SlSPX1-SlPHR complexes mediate the suppression of arbuscular mycorrhizal symbiosis by phosphate repletion in tomato.

Forming mutualistic symbioses with arbuscular mycorrhizae (AMs) improves the acquisition of mineral nutrients for most terrestrial plants. However, the formation of AM symbiosis usually occurs under phosphate (Pi)-deficient conditions. Here, we identify SlSPX1 (SYG1 (suppressor of yeast GPA1)/Pho81(phosphate 81)/XPR1 (xenotropic and polytropic retrovirus receptor 1) as the major repressor of the AM symbiosis in tomato (Solanum lycopersicum) under phosphate-replete conditions. Loss of SlSPX1 function promotes direct Pi uptake and enhances AM colonization under phosphate-replete conditions. We determine that SlSPX1 integrates Pi signaling and AM symbiosis by directly interacting with a set of arbuscule-induced SlPHR proteins (SlPHR1, SlPHR4, SlPHR10, SlPHR11, and SlPHR12). The association with SlSPX1 represses the ability of SlPHR proteins to activate AM marker genes required for the arbuscular mycorrhizal symbiosis. SlPHR proteins exhibit functional redundancy, and no defective AM symbiosis was detected in the single mutant of SlPHR proteins. However, silencing SlPHR4 in the Slphr1 mutant background led to reduced AM colonization. Therefore, our results support the conclusion that SlSPX1-SlPHRs form a Pi-sensing module to coordinate the AM symbiosis under different Pi-availability conditions.

NRP2 promotes atherosclerosis by upregulating PARP1 expression and enhancing low shear stress-induced endothelial cell apoptosis.

Atherosclerosis-related cardiovascular diseases are leading causes of mortality worldwide, characterized by the development of endothelial cell dysfunction, increased oxidized low-density lipoprotein uptake by macrophages, and the ensuing formation of atherosclerotic plaque. Local blood flow patterns cause uneven atherosclerotic lesion distribution, and endothelial dysfunction caused by disturbed flow is an early step in the development of atherosclerosis. The present research aims to elucidate the mechanism underlying the regulation of Neuropilin 2 (NRP2) under low shear stress (LSS) in the atheroprone phenotype of endothelial cells. We observed that NRP2 expression was significantly upregulated in LSS-stimulated human umbilical vein endothelial cells (HUVECs) and in mouse aortic endothelial cells. Knockdown of NRP2 in HUVECs significantly ameliorated cell apoptosis induced by LSS. Conversely, overexpression of NRP2 had the opposite effect on HUVEC apoptosis. Animal experiments suggest that NRP2 knockdown markedly mitigated the development of atherosclerosis in Apoe-/- mice. Mechanistically, NRP2 knockdown and overexpression regulated PARP1 protein expression in the condition of LSS, which in turn affected the expression of apoptosis-related genes. Moreover, the upstream transcription factor GATA2 was found to regulate NRP2 expression in the progression of atherosclerosis. These findings suggest that NRP2 plays an essential proatherosclerotic role through the regulation of cell apoptosis, and the results reveal that NRP2 is a promising therapeutic target for the treatment of atherosclerotic disorders.

Functional analysis of the OsNPF4.5 nitrate transporter reveals a conserved mycorrhizal pathway of nitrogen acquisition in plants.

Low availability of nitrogen (N) is often a major limiting factor to crop yield in most nutrient-poor soils. Arbuscular mycorrhizal (AM) fungi are beneficial symbionts of most land plants that enhance plant nutrient uptake, particularly of phosphate. A growing number of reports point to the substantially increased N accumulation in many mycorrhizal plants; however, the contribution of AM symbiosis to plant N nutrition and the mechanisms underlying the AM-mediated N acquisition are still in the early stages of being understood. Here, we report that inoculation with AM fungus Rhizophagus irregularis remarkably promoted rice (Oryza sativa) growth and N acquisition, and about 42% of the overall N acquired by rice roots could be delivered via the symbiotic route under N-NO3- supply condition. Mycorrhizal colonization strongly induced expression of the putative nitrate transporter gene OsNPF4.5 in rice roots, and its orthologs ZmNPF4.5 in Zea mays and SbNPF4.5 in Sorghum bicolor OsNPF4.5 is exclusively expressed in the cells containing arbuscules and displayed a low-affinity NO3- transport activity when expressed in Xenopus laevis oocytes. Moreover, knockout of OsNPF4.5 resulted in a 45% decrease in symbiotic N uptake and a significant reduction in arbuscule incidence when NO3- was supplied as an N source. Based on our results, we propose that the NPF4.5 plays a key role in mycorrhizal NO3- acquisition, a symbiotic N uptake route that might be highly conserved in gramineous species.

