Hemibiotrophic Phytophthora infestans Modulates the Expression of SWEET Genes in Potato (Solanum tuberosum L.).

Sugar Efflux transporters (SWEET) are involved in diverse biological processes of plants. Pathogens have exploited them for nutritional gain and subsequently promote disease progression. Recent studies have implied the involvement of potato SWEET genes in the most devastating late blight disease caused by Phytophthora infestans. Here, we identified and designated 37 putative SWEET genes as StSWEET in potato. We performed detailed in silico analysis, including gene structure, conserved domains, and phylogenetic relationship. Publicly available RNA-seq data was harnessed to retrieve the expression profiles of SWEET genes. The late blight-responsive SWEET genes were identified from the RNA-seq data and then validated using quantitative real-time PCR. The SWEET gene expression was studied along with the biotrophic (SNE1) and necrotrophic (PiNPP1) marker genes of P. infestans. Furthermore, we explored the co-localization of P. infestans resistance loci and SWEET genes. The results indicated that nine transporter genes were responsive to the P. infestans in potato. Among these, six transporters, namely StSWEET10, 12, 18, 27, 29, and 31, showed increased expression after P. infestans inoculation. Interestingly, the observed expression levels aligned with the life cycle of P. infestans, wherein expression of these genes remained upregulated during the biotrophic phase and decreased later on. In contrast, StSWEET13, 14, and 32 didn't show upregulation in inoculated samples suggesting non-targeting by pathogens. This study underscores these transporters as prime P. infestans targets in potato late blight, pivotal in disease progression, and potential candidates for engineering blight-resistant potato genotypes.

Isolation and functional validation of stress tolerant EaMYB18 gene and its comparative physio-biochemical analysis with transgenic tobacco plants overexpressing SoMYB18 and SsMYB18.

MYB transcription factors are one of the most important mediators for the survival of plants under multiple stress responses. In the present study, EaMYB18, encoding a single R3 repeat MYB DNA binding domain was isolated from stress-tolerant wild relative species of sugarcane Erianthus arundinaceus. In silico analysis of 948 bp coding mRNA sequence of EaMYB18 exhibited the presence of four exons and three introns. Further, the EaMYB18 gene was transformed in tobacco and its stable inheritance was confirmed through antibiotic resistance screening, PCR amplification and Southern hybridization blotting. Results of the estimation of MDA, proline, total chlorophyll and antioxidant activities of EaMYB18 transgenic tobacco lines exhibited least oxidative damage under drought and cold stress over the untransformed ones, the over-expression of EaMYB18 has improved drought and cold stress tolerance ability in tobacco. The comparative physiological and biochemical analysis of transgenic tobacco plants overexpressing SoMYB18, SsMYB18 and EaMYB18, revealed that the EaMYB18 and SsMYB18 transgenic plants demonstrated effective tolerance to drought and cold stresses, while SoMYB18 showed improved tolerance to salt stress alone. Amongst these three genes, EaMYB18 displayed the highest potential for drought and cold stress tolerances as compared to SoMYB18 and SsMYB18 genes.

Biochemical characterization and identification of differentially expressed candidate genes in salt stressed sugarcane.

Sugarcane productivity is worldwide subjected to increasing environmental constraints, predominantly to drought and salinity owing to their high magnitude of impact and wide distribution. The present study provides insights into the knowledge of sugarcane responses at germination, tillering and respective recovery stages to high salinity at physio-biochemical and molecular level. Our results indicated that there was a negative relationship between catalase, and peroxidase activity with lipid peroxidation and SOD activity. Increase in MDA and SOD levels at the earlier stages of stress and later increase in CAT and POD levels on prolonged stress was evidenced. Thus they can be used as indicators of stress for sugarcane plants facing unfavourable environmental conditions. At molecular level, we have identified 137 salinity tolerant candidate cDNAs from sugarcane by cDNA-SSH, representing 20% of which are novel sugarcane genes. These unique sequences, never reported elsewhere to be stress related and might provide further understanding on perception, response and adaptations mechanisms of the non-model plant like sugarcane to salinity stress and will be potential candidates for manipulating salt tolerant trait.