Rice kinase OsMRLK63 contributes to drought tolerance by regulating reactive oxygen species production.

Drought is a major adverse environmental factor that plants face in nature but the molecular mechanism by which plants transduce stress signals and further endow themselves with tolerance remains unclear. Malectin/malectin-like domains containing receptor-like kinases (MRLKs) have been proposed to act as receptors in multiple biological signaling pathways, but limited studies show their roles in drought-stress signaling and tolerance. In this study, we demonstrate OsMRLK63 in rice (Oryza sativa L.) functions in drought tolerance by acting as the receptor of 2 rapid alkalization factors, OsRALF45 and OsRALF46. We show OsMRLK63 is a typical receptor-like kinase that positively regulates drought tolerance and reactive oxygen species (ROS) production. OsMRLK63 interacts with and phosphorylates several nicotinamide adenine dinucleotide phosphate (NADPH) oxidases with the primarily phosphorylated site at Ser26 in the N-terminal of RESPIRATORY BURST OXIDASE HOMOLOGUE A (OsRbohA). The application of the 2 small signal peptides (OsRALF45/46) on rice can greatly alleviate the dehydration of plants induced by mimic drought. This function depends on the existence of OsMRLK63 and the NADPH oxidase-dependent ROS production. The 2 RALFs interact with OsMRLK63 by binding to its extracellular domain, suggesting they may act as drought/dehydration signal sensors for the OsMRLK63-mediated process. Our study reveals a OsRALF45/46-OsMRLK63-OsRbohs module which contributes to drought-stress signaling and tolerance in rice.

Characterization of B-BOX gene family and their expression profiles under hormonal, abiotic and metal stresses in Poaceae plants.

BACKGROUND: B-box (BBX) proteins play important roles in plant growth regulation and development including photomorphogenesis, photoperiodic regulation of flowering, and responses to biotic and abiotic stresses. RESULTS: In the present study we retrieved total 131 BBX members from five Poaceae species including 36 from maize, 30 from rice, 24 from sorghum, 22 from stiff brome, and 19 from Millet. All the BBX genes were grouped into five subfamilies on the basis of their phylogenetic relationships and structural features. The expression profiles of 12 OsBBX genes in different tissues were evaluated through qRT-PCR, and we found that most rice BBX members showed high expression level in the heading stage compared to seedling and booting stages. The expression of OsBBX1, OsBBX2, OsBBX8, OsBBX19, and OsBBX24 was strongly induced by abiotic stresses such as drought, cold and salt stresses. Furthermore, the expression of OsBBX2, OsBBX7, OsBBX17, OsBBX19, and OsBBX24 genes was up-regulated under GA, SA and MeJA hormones at different time points. Similarly, the transcripts level of OsBBX1, OsBBX7, OsBBX8, OsBBX17, and OsBBX19 genes were significantly affected by heavy metals such as Fe, Ni, Cr and Cd. CONCLUSION: Change in the expression pattern of BBX members in response to abiotic, hormone and heavy metal stresses signifies their potential roles in plant growth and development and in response to multivariate stresses. The findings suggest that BBX genes could be used as potential genetic markers for the plants, particularly in functional analysis and determining their roles under multivariate stresses.

Socioeconomic support, quality of life, and prognosis of frailty among the older adults.

Background: Although socioeconomic support is recommended for frailty management, its association with the prognosis of frailty is unclear. Methods: Using data from participants aged ≥65 years in the Chinese Longitudinal Healthy Longevity Survey (2008-2018), the associations between socioeconomic support (source of income, medical insurance, community support, living status), onset of prefrailty/frailty, and worsening of prefrailty, were analyzed using multinominal logistic regression models. The associations between self-reported low quality of life (QoL) and reversion of prefrailty/frailty were analyzed using multivariate logistic regression models. Associations with mortality risk were analyzed using Cox proportional hazard regression models. Results: A total of 13,859 participants (mean age: 85.8 ± 11.1 years) containing 2056 centenarians were included. Financial dependence was a risk factor for low QoL among prefrail/frail individuals, but not among robust individuals. Having commercial or other insurance, and receiving social support from the community were protective factors for low QoL among prefrail/frail individuals and for the worsening of prefrailty. Continuing to work was a risk factor for low QoL, but a protective factor for worsening of prefrailty. A negative association between continuing to work and mortality existed in prefrail individuals aged <85 years and ≥85 years. Living alone was a risk factor for low QoL, but was not significantly associated with frailty prognosis. Conclusions: Prefrail and frail individuals were vulnerable to changes in socioeconomic support and more sensitive to it compared with robust individuals. Preferential policies regarding financial support, social support, and medical insurance should be developed for individuals with frailty.

