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Chromatin-remodeling factors regulate the establishment of transcriptional programs during plant development. Although 42 genes encoding members of the SWI2/SNF2 family have been identified in Arabidopsis thaliana, imitation of switch proteins | megagametophyte | RNA interference | seed development | functional megaspore

In plants, the outer epidermal cell wall and cuticle presents a semipermeable barrier that maintains the external integrity of the plant and regulates the passage of various classes of molecules into and out of the organism. During vegetative development, the epidermal cells remain relatively inert, failing to respond to wounding or grafting. During reproductive development and fertilization, however, the epidermis is developmentally more labile and participates in two types of contact-mediated cell interactions: organ fusion and pollen hydration. Here we describe the isolation and characterization of one gene whose product normally functions in blocking both types of epidermal cell interactions during vegetative development: the FIDDLEHEAD gene. As suggested by previous biochemical analyses, the gene encodes a protein that is probably involved in the synthesis of long-chain lipids found in the cuticle and shows similarity to a large class of genes encoding proteins related to [Beta]-ketoacyl-CoA synthases and chalcone synthases. In situ hybridization reveals an epidermal pattern of expression consistent with a role for this protein in the synthesis of lipid components that are thought to localize extracellularly and probably modify the properties of the cuticle.

The article presents a study of the earliest maize from San Marcos Tehuacán in Mexico. It suggests that the earliest maize from San Marcos was a partial domesticate from landraces with ancestral allelic variants suggestive of inbreeding and potential evolution of maize cultivation from reduced founder populations of isolated and self-pollinated individuals.

Efforts to understand the phenotypic transition that gave rise to maize from teosinte have mainly focused on the analysis of aerial organs, with little insights into possible domestication traits affecting the root system. Archeological excavations in San Marcos cave (Tehuacán, Mexico) yielded two well-preserved 5,300 to 4,970 calibrated y B.P. specimens (SM3 and SM11) corresponding to root stalks composed of at least five nodes with multiple nodal roots and, in case, a complete embryonic root system. To characterize in detail their architecture and anatomy, we used laser ablation tomography to reconstruct a three-dimensional segment of their nodal roots and a scutellar node, revealing exquisite preservation of the inner tissue and cell organization and providing reliable morphometric parameters for cellular characteristics of the stele and cortex. Whereas SM3 showed multiple cortical sclerenchyma typical of extant maize, the scutellar node of the SM11 embryonic root system completely lacked seminal roots, an attribute found in extant teosinte and in two specific maize mutants: root with undetectable meristem1 (rum1) and rootless concerning crown and seminal roots (rtcs). Ancient DNA sequences of SM10—a third San Marcos specimen of equivalent age to SM3 and SM11—revealed the presence of mutations in the transcribed sequence of both genes, offering the possibility for some of these mutations to be involved in the lack of seminal roots of the ancient specimens. Our results indicate that the root system of the earliest maize from Tehuacán resembled teosinte in traits important for maize drought adaptation.