Proline induces heat tolerance in chickpea (Cicer arietinum L.) plants by protecting vital enzymes of carbon and antioxidative metabolism

Abstract

Chickpea is a heat sensitive crop hence its potential yield is considerably reduced under high temperatures exceeding 35°C. In the present study, we evaluated the efficacy of proline in countering the damage caused by heat stress to growth and to enzymes of carbon and antioxidative metabolism in chickpea. The chickpea seeds were raised without (control) and with proline (10 μM) at temperatures of 30/25°C, 35/30°C, 40/35°C and 45/40°C as day/ night (12 h/12 h) in a growth chamber. The shoot and root length at 40/35°C decreased by 46 and 37 %, respectively over control while at 45/40°C, a decrease of 63 and 47 %, respectively over control was observed. In the plants growing in the presence of 10 μM proline at 40/35°C and 45/40°C, the shoot length showed improvement of 32 and 53 %, respectively over untreated plants, while the root growth was improved by 22 and 26 %, respectively. The stress injury (as membrane damage) increased with elevation of temperatures while cellular respiration, chlorophyll content and relative leaf water content reduced as the temperature increased to 45/40°C. The endogenous proline was elevated to 46 μmol g −1 dw at 40/35°C but declined to 19 μmol g −1 dw in plants growing at 45/40°C that was associated with considerable inhibition of growth at this temperature. The oxidative damage measured as malondialdehyde and hydrogen peroxide content increased manifolds in heat stressed plants coupled with inhibition in the activities of enzymatic (superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase) and levels of non-enzymatic (ascorbic acid, glutathione, proline) antioxidants. The enzymes associated with carbon fixation (RUBISCO), sucrose synthesis (sucrose phosphate synthase) and sucrose hydrolysis (invertase) were strongly inhibited at 45/40°C. The plants growing in the presence of proline accumulated proline up to 63 μmol g −1 dw and showed less injury to membranes, had improved content of chlorophyll and water, especially at 45/40°C. Additionally, the oxidative injury was significantly reduced coupled with elevated levels of enzymatic and non-enzymatic antioxidants. A significant improvement was also noticed in the activities of enzymes of carbon metabolism in proline-treated plants. We report here that proline imparts partial heat tolerance to chickpea's growth by reducing the cellular injury and protection of some vital enzymes related to carbon and oxidative metabolism and exogenous application of proline appears to have a countering effect against elevated high temperatures on chickpea.

Responses to drought induced oxidative stress in five finger millet varieties differing in their geographical distribution

“…Lowest CSI was recorded for the varieties PES400 (67.65 %) and VR708 (70.07 %), which indicates a susceptible character to drought. H 2 O 2 is an important signaling molecule and its levels are kept under check by a battery of H 2 O 2 metabolizing enzymes (Kaushal et al 2011). Any increase in H 2 O 2 has severe consequences for the affected cell.…”

Influence of osmoregulators on plant tolerance to water stress

“…Moreover, application of different osmoregulators as glycinebetaine (GB) or proline had a significant role on plant growth promotion and seed yield under normal or stress conditions as observed in some crops e.g., maize (Yang and Lu, 2006;Kaya et al,2013;Reddy et al, 2013),canola (Dawood and Sadak, 2014), rice (Mohammed and Tarpley, 2011), wheat (Raza et al, 2014), chickpea ( Kaushal et al,2011) and faba bean (Taie et al, 2013;.…”

“…There are several reports indicated that abiotic stress conditions trigger the accumulation of proline in plant tissues (Kaushal et al,2011;Hayat et al, 2012;Slama et al, 2014). Moreover, exogenous application of proline caused increases in its endogenous levels in plant tissues subjected to water stress conditions and induced plant tolerance (Ashraf and Foolad, 2007;Ali et al, 2008).…”

“…Several studies reported that exogenous proline application may improve the plant stress tolerance against different types of abiotic stresses such as drought (Ali et al, 2007;, salt (Hoque et al, 2007), chilling (Posmyk and Janas, 2007), and heat stress (Kaushal et al, 2011).…”

Heat shock increases oxidative stress to modulate growth and physico-chemical attributes in diverse maize cultivars

“…Proline, an amino acid, which is increased in response to diverse types of abiotic stresses (Kaushal et al, 2011), has several roles in turgor generation, osmotic adjustment, storage of carbon and nitrogen, and cellular redox potential. Furthermore, proline could maintain the enzyme structure and activity (Kaushal et al, 2011) and thus protect membrane integrity (Hayat et al, 2012).…”