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The development of lateral roots and apoplastic barriers in maize (zea mays L.) root system
Pecková, Eva ; Soukup, Aleš (advisor) ; Čiamporová, Milada (referee) ; Martinka, Michal (referee)
ABSTRACT The formation of plant root system is an important ecophysiological and agronomical parameter and also an actual topic of developmental plant biology. Lateral roots are its very important part which creates majority of the main absorbent portion of the plant surface in the rhizosphere. One of the few described mutants (except the model plant Arabidopsis thaliana) with impaired development of lateral roots in early postembryonic development is maize (Zea mays) mutant lrt1 (lateral rootless 1). Our detailed anatomical-morphological study of lrt1 provides new insight into LRT1 gene function. We found out that initiation of lrt1 primordia takes place and is strongly dependent on environmental conditions. The structure of primordia, also their emergence and later development is strongly affected. On the contrary, the main roots do not show so strong influence by this mutation, although some disruptions were found in surface root layers. These disturbances were connected with induced lignification, increased activity of peroxidase and with changes in permeation of root surface. Changes in permeability of surface layers led us to the issue of apoplastic barriers, what was dealt to the traditional and previously tested another genotype of maize (Z. mays). Our work provides a unique insight into...
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Characterization of programmed cell death during lyzigenous aerenchyma formation
Lenochová, Zuzana ; Votrubová, Olga (advisor) ; Čiamporová, Milada (referee) ; Kummerová, Marie (referee)
Abstract____________________________________________________________________ 2 ABSTRACT: Zea mays is generally considered to be a plant with inducible lysigenous aerenchyma formation. The degradation of some cortical cells is triggered by environmental conditions, usually in the form of stress (submergence etc.). These cells die in a process that shows signs characteristic for programmed cell death, such as nuclear DNA fragmentation or apoptotic ultrastructural alterations. Aerenchyma formed in primary roots of thirteen examined maize accessions, irrespective of cultivation conditions. The aerenchyma fraction correlated with the root length, not with its age. The dependence of aerenchyma formation on the presence of this phytohormone was proved by using an inhibitor of ethylene synthesis (AOA). It was found out that the aerenchyma formation depended on light conditions and that the lysigenous intercellulars intercellular spaces colocalized with areas with cells with characteristically fragmented nuclear DNA (TUNEL-positive nuclei). In experiments using the TUNEL reaction it was necessary to determine new dilution of the enzymatic mixture for the examined plant material. Only the observation of surface planes of free-hand root sections was considered relevant in both TUNEL-TMR and TUNEL-AP assays. TUNEL-AP...
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