@article{6897, abstract = {The apical hook is a transiently formed structure that plays a protective role when the germinating seedling penetrates through the soil towards the surface. Crucial for proper bending is the local auxin maxima, which defines the concave (inner) side of the hook curvature. As no sign of asymmetric auxin distribution has been reported in embryonic hypocotyls prior to hook formation, the question of how auxin asymmetry is established in the early phases of seedling germination remains largely unanswered. Here, we analyzed the auxin distribution and expression of PIN auxin efflux carriers from early phases of germination, and show that bending of the root in response to gravity is the crucial initial cue that governs the hypocotyl bending required for apical hook formation. Importantly, polar auxin transport machinery is established gradually after germination starts as a result of tight root-hypocotyl interaction and a proper balance between abscisic acid and gibberellins.}, author = {Zhu, Qiang and Gallemi, Marçal and Pospíšil, Jiří and Žádníková, Petra and Strnad, Miroslav and Benková, Eva}, issn = {14779129}, journal = {Development}, number = {17}, publisher = {The Company of Biologists}, title = {{Root gravity response module guides differential growth determining both root bending and apical hook formation in Arabidopsis}}, doi = {10.1242/dev.175919}, volume = {146}, year = {2019}, } @inbook{1210, abstract = {Mechanisms for cell protection are essential for survival of multicellular organisms. In plants, the apical hook, which is transiently formed in darkness when the germinating seedling penetrates towards the soil surface, plays such protective role and shields the vitally important shoot apical meristem and cotyledons from damage. The apical hook is formed by bending of the upper hypocotyl soon after germination, and it is maintained in a closed stage while the hypocotyl continues to penetrate through the soil and rapidly opens when exposed to light in proximity of the soil surface. To uncover the complex molecular network orchestrating this spatiotemporally tightly coordinated process, monitoring of the apical hook development in real time is indispensable. Here we describe an imaging platform that enables high-resolution kinetic analysis of this dynamic developmental process. © Springer Science+Business Media New York 2017.}, author = {Zhu, Qiang and Žádníková, Petra and Smet, Dajo and Van Der Straeten, Dominique and Benková, Eva}, booktitle = {Plant Hormones}, pages = {1 -- 8}, publisher = {Humana Press}, title = {{Real time analysis of the apical hook development}}, doi = {10.1007/978-1-4939-6469-7_1}, volume = {1497}, year = {2016}, } @article{1283, abstract = {The impact of the plant hormone ethylene on seedling development has long been recognized; however, its ecophysiological relevance is unexplored. Three recent studies demonstrate that ethylene is a critical endogenous integrator of various environmental signals including mechanical stress, light, and oxygen availability during seedling germination and growth through the soil.}, author = {Zhu, Qiang and Benková, Eva}, journal = {Trends in Plant Science}, number = {10}, pages = {809 -- 811}, publisher = {Cell Press}, title = {{Seedlings’ strategy to overcome a soil barrier}}, doi = {10.1016/j.tplants.2016.08.003}, volume = {21}, year = {2016}, } @article{1593, abstract = {Plants are sessile organisms that are permanently restricted to their site of germination. To compensate for their lack of mobility, plants evolved unique mechanisms enabling them to rapidly react to ever changing environmental conditions and flexibly adapt their postembryonic developmental program. A prominent demonstration of this developmental plasticity is their ability to bend organs in order to reach the position most optimal for growth and utilization of light, nutrients, and other resources. Shortly after germination, dicotyledonous seedlings form a bended structure, the so-called apical hook, to protect the delicate shoot meristem and cotyledons from damage when penetrating through the soil. Upon perception of a light stimulus, the apical hook rapidly opens and the photomorphogenic developmental program is activated. After germination, plant organs are able to align their growth with the light source and adopt the most favorable orientation through bending, in a process named phototropism. On the other hand, when roots and shoots are diverted from their upright orientation, they immediately detect a change in the gravity vector and bend to maintain a vertical growth direction. Noteworthy, despite the diversity of external stimuli perceived by different plant organs, all plant tropic movements share a common mechanistic basis: differential cell growth. In our review, we will discuss the molecular principles underlying various tropic responses with the focus on mechanisms mediating the perception of external signals, transduction cascades and downstream responses that regulate differential cell growth and consequently, organ bending. In particular, we highlight common and specific features of regulatory pathways in control of the bending of organs and a role for the plant hormone auxin as a key regulatory component.}, author = {Žádníková, Petra and Smet, Dajo and Zhu, Qiang and Van Der Straeten, Dominique and Benková, Eva}, journal = {Frontiers in Plant Science}, number = {4}, publisher = {Frontiers Research Foundation}, title = {{Strategies of seedlings to overcome their sessile nature: Auxin in mobility control}}, doi = {10.3389/fpls.2015.00218}, volume = {6}, year = {2015}, }