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Aluminium (Al) toxicity is a primary limitation of crop production in acid soils, which take over 40% of arable soil worldwide. In previous studies, a series of genes have been identified to regulate the plant Al resistance or tolerance. However, none of E3 ubiquitin ligase, the key factor of ubiquitination that plays an important role in plant growth and development, has been characterized for Al response in Arabidopsis. In this study, an E3 ubiquition ligase gene AtATRF1 (Al Tolerance RING Finger 1), a homolog of RAD18 interacting RAD6 to repair the damaged DNA in human and yeast, is isolated from Arabidopsis. It encodes a predicted protein of 296 amino acids with a C3HC4 type RING finger domain. The expression of AtATRF1 is induced by Al, and the transgenic plant overexpressing AtATRF1 enhances the Al tolerance. Similar as RAD18, the AtATRF1 locates in nucleus and regulates the expression of AtATR, which involves in DNA repair and Al response in Arabidopsis. Our results indicate that nuclearlocated AtATRF1 may interact and ubiquitinate the transcriptional regulator of AtATR to mediate the Al tolerance of Arabidopsis. [ABSTRACT FROM AUTHOR]

Alternative splicing (AS), i.e., generating multiple mRNA transcripts from a single gene, is known to contribute to proteome diversity and gene regulation in eukaryotes. OsHsfA2a, a gene encoding a heat shock transcription factor (HSF) in rice ( Oryza. sativa L. cv. Nipponbare) generates six transcript isoforms ( OsHsfA2a-1 to OsHsfA2a-6) by AS. In this study, an OsHsfA2a has been identified and the genomic sequence found to be composed of three exons and two introns. Moreover, stress-responsive and phytohormone-responsive cis-elements in the promoter regions of OsHsfA2a have been identified. Real-time quantitative polymerase chain reaction analysis has revealed that the six isoforms have different tissue-specific expression patterns under normal growth conditions in rice. Interestingly, when treated with ABA (abscisic acid) and various abiotic stresses such as heat shock, simulated drought and high NaCl, these isoforms also show various stress responsive patterns in rice seedlings. These results indicate that AS of OsHsfA2a may play an important role not only in rice growth and development, but also in regulating stress-specific cellular adaptation responses. [ABSTRACT FROM AUTHOR]

Background and aims: Aluminum (Al)-induced citrate exudation has been identified as an important Al-resistance mechanism in soybean. Salicylic acid (SA) is a crucial signal molecule modulating numerous environment stresses in plants. This study was to investigate the role of SA in Al-induced citrate exudation from soybean roots. Methods: HPLC was used to test the Al-induced endogenous SA changes, effect of exogenous SA / an inhibitor of SA biosynthesis paclobutrazol (PAC) on Al-induced citrate efflux. The activity / transcriptional expression of mitochondrial aconitase (ACO) and a putative citrate transporter gene Gm-MATE1 were examined by an enzyme method or qRT-PCR. Results: Al stress caused increase of endogenous free-SA and conjugated SA (SAG). Exogenous SA enhanced the amount of Al-induced citrate secretion from roots, decreased the Al accumulation in root apices and alleviated the Al-induced inhibition of root elongation. PAC decreased the Al-induced enhancement of endogenous free SA and reduced the amount of citrate exudation. SA and Al together treatment further decreased mitochondrial aconitase (ACO) activity and enhanced the transcriptional expression of Gm-MATE1compared to the sole Al treatment. Conclusions: Al-induced SA production may act as an early signal to regulate the metabolism and transportation of citrate in soybean roots. [ABSTRACT FROM AUTHOR]

Nitric oxide (NO) and Jasmonic acid (JA) are two key signaling molecules involved in many and diverse biological pathways in plants. Growing evidence suggested that NO signaling interacts with JA signaling. In this work, Our experiment showed that NO exists in guard cell of Vicia faba L., and NO is involved in signal transduction of JAinduced stomata closuring: ( i ) JA enhances NO synthesis in guard cell; ( ii ) both JA and NO induced stomatal closure, and had dose response to their effects; (iii) there are synergetic correlation between JA and lower NO concentration in regulation of stomatal movement; (iv) JA-induced stomatal closure was largely prevented by 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO), a specific NO scavenger. An inhibitor of NO synthase (NOS) in mammalian cells, NG-nitro-L-Arg-methyl eater (L-NAME) also inhibits plant NOS, repressing JA-induced NO generation and JA-induced stomatal closure. We presumed that NO mainly comes from NOS after JA treatment. [ABSTRACT FROM AUTHOR]