Elucidating molecular mechanisms of seed development in Arabidopsis and fiber development in cotton
MetadataShow full item record
Seeds are important energy resource and source of fabric materials for humans. We intake more than 40% of calories as well as nutrients from various angiosperm seeds, and use cotton fibers derived from seed coats for the majority natural fabric materials. In this dissertation, I investigated two seed development mechanisms; imprinting effects on seed size in Arabidopsis and fiber cell differentiation from seed coats in cotton. Seed size is affected by genetic mutations and imprinting. Imprinting is a widespread epigenetic phenomenon in mammals and flowering plants, in which selected genes are differentially expressed between alleles in a parent-of-origin manner. ETHYLENE INSENSITIVE2 (EIN2) encodes an essential signal molecule that links the ethylene perception on endoplasmic reticulum (ER) to transcriptional regulation in the nucleus. Interestingly, EIN2 is an imprinted gene in both Arabidopsis and maize, and is maternally expressed in the endosperm. The function of most imprinted genes including EIN2 is largely unknown in plants. In chapter two, I show how the imprinted expression of EIN2 regulates seed size in Arabidopsis. Cotton (Gossypium spp.) is the largest renewable source of textile fiber in the world and it is also an important oil crop. Cotton fibers are made up of individual cells that are derived from ~30% of epidermal cells on surface of the cotton seed, which each elongate up to several centimeters. Efforts to understand the causes of this shift has been hampered by the difficulty of isolating fiber cells from epidermal cells at the earliest stages of development. In chapter three and four, I show the gene expression and RNA modification of various tissues as well as different stages of fibers including early stage fibers collected by Laser Capture Microdissection technology, to identify the underlying mechanism of fiber development in cotton. These results provide mechanistic insights into the imprinting effect of EIN2 on seed development and shed light on the early changes in gene activity controlling fiber development in cotton, which may help manipulate seed and fiber yields.