OsMFT1 Inhibits Seed Germination by Modulating Abscisic Acid Signaling and Gibberellin Biosynthesis under Salt Stress in Rice

Investigating how reproductive traits in rice respond to abiotic stress

Rice (Oryza sativa) is one of the most important crops and a food source for billions of people. Anthropogenic global warming, soil erosion, and unstable environmental conditions affect both rice vegetative and reproductive growth, and consequently its final yield. The reproductive phase starts with the transition of the apical meristem from the vegetative to the reproductive phase in which it develops into a panicle and proceeds through the differentiation of the floret and, after fertilization, to the filling of the grain. The physiological events that occur during these stages influence the ability of new seeds to respond to stresses during the future germination phase, a key step for successful seedling growth and future plant establishment. This review explores the impacts of different abiotic stresses on the physiological and molecular pathways of reproductive growth.

Synergistic effects of phytohormones and membrane transporters in plant salt stress mitigation

Plants are frequently exposed to high salinity, negatively affecting their development and productivity. This review examined the complex roles of membrane transporters (MTs) and phytohormones in mediating salt stress. MTs are crucial in capturing sodium ions (Na+) and maintaining a delicate balance between sodium (Na+) and potassium (K+), essential for supporting cellular homeostasis and enhancing overall plant health. These MTs were instrumental in regulating ion balance and promoting the absorption and segregation of vital nutrients, thereby enhancing salt stress tolerance. Various plant hormones, including abscisic acid, auxin, ethylene, cytokinin, and gibberellins, along with gaseous growth regulators such as nitric oxide and hydrogen sulfide, collaborate to regulate and synchronize numerous aspects of plant growth, development, and stress responses to environmental factors. These transporters and other phytohormones, including brassinosteroids, melatonin, and salicylic acid, also collaborated to initiate adaptation processes, such as controlling osmotic pressure, removing ions, and initiating stress signaling pathways. This study consolidated the advancements in understanding the molecular and physiological processes contributing to plant salt tolerance, emphasizing the intricate relationships between MTs and phytohormones. The aim was to elucidate these interactions to promote further research and develop strategies for enhancing plant salt tolerance.

Foliar Application of Equisetum arvense Extract Enhances Growth, Alleviates Lipid Peroxidation and Reduces Proline Accumulation in Tomato Plants Under Salt Stress

Salinity is a major abiotic stress that affects physiological and biochemical processes in plants, reducing the growth, yield, and quality of crops. This problem has been intensified with the reduction of the cultivated area. This study evaluated the response of hydroponically grown tomato plants under salt stress to foliar applications of E. arvense extracts. Macro- and micronutrients, as well as silicon and phenolic compounds, were extracted using magnetic stirring and water reflux methods, the latter being the most effective. To evaluate the efficacy of E. arvense extracts, spraying was applied at two different doses: EQ-R-1 (23.6 mg·L-1 Si and 0.5 mM phenolic compounds) and EQ-R-2 (5.9 mg·L-1 Si and 0.125 mM phenolic compounds). Foliar application of both extracts alleviated salinity effects by reducing sodium uptake. E. arvense extracts mitigated oxidative stress by a decrease in electrolyte leakage by 29% and malondialdehyde and H2O2 concentrations by 69% and 39%, respectively, for the extract with the lowest dose. In addition, EQ-R-2 was also more effective by reducing 51.5% proline accumulation. These findings showed the potential use of E. arvense extracts as biostimulants to enhance plant tolerance to salinity providing new perspectives in agricultural systems.

Characterization of pecan PEBP family genes and the potential regulation role of CiPEBP-like1 in fatty acid synthesis

Phosphatidyl ethanolamine-binding protein (PEBP) plays important roles in plant growth and development. However, few studies have investigated the PEBP gene family in pecan (Carya illinoinensis), particularly the function of the PEBP-like subfamily. In this study, we identified 12 PEBP genes from the pecan genome and classified them into four subfamilies: MFT-like, FT-like, TFL1-like and PEBP-like. Multiple sequence alignment, gene structure, and conserved motif analyses indicated that pecan PEBP subfamily genes were highly conserved. Cis-element analysis revealed that many light responsive elements and plant hormone-responsive elements are found in CiPEBPs promoters. Additionally, RNA-seq and RT-qPCR showed that CiPEBP-like1 was highly expressed during kernel filling stage. GO and KEGG enrichment analysis further indicated that CiPEBP-like1 was involved in fatty acid biosynthesis and metabolism progress. Overexpression of CiPEBP-like1 led to earlier flowering and altered fatty acid composition in Arabidopsis seeds. RT-qPCR confirmed that CiPEBP-like1 promoted fatty acid synthesis by regulating the expression of key genes. Overall, this study contributes to a comprehensive understanding of the potential functions of the PEBP family genes and lay a foundation to modifying fatty acid composition in pecan kernel.

