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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To understand the molecular stress response in maize plants to high salt and boron (B) stress, we focused on the transcript accumulation of six stress-related genes in Lluteño maize, a sweet corn landrace from the Lluta valley (northern Chile). This landrace is tolerant to salt and B stress. A randomized complete block design with four replications was used. Seedlings of Lluteño maize and maize hybrid B73 were exposed to 150 mM NaCl and 20 ppm B in nutrient solution for 120 hrs, then root and leaf samples were collected and Na + and B content were determined. Transcript accumulation of three salt stress-related genes SOS1, NHX2 and HKT1 and three B stress-related genes BOR1, BOR2 and PIP1;2 were determined in roots and leaves of Lluteño maize using RT-PCR and real-time PCR at 3 and 96 h after treatment with 150 mM NaCl and/or 20 ppm B. The results indicated that combined salt and B stress caused changes in physiological parameters. The damage was more severe in B73 than in Lluteño maize, confirming that this landrace behaves as a plant tolerant to these stresses. Regulation of stress-related genes under combined stress was different under individual stresses. The ability of Lluteño maize to survive and thrive in soil with high salinity and B concentration is probably based on a decrease in membrane water permeability, preventing salt and B uptake from the roots through down-regulation of BOR1, BOR2 transporters and PIP1;2 aquaporin. The increased water transport is mediated by the upregulation of the PIP1;2 in leaves, allowing cellular water conservation, and the retrieval of Na + from xylem through up-regulation of HKT1;1 transporters in roots and leaves.

Amphigenous black pulvinate basidiomata were abundant on the leaf blades and rachides, causing extensive foliar damage. The samples were examined by a light microscope after three days in a humid chamber. In addition, the molecular tools scanning electron microscopy and histological sectioning were used to study the fungal/host relationship, complementing the identification. Morphometric and molecular characteristics led to the identification of the fungus as Graphiola phoenicis causing false smut on the Canary date palms (Phoenix canariensis). This is the first report of this plant pathogen in Chilean territory. Keywords Materials and methods Plant Sample and morphologic identificationIn January 2015, a random sample of diseased leaves from palms of P. canariensis was collected in Hanga Roa, Avenue Atanu Tekena (27° 09'08.48"S; 109° 25'53.52"W; 28 masl). Symptoms were characterized initially by very small yellow lesions that turned dark brown in the center with fuzzy edges, affecting primarily the oldest leaves. Lesions appeared isolated or else grouped on both side of the leaves. Morphometric studies were conducted on additional herbarium samples of diseased leaves, and micrometric leaf sections were obtained for optical microscope observations. Sections of approximately 0.25 cm 2 were obtained for environmental scanning electron microscope (SEM) observations in an EVO LS 10 microscope (Carl Zeiss, Germany), placed in aluminum sample holders with carbon-contact-bearing adhesives, and analyzed under vacuum with variable pressure mode (VP) (chamber pressure 150 Pa (under vacuum) and column 2×10 -5 Torr (high vacuum)). The working distance (WD) varied depending on the sample type. The acceleration voltage was 15 KV, the tilt was 0° to 90°, and the images were taken with a resolution of 3.024 × 2.304 pixels at a scanning speed of 12 min 54 s. Molecular identificationFor molecular identification, dark lesions on foliar pinnae were collected, and DNA extraction was successful using an E.Z.N.A.® Insect DNA Kit (Omega Bio-Tek, Georgia, EEUU) according to the manufacturer's instructions. Subsequently, the internal transcribed spacer region (ITS) and the D1/ D2 domain of the large subunit ribosomal DNA 28S (LSU rDNA) were amplified using primers ITS4 (5'-TCCTCCGCTTATTGATATGC-3) and ITS1 (5'-TGAACCTGCAGAAGGATCATTA-3') (White et al., 1990;Barnes and Szabo, 2007) as well as NL1m (5'-GCATATCAATAAGCGGAGGAAAAG-3') and NL-4m (5'-GGTCCGTGTTTCAAGACG-3') (O'Donnell, 1993). PCR amplifications of the LSU and ITS rDNA were performed in a final volume of 20 μL. The reactions contained 1 µL of DNA extract; 5 p moles of each primers; 2.5 mM each dNTP; 2 mM MgCl2; 1X PCR buffer (KCl); 1 unit of Taq DNA polymerase (Thermo Scientific) and sterile distilled water. Cycling conditions were 5 min at 94 °C; 35 cycles of 1 min at 94 °C, 1 min at 55 °C and 1 min at 72 °C; and a final elongation step of 2 min at 72 °C. PCR blank reaction controls were incorporated. Each PCR product (3 μL) was visualized on a 1.5% agarose gel stained with gelred ...

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