Rice Carbohydrate-Binding Malectin-Like Protein, OsCBM1, Contributes to Drought-Stress Tolerance by Participating in NADPH Oxidase-Mediated ROS Production.

Carbohydrate-binding malectin/malectin-like domain-containing proteins (CBMs) are a recently identified protein subfamily of lectins that participates various functional bioprocesses in the animal, bacterial, and plant kingdoms. However, little is known the roles of CBMs in rice development and stress response. In this study, OsCBM1, which encodes a protein containing only one malectin-like domain, was cloned and characterized. OsCBM1 is localized in both the endoplasmic reticulum and plasma membrane. Its transcripts are dominantly expressed in leaves and could be significantly stimulated by a number of phytohormone applications and abiotic stress treatments. Overexpression of OsCBM1 increased drought tolerance and reactive oxygen species production in rice, whereas the knockdown of the gene decreased them. OsCBM1 physically interacts with OsRbohA, a NADPH oxidase, and the expression of OsCBM1 in osrbohA, an OsRbohA-knockout mutant, is significantly downregulated under both normal growth and drought stress conditions. Meanwhile, OsCBM1 can also physically interacts with OsRacGEF1, a specific guanine nucleotide exchange factor for the Rop/Rac GTPase OsRac1, and transient coexpression of OsCBM1 with OaRacGEF1 significantly enhanced ROS production. Further transcriptome analysis showed that multiple signaling regulatory mechanisms are involved in the OsCBM1-mediated processes. All these results suggest that OsCBM1 participates in NADPH oxidase-mediated ROS production by interacting with OsRbohA and OsRacGEF1, contributing to drought stress tolerance of rice. Multiple signaling pathways are likely involved in the OsCBM1-mediated stress tolerance in rice.

A systematic in silico prediction of gibberellic acid stimulated GASA family members: A novel small peptide contributes to floral architecture and transcriptomic changes induced by external stimuli in rice.

The GASA (GA-stimulated Arabidopsis) gene family is highly specific to plants, signifying a crucial role in plant growth and development. Herein, we retrieved 119 GASA genes in 10 different plant species in two major lineages (monocots and eudicots). Further, in the phylogenetic tree we classified these genes into four well-conserved subgroups. All the proteins contain a conserved GASA domain with similar characteristics and a highly specific 12-cysteine residue of the C-terminus position. According to the global microarray data and qRT-PCR based analysis, the OsGASA gene family was dominantly expressed in the seedling and transition phase of floral stages. Despite this, OsGASA genes profoundly contribute to rice grain size and length, whereas the highest abundance of transcript level was noticed in stage-2 (Inf 6, 3.0-cm-long spikelet) and stage-3 (Inf 7, 5.0-cm-long spikelet) under GA treatment during panicle formation. Additionally, the maximum expression level of these genes was recorded in response to GA and ABA in young seedlings. Further, in response to abiotic stresses, OsGASA1/8/10 was up- regulated by salt, OsGASA2/5/7 by drought, OsGASA3/6 by cold, and OsGASA4/9 by heat stress. With the exception of OsGASA4, the higher transcription levels of all the other GASA genes were induced by Cd and Cr metal stresses (8-10 fold changes) at various time points. Finally, the GO ontology analysis of GASAs revealed the biological involvement in the GA-mediated signaling pathway and abiotic stresses. Prominently, most of these proteins are localized in cellular components such as the cell wall and extracellular region, where the molecular functions such as ATP binding and protein binding were observed. These results imply that GASAs are significantly involved in rice panicle developmental stages, responses to external stimuli, and hormones.