<p>Iron is
an essential micronutrient for plant growth, development and productivity.
Although it is abundant in soil, the bio-availability of iron is often low for
plants in many areas of the world. The insufficient quantity of usable iron in
plants causes reduction in chlorophyll synthesis, reduced photosynthesis rate
and decreased growth and yield. Two major strategies, Strategy I and II, have
been discovered to be involved in response to low iron and a complex network of
biochemical and molecular pathways participate in the processes. </p>
<p> </p>
<p>Cellular
transcriptional regulation is associated with iron deficiency responses.
Multiple genes and pathways involved in iron-deficiency responses have been
identified in plants in the past decade. Here, we measured different
physiological parameters and used RNA-Seq to elucidate the physiological and
molecular responses in early stage of iron deficiency in the whole leaf of
model plant species Arabidopsis thaliana. In this study, Arabidopsis showed
reduced chlorophyll content, increased ferric reductase activity and reduced
antioxidant enzyme activities when stressed by iron deficiency. In addition, we
have identified multiple pathways that may play promising roles in the response
to iron deficiency, e.g., 1) we found that the auxin biosynthesis under iron
deficiency is preferentially depended on the TAA-YUC pathway rather than the
CYP79 pathways; 2) TCA cycle is involved in mediating the acclimation process
to the stress condition; 3) glucosinolate synthesis could be a limiting factor
for iron deficiency response due to its negative relationship with hormone and
energy metabolism.</p>
<p> </p>
Systemic
signals generated from leaves are critical for triggering iron deficiency
responses in roots. Due to the physiological characteristic and cellular
ultrastructure of companion cells (CCs), we hypothesize that the CCs located in
phloem play essential roles in regulating systemic nutrient signaling. In this
study, by using a cell-specific TRAP-Seq, we discovered that not only CCs
respond more drastically than the other cells in leaf, the altered molecular
pathways in the CCs are also more diverse during early iron deficiency
response. In particular, we found that auxin and sucrose transport and
metabolism in the CCs may be two of the key regulatory processes that plants
use to exert the shoot-to-root signaling process. Our discoveries have
collectively suggested that CCs may function as the central machinery in the
systemic signaling in response to iron deficiency. A comparison between whole
leaf transcriptome and translatome also suggested that translatomic analysis is
a more sensitive method for gene profiling than conventional transcriptomic
analysis.
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/9117098 |
| Date | 13 August 2019 |
| Creators | Ruijie Han (7046801) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/Transcriptomic_and_Cell-Specific_Translatomic_Aanalysis_in_Early_Iron_Deficiency_Response_in_Arabidopsis/9117098 |
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