Identification, characterization, and comprehensive expression profiling of floral master regulators in pigeon pea (Cajanus cajan [L.] Millspaugh).

Pigeon pea is an important protein-rich pulse crop. Identification of flowering master regulators in pigeon pea is highly imperative as indeterminacy and late flowering are impediments towards yield improvement. A genome-wide analysis was performed to explore flowering orthologous groups in pigeon pea. Among the 412 floral orthologs identified in pigeon pea, 148 genes belong to the meristem identity, photoperiod-responsive, and circadian clock-associated ortholog groups. Our comparative genomics study revealed purifying selection pressures (ka/ks) on floral orthologs, and duplication patterns and evolution through synteny with other model species. Phylogenetic analysis of floral genes substantiated a connection between pigeon pea plant architecture and flowering time as all the PEBP domain-containing genes belong to meristem identity floral networks of pigeon pea. Expression profiling of eleven major orthologs in contrasting determinate and indeterminate genotypes indicated that these orthologs might be involved in flowering regulation. Expression of floral inducer, FT, and floral repressor, TFL1, was non-comparable in indeterminate genotypes across all the developmental stages of pigeon pea. However, dynamic FT/TFL1 expression ratio detected in all tissues of both the genotypes suggested their role in floral transition. One TFL1 ortholog having high sequence conserveness across pigeon pea genotypes showed differential expression indicating genotype-dependent regulation of this ortholog. Presence of conserved 6mA-methylation patterns in light-responsive elements and in other cis-regulatory elements of FT and TFL1 across different plant genotypes indicated possible involvement of epigenetic regulation in flowering.

Identification of dynamic microRNA associated with systemic defence against Helicoverpa armigera infestation in Cajanus scarabaeoides.

BACKGROUND: Helicoverpa armigera is a major insect pest of several crop plants, including pigeonpea. Resistant gene sources are not available in the cultivated gene pool, but resistance has been observed in its crop wild relative, Cajanus scarabaeoides. Gene regulatory mechanisms governing the systemic immune response of this plant to pod borer infestation have not yet been deciphered. MicroRNA (miRNA) profiles of H. armigera-infested and undamaged adjacent leaves of C. scarabaeoides were compared to gain an insight into the plant-insect interactions and to identify dynamic miRNA molecules potentially acting as mediators of systemic defence responses. RESULTS: A total of 211 conserved, temporally dynamic miRNA were identified in the unfed adjacent leaves, out of which 98 were found to be differentially expressed in comparison to control leaves. On further analysis, most of the miRNA detected in the adjacent leaves was found to target genes involved in the defence pathways and plant immune response. An overlap of the differentially expressing miRNAs was observed between insect-fed and adjacent unfed leaves, indicating the transmission of signal from the site of infestation to the undamaged parts of the plant, indicative of induction of a systemic defence response. CONCLUSION: The miRNA response in the unfed leaves had the signatures of induced changes in metabolism and signal transduction for induction of defence pathway genes. This study reveals the participation of miRNAs in imparting pod borer resistance and mounting a systemic defence response against pod borer infestation in C. scarabaeoides. © 2022 Society of Chemical Industry.

Expression of Finger Millet EcDehydrin7 in Transgenic Tobacco Confers Tolerance to Drought Stress.

One of the critical alarming constraints for agriculture is water scarcity. In the current scenario, global warming due to climate change and unpredictable rainfall, drought is going to be a master player and possess a big threat to stagnating gene pool of staple food crops. So it is necessary to understand the mechanisms that enable the plants to cope with drought stress. In this study, effort was made to prospect the role of EcDehydrin7 protein from normalized cDNA library of drought tolerance finger millet in transgenic tobacco. Biochemical and molecular analyses of T0 transgenic plants were done for stress tolerance. Leaf disc assay, seed germination test, dehydration assay, and chlorophyll estimation showed EcDehydrin7 protein directly link to drought tolerance. Northern and qRT PCR analyses shows relatively high expression of EcDehydrin7 protein compare to wild type. T0 transgenic lines EcDehydrin7(11) and EcDehydrin7(15) shows superior expression among all lines under study. In summary, all results suggest that EcDehydrin7 protein has a remarkable role in drought tolerance and may be used for sustainable crop breeding program in other food crops.