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.