Instituto de Biotecnologia UNAM

Grupo del Dr. Iossif Doubrovski

Laboratory of Developmental Biology of Plant Roots

Developmental Biology aims to understand developmental mechanisms involved in tissue and organ formation. Contrary to animals, in plants almost all organs are formed during postembryonic development, therefore, these mechanisms are decisive not only during embryogenesis, but, even at a greater extent, after seed germination. In our laboratory we study root development as this organ is readily amenable to cellular analysis. Also, root is an important organ for plant adaptation to environmental conditions and it is essential for plant integrity as it fulfills many essential functions. We implement genetic, cell biology, imaging, microscopy, and bioinformatics approaches to address various facets of Root Developmental Biology.

Root system formation and development is comprised of two main components: root growth and branching. Both are related to root apical meristem (RAM) formation and maintenance. While roots possess the RAM, they are capable of indeterminate root growth. However, sometimes the RAM can be developmentally lost, or exhausted, leading to root determinacy. We have isolated a number of mutants affected in root development, and using deep sequencing identified the genes responsible for the abnormal root phenotypes. Some of these mutants show determinate root growth and some don´t. We are in search of new gene-regulatory pathways involved in the RAM maintenance and the maintenance of indeterminacy.

With the same purpose we also study Cactaceae species. We have found that many of them exhibit the RAM exhaustion, that is, the determinate root growth. In a giant Mexican cactus, Pachycereus pringlei, it is related to only a transient establishment of the quiescent center (distal part of the RAM involved in stem cell function). Applying transcriptomics and bioinformatics tools, we study differential gene expression in this species at the initial stage of root growth, when the RAM is present, and at the terminal stage, when it is exhausted. As part of this work we de-novo assembled and annotated the root tip transcriptome of P. pringlei. This will allow us to better comprehend how the developmental loss of indeterminacy is taking place in this plant group. We have shown that the primary root exhibits determinate growth in most but not all analyzed species of Cactaceae, therefore we are also interested in the evolutionary origin of this type of root growth and its association with drought adaptation. We expect that some genes that are differentially expressed in Cactaceae root tip are involved in the regulation of the determinate root growth. To validate experimentally a suggested role of genes of interest, we are developing a protocol for obtaining transgenic roots of Cactaceae.

Besides the root growth and importance of the RAM, another essential developmental process in root system formation is root branching. Initiation a new lateral root starts in a specialized tissue, the pericycle. Therefore, we are interested in the pericycle development and its commitment for the lateral root formation. The plant hormone auxin, which behaves as a morphogen and a morphogenetic trigger, plays a critical role in the developmental pathway that regulates an activation of cell divisions in pericycle. We have shown that the establishment of auxin maximum and auxin minimum, as well as auxin response gradients along the root axis, are involved in the determination of the site where a new lateral root primordium (LRP) will be formed. It is not well understood how LRP initiation is regulated. We isolated EMS-induced mutants of Arabidopsis to elucidate the genetic control of LRP initiation and morphogenesis. Using confocal microscopy, imaging, time-lapse analysis, and different molecular markers, we aim to understand how LRP morphogenesis takes place in Arabidopsis. By identification of genes responsible for the phenotypes of the mutants with abnormal LRPs we hope to contribute to the understanding of the genetic regulatory pathways involved in lateral root formation and morphogenesis.

In conclusion, the root growth and branching are two fundamental processes of root system development. Understanding the developmental mechanisms underlying these processes will shed light on the bases of crop production and the mechanisms of plant adaptation to the environment, which are essential to improve agricultural yield and practice.

Dr. Iossif Doubrovski
Investigador
Tutor de Maestría y Doctorado
Dra. Veronica Lira
Investigador en estancia temporal
Dr. Gustavo Rodriguez
Postdoctoral
Dr. Debee Prasad Sahoo
Postdoctoral
Dra. Svetlana Shishkova
Investigador
Tutor de Maestría y Doctorado
Dra. Selene Napsucialy
Técnico Académico
Ramsés Uriel Albarrán
Estudiante
M.C. Ramces De Jesus
Estudiante
M.C. Byanka Sthefany Espinoza
Estudiante
M.C. Bryan Santiago Galvis
Estudiante
Biol. Felipe Hernández
Estudiante
T.L. Alejandra Lara
Estudiante
M.C. Mayra Liliana Lopez
Estudiante
Sandra Zamira Morales
Estudiante
M.C. Hector Hugo Torres
Estudiante
Juan Pablo Villa
Estudiante
Lic. Erika Carrillo
Servicio Social
T.L. Sofía Esteban
Servicio Social
Lic. Lizbeth Hernandez
Servicio Social
T.L. Laura Arantzha Santos
Servicio Social
Raquel Ferrel
Auxiliar de Intendencia


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