Novel Sulfonamide Derivatives Containing a Piperidine Moiety as New Bactericide Leads for Managing Plant Bacterial Diseases.

Plant bacterial diseases are an intractable problem due to the fact that phytopathogens have acquired strong resistances for traditional pesticides, resulting in restricting the quality and yield of agricultural products around the world. To develop new agrochemical alternatives, we prepared a novel series of sulfanilamide derivatives containing piperidine fragments and assessed their antibacterial potency. The bioassay results revealed that most molecules displayed excellent in vitro antibacterial potency towards Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas axonopodis pv. citri (Xac). In particular, molecule C4 exhibited outstanding inhibitory activity toward Xoo with EC50 value of 2.02 µg mL-1, which was significantly better than those of the commercial agents bismerthiazol (EC50 = 42.38 µg mL-1) and thiodiazole copper (EC50 = 64.50 µg mL-1). A series of biochemical assays confirmed that compound C4 interacted with dihydropteroate synthase, and irreversibly damaged the cell membrane. In vivo assays showed that the molecule C4 presented acceptable curative and protection activities of 34.78% and 39.83%, respectively, at 200 µg mL-1, which were greater than those of thiodiazole and bismerthiazol. This study highlights the valuable insights for the excavation and development of new bactericides that can concurrently target dihydropteroate synthase and bacterial cell membranes.

Auxin-mediated regulation of arbuscular mycorrhizal symbiosis: A role of SlGH3.4 in tomato.

Most land plants can establish symbiosis with arbuscular mycorrhizal (AM) fungi to increase fitness to environmental challenges. The development of AM symbiosis is controlled by intricate procedures involving all phytohormones. However, the mechanisms underlying the auxin-mediated regulation of AM symbiosis remains largely unknown. Here, we report that AM colonisation promotes auxin response and indole-3-acetic acid (IAA) accumulation, but downregulates IAA biosynthesis genes in tomato (Solanum lycopersicum). External IAA application modulates the AM symbiosis by promoting arbuscule formation at low concentrations but repressing it at high concentrations. An AM-induced GH3 gene, SlGH3.4, encoding a putative IAA-amido synthetase, negatively regulates mycorrhization via maintaining cellular auxin homoeostasis. Loss of SlGH3.4 function increased free IAA content and arbuscule incidence, while constitutively overexpressing SlGH3.4 in either tomato or rice resulted in decreased IAA content, total colonisation level and arbuscule abundance in mycorrhizal roots. Several auxin-inducible expansin genes involved in AM formation or resistance to pathogen infection were upregulated in slgh3.4 mycorrhizal roots but downregulated in the SlGH3.4-overexpressing plants. Taken together, our results highlight a positive correlation between the endogenous IAA content and mycorrhization level, particularly arbuscule incidence, and suggest that the SlGH3.4-mediated auxin homoeostasis and regulation of expansin genes is involved in finely tuning the AM development.

Transport properties and regulatory roles of nitrogen in arbuscular mycorrhizal symbiosis.

