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to battery driven (electric) mobility. While a multibillion-dollar industry has come up catering various needs, the manifold consumption of Li-based resources has led to steep price rise and concerns over future geo-political tension due to its nonuniform geographic distribution. To combat this imminent issue, various alternative battery chemistries (termed as "Beyond Li-ion batteries") are widely pursued, particularly to replace Li-ion batteries in applications unrestricted by gravimetric and/or volumetric energy density. In this case, sodium-ion batteries (NIBs) are touted as the emerging futuristic battery chemistry owing to the widespread availability of sodium-based resources and well-understood electrochemical operation involving the Na + charge carriers. [1][2][3][4][5] In the quest to build robust sodiumion batteries, various 2D layered transition metal oxides and 3D polyanionic framework materials have been unraveled. While the oxide cathodes can deliver high theoretical (and reversible) capacity, they suffer from lower redox potential owing to strong covalence nature. [6] It is more so acute in case of Na-ion batteries considering the higher potential of Na/Na + (−2.71 V vs normal hydrogen electrode (NHE)) vis-à-vis Li/Li + (−3.03 V vs NHE). This issue can be circumvented by implementing polyanionic cathode materials with tunable crystal structure, robust framework providing safe operation and higher redox potential due to inductive effect. [7,8] Following the inductive effect principle, plethora of cathodes with polyanionic units [(XO 4 ) m n− : X = B, P, Si, S, W, Mo, As, Ti, V, etc.] have been discovered both for Li-ion and Na-ion batteries. [9,10] Moving a step further with polyanionic chemistry, off late, materials discovery has been realized by using different types of polyanion units. These subclass of materials are known as "mixed polyanionic" cathode materials, which can be designed by simultaneously having i) polyanionic units [(XO 4 ) m n− , X = P, S, V, etc.] along with other single anions [Y − = F − /OH − /O 2− /N 3− ], ii) different structural units of same polyanion units [(XO m ) (X 2 O m ), e.g., PO 4 -P 2 O 7 , BO 3 -B 2 O 5 , SO 4 -S 2 O 3 , etc.], and iii) two different oxyanionic [(XO 4 ) m n− ] units (e.g., PO 4 -SO 4 , PO 4 -NO 3 , PO 4 -CO 3 , etc.) as illustrated in Figure 1. These polyanionic combinations can lead to rich structural diversity and multi ple electron redox activity leading to robust electrochemical "Building better batteries" remains an ongoing process to cater diverse energy demands starting from small-scale consumer electronics to large-scale automobiles and grid storage. While Li-ion batteries have carried this burden over the last three decades, the ever-growing and highly diverse applications (based on size, energy-density, and stationary vs mobile usages) have led to an era of "beyond lithium-ion batteries." In this postlithium-battery era, sodium-ion batteries (NIBs) have emerged as a pragmatic option particularly for large-scale applications. They attract...

Rising global temperatures are proving to be detrimental for the agriculture. Hence, strategies are needed to induce thermotolerance in food crops to sustain the food production. GABA (γ-aminobutyric acid), a non-protein amino acid, can partially protect plants from high-temperature stress. This study hypothesises that declining GABA concentrations in the cells of heat-stressed mungbean plants increases the heat-sensitivity of reproductive function. Mungbean plants were grown in a natural, outdoor environment (29.3/16.1 ± 1 °C as mean day/night temperature, 1350–1550 µmol m −2 s −1 light intensity, 60–65% as mean relative humidity) until the start of the reproductive stage. Subsequently, two temperature treatments were imposed in a controlled environment—control (35/23 °C) and heat stress (45/28 °C)—at about 800 µmol m −2 s −1 light intensity and 65–70% as mean relative humidity, until pod maturity. In heat-stressed (HS) plants, endogenous GABA concentrations in leaf and anther samples had declined by 49 and 60%, respectively, and to a much lesser degree in the plants, exogenously supplemented with 1 mM GABA. The reproductive function of GABA-treated heat-stressed plants improved significantly in terms of pollen germination, pollen viability, stigma receptivity and ovule viability, compared to untreated HS controls. In addition, GABA-treated heat-stressed plants had less damage to membranes, photosynthetic machinery (chlorophyll concentration, chlorophyll fluorescence, RuBisCO activity were functionally normal) and carbon assimilation (sucrose synthesis and its utilisation) than the untreated HS controls. Leaf water status improved significantly with GABA application, including enhanced accumulation of osmolytes such as proline and trehalose due to increase in the activities of their biosynthetic enzymes. GABA-treated heat-stressed plants produced more pods (28%) and seed weight (27%) plant −1 than the untreated controls. This study is the first to report the involvement of GABA in protecting reproductive function in mungbean under heat stress, as a result of improved leaf turgor, carbon fixation and assimilation processes, through the augmentation of several enzymes related to these physiological processes.

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