Identification of a drought-induced rice gene, OsSAP, that suppresses Bax-induced cell death in yeast.

We identified rice genes that might be involved in drought stress tolerance by virtue of their anti-apoptotic activity. Potential anti-apoptosis related genes were identified by screening an Oryza sativa cDNA library derived from drought stressed tissues in a yeast functional assay. About 28 O. sativa cDNAs promoted yeast survival following engagement of Bax-induced apoptosis. An O. sativa cDNA encoding R12H780 was a highly conserved putative senescence-associated-protein (OsSAP). OsSAP was both highly and rapidly expressed in response to drought stress. Additionally, OsSAP was found to be localized to the mitochondria. Overall, OsSAP represents a new type of Bax suppressor related gene and endows multiple stress tolerance in yeast.

Applications of CRISPR/Cas9 as New Strategies for Short Breeding to Drought Gene in Rice.

Recent unpredictable climate change is the main reason for the decline in rice yield. In particular, drought stress is a major constraint in reducing yield and quality for rice at rainfed agriculture areas, such as Asia and South America. CRISPR/Cas9 provides an effective solution for gene function study and molecular breeding due to specific editing of targeted genome sequences. In addition, CRISPR/Cas9 application can significantly reduce the time required to develop new cultivars with improved traits compared to conventional complex and time-consuming breeding. Here, drought-induced gene Oryza sativa Senescence-associated protein (OsSAP) was edited by CRISPR/Cas9. To investigate the possible role of OsSAP in drought stress, genome-editing plants were subjected to drought stress until the soil moisture content reached 20%, and the reactive oxygen species (ROS) scavenging efficiency of genome-editing plants were decreased. When the genome-editing plants were subjected to drought stress, survival rate, shoot length, root length, content of chlorophyll number of tiller, and 1,000-grain weight decreased, and more H2O2 and O2 - were detected in leaves. In addition, expression levels of several critical stress-related transcription factors were decreased in the OsSAP genome-editing plant. These results suggest that OsSAP function as a positive regulator during drought stress response in rice. We analyzed the expression of OsSAP and Cas9 in T0 and T1 plants as well as T2 seeds. As the course of generation advancement progressed, Cas9 expression remained stable or weakened but the OsSAP expression was continuously removed from the T0 plant. The coefficient of variation (CV) in both T1 plants and T2 seeds was lower than 5%. Overall, our results suggest that CRISPR/Cas9 could be a novel and important tool for efficiently generating specific and inheritable targeted genome editing in rice, with short breeding cycles.

Effect on Chemical and Physical Properties of Soil Each Peat Moss, Elemental Sulfur, and Sulfur-Oxidizing Bacteria.

Peat moss is an organic substance corroded by sphagnum moss and has a pH of 3.0-4.0. Elemental sulfur is sulfated and oxidized by the action of bacteria to become sulfuric acid. These biological factors can alter the soil environment. Blueberries require soil with a pH of 4.5-5.2 and high organic matter content. In this experiment, we investigated whether different treatment rates of peat moss, elemental sulfur, and sulfur-oxidizing bacteria affect changes in soil pH, physicochemical properties, and electrical conductivity. We detected strong changes in soil pH as a reaction to the supply of peat moss, elemental sulfur, and sulfur-oxidizing bacteria. The pH of the soil when peat moss and elemental sulfur each were supplied was reduced. In addition, the pH decreased faster when elemental sulfur and sulfur-oxidizing bacteria were supplied together than elemental sulfur alone, satisfying an acidic soil environment suitable for blueberry cultivation. In this experiment, it is shown that peat moss, elemental sulfur, and sulfur-oxidizing bacteria are suitable for lowering soil pH. It was demonstrated that when elemental sulfur and sulfur-oxidizing bacteria were treated together, the pH decreased faster than when treated with peat moss. It could be economically beneficial to farmers to use elemental sulfur and sulfur-oxidizing bacteria, which are cheaper than peat moss, to reduce the pH of the soil.

Roles of plant hormones and anti-apoptosis genes during drought stress in rice (Oryza sativa L.).

We previously identified the rice (Oryza sativa) senescence-associated gene OsSAP which encodes a highly conserved protein involved in anti-apoptotic activity. This novel Bax suppressor-related gene regulates tolerance to multiple stresses in yeast. Here, we show the effects of drought stress on leaf and root tissues of plants over-expressing OsSAP in relation to the levels of phytohormones, abscisic acid (ABA), jasmonic acid (JA), indole-3-carboxylic acid (ICA), gibberellic acid (GA3), and zeatin. Results showed that rice plants over-expressing SAP were tolerant to drought stress compared to wild type and the plants over-expressing AtBI-1, which is a homolog of the human Bax inhibitor-1 in Arabidopsis. ABA and JA levels in OsSAP and AtBI-1 transgenic plants consistently increased up to at least 3 days after drought treatment, whereas lower GA3 levels were recorded during early drought period. Comparison between control and transgenic plants overexpressing anti-apoptosis genes OsSAP and AtBI-1 resulted in different patterns of hormone levels, indicating that these genes are involved in the plant responses to drought stress and present an opportunity for further study on drought stress tolerance in rice and other plant species.