Physiological responses and Ethylene-Response AP2/ERF Factor expression in Indica rice seedlings subjected to submergence and osmotic stress.

BACKGROUND: The increased frequency of heavy rains in recent years has led to submergence stress in rice paddies, severely affecting rice production. Submergence causes not only hypoxic stress from excess water in the surrounding environment but also osmotic stress in plant cells. We assessed physiological responses and Ethylene-Response AP2/ERF Factor regulation under submergence conditions alone and with ionic or nonionic osmotic stress in submergence-sensitive IR64 and submergence-tolerant IR64-Sub1 Indica rice cultivars. RESULTS: Our results indicate that both IR64 and IR64-Sub1 exhibited shorter plant heights and root lengths under submergence with nonionic osmotic stress than normal condition and submergence alone. IR64-Sub1 seedlings exhibited a significantly lower plant height under submergence conditions alone and with ionic or nonionic osmotic stress than IR64 cultivars. IR64-Sub1 seedlings also presented lower malondialdehyde (MDA) concentration and higher survival rates than did IR64 seedlings after submergence with ionic or nonionic osmotic stress treatment. Sub1A-1 affects reactive oxygen species (ROS) accumulation and antioxidant enzyme activity in rice. The results also show that hypoxia-inducible ethylene response factors (ERF)-VII group and alcohol dehydrogenase 1 (ADH1) and lactate dehydrogenase 1 (LDH1) genes exhibited different expression levels under nonionic or ionic osmotic stress during submergence on rice. CONCLUSIONS: Together, these results demonstrate that complex regulatory mechanisms are involved in responses to the aforementioned forms of stress and offer new insights into the effects of submergence and osmotic stress on rice.

Analyzing organic tea certification and traceability system within the Taiwanese tea industry.

BACKGROUND: We applied game theory to the organic tea certification process and traceability system used by the Taiwanese tea industry to elucidate the strategic choices made by tea farmers and organic tea certification agencies. Thus, this paper clarifies how relevant variables affect the organic certification process and traceability system used within the tea industry. RESULTS: The findings indicate that farmers who generate high revenues experience failures regarding tea deliveries, cash outflow, damage compensation, and quasi-rent. An additional problem included the high costs yielded when tea farmers colluded with or switched organic tea certification agencies. Furthermore, there could be decreasing levels of personal interest in planting non-organic tea and lowering the costs of planting organic tea and the managerial accounting costs of building comprehensive traceability systems; thus, the analysis yielded strong results and a superior equilibrium. CONCLUSION: This research is unprecedented, using an innovative model and providing a novel analysis structure for use in the tea industry. These results contribute to the field of literature and should serve as a valuable reference for members of the tea industry, government, and academia.

NADPH Oxidase RbohD and Ethylene Signaling are Involved in Modulating Seedling Growth and Survival Under Submergence Stress.

In higher plants under low oxygen or hypoxic conditions, the phytohormone ethylene and hydrogen peroxide (H2O2) are involved in complex regulatory mechanisms in hypoxia signaling pathways. The respiratory burst oxidase homolog D (RbohD), an NADPH oxidase, is involved in the primary stages of hypoxia signaling, modulating the expression of downstream hypoxia-inducible genes under hypoxic stress. In this study, our data revealed that under normoxic conditions, seed germination was delayed in the rbohD/ein2-5 double mutant, whereas postgermination stage root growth was promoted. Under submergence, the rbohD/ein2-5 double mutant line had an inhibited root growth phenotype. Furthermore, chlorophyll content and leaf survival were reduced in the rbohD/ein2-5 double mutant compared with wild-type plants under submerged conditions. In quantitative RT-PCR analysis, the induction of Ethylene-responsive factor 73/hypoxia responsive 1 (AtERF73/HRE1) and alcohol dehydrogenase 1 (AtADH1) transcripts was lower in the rbohD/ein2-5 double mutant during hypoxic stress than in wild-type plants and in rbohD and ein2-5 mutant lines. Taken together, our results indicate that an interplay of ethylene and RbohD is involved in regulating seed germination and post-germination stages under normoxic conditions. Moreover, ethylene and RbohD are involved in modulating seedling root growth, leaf chlorophyll content, and hypoxia-inducible gene expression under hypoxic conditions.