• Energy Research

Plants under salt stress require additional energy supply to fuel salt tolerance mechanisms and growth. Bandehagh and Taylor (2020) establish that plants must strike a balance between energy supply and demand to maintain growth and development during salt stress. This review (1) summaries how salt stress affects different physiological and biochemical process altering the abundance of different metabolites that are feeding into regular and alternative respiratory pathways and shunts; (monomeric complex I, dimeric complex III and I + III2 supercomplex) found to be higher in halophyte mitochondria in comparison with glycophyte, implying efficient electron transfer from complex I to complex III in halophyte mitochondria. Further, the stability of ATP synthase (complex V) also found to be higher in halophyte suggesting halophyte mitochondria better equipped to supply additional ATP required to support salt stress response.Synthesis of organic compatible solutes is an important component for plant salt stress tolerance. In this regard, proline plays an important role in protecting plants from under salinity conditions and showed that salt tolerance is associated with changes in lipid metabolic processes. They also discovered the important role of phosphatidylserine (PS) in mediating enzyme activity, and exogenous application of PS alleviated the effects of NaCl tissue toxicity. The results showed that the superior K + retention ability in both mature and elongation zone of rice root is the key trait conferring its differential salinity stress tolerance. They suggested that besides the superior ability to activate root H + -ATPase pump operation, this key trait is also related to the reduced sensitivity of K + efflux channels to reactive oxygen species and the lower upregulation in OsGORK and higher upregulation of OsAKT1.A key trait long recognized to improve salinity tolerance in many plants is the maintenance of a low Na + /K + ratio. Transient expression experiment showed that JcHDZ07 is a nuclear-localized protein.In improving Na + exclusion ability to maintain root ion homeostasis to ensure a relatively 9 low shoot Na + concentration under saline conditions; 2) maintaining a high shoot sugar content under saline conditions which is enabled by protecting photosystems structures, enhancing photosynthetic performance and sucrose synthetase activity, and inhibiting sucrose degradation. Further, authors suggested that targeting the key genes related to the regulatory mechanisms could provide opportunities to breed more salt tolerant sweet sorghum.Overall, we hope this special issue of benefit to plant breeders and land managers by delivering novel information and insights on the salinity stress response, signalling and adaptive mechanisms operating in plants.

Against the backdrop of a warming climate, heat stress has become one of the most limiting factors to crop productivity and food security worldwide. The flowering stage is susceptible to high temperatures in cereal crops, leading to severe grain yield losses by decreasing fertility and seed-setting rate. Our objective was to (1) assess a global panel of 572 barley varieties with contrasting genetic backgrounds for various agronomic traits related to spikelet fertility and grain quality, (2) identify barley germplasm with superior spikelet fertility and seed set under extreme heat conditions, and (3) understand the relationship between spikelet fertility and grain quality traits under heat stress at flowering time. Delayed sowing in target field environments as well as combined birdcage and heat chamber experiments were conducted in Western Australia for two consecutive years. Twenty-one agronomic traits, including spikelet fertility, grain plumpness, thousand-kernel weight, and screenings, were assessed when heat stress occurred during the crucial flowering period. Our study showed that varieties that flowered during heat stress periods recorded an average of 5–20 ​% lower spikelet fertility than those flowered outside the stress windows. Varieties with high or reduced spikelet fertility under heat stress were identified in the barley panel and showed significant differences of more than 80 ​% in Australian varieties. Based on decreased spikelet fertility, several research lines, but only a few cultivars, maintain spikelet fertility after heat stress compared to control conditions, providing evidence of adaptation to high temperatures in some genotypes. Our study shows that spikelet fertility at high temperatures is a valuable screening tool for heat tolerance during the reproductive phase. Information on heat-tolerant and susceptible varieties can improve the spikelet fertility of the next generation of barley cultivars and enhance adaptation to a changing climate.