Jessica Regan Lucas

Southern Illinois University Carbondale | SIU · Department of Plant Biology

As one of the earliest plant groups to evolve stomata, hornworts are key to understanding stomata origin and function. Hornwort stomata are large and scattered on sporangia that grow from their bases and release spores at their tips. We present data from development and immunocytochemistry that identify a role for hornwort stomata that is correlate...

Premise of the study: Self incompatibility (SI) in rare plants presents a unique challenge-SI protects plants from inbreeding depression, but requires a sufficient number of mates and xenogamous pollination. Does SI persist in an endangered polyploid? Is pollinator visitation sufficient to ensure reproductive success? Is there evidence of inbreedi...

Multiple plant developmental processes, such as lateral root development, depend on auxin distribution patterns that are in part generated by the PIN-formed family of auxin-efflux transporters. Here we propose that AUXIN RESPONSE FACTOR7 (ARF7) and the ARF7-regulated FOUR LIPS/MYB124 (FLP) transcription factors jointly form a coherent feed-forward...

PREMISE OF THE STUDY The FOUR LIPS (FLP) and MYB88 transcription factors, which are closely related in structure and function, control the development of stomata, as well as entry into megasporogenesis in Arabidopsis thaliana . However, other locations where these transcription factors are expressed are poorly described. Documenting additional loca...

Stomata display a mirror-like symmetry that is adaptive for shoot-atmosphere gas exchange. This symmetry includes facing guard cells around a lens-shaped and bilaterally symmetric pore, as well as radially arranged microtubule arrays that primarily originate at the pore and then grow outwards. Mutations in MUSTACHES (MUS), which encodes a Leucine-R...

Arabidopsis guard cell (GC) fate is conferred via a transient pulse of expression of FAMA that encodes a bHLH transcription factor. Stomata often function for years, suggesting that the FAMA expression window stabilizes long-term GC identity or that additional factors operate. Transgenic lines harboring a copy of a FAMA transgene were found to indu...

Functional redundancy arises between gene paralogs as well as non-homologous genes that play a common role at a shared node. The bHLH transcription factor FAMA, along with the paralogous MYB genes, FOUR LIPS (FLP) and MYB88 all ensure that Arabidopsis stomata contain just two guard cells (GCs) by enforcing a single symmetric precursor cell division...

Microtubules and microtubule-associated proteins (MAPs) play fundamental roles in plant growth and morphogenesis. The ability to observe microtubules and MAPs in living cells using fluorescent protein fusions has propelled plant scientists forward and given them the opportunity to answer longstanding biological questions. In combination with the ge...

The acentriolar cortical microtubule arrays in dark-grown hypocotyl cells organize into a transverse coaligned pattern that is critical for axial plant growth. In light-grown Arabidopsis thaliana seedlings, the cortical array on the outer (periclinal) cell face creates a variety of array patterns with a significant bias (>3:1) for microtubules poly...

We investigated the role of the Arabidopsis microtubule associated proteins 65-1 and 65-2 (MAP65-1 and MAP65-2) in the control of axial root growth. Transgenic plants expressing fluorescent fusion proteins from native promoters indicated exactly overlapping accumulation of MAP65-1 and MAP65-2 in the root tip and elongation zone. Nearly identical pr...

Preprophase bands are belts of cortical microtubules that appear at the end of interphase and predict where cell plates will fuse with parental walls during division. Phragmoplasts are microtubule-rich arrays that orchestrate the growth and guidance of cell plates during cytokinesis. Descriptions of the development of these arrays often assume non-...

The Arabidopsis thaliana MAP65-1 and MAP65-2 genes are members of the larger eukaryotic MAP65/ASE1/PRC gene family of microtubule-associated proteins. We created fluorescent protein fusions driven by native promoters that colocalized MAP65-1 and MAP65-2 to a subset of interphase microtubule bundles in all epidermal hypocotyl cells. MAP65-1 and MAP6...

We tested the general hypothesis that bundling stabilizes the dynamic properties of the constituent microtubules (MTs) in vivo. We quantified the assembly dynamics of bundled and unbundled MTs in the interphase cortical array of Arabidopsis hypocotyl cells using high dynamic range spinning disk confocal microscopy. We find no evidence that bundled...

Stomata, which are epidermal pores surrounded by two guard cells, develop from a specialized stem cell lineage and function in shoot gas exchange. The Arabidopsis thaliana FOUR LIPS (FLP) and MYB88 genes encode closely related and atypical two-MYB-repeat proteins, which when mutated result in excess divisions and abnormal groups of stomata in conta...

Mutations in TOO MANY MOUTHS (TMM), which encodes a receptor-like protein, cause stomatal patterning defects in Arabidopsis leaves but eliminate stomatal formation in stems. Stomatal development in wild-type and tmm stems was analyzed to define TMM function. Epidermal cells in young tmm stems underwent many asymmetric divisions characteristic of en...

Advances in live-cell imaging technology have provided an unprecedented look at the dynamic behaviors of the plant microtubule cytoskeleton. Recent studies revisit the classic question of how plants create cell shape through the patterned construction of the cell wall. Visualization of the cellulose synthase complex traveling in the plasma membrane...

Microtubule arrays in living cells were analysed during Arabidopsis stomatal development in order to more closely define stages in the pathway and contexts where intercellular signalling might operate. Arabidopsis stomata are patterned iteratively via the orientation of an asymmetric division in a cell located next to an existing stoma. It was foun...

The two guard cells of a stoma are produced by a single symmetric division just before terminal differentiation. Recessive mutations in the FOUR LIPS (FLP) gene abnormally induce at least four guard cells in contact with one another. These pattern defects result from a persistence of precursor cell identity that leads to extra symmetric divisions a...

In addition to shoots and roots, the gravity (g)-vector orients the growth of specialized cells such as the apical cell of dark-grown moss protonemata. Each apical cell of the moss Ceratodon purpureus senses the g-vector and adjusts polar growth accordingly producing entire cultures of upright protonemata (negative gravitropism). The effect of with...

Abstract: Little is known about how preprophase bands (PPBs) of microtubules mark division sites, or how phragmoplasts later grow towards these sites. To more clearly define these aspects of cell division, PPBs and phragmoplasts were characterized in three dimensions in living Arabidopsis leaf epidermal cells that expressed a constitutively active...