Search

It has been suggested that L-type [Ca.sup.2+] channels play an important role in cell swelling-induced vasoconstriction. However, there is no direct evidence that [Ca.sup.2+] channels in vascular smooth muscle are modulated by cell swelling. We tested the hypothesis that L-type [Ca.sup.2+] channels in rabbit portal vein myocytes are modulated by hypotonic cell swelling via protein kinase activation. [Ba.sup.2+] currents ([I.sub.Ba]) through L-type [Ca.sup.2+] channels were recorded in smooth muscle cells freshly isolated from rabbit portal vein with the conventional whole cell patch-clamp technique. Superfusion of cells with hypotonic solution reversibly enhanced [Ca.sup.2+] channel activity but did not alter the voltage-dependent characteristics of [Ca.sup.2+] channels. Bath application of selective inhibitors of protein kinase C (PKC), Ro-31-8425 or Go-6983, prevented [I.sub.Ba] enhancement by hypotonic swelling, whereas the specific protein kinase A (PKA) inhibitor KT-5720 had no effect. Bath application of phorbol 12,13-dibutyrate (PDBu) significantly increased [I.sub.Ba], under isotonic conditions and prevented current stimulation by hypotonic swelling. However, PDBu did not have any effect on [I.sub.Ba] when cells were first exposed to hypotonic solution. Furthermore, downregulation of endogenous PKC by overnight treatment of cells with PDBu prevented current enhancement by hypotonic swelling. These data suggest that hypotonic cell swelling can enhance [Ca.sup.2+] channel activity in rabbit portal vein smooth muscle cells through activation of PKC. cell swelling; protein kinases; calcium current

The essential role of auxin in plant growth and development is well known. Pathways related to auxin synthesis, transport and signaling have been extensively studied in recent years, and the PIN-FORMED (PIN) protein family has been identified as being pivotal for polar auxin transport and distribution. However, research focused on the functional characterization of PIN proteins in rice is still lacking. In this study, we investigated the expression and function of OsPIN1c and OsPIN1d in the japonica rice variety (Nipponbare) using gene knockout and high-throughput RNA sequencing analysis. The results showed that OsPIN1c and OsPIN1d were mainly expressed in young panicles and exhibited a redundant function. Furthermore, OsPIN1c or OsPIN1d loss-of-function mutants presented a mild phenotype compared with the wild type. However, in addition to significantly decreased plant height and tiller number, panicle development was severely disrupted in double-mutant lines of OsPIN1c and OsPIN1d. Severe defects included smaller inflorescence meristem and panicle sizes, fewer primary branches, elongated bract leaves, non-degraded hair and no spikelet growth. Interestingly, ospin1cd-3 , a double-mutant line with functional retention of OsPIN1d, showed milder defects than those observed in other mutants. Additionally, several critical regulators of reproductive development, such as OsPID, LAX1, OsMADS1 and OsSPL14 / IPA1 , were differentially expressed in ospin1c-1 ospin1d-1 , supporting the hypothesis that OsPIN1c and OsPIN1d are involved in regulating panicle development. Therefore, this study provides novel insights into the auxin pathways that regulate plant reproductive development in monocots. [ABSTRACT FROM AUTHOR]

Poor light stress causes lodging risks in hybrid indica rice (Oryza sativa L.) in Sichuan Basin, China. However, the effective way of improving lodging resistance of hybrid indica rice by plant regulation strategy under poor light stress has not yet been investigated. A 2‐yr field study, comparing the three foliar application uniconazole rates under normal light and shading condition, was conducted to determine the lodging resistance and its physiological mechanism by using two hybrid rice varieties (Yuxiang203 [YX203] and Cliangyouhuazhan [CLYHZ]). The results showed that shading significantly decreased grain yield, but, increased lodging index (LI) due to poor stem breaking strength (M). Also, shading increased the non‐structural carbohydrates (NSC), but reduced structural carbohydrate (SC), especially for lignin in basal culm and thus, weakened the stem stiffness. Grain yield was first increased, and then declined with increasing foliar uniconazole rates. And, LI decreased sharply owing to improvement of M while reduction of bending moment by whole plant (WP). Larger section modulus (SM) of YX203 and higher bending stress (BS) of CLYHZ were contributed to higher M. Correlation analysis showed that M was significantly correlated with culm diameter, culm wall thickness and SC content for YX203, and that with SC content for CLYHZ, respectively. The results indicated that foliar application of uniconazole increased lodging resistance of hybrid indica rice for larger M and SC accumulation in basal stem. Uniconazole foliar application at 40 mg L–1 can increase lodging resistance while maintaining grain yield of hybrid indica rice in the Sichuan Basin, China. Core Ideas: Shading rapidly raised lodging risks of hybrid indica rice due to poor stem strength of basal stem.The foliar application uniconazole increased lodging resistance of hybrid indica rice.The higher stem strength of Yuxiang203 rely on section modulus and structural carbohydrates.Uniconazole rate at 40 mg L–1 rose lodging resistance and yield of hybrid indica rice in the Sichuan Basin. [ABSTRACT FROM AUTHOR]

SUMMARY: The CUP‐SHAPED COTYLEDON (CUC) genes (CUC1, CUC2 and CUC3) regulate organ boundary formation in Arabidopsis. However, the functions of their homologous genes in rice (Oryza sativa) are still unknown. Here, we have identified an orthologous gene of CUC1 and CUC2 in rice, named OsNAM. Subcellular localization and yeast two‐hybrid assay results have suggested that OsNAM encodes a conserved nuclear NAC (NAM/ATAF1/CUC2) protein with a transcriptional activator. The null mutant osnam‐1 presented a fused leaf structure, small panicles, reduced branches and aberrant floral organ identities when compared with those of the wild type. Beta‐glucuronidase staining and GFP reporter lines indicated that OsNAM was expressed in young tissues and that its boundary enrichment expression was regulated by OsmiR164. Loss‐of‐function mutants for OsCUC3 resulted in no obvious defects throughout rice development. The osnam oscuc3 double mutant, however, resulted in severe leaf fusion of the first two leaves, while the osnam single mutant showed a similar phenotype from the seventh leaf. These results indicated that OsNAM and OsCUC3 act redundantly for boundary specification during post‐embryonic development. Overall, we describe the biological functions of OsNAM and OsCUC3 in rice development and the expression characteristics of OsNAM. This work reveals the important role of CUC genes in rice. [ABSTRACT FROM AUTHOR]

Abstract To simulate expected future global warming, hexagonal arrays of infrared heaters have previously been used to warm open-field canopies of upland crops such as wheat. Through the use of concrete-anchored posts, improved software, overhead wires, extensive grounding, and monitoring with a thermal camera, the technology was safely and reliably extended to paddy rice fields. The system maintained canopy temperature increases within 0.5°C of daytime and nighttime set-point differences of 1.3 and 2.7°C 67% of the time.