Many terrestrial plants can form root symbiosis with beneficial microorganisms for enhancing uptake of mineral nutrients or increasing fitness to adverse environmental challenges. Arbuscular mycorrhizal (AM) symbiosis that is formed by AM fungi and the roots of vascular flowering plants is the most widespread mutualistic associations in nature. As a typical endosymbiosis, AM interactions involves the differentiation of both symbionts to create novel symbiotic interfaces within the root cells, and requires a continuous nutrient exchange between the two partners. AM plants have two pathways for nutrient uptake, either direct uptake via the root hairs and root epidermis at the plant-soil interface, or indirectly through the AM fungal hyphae at the plant-fungus interface. Over the last few years, great progress has been made in deciphering the mechanisms underlying the AM-mediated modulation of nutrient uptake processes, and an increasing number of plant and fungal genes responsible for transporting nutrients from the soil or across the intraradical symbiotic interfaces have been identified and functionally characterized. Here, we summarize the recent advances in the nitrogen uptake, assimilation and translocation in the AM symbiosis, and also explore the current understanding of how the N status and interplay with C and P in modulating the development of AM associations.

The Potassium Transporter SlHAK10 Is Involved in Mycorrhizal Potassium Uptake.

Most terrestrial plants form a root symbiosis with arbuscular mycorrhizal (AM) fungi, which receive fixed carbon from the plant and enhance the plant's uptake of mineral nutrients. AM symbiosis improves the phosphorous and nitrogen nutrition of host plants; however, little is known about the role of AM symbiosis in potassium (K+) nutrition. Here, we report that inoculation with the AM fungus Rhizophagus irregularis improved tomato (Solanum lycopersicum) plant growth and K+ acquisition and that K+ deficiency has a negative effect on root growth and AM colonization. Based on its homology to a Lotus japonicus AM-induced K+ transporter, we identified a mycorrhiza-specific tomato K+ transporter, SlHAK10 (Solanum lycopersicum High-affinity Potassium Transporter10), that was exclusively expressed in arbuscule-containing cells. SlHAK10 could restore a yeast K+ uptake-defective mutant in the low-affinity concentration range. Loss of function of SlHAK10 led to a significant decrease in mycorrhizal K+ uptake and AM colonization rate under low-K+ conditions but did not affect arbuscule development. Overexpressing SlHAK10 from the constitutive cauliflower mosaic virus 35S promoter or the AM-specific Solanum melongena Phosphate Transporter4 not only improved plant growth and K+ uptake but also increased AM colonization efficiency and soluble sugar content in roots supplied with low K+ Our results indicate that tomato plants have a SlHAK10-mediated mycorrhizal K+ uptake pathway and that improved plant K+ nutrition could increase carbohydrate accumulation in roots, which facilitates AM fungal colonization.

A mycorrhiza-specific H+ -ATPase is essential for arbuscule development and symbiotic phosphate and nitrogen uptake.

Most land plants can form symbiosis with arbuscular mycorrhizal (AM) fungi to enhance uptake of mineral nutrients, particularly phosphate (Pi) and nitrogen (N), from the soil. It is established that transport of Pi from interfacial apoplast into plant cells depends on the H+ gradient generated by the H+ -ATPase located on the periarbuscular membrane (PAM); however, little evidence regarding the potential link between mycorrhizal N transport and H+ -ATPase activity is available to date. Here, we report that a PAM-localized tomato H+ -ATPase, SlHA8, is indispensable for arbuscule development and mycorrhizal P and N uptake. Knockout of SlHA8 resulted in truncated arbuscule morphology, reduced shoot P and N accumulation, and decreased H+ -ATPase activity and acidification of apoplastic spaces in arbusculated cells. Overexpression of SlHA8 in tomato promoted both P and N uptake, and increased total colonization level, but did not affect arbuscule morphology. Heterogeneous expression of SlHA8 in the rice osha1 mutant could fully complement its defects in arbuscule development and mycorrhizal P and N uptake. Our results propose a pivotal role of the SlHA8 in energizing both the symbiotic P and N transport, and highlight the evolutionary conservation of the AM-specific H+ -ATPase orthologs in maintaining AM symbiosis across different mycorrhizal plant species.

Application of GFR estimation equations in elderly patients with measured GFR below 60 mL/min/1.73 m2.

