Mechanism of Dioecy Determination in Diospyros

点击翻译按钮获取中文摘要

Most plants are hermaphrodites, which means that they carry both male and female organs. Some, like tomato, rice, beans and other cultivated species, cast pollen from male to female organs in the same flower. Others employ ingenious schemes to ensure that one individual pollinates the flower of another. Persimmon, pistachio, kiwi, hops, and spinach are amongst the few percent of plant species in which these functions are found in separate individuals, a condition called dioecy. In mammals maleness or femaleness are determined by X and Y chromosomes: males have an X and a Y and females have two Xs. A single gene on the Y is responsible for triggering the development of male traits. Most dioecious plants resemble the human system, with XY males and XX females. But what gene(s) may be responsible for determining whether a particular plant carries male or female flowers has been a long-standing mystery. Recently, the authors combed through the genomes of persimmon trees looking for genes that were exclusive to males and found pair of genes, called OGI and MeGI. In females, MeGI builds to high level and acts like a neutering agent, repressing pollen formation. In males, OGI prevents the accumulation of MeGI. Discovery of the OGI-MeGI system in persimmon opens up new possibilities in plant breeding. Controlling flower organs is also important for facilitating production of high yielding hybrids from controlled hybridization of selected inbreds. Broader impacts include an outreach aimed at increasing skills and confidence in Big Data Analysis for high school or early college students of underpresented background. Additionally, because dioecy evolved independently many times in plants, this work provides a foundation to ask whether plants invented similar or different solutions to the same problem.These results cast light on the organization of a plant Y chromosome and provide a working model for dioecy determination in Diospyros species. The authors aim to capitalize on these findings to further investigate the molecular function of the OGI and MeGI genes, as well as ask more general questions about the evolution of dioecy determination in dioecious species. Their specific objectives are to: 1) Define the Y chromosome in Diospyros lotus using a combination of sequencing and genetic approaches 2) Unravel the molecular function of OGI and MeGI using transgenic technology in A. thaliana and genome-wide genomic analyses in Diospryros and 3) Characterize variation in the Y-chromosome dioecy determination region in Diospyros and closely-related species and test whether similar systems are at play in other dioecious systems. This work provides a model for unraveling dioecy determination systems in economically-relevant plant species, an area important for human sustenance and well being.