No abstract

Using photothermosensitive genic male sterile (PTSGMS) rice (Oryza sativa L.) lines to produce hybrids can obtain great heterosis. However, PTSGMS rice lines exhibit low stigma vitality when high-temperature (HT) stress happens during anthesis. Jasmonates (JAs) are novel phytohormones and play vital roles in mediating biotic and abiotic stresses. Little is known, however, if and how JAs could alleviate the harm of HT stress during anthesis to the stigma vitality of PTSGMS lines. This study investigated the question. Two PTSGMS lines and one restorer line of rice were pot-grown and subjected to normal temperature and HT stress during anthesis. The stigma exertion rate, sigma fresh weight, stigma area, contents of JAs, hydrogen peroxide (H2O2), and ascorbic acid (AsA), activity of catalase in stigmas, and the number of pollens germinated on the stigma of PTSGMS lines were determined. The results showed that a rice line with higher JAs content in the stigma under HT stress showed lower H2O2 content, higher AsA content and catalase activity in stigmas, larger stigma area, heavier stigma fresh weight, more pollens germinated on the stigma, and higher fertilization and seed-setting and rates. Applying methyl JAs during anthesis to rice panicles decreased the accumulation of reactive oxygen species and enhanced stigma vitality, thereby increasing fertilization and seed-setting rates of the hybrids of PTSGMS rice lines under HT stress. The results demonstrate that JAs attenuate the injury of HT stress to the stigma vitality of PTSGMS rice lines through enhancing antioxidant ability.

Magnesium is an essential element to sustain all forms of life. Total intracellular magnesium content is determined by the balance of magnesium influx and efflux. CorA is a divalent selective channel in the metal ion transport superfamily and is the major Mg2+ uptake pathway in prokaryotes and eukaryotic mitochondria. Previous studies have demonstrated that CorA showed distinct magnesium bound closed conformation and Mg2+-free states. In addition, CorA is regulated by cytoplasmic magnesium ions and its gating mechanism has been investigated by electron paramagnetic resonance technique and molecular dynamic simulations. Here, we report a study of the putative CorA-type channel Bpss1228 from Burkholderia pseudomallei, which has been shown to be significantly associated with pseudomallei infection. We expressed and purified the Bpss1228 in full-length. Subsequently, electrophysiological experiments further investigated the electrical characteristics of Bpss1228 and revealed that it was a strictly cation-selective channel. We also proved that Bpss1228 not only possessed magnesium-mediated regulatory property a remarkable ability to be modulated by magnesium ions. Finally, we observed the three-step gating behavior of Bpss1228 on planar lipid bilayer, and further proposed a synergistic gating mechanism by which CorA family channels control intracellular magnesium homeostasis.