BACKGROUND: Estimated glomerular filtration rate (eGFR) equations can be inaccurate when applied to elderly patients. Newly, the full-age-spectrum (FAS) equation was developed for use in elderly patients. AIM: We compared the available eGFR equations in elderly Chinese patients with mGFRs < 60 mL/min/1.73 m2. METHODS: Measured glomerular filtration rates (mGFRs) were obtained using 99mTc-DTPA (diethylene-triamine-pentaacetic acid) scans, 220 patients ≥ 80 years with mGFRs < 60 mL/min/1.73 m2 were enrolled. Serum creatinine (SCr) levels were measured simultaneously, and eGFRs based on SCr were calculated using four formulas: the modification of diet in renal disease (MDRD), chronic kidney disease epidemiology collaboration (CKD-EPI-SCr), Berlin initiative study (BIS1), and the FAS-SCr equations. RESULTS: All the equations tended to overestimate GFR. The FAS-SCr equation provided the least bias (1.84), the highest proportion of eGFR within 30% of mGFR (P30, 72.7%), the bias and P30 of the BIS1 equation were 3.45 and 72.3%, respectively. In patients with mGFRs of 30-60 mL/min/1.73 m2, the BIS1 and FAS-SCr equations demonstrated better performances than the MDRD and CKD-EPI-SCr equations. While in patients with mGFR < 30 mL/min/1.73 m2, the accuracy of all equations was poor. DISCUSSION: In older patients with mGFRs of 30-60 mL/min/1.73 m2, the BIS1 and the FAS-SCr equations exhibited good performance, none of the equations based on SCr were suitable for older subjects with mGFRs < 30 mL/min/1.73 m2. CONCLUSIONS: The BIS1 and FAS-SCr equations may be optimal for older patients with moderately reduced kidney function.

Associations of sclerostin with carotid artery atherosclerosis and all-cause mortality in Chinese patients undergoing maintenance hemodialysis.

BACKGROUND: Previous clinical studies found inconsistent relationship between circulating sclerostin levels and treatment outcome in patients undergoing maintenance hemodialysis (MHD). Therefore, this study aimed to assess the associations of sclerostin with carotid artery atherosclerosis and all-cause mortality in Chinese patients undergoing MHD. METHODS: This retrospective study assessed 84 patients undergoing MHD at the Nephrology Department of Beijing Hospital from January to April 2012, with a median follow-up of 61.2 months (range: 11.5 to 63 months). Carotid artery intima-media thicknesses (CIMTs) and atherosclerotic plaques were measured by B-mode Doppler ultrasound at baseline. Blood samples were collected for measuring serum sclerostin and soluble klotho (s-klotho) levels. The associations of sclerostin levels with carotid artery atherosclerosis was evaluated by correlation methods. Predictive factors of mortality were assessed by multivariate COX regression. RESULTS: Baseline serum sclerostin averaged 162.01 pmol/L, with an interquartile range of 121.69 to 225.22 pmol/L, while CIMT values were 1.35 ± 0.39 mm. Carotid artery atherosclerotic plaques were detected in 68 subjects (81%). Subjects with sclerostin levels above the median value had higher CIMT (p = 0.038) and higher prevalence of atherosclerotic plaque (p = 0.025). During follow-up, 27 patients died; Kaplan-Meier curves indicated that subjects with high sclerostin levels (above the median value at baseline) had shorter survival (log rank p = 0.011). In multivariate COX regression analysis, serum sclerostin (HR, 1.095; 95% confidence interval [CI] 1.022-1.174, p = 0.010) and albumin (HR, 0.742; 95%CI 0.612-0.900, p = 0.002) levels were independent predictors of all-cause mortality. CONCLUSIONS: Sclerostin is positively associated with CIMT. In addition, patients with low baseline serum sclerostin undergoing MHD show better survival.

Phytohormones Regulate the Development of Arbuscular Mycorrhizal Symbiosis.

