ORIGINAL ARTICLE

Comparative Analysis of Stress Tolerance in Millets

Background: In the current scenario of a changing environment, climate resilient crops like Millets are promising. Various types of stress limit agricultural crop productivity and threaten food security. A comparative analysis of stress tolerance examines the ability of different millet varieties to withstand various environmental stresses like drought, cold, heat, flooding, rainfall, humidity, wind, light, radiation, elevated carbon-di-oxide, salinity, heavy metal, nutrient stress, etc. There are various morphological, physiological, biochemical and genetic characters (genes, transcription factors & proteins) present in millets contributing to their abiotic tolerance.

Results: Millet crops possess diverse adaptive mechanisms to combat abiotic stresses like elevated carbohydrate level, low Na+/K+ ratio, decreased relative water content (RWC), decreased chlorophyll levels, increased proline, betaine, increase in the phytohormones like ABA & Jasmonic acid. Millets follow the C4 type carbon fixation pathway. Key genes involved in climate resilience are DREB, LEA, HSP, SOD, ABF, CBF. Key proteins like catalases, peroxidases, aquaporins, Zinc finger, PR-proteins & transcription factors like MYB, NAM, NAC, WRKY, bHLH are involved in stress tolerance. The paper reports the study on evolutionary relationship of ABA responsive bZIP, WRKY, DREB and HSP transcription factors in millets (Eleusine, Setaria, Panicum, Cenchrus, Sorghum) and cereal grasses (Maize and Rice).

Conclusions: Millets (Eleusine, Setaria, Panicum) share strong evolutionary ties across all major stress related TF families. Cenchrus aligns with Panicum/ Setaria, but shows independent divergence in some TFs. Sorghum and Maize form a distinct cluster. Rice appears as a distant relative but useful as a reference but closely related to stress resilient millets.

Foxtail millet (Setaria italica) has excellent abiotic stress tolerance due to its efficient ROS scavenging mechanism. In Pearl millet (Cenchrus americanus/Pennisetum glaucum) drought responsive genes belong to 8 functional groups -ABA signaling, hormone signaling, ion and osmotic homeostasis, TF mediated regulation, molecular adaptation, signal transduction, physiological adaptations, detoxification. Finger millet (Eleusine coracana) is an important climate smart crop with nutraceutical potential grown for creating sustainability in feed and fodder.