Seed priming and foliar application with jasmonic acid enhance salinity stress tolerance of soybean (Glycine max L.) seedlings

Abstract

BACKGROUND Jasmonic acid (JA) is an important molecule that has a regulatory effect on many physiological processes in plant growth and development under abiotic stress. This study investigated the effect of 60 μmol L−1 of JA in seed priming (P) at 15 °C in darkness for 24 h, foliar application (F), and/or their combination effect (P + F) on two soybean cultivars – ‘Nannong 99‑6’ (salt tolerant) and ‘Lee 68’ (salt sensitive) – under salinity stress (100 mmol L−1 sodium chloride (NaCl)). RESULTS Salinity stress reduced seedling growth and biomass compared with that in the control condition. Priming and foliar application with JA and/or their combination significantly improved water potential, osmotic potential, water use efficiency, and relative water content of both cultivars under salinity stress. Similarly, seed priming with JA, foliar application of JA, and/or their combination significantly improved the following properties under salinity stress compared with the untreated seedlings: net photosynthetic rate by 68.03%, 59.85%, and 76.67% respectively; transpiration rate by 74.85%, 55.10%, and 80.26% respectively; stomatal conductance by 69.88%, 78.25%, and 26.24% respectively; intercellular carbon dioxide concentration by 61.64%, 40.06%, and 65.79% respectively; and total chlorophyll content by 47.41%, 41.02%, and 55.73% respectively. Soybean plants primed, sprayed with JA, or treated with their combination enhanced the chlorophyll fluorescence, which was damaged by salinity stress. JA treatments improved abscisic acid, gibberellic acid, and JA levels by 60.57%, 62.50% and 52.25% respectively under salt stress compared with those in the control condition. The transcriptional levels of the FeSOD, POD, CAT, and APX genes increased significantly in the NaCl‐stressed seedlings irrespective of JA treatments. Moreover, JA treatment resulted in a reduction of sodium ion concentration and an increase of potassium ion concentrations in the leaf and root of both cultivars regardless of salinity stress. Monodehydroascorbate reductase, dehydroascorbate reductase, and proline contents decreased in the seedlings treated with JA under salinity stress, whereas the ascorbate content increased with JA treatment combined with NaCl stress. CONCLUSION The application of 60 μmol L−1 JA improved plant growth by regulating the interaction between plant hormones and hydrogen peroxide, which may be involved in auxin signaling and stomatal closure under salt stress. These methods could efficiently protect early seedlings and alleviate salt stress damage and provide possibilities for use in improving soybean growth and inducing tolerance against excessive soil salinity. © 2020 Society of Chemical Industry

Arbuscular Mycorrhizae Mitigate Aluminum Toxicity and Regulate Proline Metabolism in Plants Grown in Acidic Soil

“…As such, Al interferes with light absorption, electron transport, gas exchange, pigments, carbohydrates, photo-protective systems, photosynthetic enzymes, and CO 2 assimilation [ 49 , 50 , 51 ]. A previous study demonstrated that AMF improve the growth and photosynthesis rate of C4 ( Hemarthria altissima ) and C3 ( Leymus chinensis ) species via promoting their ROS-scavenging systems [ 52 , 53 ] or by accumulating greater osmoprotectants, such as Pro [ 54 ]. In the present study, lotus and barley plants differentially responded to Al stress, where the photosynthetic rate of barley was more affected compared with that of lotus.…”

“…However, for lotus plants, the average values of dry mass and rate of photosynthesis reduced by only 46% and 53%, respectively. Interestingly, AMF diminished the inhibition role of Al stress in both plant species ( Table 2 ); therefore, biomass production increased under the effect of AMF–plant symbiosis, which might be due to the potentiality of AMF to increase nutrient uptake [ 53 ]. Moreover, the use of photosynthates could contribute to increasing the hyphal growth of AMF, which ensure symbiotic Pi acquisition by the host plant under Al stress, which, in turn, helps in maintenance of photosynthesis and C flow to the root system [ 20 ].…”

Function and Mechanism of Jasmonic Acid in Plant Responses to Abiotic and Biotic Stresses

“…JA effectively protected wheat seedlings from salt stress damage by enhancing antioxidant enzyme activity and antioxidative compound concentrations [141]. Foliar JA application enhanced salinity stress tolerance in soybean (Glycine max L.) seedlings under salt stress, possibly through the regulation of auxin signaling and stomatal closure [142]. However, the combination of salinity and MeJA intensified plant growth inhibition and senescence [143].…”

Physiological and biochemical responses of soybean plants inoculated with Arbuscular mycorrhizal fungi and Bradyrhizobium under drought stress

“…Soybean ( Glycine max L.) is an important legume crop and consider one of the most valuable oilseed crops in the world, being contains about 18–22% cholesterol-free oil with 85% unsaturated fatty acids and 40–42% protein [ 2 , 3 ]. Recent studies reported that adequate water supply are needed for soybean production to achieve high yield [ 4 , 5 ]. However, plants can tolerate water stress only up to a certain limit (threshold level) and beyond that limit, there is a severe decline in yield [ 6 ].…”