Chromatin-remodeling factors regulate the establishment of transcriptional programs during plant development. Although 42 genes encoding members of the SWI2͞SNF2 family have been identified in Arabidopsis thaliana, <10 have been assigned a precise function on the basis of a mutant phenotype, and none have been shown to play a specific role during the gametophytic phase of the plant life cycle. A. thaliana chromatin-remodeling protein 11 (CHR11) encodes an imitation of switch (ISWI)-like chromatin-remodeling protein abundantly expressed during female gametogenesis and embryogenesis in Arabidopsis. To determine the function of CHR11 in wild-type plants, we introduced a hairpin construct leading to the production of double-stranded RNA, which specifically degraded the endogenous CHR11 mRNA by RNA interference (RNAi). Transcription of the RNAi-inducing hairpin RNA was driven by either a constitutive cauliflower mosaic virus 35S promoter (CaMV35S) acting at most stages of the sporophytic phase or a newly identified specific promoter acting at the onset of the female gametophytic phase (pFM1). All adult transformants that constitutively lacked sporophytic CHR11 activity showed reduced plant height and small cotyledonary embryos with limited cell expansion. In contrast, RNAi lines in which CHR11 was specifically silenced at the onset of female gametogenesis (megagametogenesis) had normal height and embryo size but had defective female gametophytes arrested before the completion of the mitotic haploid nuclear divisions. These results show that CHR11 is essential for haploid nuclear proliferation during megagametogenesis and cell expansion during the sporophytic phase, demonstrating the functional versatility of SWI2͞SNF2 chromatinremodeling factors during both generations of the plant life cycle.imitation of switch proteins ͉ megagametophyte ͉ RNA interference ͉ seed development ͉ functional megaspore T he accessibility of DNA to transcription factors or other types of interacting molecules is regulated by enzymatic complexes that modify nucleosomal structure by means of ATP-dependent chromatin-remodeling or histone modification (1). ATPdependent chromatin-remodeling factors are multisubunit complexes that alter the chromatin structure by changing the conformational state of the nucleosome. These structural changes are accomplished without covalent modification and can be involved in either the activation or the repression of transcription (2). Members of the SWI2͞SNF2 family of ATP-dependent proteins share an ATPase domain that is essential for their chromatin-remodeling activity. In addition, SWI2͞SNF2 proteins have a large variety of Nand C-terminal domains that are often involved in their interaction with other members of specific chromatin-associated complexes. The largest eukaryotic group of SWI2͞SNF2, ATP-dependent, chromatin-remodeling proteins is the imitation of switch (ISWI) subfamily. Originally identified in Drosophila (3, 4), ISWI members are distinguished from other SWI2͞SNF2 proteins by the presence of t...

Long non-coding RNAs (lncRNAs) have been defined as transcripts longer than 200 nucleotides, which lack significant protein coding potential and possess critical roles in diverse cellular processes. Long non-coding RNAs have recently been functionally characterized in plant stress–response mechanisms. In the present study, we perform a comprehensive identification of lncRNAs in response to combined stress induced by salinity and excess of boron in the Lluteño maize, a tolerant maize landrace from Atacama Desert, Chile. We use deep RNA sequencing to identify a set of 48,345 different lncRNAs, of which 28,012 (58.1%) are conserved with other maize (B73, Mo17 or Palomero), with the remaining 41.9% belonging to potentially Lluteño exclusive lncRNA transcripts. According to B73 maize reference genome sequence, most Lluteño lncRNAs correspond to intergenic transcripts. Interestingly, Lluteño lncRNAs presents an unusual overall higher expression compared to protein coding genes under exposure to stressed conditions. In total, we identified 1710 putatively responsive to the combined stressed conditions of salt and boron exposure. We also identified a set of 848 stress responsive potential trans natural antisense transcripts (trans-NAT) lncRNAs, which seems to be regulating genes associated with regulation of transcription, response to stress, response to abiotic stimulus and participating of the nicotianamine metabolic process. Reverse transcription-quantitative PCR (RT-qPCR) experiments were performed in a subset of lncRNAs, validating their existence and expression patterns. Our results suggest that a diverse set of maize lncRNAs from leaves and roots is responsive to combined salt and boron stress, being the first effort to identify lncRNAs from a maize landrace adapted to extreme conditions such as the Atacama Desert. The information generated is a starting point to understand the genomic adaptabilities suffered by this maize to surpass this extremely stressed environment.

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ABSTRACT. In this study, we report a modified CTAB-PVP method combined with silicon dioxide (silica) treatment for the extraction of high quality genomic DNA from a single larva or pupa. This method efficiently obtains DNA from small specimens, which is difficult and challenging because of the small amount of starting tissue. Maceration with liquid nitrogen, phenol treatment, and the ethanol precipitation step are eliminated using this methodology. The A 260 /A 280 absorbance ratios of the isolated DNA were approximately 1.8, suggesting that the DNA is pure and can be used for further molecular analysis. The quality of the isolated DNA permits molecular applications and represents a fast, cheap, and effective alternative method for laboratories with low budgets.

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Although considered the driest desert in the world, the Atacama provides unique habitats and a reservoir of biodiversity for plants and insects. Caloptilia Hübner, 1825 (Gracillariinae), is a highly diverse genus of leaf miner micromoths that has not yet been recorded in Chile. In this study, we describe a new species of Caloptilia from a relict, vulnerable ecotone in the transverse valleys of the Atacama Desert in northern Chile. Adults, immature stages and natural history, including the mine of Caloptilia guacanivora Vargas-Ortiz & Vargas sp. nov., are described and illustrated. The larva is a leaf miner of the vulnerable, native, guacano tree Morella pavonis (Myricaceae). DNA barcode sequences were used to infer the specific status of C. guacanivora sp. nov. Results indicate that the new species is monophyletic with a genetic distance of around 5% to the nearest congener. We also used genetic variation to make preliminary inferences on the population structure and demography of this new taxon. This data revealed the presence of haplotypes shared among distant valleys, suggesting an ancient polymorphism that is widespread throughout populations in the region.

The adult, pupa, larva and biology of Adenogasteria leguminivora Davis & Vargas gen. et sp. nov. (Lepidoptera: Gracillariidae: Ornixolinae) from Peru and Chile are described and illustrated. This micromoth was previously reported in the agronomic literature as a pest of Caesalpinia spinosa (Molina) (Fabaceae) in Peru, but its taxonomic status remained unknown until now. Its larvae feed on the seeds of three legume trees: Acacia macracantha, C. spinosa and Inga feuillei. Adenogasteria leguminivora superficially resembles other sympatric gracillariids but can be separated on key morphological features and host plant preferences. Eggs of A. leguminivora are laid on the fruit surface, from where the larva burrows until it reaches the cotyledons, which are mined by the two early (sap‐feeding) instars and almost completely consumed by the last three (tissue‐feeding) instars. Subsequently, the mature larva leaves the fruit and constructs an elongated silk cocoon ornamented with a few silk bubbles before pupation. A maximum likelihood analysis of DNA barcodes clustered the A. leguminivora sequences as a single independent phylogenetic unit within Ornixolinae, sister to the Chileoptilia + Philodoria clade, regardless of the host plant and geographic origin of the samples. The genetic divergence of A. leguminivora to the nearest neighbour in COI barcodes was >10%.