ABSTRACT
Homeobox proteins (HOXs) comprise a large family in eukaryotes and share a highly conserved DNA-binding motif, the homeodomain (HD). HOXs play an important role in the regulation of plant growth, development and stress response. However, systematic analysis and expression profiling of these genes have not been reported in Malus domestica. In this study, a total of 207 HOXs of M. domestica (MdHOXs) were identified and classified into 11 distinct subfamilies, and an unclassified group according to their functional domains. The MdHOXs were localized in all 17 chromosomes with various densities and a majority of them tended to form gene clusters. Analysis of the Ka/Ks ratios suggested that the duplicated genes of MdHOXs mainly underwent purifying selection with restrictive functional divergence after the duplication events. The expression of MdHOXs has organ specific characteristics and were divided into seven different groups. Stress-related cis-acting elements were prevalent in the upstream sequence of MdHOXs by systematic analysis. To explore the response to abiotic stress, eight MdHOXs were randomly selected to investigate their expression using quantitative real-time polymerase chain reaction. Transcription levels of MdHOXs were upregulated in the leaves and roots under cold, osmotic, high salinity or exogenous ABA treatments, which suggested that they may take part in the plant response to abiotic stress. These results provided basic information of HOXs in apple and will further contribute to the functional research of MdHOXs, especially the response to abiotic stress.
ABSTRACT
Cadmium (Cd) toxicity is a worldwide problem for crop production. The present work used hydroponic experiments to investigate the ameliorating effects and physiological mechanisms of glutathione (GSH) mitigation of Cd toxicity in cucumber seedlings. The results revealed that Cd was mainly accumulated in roots of cucumber, 100 µM GSH pretreatment in 50 µM Cd solution significantly recovered Cd-induced growth inhibition, improved photosynthetic and chlorophyll fluorescence performance. Moreover, external GSH obviously depressed hydroxyl free radical (·OH) and malondialdehyde accumulation, increased the total antioxidant capacity in cucumber exposed to Cd. Results indicated that pre-treatment of GSH can alleviate Cd toxicity by reducing Cd uptake and ROS accumulation, reduce the negative consequences of oxidative stress caused by Cd toxicity, moreover protect photosynthetic machinery from damaging, balance nutrients and antioxidants in cucumber.
A toxicidade do Cádmio (Cd) é um problema mundial para a produção de plantas olerícolas. O presente trabalho com o uso experimentos hidropônicos objetivou investigar a atenuação dos efeitos do cádmio por meio de mecanismos envolvendo a glutationa (GSH) e redução da toxicidade em plântulas de pepino submetidas ao Cd. OS resultados revelaram que o Cd acumulou principalmente nas raízes do pepino, Na dose de 100 µM GSH-50 esta reduziu a concentração em µM Cd na solução ea mesma melhora a ou reduz a inibição do crescimento ,bem como melhora o desempenho e a fluorescência clorofílica. Além disso, obviamente, radical Livre hidroxila GSH externa ·OH) aumenta a acumulação do malondialdeído e aumento da capacidade antioxidante total no pepino expostos ao Cd. OS resultados indicaram que o pré -tratamento de GSH pode reduzir a toxicidade, reduzindo a captação Cd e acumulação ROS , reduzir os efeitos negativos do stress oxidativo reduzindo a sua toxicidade, além de proteger o equilíbrio da disponibilidade de nutrientes e antioxidantes.
Subject(s)
Cadmium , Cucumis sativus , Seedlings , GlutathioneABSTRACT
Being a good anti-tumor drug, camptothecin (CPT) is a kind of modified monoterpene indole alkaloid firstly isolated from the deciduous Chinese happy tree with rapidly increasing clinical demand. Due to the great importance and low content of this compound, it is very important to improve CPT production by modern biotechnology. ORCA3 is a jasmonateresponsive APETALA2-domain transcript factor isolated from Catharanthus roseus, with strong ability to up-regulate expression of serveral key genes involved in TIA biosynthetic pathway. To investigate physiological function of ORCA3 gene in Camptotheca acuminata, the ORCA3 gene was transformed using Agrobacterium-mediated gene transfer technology. PCR analysis confirmed that the ORCA3 gene was integrated into the plant genome. HPLC showed that overexpression of ORCA3 in transgenic hairy root lines can effectively enhance the production of camptothecin with 1.5-fold compared with the control (1.12 mg/g dw). The results revealed that ORCA3 is an effective regulatory gene for improving metabolic flux in camptothecin biosynthetic pathway at the first time.