Effect of strigolactone on growth, photosynthetic efficiency, antioxidant activity, and osmolytes accumulation in different maize (Zea mays L.) hybrids grown under drought stress.

Drought alters plant physiology, morphology, and biochemical pathways, necessitating effective mitigation strategies. Strigolactones (SLs) are phytohormones known to enhance plant growth under abiotic stress. However, their specific impact on drought stress in maize remains unclear. This study aimed to determine the optimal SL concentration for mitigating drought stress in two maize hybrids (HY-1898, FH-1046). Maize plants were subjected to 60% field capacity drought stress in a pot experiment. After 40 d, different concentrations (0, 0.001, 0.01, and 0.1 mg L-1) of the synthetic SL analogue GR24 were applied to evaluate their effects on growth features, photosynthesis attributes, and osmolyte accumulation in the maize hybrids. Results showed that exogenous SL application significantly increased photosynthetic pigments in maize hybrids under drought stress. Chlorophyll content, gas exchange characteristics, net CO2 assimilation rate, stomatal conductance, water use efficiency, and antioxidant activities were enhanced by GR24. Leaf ascorbic acid and total phenolics also increased with SL application. Organic osmolytes, such as glycine betaine and free proline, were elevated in both maize hybrids under drought stress. Yield-related parameters, including cob diameter, cob weight, number of seeds per cob, and number of seeds per plant, were significantly increased by GR24 under drought stress. Our findings highlight the potential of GR24 foliar application to mitigate drought stress and promote maize growth and grain yield in a concentration-dependent manner. The minimum effective SL concentration against drought stress was determined to be 0.01 mg L-1. Overall, foliar application of GR24 could serve as a sustainable approach for drought tolerance in agriculture.

Study of the responses of two biomonitor plant species (Datura alba & Ricinus communis) to roadside air pollution.

Various physiological and biochemical responses of two good biomonitor plant species i.e. Datura alba and Ricinus communis were studied along two roads in the Punjab, Pakistan. Chlorophyll a, b, total chlorophylls, carotenoids, total free amino acids, total soluble proteins, total antioxidant activity, stomatal conductance, photosynthetic rate, internal CO2 concentration, transpiration rate, and water use efficiency of D. alba and R. communis were examined at different sites along both roads. Photosynthetic rate of both plant species was found to be affected. Reduced transpiration rate and stomatal conductance were also noted. However, elevated internal CO2 concentration and water use efficiency were recorded. Total soluble proteins got reduced, but, we found a tremendous increase in total antioxidant activity and total free amino acids in both plant species. D. alba was found to be more affected by the adverse effects of roadside air borne pollutants. Although R. communis was also affected but it showed minimal variation in all parameters compared to the control. Hence, our results suggest that R. communis is more resistant to urban roadside air pollution compared to D. alba and would be a good choice as phytoremediator of traffic borne pollutants, whereas, D. alba could be a better biomonitoring plant.

Perspective Research Progress in Cold Responses of Capsella bursa-pastoris.

Plants respond to cold stress by modulating biochemical pathways and array of molecular events. Plant morphology is also affected by the onset of cold conditions culminating at repression in growth as well as yield reduction. As a preventive measure, cascades of complex signal transduction pathways are employed that permit plants to endure freezing or chilling periods. The signaling pathways and related events are regulated by the plant hormonal activity. Recent investigations have provided a prospective understanding about plant response to cold stress by means of developmental pathways e.g., moderate growth involved in cold tolerance. Cold acclimation assays and bioinformatics analyses have revealed the role of potential transcription factors and expression of genes like CBF, COR in response to low temperature stress. Capsella bursa-pastoris is a considerable model plant system for evolutionary and developmental studies. On different occasions it has been proved that C. bursa-pastoris is more capable of tolerating cold than A. thaliana. But, the mechanism for enhanced low or freezing temperature tolerance is still not clear and demands intensive research. Additionally, identification and validation of cold responsive genes in this candidate plant species is imperative for plant stress physiology and molecular breeding studies to improve cold tolerance in crops. We have analyzed the role of different genes and hormones in regulating plant cold resistance with special reference to C. bursa-pastoris. Review of collected data displays potential ability of Capsella as model plant for improvement in cold stress regulation. Information is summarized on cold stress signaling by hormonal control which highlights the substantial achievements and designate gaps that still happen in our understanding.