Morphoanatomical and genome-wide association studies (GWAS) analyses of cold stress tolerance mechanisms in rice

Date

12-2025

Abstract

Cold stress in rice results in massive yield losses not only in the temperate region but also in high-altitude areas in the tropics due to constant suboptimal temperatures. This study investigated cold stress responses in rice at the reproductive stage using 20 lines from the Rice Variety 23DS Panel, 183 japonica lines from the 3KRG Panel, and 59 indica lines from the Irrigated Core Panel in four separate experiments. The first experiment found no correlation between anther length and cold tolerance because cold stress only affected pollen development and not pollen mother cell differentiation. Anatomical analyses revealed that cold directly affected the panicles because there were no changes in leaf and root development that could contribute to pollen sterility. The relative growth rate of seedlings in the second experiment also did not coincide with the yield profile of their counterpart in the first experiment, highlighting unique stress response mechanisms between the two stages. In the third experiment, GWAS found three candidate genes described as Enhanced Downy Mildew 2. These genes coexpress with other genes involved in male sterility, cell cycle progression, phytohormone biosynthesis, and the ICE-CBF- COR cascade. Lastly, the fourth experiment revealed the susceptibility of indica lines to cold stress, with < 40% percent filled grains across all lines. Three promising lines identified here are IRRI 141 and IRRI 188, which exhibited cold tolerance at both the seedling and reproductive stages, and FORTUNA COLORADO, a tropical japonica line with phenotypes comparable to a known cold-tolerant line. The cold stress response mechanisms and genetic regions identified here will be useful in breeding candidate cold- tolerant lines.

Document Type

Master Thesis

Degree

Master of Science in Botany

College

Graduate School (GS)

Adviser/Committee Chair

Mariaa Celeste N. Banaticla-Hilario

Co-adviser

Jae-Sung Lee

Committee Member

Stephen Timple, Maribel Dionisio-Sese

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

En – AGROVOC descriptors

ORYZA SATIVA; COLD STRESS; PLANT MORPHOLOGY; POLLEN CULTURE; GENOME-WIDE ASSOCIATION STUDIES

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