABA concentration and rhizosheath weight of WT plants, indicating an important role for ABA in rhizosheath formation. Neither genotype nor drying stress treatment affected root hair length, but drying stress treatment decreased root hair density of not. Under drying stress conditions, root hair length was positively correlated with rhizosheath weight in both genotypes, while root hair density was positively correlated with rhizosheath weight in well-watered not plants. Root transcriptome analysis revealed that drought stress increased the expression of ABA-responsive transcription factors, such as AP2-like ER TF, alongside other drought-regulatory genes associated with ABA (ABA 8′-hydroxylase and protein phosphatase 2C). Thus, root ABA status modulated the expression of specific gene expression pathways. Taken together, drought-induced rhizosheath enhancement was ABA-dependent, but independent of root hair length.

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Exogenous Phytohormones Modulate Mycorrhiza-Induced Changes in Root Hair Configuration of Trifoliate Orange

Notulae Botanicae Horti Agrobotanici Cluj-Napoca ◽

10.15835/nbha44210540 ◽

2016 ◽

Vol 44 (2) ◽

pp. 548-556 ◽

Cited By ~ 4

Author(s):

Chun-Yan LIU ◽

A.K. SRIVASTAVA ◽

De-Jian ZHANG ◽

Ying-Ning ZOU ◽

Qiang-Sheng Wu

Keyword(s):

Root Hair ◽

Lateral Roots ◽

Poncirus Trifoliata ◽

Hair Length ◽

Trifoliate Orange ◽

Hair Density ◽

Root Hair Length ◽

Nylon Mesh ◽

Root Hair Density ◽

Induced Changes

Mycorrhizas alter root hair profile, but it is not clear whether exogenous phytohormones regulate the mycorrhizal effects on root hair. Studies were carried out in a two-chambered rootbox separated by 37-Î¼m nylon mesh to establish root+hyphae chamber carrying trifoliate orange [Poncirus trifoliata (L.) Raf.] as the test plant inoculated with Diversispora versiformis and hyphae chamber (without roots). Indole butyric acid (IBA), abscisic acid (ABA), and jasmonic acid (JA) (each at 0.1 Î¼M concentration) were weekly applied into hyphae chamber, in total of six times before plant harvest. Mycorrhization strongly stimulated plant growth performance, and exogenous phytohormones, especially IBA, further magnified the mycorrhizal-stimulated growth responses. Three exogenous phytohormones decreased mycorrhizal colonization in taproot and first-order lateral roots, but increased in second- and third-order lateral roots. These phytohormones also increased hyphal length in nylon mesh and soil, irrespective of root+hyphae or hyphae chamber. Mycorrhizal inoculation significantly increased root hair density of different root classes, and exogenous hormones further strengthened the mycorrhizal effect. Average root hair length was stimulated by mycorrhization, but all exogenous phytohormones weakened the mycorrhizal response. Mycorrhization in combination with exogenous phytohormones showed no response on root hair diameter. Our studies, hence, suggested that application of exogenous phytohormones in hyphae chamber strengthened the D. versiformis-induced changes in average root hair density but weakened in average root hair length in trifofliate orange grown in root+hyphae chamber.

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Variation in root morphology and P acquisition efficiency among Trifolium subterraneum genotypes

Crop and Pasture Science ◽

10.1071/cp19078 ◽

2019 ◽

Vol 70 (11) ◽

pp. 1015 ◽

Cited By ~ 2

Author(s):

Jonathan W. McLachlan ◽

Rebecca E. Haling ◽

Richard J. Simpson ◽

Xiaoxi Li ◽

Richard J. Flavel ◽

...

Keyword(s):

Root Hair ◽

Root Length ◽

Morphological Traits ◽

Trifolium Subterraneum ◽

P Uptake ◽

Hair Length ◽

Root Hair Length ◽

P Acquisition ◽

Plant P Uptake ◽

Total Plant

Trifolium subterraneum L. is widely grown in the phosphorus (P) deficient soils of southern Australia. However, this pasture legume has a high critical external P requirement and requires frequent applications of P fertiliser to achieve high productivity. Twenty-six genotypes of T. subterraneum were grown to determine: (i) differences in shoot growth and P acquisition under low-P supply; (ii) the root morphological traits important for P acquisition; and (iii) the feasibility of selection among genotypes for these root morphological traits. Micro-swards of each genotype were grown with a topsoil layer that was either moderately P-deficient or had P supplied in excess of the critical requirement for maximum yield; the subsoil layer was P-deficient. Yield and P content of shoots and roots were determined after 5 weeks’ growth, and root samples were assessed for diameter, length and root hair length. All genotypes were equally highly productive when excess P was supplied. However, relative shoot yield in the moderately P-deficient soil ranged from 38–71%. Total root length ranged from 63–129 m pot–1, and was correlated with total plant P uptake (R2 = 0.78, P < 0.001). Variation was also observed in average root diameter (0.29–0.36 mm) and root hair length (0.19–0.33 mm). These traits were combined with root length to calculate the total surface area of the root hair cylinder, which was also correlated with total plant P uptake (R2 = 0.69, P < 0.001). The results demonstrated that there was significant variation in P acquisition efficiency and shoot yield among genotypes of T. subterraneum when grown in P-deficient soil, and that root length was important for improved P uptake. The results indicate potential to identify superior genotypes that achieve improved P acquisition and higher shoot yields in low-P soil.

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