High-throughput phenotyping and physiological genetics of stomatal patterning and water use efficiency in maize

Xie, Jiayang

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https://hdl.handle.net/2142/113034 Copy

Description

Title

High-throughput phenotyping and physiological genetics of stomatal patterning and water use efficiency in maize

Author(s)

Xie, Jiayang

Issue Date

2021-07-13

Director of Research (if dissertation) or Advisor (if thesis)

Leakey, Andrew D. B.

Doctoral Committee Chair(s)

Ort, Don R.

Committee Member(s)

• Studer, Anthony J.
• Marshall-Colon, Amy

Department of Study

Crop Sciences

Discipline

Crop Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• water use efficiency
• stomata

Abstract

Maize (Zea mays L.) is the world’s most produced crop. However, the gain in breeding for higher yield of maize has shown to be associated with greater water inputs, which makes maize production more sensitive and vulnerable to drought events. In addition, the greater atmospheric vapor pressure deficit in the future climate will pose greater forces to pull water vapor out of plants. Thus, there is a great need for improvements in crop water use efficiency and drought tolerance, to reduce risks brought by water limitations. Stomata are the pores on leaf surfaces controlling the influx of CO2 used in photosynthesis and efflux of H2O as water transpires. Stomatal patterning on the epidermis (stomatal density, area, size dimensions, degree of clustering etc.) has been speculated to affect gas exchange in different ways, and this thesis aims to examine the characteristics of stomatal pattering in maize from multiple angles. Firstly, we propose a high-throughput epidermal cell phenotyping pipeline which was proven to be efficient, robust, and versatile in extracting anatomical traits for multiple cell types on the epidermis. Two years of Quantitative Trait Locus (QTL) mapping in a B73 x MS71 Recombinant Inbred Line (RIL) population for various epidermal traits identified 36 consistent QTL for a given trait in both years, as well as 24 clusters in the genome containing overlapping QTL for multiple traits. Next, we evaluated the plasticity of the epidermal traits and structural functional relationships in response to drought using B73, MS71 and two of their progenies that collectively represent a gradient of stomatal density. Significant amount of variation was found in the response patterns for the epidermal traits among the genotypes. Notably, the abaxial leaf surface seemed to be driving the drought responses of gas exchange traits. In addition, stomatal width was shown to be significantly affecting gas exchange in the two independent studies above. Finally, transcriptomic analysis was performed in six growth zones in maize leaves, which represented the spatial-temporal gradient of stomatal development stages. Comparing B73 and MS71, expression patterns for putative stomatal regulating genes in maize were found to be qualitatively conserved. Comparisons were also made between a maize stomataless mutant designated as “abnormal stomates” (abs1) and non-mutant plants. This revealed that the gene regulatory network (GRN) of abs1 was substantially damaged. A list of previously undescribed candidate genes was inferred from both the B73-MS71 consensus GRN and the deficient abs1 GRN. Combined together, these results enhance our understanding of the development, coordination, plasticity, and function for stomatal patterning in maize and promote the potential for stomata patterning to be leveraged for crop improvement through biotechnology or breeding.

Graduation Semester

2021-08

Type of Resource

Thesis

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http://hdl.handle.net/2142/113034

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Copyright 2021 Jiayang Xie

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