@misc{10481/62885,
year = {2020},
url = {http://hdl.handle.net/10481/62885},
abstract = {This Doctoral Thesis was focused on the study of the root morphology, organic
acid and phosphatase exudation, expression of phosphate transporters, and root
mycorrhizal colonization as the main mechanisms involved in the PAE of wheat
genotypes growing under P-limiting conditions, and the underlying SL modulation
behind those traits. In chapter I, a general overview on the topic was presented, describing
the state of the art and showing the hypothesis and aims of this study. In chapter II, plant
adaptations related to P acquisition root traits, with emphasis on AM symbiosis and its
possible effects on plant’ P-related root traits were deeply reviewed. A summary of results
from 1980-2018 regarding AM growth responses and P uptake in wheat plants was
presented to discuss the generally accepted lack of positive responses in this plant species.
The importance of considering AM functional diversity on future studies and the need to
improve PAE definition considering carbon trade between all the directly related PAE
traits and its benefits to the host plant were also discussed.
In chapter III, the effects of two indigenous AM fungal isolates (Claroideoglomus
claroideum and Rhizophagus intraradices) on nutrient uptake and root traits of two
commercial Chilean wheat genotypes with contrasting P-acquisition efficiency were
evaluated in order to determine if the responses were dependent on the interaction
between host plant genotype and AM ecotype and if the symbiosis can effectively
enhance P acquisition on these cultivars (specific objective 1). The results showed that
biomass production and root morphological responses to AM colonization significantly
varied between genotypes and AM isolate, being the most P-efficient genotype – cv. Crac
iv
– not affected by the symbiosis in these parameters, while the less efficient – cv. Tukan –
showed a higher mycorrhizal dependency. Moreover, P and Ca accumulation were
increased in both cultivars when colonized by C. claroideum and R. intraradices,
respectively. It was demonstrated that AM growth responses vary at intra-specific level,
depending on the basal efficiency of each cultivar and that the nutritional benefits were
specific to each AM isolate. Therefore, AM symbiosis could contribute to increase
agricultural sustainability; however, genotype and environmental-specific combinations
should be considered to maximize the benefits from the symbiosis.
The chapter IV is related to the specific objective 2, where the P acquisitionrelated
root traits (root morphology, organic acid and phosphatase exudation, and root
mycorrhizal colonization) of the wheat genotypes under study were evaluated to
determine those that mainly contributed to P accumulation. To that, a pot and rhizobox
experiments were performed using a high P-fixing volcanic soil, either fertilized or not
with P. Crac plants showed higher P accumulation regardless of P treatment and
experiment, being root morphological traits the most correlated with P acquisition, both
in the presence and in absence of Pi fertilization. Also, the results suggest that AM
symbiosis and oxalate exudation could be other important mechanisms to enhance P
acquisition under P-limiting conditions. Finally, the traits evaluated in this study can
become important targets for future breeding programs oriented to generate cultivars
adapted to both high- and low-P input systems.
In chapter V, the SL production among the studied wheat cultivars and its effects
on Pi-starvation responses (PSRs) and P acquisition (specific objective 3) were assessed.
To accomplish this goal, plants were grown hydroponically, and P-starvation was applied
to evaluate the main PSRs at the transcriptional level – especially related to the
modulation of the P signaling and homeostasis pathway (IPS1-mir399-PHO2) and Pi
v
transporters expressions. Here, a higher expression of the Pi transporters TaPht1;2 and
TaPht1;10 and a faster and higher modulation of the IPS1–miR399–PHO2 pathway was
observed in Crac plants. Remarkably, Crac presented higher levels of SLs, suggesting a
direct relationship with the responses mentioned above. Finally, an improved model for
the regulation of the P homeostasis module was proposed. Taking together, the higher
PAE in Crac was associated with a faster and improved P signaling through a fine-tuning
regulation of PHO2, which seems to be regulated by SLs. This knowledge could help to
develop new strategies for improved plant performance under P stress limitation. All the
results obtained here are discussed comprehensively in chapter VI of this Thesis.},
organization = {Tesis Univ. Granada.},
organization = {Fondo Nacional de Desarrollo Científico Tecnológico, a través del Proyecto FONDECYT 11160385},
organization = {Programa de Formación de Capital Humano Avanzado de la Comisión Nacional de Investigación Científica y Tecnológica (CONICYT), por la beca CONICYT Nº 21161474},
organization = {Programa de Atracción e Inserción de Capital Humano Avanzado (PAI-CONICYT) a través del Concurso Nacional Tesis de Doctorado en el Sector Productivo por el Proyecto Nº T7817120011},
organization = {Campex Baer Proyecto Nº T7817120011},
publisher = {Universidad de Granada},
keywords = {Raíces (Botánica)},
keywords = {Sostenibilidad},
keywords = {Productividad agrícola},
keywords = {Fósforo},
title = {Assessment of the phosphorus acquisition related root traits of two wheat cultivars differing on efficiency: towards phosphorus sustainability},
author = {Montesano de Souza Campos, Pedro},
}