Biology subjects

Chandran, A. K. N.

Publications and source records attributed to Chandran, A. K. N..

2 recordsLinked to original sources

bioRxiv2026

OsRAD23a negatively regulates salt tolerance and phosphorus uptake in rice

Salinity stress affects rice productivity due to reduced growth and sodium ion toxicity. Previously, we identified a splice variant of RADIATION SENSITIVE23a (RAD23a) as the potential basis for variation in salt-tolerance in rice germplasm. RAD23 is a known moonlighting protein associated with protein degradation. To validate the role of RAD23a in salt stress response, we characterized gene edited mutant lines that targeted the UBL and UBA2 domains of this protein. Mutation in either domain promoted shoot growth under saline and control conditions. The mutants also differed from wildtype plants in Na and K accumulation in roots and shoots under salt stress. Transcriptome analysis of mutants versus wildtype showed differential transcript abundance of multiple inorganic phosphate (Pi) starvation related genes, including OsSPX2 and OsPHO2. As a result, mutants accumulate higher Pi compared to wildtype plants. The two allelic groups for RAD23a locus also differ in root and shoot phosphorus (P) content. Further, we show that RAD23a interacts with OsSPX2, a negative post-translational regulator of OsPHR2, the master regulator of Pi starvation response. Mutants have higher shoot growth and Pi levels under low Pi conditions, linking enhanced growth of mutants to increased Pi uptake. The UBA2 domain specific mutants have higher single grain weight and per plant grain weight than wildtype. In summary, we show that the RAD23a regulates differential growth, salt response and Pi uptake in rice in a domain-specific manner supporting the moonlighting roles of RAD23a in salt tolerance and phosphorus-dependent shoot growth.

plant biology↗

bioRxiv2024

Transcriptome Enhanced Rice Grain Metabolic Model Identifies Histidine Level as a Marker for Grain Chalkiness

Rising temperatures due to global warming can negatively impact rice grain quality and yield. This study investigates the effects of increased warmer night temperatures (WNT), a consequence of global warming, on the quality of rice kernel, particularly grain chalkiness. By integrating computational and experimental approaches, we used a rice grain metabolic network to discover the metabolic factors of chalkiness. For this, we reconstructed the rice grain genome-scale metabolic model (GSM), iOSA3474-G and incorporated transcriptomics data from three different times of the day (dawn, dawn 7h, and dusk) for both control and WNT conditions with iOSA3474-G. Three distinct growth phases: anoxia, normoxia, and hyperoxia, were identified in rice kernels from the GSMs, highlighting the grain-filling pattern under varying oxygen levels. We predicted histidine as a marker of normoxia, during which kernel chalkiness occurs. Moreover, we proposed tyrosine as a marker for the hyperoxic growth phase. We also proposed a potential link between monodehydroascorbate reductase, an enzyme with evolutionary significance dating back to the carboniferous era, in regulating the hyperoxic growth phase. Metabolic bottleneck analysis identified nucleoside diphosphate kinase as a central regulator of metabolic flux under different conditions. These findings provide targeted insights into the complex metabolic network governing rice grain chalkiness under WNT conditions. Integration of GSM and transcriptomics data, enhanced our understanding of the intricate relationship between environmental factors, metabolic processes, and grain quality and also offer markers that can be useful to develop rice with improved resilience.

systems biology↗