Most terrestrial plants are able to form a root symbiosis with arbuscular mycorrhizal (AM) fungi for enhancing the assimilation of mineral nutrients. AM fungi are obligate symbionts that depend on host plants as their sole carbon source. Development of an AM association requires a continuous signal exchange between the two symbionts, which triggers coordinated differentiation of both partners, to enable their interaction within the root cells. The control of the AM symbiosis involves a finely-tuned process, and an increasing number of studies have pointed to a pivotal role of several phytohormones, such as strigolactones (SLs), gibberellic acids (GAs), and auxin, in the modulation of AM symbiosis, through the early recognition of events up to the final arbuscular formation. SLs are involved in the presymbiotic growth of the fungus, while auxin is required for both the early steps of fungal growth and the differentiation of arbuscules. GAs modulate arbuscule formation in a dose-dependent manner, via DELLA proteins, a group of GRAS transcription factors that negatively control the GA signaling. Here, we summarize the recent findings on the roles of these plant hormones in AM symbiosis, and also explore the current understanding of how the DELLA proteins act as central regulators to coordinate plant hormone signaling, to regulate the AM symbiosis.

Three cis-Regulatory Motifs, AuxRE, MYCRS1 and MYCRS2, are Required for Modulating the Auxin- and Mycorrhiza-Responsive Expression of a Tomato GH3 Gene.

Auxin is well known to be a key regulator that acts in almost all physiological processes during plant growth, and in interactions between plants and microbes. However, to date, the regulatory mechanisms underlying auxin-mediated plant-arbuscular mycorrhizal (AM) fungi symbiosis have not been well deciphered. Previously we identified a GH3 gene, SlGH3.4, strongly responsive to both auxin induction and mycorrhizal symbiosis. Here, we reported a refined dissection of the SlGH3.4 promoter activity using the ß-glucuronidase (GUS) reporter. The SlGH3.4 promoter could drive GUS expression strongly in mycorrhizal roots of soybean and rice plants, and in IAA-treated soybean roots, but not in IAA-treated rice roots. A promoter deletion assay revealed three cis-acting motifs, i.e. the auxin-responsive element, AuxRE, and two newly identified motifs named MYCRS1 and MYCRS2, involved in the activation of auxin- and AM-mediated expression of SlGH3.4. Deletion of the AuxRE from the SlGH3.4 promoter caused almost complete abolition of GUS staining in response to external IAA induction. Seven repeats of AuxRE fused to the Cauliflower mosaic virus (CaMV) 35S minimal promoter could direct GUS expression in both IAA-treated and AM fungal-colonized roots of tobacco plants. Four repeats of MYCRS1 or MYCRS2 fused to the CaMV35S minimal promoter was sufficient to drive GUS expression in arbuscule-containing cells, but not in IAA-treated tobacco roots. In summary, our results offer new insights into the molecular mechanisms underlying the potential cross-talk between the auxin and the AM regulatory pathways in modulating the expression of AM-responsive GH3 genes in diverse mycorrhizal plants.

Involvement of OsPht1;4 in phosphate acquisition and mobilization facilitates embryo development in rice.

Phosphate (Pi) transporters mediate acquisition and transportation of Pi within plants. Here, we investigated the functions of OsPht1;4 (OsPT4), one of the 13 members of the Pht1 family in rice. Quantitative real-time RT-PCR analysis revealed strong expression of OsPT4 in roots and embryos, and OsPT4 promoter analysis using reporter genes confirmed these findings. Analysis using rice protoplasts showed that OsPT4 localized to the plasma membrane. OsPT4 complemented a yeast mutant defective in Pi uptake, and also facilitated increased accumulation of Pi in Xenopus oocytes. Further, OsPT4 genetically modified (GM) rice lines were generated by knockout/knockdown or over-expression of OsPT4. Pi concentrations in roots and shoots were significantly lower and higher in knockout/knockdown and over-expressing plants, respectively, compared to wild-type under various Pi regimes. (33) Pi uptake translocation assays corroborated the altered acquisition and mobilization of Pi in OsPT4 GM plants. We also observed effects of altered expression levels of OsPT4 in GM plants on the concentration of Pi, the size of the embryo, and several attributes related to seed development. Overall, our results suggest that OsPT4 encodes a plasma membrane-localized Pi transporter that facilitates acquisition and mobilization of Pi, and also plays an important role in development of the embryo in rice.

