RESUMEN
Rhizobium leguminosarum has been widely used as a model to study nodule biochemistry, its genomic sequence has been published. We screened the Rhizobium leguminosarum bv. viciae 3841 genome sequence using a bioinformatics analysis for discovering potential small non-coding RNAs. One of these identified non-coding RNAs, cis-encoded antisense RLS1, was found to affect the symbiotic nodulation and nitrogen fixation. The mature form of RLS1 was 258 nt of non-coding RNA, its disruption mutant strain (â³RLS1) caused that the nodulation stages were delayed dramatically and the total number of nodules decreased, leading to a 25% reduction in the total amount of nitrogen fixed in the symbiotic system of Rhizobium- Pisum sativum, compared with wild-type strain. RLS1 targets an ABC transporter mRNA, bind to Hfq in vitro, and to be stable in the absence of Hfq. Further analysis showed that Hfq is not required for interactions between RLS1 and its target mRNAs. â³RLS1 strain exhibited that its production of extracellular polysaccharide (EPS) was over three times higher than in wild-type strain. The findings suggest that RLS1 might affect nodulation by participating in the regulatory network for EPS accurate secretion, playing a pivotal role in the infection process and in root nodule formation.
Asunto(s)
Rhizobium leguminosarum , Rhizobium , Transportadoras de Casetes de Unión a ATP/genética , Fijación del Nitrógeno/genética , ARN no Traducido , Rhizobium/genética , Rhizobium leguminosarum/genética , Simbiosis/genéticaRESUMEN
BACKGROUND: Brassica rapa includes several important leaf vegetable crops whose production is often damaged by high temperature. Cis-natural antisense transcripts (cis-NATs) and cis-NATs-derived small interfering RNAs (nat-siRNAs) play important roles in plant development and stress responses. However, genome-wide cis-NATs in B. rapa are not known. The NATs and nat-siRNAs that respond to heat stress have never been well studied in B. rapa. Here, we took advantage of RNA-seq and small RNA (sRNA) deep sequencing technology to identify cis-NATs and heat responsive nat-siRNAs in B. rapa. RESULTS: Analyses of four RNA sequencing datasets revealed 1031 cis-NATs B. rapa ssp. chinensis cv Wut and B. rapa ssp. pekinensis cv. Bre. Based on sequence homology between Arabidopsis thaliana and B. rapa, 303 conserved cis-NATs in B. rapa were found to correspond to 280 cis-NATs in Arabidopsis; the remaining 728 novel cis-NATs were identified as Brassica-specific ones. Using six sRNA libraries, 4846 nat-siRNAs derived from 150 cis-NATs were detected. Differential expression analysis revealed that nat-siRNAs derived from 12 cis-NATs were responsive to heat stress, and most of them showed strand bias. Real-time PCR indicated that most of the transcripts generating heat-responsive nat-siRNAs were upregulated under heat stress, while the transcripts from the opposite strands of the same loci were downregulated. CONCLUSIONS: Our results provide the first subsets of genome-wide cis-NATs and heat-responsive nat-siRNAs in B. rapa; these sRNAs are potentially useful for the genetic improvement of heat tolerance in B. rapa and other crops.
Asunto(s)
Brassica/genética , Regulación de la Expresión Génica de las Plantas , ARN sin Sentido/genética , ARN Interferente Pequeño/genética , Calor , Reacción en Cadena en Tiempo Real de la PolimerasaRESUMEN
Many higher plants must experience a period of winter cold to accomplish the transition from vegetative to reproductive growth. This biological process is called vernalization. Some crops such as wheat (Triticum aestivum L.) and oilseed rape (Brassica napus L.) produce seeds as edible organs, and therefore special measures of rotation and cultivation are necessary for plants to go through an early vernalization for flower differentiation and development, whereas the other crops such as Chinese cabbage (B rapa ssp. pekinenesis) and cabbage (Brassica napus L.) produce leafy heads as edible organs, and additional practice should be taken to avoid vernalization for a prolonged and fully vegetative growth. Before vernalization, flowering is repressed by the action of a gene called Flowering Locus C (FLC). This paper reviewed the function of non-coding RNAs and some proteins including VRN1, VRN2, and VIN3 in epigenetic regulation of FLC during vernalization.