Genomic dissection of ROS detoxifying enzyme encoding genes for their role in antioxidative defense mechanism against Tomato leaf curl New Delhi virus infection in tomato.

In the present study, genes encoding for six major classes of enzymatic antioxidants, namely superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), Peroxidase (Prx) and glutathione S-transferase (GST) are identified in tomato. Their expression was studied in tomato cultivars contrastingly tolerant to ToLCNDV during virus infection and different hormone treatments. Significant upregulation of SlGR3, SlPrx25, SlPrx75, SlPrx95, SlGST44, and SlGST96 was observed in the tolerant cultivar during disease infection. Virus-induced gene silencing of SlGR3 in the tolerant cultivar conferred disease susceptibility to the knock-down line, and higher accumulation (~80%) of viral DNA was observed in the tolerant cultivar. Further, subcellular localization of SlGR3 showed its presence in cytoplasm, and its enzymatic activity was found to be increased (~65%) during ToLCNDV infection. Knock-down lines showed ~3- and 3.5-fold reduction in GR activity, which altogether underlines that SlGR3 is vital component of the defense mechanism against ToLCNDV infection.

Genomic dissection and expression analysis of stress-responsive genes in C4 panicoid models, Setaria italica and Setaria viridis.

The study reports the identification and expression profiling of five major classes of C4 pathway-specific genes, namely, carbonic anhydrase (CaH), phosphoenolpyruvate carboxylase (PEPC), pyruvate orthophosphate dikinase (PPDK), NADP-dependent malate dehydrogenase (MDH) and NADP-dependent malic enzyme (NADP-ME), in the model species, Setaria italica and Setaria viridis. A total of 42 and 41 genes were identified in S. italica and S. viridis, respectively. Further analysis revealed that segmental and tandem duplications have contributed to the expansion of these gene families. RNA-Seq derived expression profiles of the gene family members showed their differential expression pattern in tissues and dehydration stress. Comparative genome mapping and Ks dating provided insights into their duplication and divergence in the course of evolution. Expression profiling of candidate genes in contrasting S. italica cultivars subjected to abiotic stresses and hormone treatments showed distinct stress-specific upregulation of SiαCaH1, SißCaH5, SiPEPC2, SiPPDK2, SiMDH8, and SiNADP-ME5 in the tolerant cultivar. Overexpression of SiNADP-ME5 in heterologous yeast system enabled the transgenic cells to survive and grow in dehydration stress conditions, which highlights the putative role of SiNADP-ME5 in conferring tolerance to dehydration stress. Altogether, the study highlights key genes that could be potential candidates for elucidating their functional roles in abiotic stress response.

Identification, characterization, expression profiling, and virus-induced gene silencing of armadillo repeat-containing proteins in tomato suggest their involvement in tomato leaf curl New Delhi virus resistance.

Armadillo repeat family is well-characterized in several plant species for their involvement in multiple regulatory processes including growth, development, and stress response. We have previously shown a three-fold higher expression of ARM protein-encoding in tomato cultivar tolerant to tomato leaf curl New Delhi virus (ToLCNDV) compared to susceptible cultivar upon virus infection. This suggests the putative involvement of ARM proteins in defense response against virus infection; however, no comprehensive investigation has been performed to address this inference. In the present study, we have identified a total of 46 ARM-repeat proteins (SlARMs), and 41 U-box-containing proteins (SlPUBs) in tomato. These proteins and their corresponding genes were studied for their physicochemical properties, gene structure, domain architecture, chromosomal localization, phylogeny, and cis-regulatory elements in the upstream promoter region. Expression profiling of candidate genes in response to ToLCNDV infection in contrasting tomato cultivars showed significant upregulation of SlARM18 in the tolerant cultivar. Virus-induced gene silencing of SlARM18 in the tolerant tomato cultivar conferred susceptibility, which suggests the involvement of this gene in resistance mechanism. Further studies are underway to functionally characterize SlARM18 to delineate its precise role in defense mechanism.