Identification and expression analysis of OsLPR family revealed the potential roles of OsLPR3 and 5 in maintaining phosphate homeostasis in rice.

BACKGROUND: Phosphorus (P), an essential macronutrient, is often limiting in soils and affects plant growth and development. In Arabidopsis thaliana, Low Phosphate Root1 (LPR1) and its close paralog LPR2 encode multicopper oxidases (MCOs). They regulate meristem responses of root system to phosphate (Pi) deficiency. However, the roles of LPR gene family in rice (Oryza sativa) in maintaining Pi homeostasis have not been elucidated as yet. RESULTS: Here, the identification and expression analysis for the homologs of LPR1/2 in rice were carried out. Five homologs, hereafter referred to as OsLPR1-5, were identified in rice, which are distributed on chromosome1 over a range of 65 kb. Phylogenetic analysis grouped OsLPR1/3/4/5 and OsLPR2 into two distinct sub-clades with OsLPR3 and 5 showing close proximity. Quantitative real-time RT-PCR (qRT-PCR) analysis revealed higher expression levels of OsLPR3-5 and OsLPR2 in root and shoot, respectively. Deficiencies of different nutrients ie, P, nitrogen (N), potassium (K), magnesium (Mg) and iron (Fe) exerted differential and partially overlapping effects on the relative expression levels of the members of OsLPR family. Pi deficiency (-P) triggered significant increases in the relative expression levels of OsLPR3 and 5. Strong induction in the relative expression levels of OsLPR3 and 5 in osphr2 suggested their negative transcriptional regulation by OsPHR2. Further, the expression levels of OsLPR3 and 5 were either attenuated in ossiz1 and ospho2 or augmented in rice overexpressing OsSPX1. CONCLUSIONS: The results from this study provided insights into the evolutionary expansion and a likely functional divergence of OsLPR family with potential roles of OsLPR3 and 5 in the maintenance of Pi homeostasis in rice.

Analysis of tomato plasma membrane H(+)-ATPase gene family suggests a mycorrhiza-mediated regulatory mechanism conserved in diverse plant species.

In plants, the plasma membrane H(+)-ATPase (HA) is considered to play a crucial role in regulating plant growth and respoding to environment stresses. Multiple paralogous genes encoding different isozymes of HA have been identified and characterized in several model plants, while limited information of the HA gene family is available to date for tomato. Here, we describe the molecular and expression features of eight HA-encoding genes (SlHA1-8) from tomato. All these genes are interrupted by multiple introns with conserved positions. SlHA1, 2, and 4 were widely expressed in all tissues, while SlHA5, 6, and 7 were almost only expressed in flowers. SlHA8, the transcripts of which were barely detectable under normal or nutrient-/salt-stress growth conditions, was strongly activated in arbuscular mycorrhizal (AM) fungal-colonized roots. Extreme lack of SlHA8 expression in M161, a mutant defective to AM fungal colonization, provided genetic evidence towards the dependence of its expression on AM symbiosis. A 1521-bp SlHA8 promoter could direct the GUS reporter expression specifically in colonized cells of transgenic tobacco, soybean, and rice mycorrhizal roots. Promoter deletion assay revealed a 223-bp promoter fragment of SlHA8 containing a variant of AM-specific cis-element MYCS (vMYCS) sufficient to confer the AM-induced activity. Targeted deletion of this motif in the corresponding promoter region causes complete abolishment of GUS staining in mycorrhizal roots. Together, these results lend cogent evidence towards the evolutionary conservation of a potential regulatory mechanism mediating the activation of AM-responsive HA genes in diverse mycorrhizal plant species.

The characterization of six auxin-induced tomato GH3 genes uncovers a member, SlGH3.4, strongly responsive to arbuscular mycorrhizal symbiosis.

