Spatiotemporal regulation of lateral root organogenesis in Arabidopsis by cytokinin

The architecture of a plant's root system, established postembryonically, results from both coordinated root growth and lateral root branching. The plant hormones auxin and cytokinin are central endogenous signaling molecules that regulate lateral root organogenesis positively and negatively, respectively. Tight control and mutual balance of their antagonistic activities are particularly important during the early phases of lateral root organogenesis to ensure continuous lateral root initiation (LRI) and proper development of lateral root primordia (LRP). Here, we show that the early phases of lateral root organogenesis, including priming and initiation, take place in root zones with a repressed cytokinin response. Accordingly, ectopic overproduction of cytokinin in the root basal meristem most efficiently inhibits LRI. Enhanced cytokinin responses in pericycle cells between existing LRP might restrict LRI near existing LRP and, when compromised, ectopic LRI occurs. Furthermore, our results demonstrate that young LRP are more sensitive to perturbations in the cytokinin activity than are developmentally more advanced primordia. We hypothesize that the effect of cytokinin on the development of primordia possibly depends on the robustness and stability of the auxin gradient

Una herramienta eficaz en el estudio de la Botánica: la citometría de flujo

Over the last decade there has been a tremendous increase in the use of flow cytometry (FCM) in studies on the biosystematics, ecology and population biology of vascular plants. Most studies, address questions related to spatial distribution and evolutionary significance of genome duplication (polyploidy), chromosomal variation (aneuploidy) and variation in genome size. The unsurpassed speed and reliability of estimating differences in nuclear DNA content by FCM paves the way for large-scale surveys at the landscape, population, individual and tissue levels. Another attractive feature of FCM is the possibility of reformulating former taxonomic concepts to propose robust classifications based on a detailed understanding of population structure and phenotypic variation of plant groups under investigation. In this review, special attention is paid to FCM as applied to Botany studies, and some new and less wellknown uses of it for plants will be discussed. It is likely that in the future the use of FCM in studies on taxonomy, ecology and population biology of plants will increase both in scope and frequency. Flow cytometry alone, but especially in combination with other molecular and phenotypic approaches, promises advances in our understanding of the functional significance of variation in genome size in plants

An effective tool in the study of botany: flow cytometry

Over the last decade there has been a tremendous increase in the use of flow cytometry (FCM) in studies on the biosystematics, ecology and population biology of vascular plants. Most studies, address questions related to spatial distribution and evolutionary significance of genome duplication (polyploidy), chromosomal variation (aneuploidy) and variation in genome size. The unsurpassed speed and reliability of estimating differences in nuclear DNA content by FCM paves the way for large-scale surveys at the landscape, population, individual and tissue levels. Another attractive feature of FCM is the possibility of reformulating former taxonomic concepts to propose robust classifications based on a detailed understanding of population structure and phenotypic variation of plant groups under investigation. In this review, special attention is paid to FCM as applied to Botany studies, and some new and less wellknown uses of it for plants will be discussed. It is likely that in the future the use of FCM in studies on taxonomy, ecology and population biology of plants will increase both in scope and frequency. Flow cytometry alone, but especially in combination with other molecular and phenotypic approaches, promises advances in our understanding of the functional significance of variation in genome size in plants