Os08g0504700

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OsSAP11 confers abiotic stress tolerance in rice[1].

Annotated Information

Function

Figure 1. Cloning and overexpression of OsSAP11 and OsRLCK253 genes in Arabidopsis plants.(from reference [1]).
  • Open reading frames (ORFs) of OsSAP1/11 and OsRLCK253 were cloned in pSITE-3CA/1CA binary vectors, as YFP/CFP fusion proteins(Figure 1). OsSAP1/11 showed interactions with self as well as each other through A20 domain. Although AN1 also interacted with the A20 domain, no clear interaction of AN1 with OsSAP1/11 was observed[1].
  • Both OsSAP11 and OsRLCK253 could improve the water-deficit and salt stress tolerance in transgenic Arabidopsis plants via a signaling pathway affecting the expression of several common endogenous genes. OsSAP11 and OsRLCK253 in conferring abiotic stress tolerance. Both OsSAP11 and OsRLCK253 not only improved plant survival under stress but also protected against loss in yield caused by salt stress[1].
  • Alternatively, OsRLCK253 may activate OsSAP1/11 protein, which, on activation, may degrade or alter the activity of negative regulator of plant abiotic stress tolerance. In OsSAP11 plants, the entire pathway for GA biosynthesis was also activated[1].


GO assignment(s): GO:0003677,GO:0008270

Mutation

Figure 2. Five-wk-old transgenic and wild-type (WT) plants.(from reference [1]).

Transgenic and wild-type plants[1]:

  • Taking the radicle emergence as a parameter for seed germination, almost all the seeds germinated on day 5 in OsSAP11 transgenic lines, while only c. 80% of wild-type (WT) seeds showed germination.
  • However, transgenics fared better with 50–70% and 50–85% survival in OsSAP11 and OsRLCK253 plants, respectively, in comparison with 20–25% survival of WT plants. The effect on yield was also tested in these plants following the recovery after salt stress.
  • At the end of stress period(18% soil moisture), RWC in WT leaves was reduced to 43% while it varied between 58%–64% in OsRLCK253 and 56%–68% in OsSAP11 expressing transgenics, pointing towards the better water retention capacity in transgenics compared with WT under water-deficit stress.
  • The OsSAP11 and OsRLCK253 expressers showed c. 6–20% and 10–22% higher seed weight per plant, respectively, over WT after water-deficit stress.
  • The growth of transgenic lines and seed production in unstressed conditions was similar to WT plants (Fig. 2), indicating no negative effects of transgenes overexpression.

Expression

  • There were only six SAP genes (OsSAP1, OsSAP9, OsSAP11, OsSAP12, OsSAP14 and OsSAP17), which showed significant increase in expression upon exposure to cold stress[2].
  • It was interesting to see that two rice gene pairs (OsSAP1OsSAP11 and OsSAP6OsSAP9) present in duplicated segments' were significantly similar in their expression pattern[2].
  • OsSAP11 and OsRLCK253 also showed responsiveness to salt and water-deficit stress. Overexpression of both OsSAP11 and OsRLCK253 in Arabidopsis could enhance the water-deficit and salt stress tolerance[1].
  • In OsSAP11 expressing plants, 633 genes showed change in their expression level, of which 231 were upregulated and 402 were downregulated. Out of 633 genes affected in OsSAP11 plants, 143 genes could be assigned functions in different metabolic pathways. In OsSAP11 plants, genes involved in all the steps of GA biosynthesis were upregulated[1].

Subcellular localization

OsSAP11 showed localization in the nucleus in addition to the cytoplasm and plasma membrane. It is worth noting that OsSAP1 and OsSAP11 show differential interactions with OsRLCK253, possibly because of subtle differences in their subcellular localizations[1].

Evolution

It was found that the A20 domain mediates the interaction of OsSAP1 with self, its close homolog OsSAP11 and a rice receptor-like cytoplasmic kinase, OsRLCK253[1].

Knowledge Extension

  • In the recent past, a new family of genes termed as SAP(Stress Associated protein) gene family was studied in rice for its role in abiotic stress conditions by expression profiling under those conditions[2]. SAP gene family members are characterized by the presence of A20/AN1 domain in their putative encoded proteins. The majority was found to have both the A20 zinc-finger domain (present at the N-terminus) and the AN1 zinc-finger domain (present at the C-terminus). This is consistent with the previous finding from animal systems that the A20 and AN1 zinc-finger domains are usually found associated with each other[3].
  • All the members of the rice SAP genenfamily present in the rice genome showed inducibility to one or the other abiotic stresses. SAP gene family members, as in the case of animal systems may be involved in downregulating the pathway associated with abiotic stress injuries such as cell death by ubiquitinylating the key proteins and hence targeting them to degradation[2]. It would be important to define the relative function of the members of this gene family in the life of the rice plant[2][3].
  • Based on the phylogenetic analysis of the AN1 zincfinger domains, Jin et al.[4] recently divided all A20/AN1 zincfinger-containing SAP genes into two groups: Type I and Type II. Type I genes contain the traditional pattern of cysteine- and histidine-rich motifs, whereas Type II SAP genes contain the expanded domain CX4CX2CX9-12CX1-2CX4CX2HX5HXC where X represents any amino acid. Most Type I genes lack introns and contain one intact A20 type domain and/or one AN1 type zincfinger domain; most Type II genes have a single intron but do not contain an A20 domain[4][5].

Labs working on this gene

  • Interdisciplinary Centre for Plant Genomics and Department of Plant Molecular Biology, University of Delhi South Campus, Benito Juarez Road, New Delhi 110021, India
  • National Institute of Plant Genome Research, Aruna Asaf Ali Road, New Delhi 110067, India

References

  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 Giri J, Vij S, Dansana P K, et al. Rice A20/AN1 zinc‐finger containing stress‐associated proteins (SAP1/11) and a receptor‐like cytoplasmic kinase (OsRLCK253) interact via A20 zinc‐finger and confer abiotic stress tolerance in transgenic Arabidopsis plants[J]. New Phytologist, 2011, 191(3): 721-732.
  2. 2.0 2.1 2.2 2.3 2.4 Vij S, Tyagi A K. Genome-wide analysis of the stress associated protein (SAP) gene family containing A20/AN1 zinc-finger (s) in rice and their phylogenetic relationship with Arabidopsis[J]. Molecular Genetics and Genomics, 2006, 276(6): 565-575.
  3. 3.0 3.1 Evans P, Ovaa H, Hamon M, et al. Zinc-finger protein A20, a regulator of inflammation and cell survival, has de-ubiquitinating activity[J]. Biochem. J, 2004, 378: 727-734.
  4. 4.0 4.1 Jin Y, Wang M, Fu J, et al. Phylogenetic and expression analysis of ZnF-AN1 genes in plants[J]. Genomics, 2007, 90(2): 265-275.
  5. Saad R B, Zouari N, Ramdhan W B, et al. Improved drought and salt stress tolerance in transgenic tobacco overexpressing a novel A20/AN1 zinc-finger “AlSAP” gene isolated from the halophyte grass Aeluropus littoralis[J]. Plant molecular biology, 2010, 72(1-2): 171-190.

Structured Information