In plants, the GH3 gene family is widely considered to be involved in a broad range of plant physiological processes, through modulation of hormonal homeostasis. Multiple GH3 genes have been functionally characterized in several plant species; however, to date, limited works to study the GH3 genes in tomato have been reported. Here, we characterize the expression and regulatory profiles of six tomato GH3 genes, SlGH3.2, SlGH3.3, SlGH3.4, SlGH3.7, SlGH3.9 and SlGH3.15, in response to different phytohormone applications and arbuscular mycorrhizal (AM) fungal colonization. All six GH3 genes showed inducible responses to external IAA, and three members were significantly up-regulated in response to AM symbiosis. In particular, SlGH3.4, the transcripts of which were barely detectable under normal growth conditions, was strongly activated in the IAA-treated and AM fungal-colonized roots. A comparison of the SlGH3.4 expression in wild-type plants and M161, a mutant with a defect in AM symbiosis, confirmed that SlGH3.4 expression is highly correlated to mycorrhizal colonization. Histochemical staining demonstrated that a 2,258 bp SlGH3.4 promoter fragment could drive ß-glucuronidase (GUS) expression strongly in root tips, steles and cortical cells of IAA-treated roots, but predominantly in the fungal-colonized cells of mycorrhizal roots. A truncated 654 bp promoter failed to direct GUS expression in IAA-treated roots, but maintained the symbiosis-induced activity in mycorrhizal roots. In summary, our results suggest that a mycorrhizal signaling pathway that is at least partially independent of the auxin signaling pathway has evolved for the co-regulation of the auxin- and mycorrhiza-activated GH3 genes in plants.

Improving rice tolerance to potassium deficiency by enhancing OsHAK16p:WOX11-controlled root development.

Potassium (K) deficiency in plants confines root growth and decreases root-to-shoot ratio, thus limiting root K acquisition in culture medium. A WUSCHEL-related homeobox (WOX) gene, WOX11, has been reported as an integrator of auxin and cytokinin signalling that regulates root cell proliferation. Here, we report that ectopic expression of WOX11 gene driven by the promoter of OsHAK16 encoding a low-K-enhanced K transporter led to an extensive root system and adventitious roots and more effective tiller numbers in rice. The WOX11-regulated root and shoot phenotypes in the OsHAK16p:WOX11 transgenic lines were supported by K-deficiency-enhanced expression of several RR genes encoding type-A cytokinin-responsive regulators, PIN genes encoding auxin transporters and Aux/IAA genes. In comparison with WT, the transgenic lines showed increases in root biomass, root activity and K concentrations in the whole plants, and higher soluble sugar concentrations in roots particularly under low K supply condition. The improvement of sugar partitioning to the roots by the expression of OsHAK16p:WOX11 was further indicated by increasing the expression of OsSUT1 and OsSUT4 genes in leaf blades and several OsMSTs genes in roots. Expression of OsHAK16p:WOX11 in the rice grown in moderate K-deficient soil increased total K uptake by 72% and grain yield by 24%-32%. The results suggest that enlarging root growth and development by the expression of WOX11 in roots could provide a useful option for increasing K acquisition efficiency and cereal crop productivity in low K soil.

Genome-wide investigation and expression analysis suggest diverse roles and genetic redundancy of Pht1 family genes in response to Pi deficiency in tomato.

