OsbZIP16 has the potential to greatly improve stress resistance of crops.
- The 877 bp genomic sequence and the 513 bp coding sequence of OsbZIP16 were cloned by PCR and RT-PCR, respectively.
- OsbZIP16 has broad functions in abiotic stress signal transduction in general and may play a prominent role in rice’s response to drought stress in particular. There is a possibility that OsbZIP16’s contribution to drought resistance in rice is related to the ABA signaling pathway, but the exact mechanism of this connection needs to be flushed out over the course of future research.
- It appears that OsbZIP16 may positively mediate the transcript levels of some drought-resistant genes(LEA7, RAB21 and RAB16D) under drought conditions.
- six transgenic lines:
- As expected, all of these transgenic lines with high OsbZIP16 expression levels showed dramatically increased survival rates compared with wild type plants. Furthermore, the transgenic lines(ox2, ox7, ox11, ox23) with higher expression levels of OsbZIP16 exhibited higher survival rates than the transgenic lines (ox4, ox5) with lower expression levels, which indicating that there is a positive correlation between the expression level of OsbZIP16 and the plants’ drought survival rate.
- Transcripts of OsbZIP16 were widely detected in the rice plants at both the seedling and heading stages. The mature leaves were observed to have the highest expression level of OsbZIP16. OsbZIP16 is up-regulated under drought and high salinity stress, thus, OsbZIP16 may be involved in the physiologic pathways that aid rice in adapting to less than habitable growth environments.
- The expression of OsbZIP16 was rapidly induced within three hours under both drought and high salinity stress. The expression level of OsbZIP16 under drought stress was observed to rapidly increase throughout the nine-hour testing period, while it was observed to plateau at the sixth hour under high salinity stress, which suggesting that OsbZIP16 is involved in rice’s response to abiotic stress.
- In comparison to wild type plants, overexpression of OsbZIP16 makes transgenic rice hypersensitive to ABA. In addition, when wild type rice seedlings were treated with exogenous ABA, the expression of OsbZIP16 was observed to increase quickly and dramatically. Thus, OsbZIP16 may be involved in the ABA signaling pathway in rice.
- No difference in the expression levels of the two upstream genes, SAPK10 and PP2C, was observed between the wild type and transgenic plants under either normal or drought conditions. In contrast, although the two downstream genes, LEA3-1 and RAB16C, were observed to have no significant difference in expression levels under normal conditions, they showed much higher expression levels in transgenic plants than in wild type plants under drought conditions, which suggesting that OsbZIP16 most likely participates in the ABA signaling pathway in rice.
- OsbZIP16 is classified as a member of the group IV bZIP transcription factors in rice.
- After sequence analysis, several kinds of stress-responsive elements were found in the promoter of OsbZIP16. ABRE, DRE, MYBRS and MYCRS can, respectively, be recognized by the presence of AREB, DREB, MYB and MYC transcription factors.
- Unlike other cereal species, rice is able to germinate and elongate under anoxia. The regulatory mechanism that configures the transcriptome of rice during anaerobic germination is yet to be established. Although some rice varieties exhibit some degree of tolerance to anaerobic stress that normally occurs during partial (hypoxia) or complete submergence (anoxia), it remains a major factor that limits productivity specially for the rainfed lowland cropping systems in Southeast Asia, where an average family relies on subsistence rice farming.
- The ability of rice to germinate under anoxia by extending the coleoptile is a highly unusual characteristic and a key feature underpinning the ability of rice seeds to establish in such a stressful environment. The process has been a focal point for research for many years. However, the molecular mechanisms underlying the anoxic growth of coleoptile still remain largely unknown.
- Combined with recent findings on ABA signal transduction in Arabidopsis (Fig. 1), investigation into the genetic regulation of core ABA signal transduction components could promote the introduction of drought tolerance responses into various crop species. Since the identification of PYR/PYL/RCARs, a better understanding of signaling networks among the canonical ABA signaling components has shed light on the genetic modification of ABA signal transduction for improving drought tolerance in plants.
- OsbZIP71 is a member of anoxia stressed up-regulated transcription factors with potential significance to the pattern of cis-element enrichment among the upregulated genes.
- Major targets for this purpose include PYR/PYL/RCARs-PP2CSnRK2s complexes as well as their phosphorylation substrates such as transcription factors or channel proteins. A PP2C binds to a SnRK2 in the absence of ABA and mediate dephosphorylation of the SnRK2 (Fig. 1). On the other hand, activation of SnRK2s as a critical positive signal for ABA signaling usually begins with autophosphorylation of SnRK2s.
Labs working on this gene
- College of Life Science, Hunan Normal University, Changsha 410081, China
- Peking–Yale Joint Center of Plant Molecular Genetics and Agrobiotechnology, State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
- National Center for Molecular Crop Design, Beijing 100085, China
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520-8104, USA
- Chen H, Chen W, Zhou J, et al. Basic leucine zipper transcription factor OsbZIP16 positively regulates drought resistance in rice[J]. Plant Science, 2012, 193: 8-17.
- Nijhawan A, Jain M, Tyagi A K, et al. Genomic survey and gene expression analysis of the basic leucine zipper transcription factor family in rice[J]. Plant Physiology, 2008, 146(2): 333-350.
- Kim T H. Mechanism of ABA signal transduction: Agricultural highlights for improving drought tolerance[J]. Journal of Plant Biology, 2014, 57(1): 1-8.
- Mohanty B, Herath V, Wijaya E, et al. Patterns of cis-element enrichment reveal potential regulatory modules involved in the transcriptional regulation of anoxia response of japonica rice[J]. Gene, 2012, 511(2): 235-242.
- JACKSON M B, RAM P C. Physiological and molecular basis of susceptibility and tolerance of rice plants to complete submergence[J]. Annals of Botany, 2003, 91(2): 227-241.
- Xu K, Xu X, Fukao T, et al. Sub1A encodes an ethylene responsive-like factor that confers submergence tolerance to rice[J]. Nature, 2006, 442: 705-708.
- Lakshmanan M, Mohanty B, Lim S H, et al. Metabolic and transcriptional regulatory mechanisms underlying the anoxic adaptation of rice coleoptile[J]. AoB Plants, 2014: plu026.