The Function of Florigen in the Vegetative-to-Reproductive Phase Transition in and around the Shoot Apical Meristem

Plants undergo a series of developmental phases throughout their life-cycle, each characterized by specific processes. Three critical features distinguish these phases: the arrangement of primordia (phyllotaxis), the timing of their differentiation (plastochron) and the characteristics of the lateral organs and axillary meristems. Identifying the unique molecular features of each phase, determining the molecular triggers that cause transitions and understanding the molecular mechanisms underlying these transitions are keys to gleaning a complete understanding of plant development. During the vegetative phase, the shoot apical meristem (SAM) facilitates continuous leaf and stem formation, with leaf development as the hallmark. The transition to the reproductive phase induces significant changes in these processes, driven mainly by the protein FT (FLOWERING LOCUS T) in Arabidopsis and proteins encoded by FT orthologs, which are specified as 'florigen'. These proteins are synthesized in leaves and transported to the SAM, and act as the primary flowering signal, although its impact varies among species. Within the SAM, florigen integrates with other signals, culminating in developmental changes. This review explores the central question of how florigen induces developmental phase transition in the SAM. Future research may combine phase transition studies, potentially revealing the florigen-induced developmental phase transition in the SAM.

Uncovering the Genomic Regions Associated with Yield Maintenance in Rice Under Drought Stress Using an Integrated Meta-Analysis Approach

The complex trait of yield is controlled by several quantitative trait loci (QTLs). Given the global water deficit issue, the development of rice varieties suitable for non-flooded cultivation holds significant importance in breeding programs. The powerful approach of Meta-QTL (MQTL) analysis can be used for the genetic dissection of complicated quantitative traits. In the current study, a comprehensive MQTL analysis was conducted to identify consistent QTL regions associated with drought tolerance and yield-related traits under water deficit conditions in rice. In total, 1087 QTLs from 134 rice populations, published between 2000 to 2021, were utilized in the analysis. Distinct MQTL analysis of the relevant traits resulted in the identification of 213 stable MQTLs. The confidence interval (CI) for the detected MQTLs was between 0.12 and 19.7 cM. The average CI of the identified MQTLs (4.68 cM) was 2.74 times narrower compared to the average CI of the initial QTLs. Interestingly, 63 MQTLs coincided with SNP peak positions detected by genome-wide association studies for yield and drought tolerance-associated traits under water deficit conditions in rice. Considering the genes located both in the QTL-overview peaks and the SNP peak positions, 19 novel candidate genes were introduced, which are associated with drought response index, plant height, panicle number, biomass, and grain yield. Moreover, an inclusive MQTL analysis was performed on all the traits to obtain "Breeding MQTLs". This analysis resulted in the identification of 96 MQTLs with a CI ranging from 0.01 to 9.0 cM. The mean CI of the obtained MQTLs (2.33 cM) was 4.66 times less than the mean CI of the original QTLs. Thirteen MQTLs fulfilling the criteria of having more than 10 initial QTLs, CI < 1 cM, and an average phenotypic variance explained greater than 10%, were designated as "Breeding MQTLs". These findings hold promise for assisting breeders in enhancing rice yield under drought stress conditions.

Impacts of salinity stress on crop plants: improving salt tolerance through genetic and molecular dissection

Improper use of water resources in irrigation that contain a significant amount of salts, faulty agronomic practices such as improper fertilization, climate change etc. are gradually increasing soil salinity of arable lands across the globe. It is one of the major abiotic factors that inhibits overall plant growth through ionic imbalance, osmotic stress, oxidative stress, and reduced nutrient uptake. Plants have evolved with several adaptation strategies at morphological and molecular levels to withstand salinity stress. Among various approaches, harnessing the crop genetic variability across different genepools and developing salinity tolerant crop plants offer the most sustainable way of salt stress mitigation. Some important major genetic determinants controlling salinity tolerance have been uncovered using classical genetic approaches. However, its complex inheritance pattern makes breeding for salinity tolerance challenging. Subsequently, advances in sequence based breeding approaches and functional genomics have greatly assisted in underpinning novel genetic variants controlling salinity tolerance in plants at the whole genome level. This current review aims to shed light on physiological, biochemical, and molecular responses under salt stress, defense mechanisms of plants, underlying genetics of salt tolerance through bi-parental QTL mapping and Genome Wide Association Studies, and implication of Genomic Selection to breed salt tolerant lines.