BACKGROUND: Phosphorus (P) deficiency is one of the major nutrient stresses limiting plant growth. The uptake of P by plants is well considered to be mediated by a number of high-affinity phosphate (Pi) transporters belonging to the Pht1 family. Although the Pht1 genes have been extensively identified in several plant species, there is a lack of systematic analysis of the Pht1 gene family in any solanaceous species thus far. RESULTS: Here, we report the genome-wide analysis, phylogenetic evolution and expression patterns of the Pht1 genes in tomato (Solanum lycopersicum). A total of eight putative Pht1 genes (LePT1 to 8), distributed on three chromosomes (3, 6 and 9), were identified through extensive searches of the released tomato genome sequence database. Chromosomal organization and phylogenetic tree analysis suggested that the six Pht1 paralogues, LePT1/3, LePT2/6 and LePT4/5, which were assigned into three pairs with very close physical distance, were produced from recent tandem duplication events that occurred after Solanaceae splitting with other dicot families. Expression analysis of these Pht1 members revealed that except LePT8, of which the transcript was undetectable in all tissues, the other seven paralogues showed differential but partial-overlapping expression patterns. LePT1 and LePT7 were ubiquitously expressed in all tissues examined, and their transcripts were induced abundantly in response to Pi starvation; LePT2 and LePT6, the two paralogues harboring identical coding sequence, were predominantly expressed in Pi-deficient roots; LePT3, LePT4 and LePT5 were strongly activated in the roots colonized by arbuscular mycorrhizal fungi under low-P, but not high-P condition. Histochemical analysis revealed that a 1250-bp LePT3 promoter fragment and a 471-bp LePT5 promoter fragment containing the two elements, MYCS and P1BS, were sufficient to direct the GUS reporter expression in mycorrhizal roots and were limited to distinct cells harboring AM fungal structures. Additionally, the four paralogues, LePT1, LePT2, LePT6 and LePT7, were very significantly down-regulated in the mycorrhizal roots under low Pi supply condition. CONCLUSIONS: The results obtained from this study provide new insights into the evolutionary expansion, functional divergence and genetic redundancy of the Pht1 genes in response to Pi deficiency and mycorrhizal symbiosis in tomato.

Identification of microRNAs in six solanaceous plants and their potential link with phosphate and mycorrhizal signaling.

To date, only a limited number of solanaceous miRNAs have been deposited in the miRNA database. Here, genome-wide bioinformatic identification of miRNAs was performed in six solanaceous plants (potato, tomato, tobacco, eggplant, pepper, and petunia). A total of 2,239 miRNAs were identified following a range of criteria, of which 982 were from potato, 496 from tomato, 655 from tobacco, 46 from eggplant, 45 were from pepper, and 15 from petunia. The sizes of miRNA families and miRNA precursor length differ in all the species. Accordingly, 620 targets were predicted, which could be functionally classified as transcription factors, metabolic enzymes, RNA and protein processing proteins, and other proteins for plant growth and development. We also showed evidence for miRNA clusters and sense and antisense miRNAs. Additionally, five Pi starvation- and one arbuscular mycorrhiza (AM)-related cis-elements were found widely distributed in the putative promoter regions of the miRNA genes. Selected miRNAs were classified into three groups based on the presence or absence of P1BS and MYCS cis-elements, and their expression in response to Pi starvation and AM symbiosis was validated by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). These results show that conserved miRNAs exist in solanaceous species and they might play pivotal roles in plant growth, development, and stress responses.

Longitudinal Analysis of Renal Function Changes in Elderly Populations: Health Status Evaluation and Risk Factor Assessment.

Background: This study aims to investigate GFR decline in elderly subjects with varying physical conditions and analyze key risk factors impacting renal function changes. Methods: We obtained data from patients between 2017 and 2019, and matched healthy elderly subjects based on gender and age. Data collected for all subjects included annual measurements of fast blood glucose (GLU), glycated hemoglobin (HbA1c), low-density lipoprotein cholesterol (LDL-c), blood albumin (ALB), blood uric acid (UA), urine protein (UP), and systolic blood pressure (SBP). Additionally, information on coexisting diseases was gathered. The Full Age Spectrum (FAS) equation was used to calculate eGFR. Results: A total of 162 patients with complete 3-year renal dynamic imaging were included, including 84 patients in the kidney disease group (K group) and 78 patients in the non-kidney disease group (NK group). Ninety individuals were selected as the healthy group (H group). The annual decline rate in the K group was the fastest, which exceeded 5mL/min/1.73m2 (P < 0.05). Group (K group: ß=-40.31, P<0.001; NK group: ß=-26.96, P<0.001), ALB (ß=-0.38, P=0.038) and HbA1c (ß=1.36, P=0.029) had a significant negative impact on the eGFR changes. For participants who had negative proteinuria: K group had the most significant annual eGFR decline. Conclusion: The presence of kidney disease, along with proteinuria nor not, can lead to a marked acceleration in kidney function decline in elderly. We categorize elderly individuals with an annual eGFR decline of more than 5 mL/min/1.73m2 as the "kidney accelerated aging" population.