Selection of suitable reference genes for qRT-PCR analysis of Begonia semperflorens under stress conditions

Molecular Biology Reports - Begonia semperflorens (B. semperflorens), belonging to the family Begoniaceae, has now been widely cultivated worldwide and is famous for its ornamental plants with...     

The alternative oxidase pathway is involved in the BR-induced salt resistance in mustard

In this study, the role of Brassinosteroids (BRs) and the relationship between the mitochondrial alternative oxidase (AOX) and ROS in the BR-induced defence response to salt stress was studied in mustard plants. Salt stress induced a significant activation of AOX. Exogenous BR significantly enhanced the capacity of the cyanide-resistant pathway, and reduced the damage of cell membrane. Pretreatment with brassinazole (Brz, an inhibitor of the BR biosynthesis pathway) significantly blocked the capacity of the cyanide-resistant pathway. BR could partly recover the AOX inactivation under salicylhydroxamic acid (SHAM, an inhibitor of the cyanide-resistant pathway) pretreatment. It was also found that BR could enhance the ROS accumulation and the antioxidant enzyme activities, while the AOX could eliminate the excessive ROS and enhance the antioxidant enzyme activities. Furthermore, the suppression of the cyanide-resistant pathway significantly increased the MDA content and the electrolyte leakage in mustard leaves, and the suppression of the BR biosynthesis had little effect on their recovering. Taken together, the cyanide-resistant pathway was involved in BR-induced salt tolerance and played an important role in maintaining the permeability of the cell membrane.     

Identification of Down-regulated Genes Modulated by an Alternative Oxidase Pathway Under Cold Stress Conditions in Watermelon Plants

This study investigated the cold responses of watermelon plants modulated by the alternative oxidase (AOX) pathway. Salicylhydroxamic acid was used in watermelon (Citrullus lanatus) plants in order to chemically inhibit the AOX pathway. After exposure to cold temperature (10°C) for 24 h, the SHAM-treated plants showed more serious cold-induced damage compared to non-treated plants. To investigate how the AOX pathway modulated the watermelon plants’ responses to cold, a polymerase chain reaction (PCR)-based suppression subtractive hybridization technique was used to isolate genes differently expressed between cold-stressed leaves of SHAM-treated and non-treated watermelon germplasm “IVSM No. 9”. After sequencing 400 randomly chosen cDNA clones, 314 uniquely expressed sequence tags (ESTs) were obtained. A total of 114 ESTs encoded unknown proteins or had no similarity in the database. Identified genes with significant protein homology mainly participated in stress and defense responses, metabolism and energetic processes, regulation of gene expression, signal transduction, protein fate and synthesis, cellular transport and others. These results indicated that watermelon plants could not respond appropriately to cold stress and suffer greater damage with an inhibited AOX pathway, thus, the AOX pathway had an important role in defining the plants cold responses.