Pb1 - Revision history

Lingquanmeng at 07:06, 3 June 2014

2014-06-03T07:06:48Z

Lingquanmeng: /* Annotated Information */

2014-06-03T07:01:59Z

‎Annotated Information

Lingquanmeng: /* Knowledge Extension */

2014-06-03T06:57:33Z

‎Knowledge Extension

Lingquanmeng: /* Expression */

2014-06-03T06:47:42Z

‎Expression

Lingquanmeng: /* Expression */

2014-06-03T06:46:18Z

‎Expression

Lingquanmeng: /* Expression */

2014-06-03T06:36:10Z

‎Expression

Lingquanmeng: /* Mutation */

2014-06-03T06:23:10Z

‎Mutation

Lingquanmeng at 06:15, 3 June 2014

2014-06-03T06:15:03Z

Lingquanmeng at 05:51, 3 June 2014

2014-06-03T05:51:31Z

Lingquanmeng at 05:49, 3 June 2014

2014-06-03T05:49:49Z

← Older revision		Revision as of 07:06, 3 June 2014
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−	== ~~Structured Information~~ ==	+	== Evolution ==

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 === Knowledge Extension ===
-  Pb1-mediated blast resistance partially depends on the SA signaling pathway. Two possible mechanisms can account for the partial SA dependence of Pb1-mediated blast resistance. One is that Pb1 activates the SA pathway upstream of SA as many R proteins do , leading to WRKY45 induction through the SA
+  Pb1-mediated blast resistance partially depends on the SA signaling pathway. Two possible mechanisms can account for the partial SA dependence of Pb1-mediated blast resistance. One is that Pb1 activates the SA pathway upstream of SA as many R proteins do , leading to WRKY45 induction through the SA pathway. Another is that reduction of basal SA levels results in a decrease of basal WRKY45 protein levels, which consequently leads to reduced accumulation of WRKY45 proteins despite the inhibition of WRKY45 degradation by Pb1<ref name="ref3" />.
 == Labs working on this gene ==

← Older revision		Revision as of 06:57, 3 June 2014
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	=== Knowledge Extension ===		=== Knowledge Extension ===
		+	Pb1-mediated blast resistance partially depends on the SA signaling pathway. Two possible mechanisms can account for the partial SA dependence of Pb1-mediated blast resistance. One is that Pb1 activates the SA pathway upstream of SA as many R proteins do , leading to WRKY45 induction through the SA
		+	pathway. Another is that reduction of basal SA levels results in a decrease of basal WRKY45 protein levels, which consequently leads to reduced accumulation of WRKY45 proteins despite the inhibition of WRKY45 degradation by Pb1.

	== Labs working on this gene ==		== Labs working on this gene ==

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 === Expression ===
-[[File:Pb1 figure 6.jpg|right|thumb|200px|''Pb1 figure 6.Pb1 protein sequence and conserved motifs.
+[[File:Pb1 figure 6.jpg|left|thumb|200px|''Pb1 figure 6.Pb1 protein sequence and conserved motifs.
 Protein sequence of Pb1. Relatively well-conserved sequence motifs with rice R proteins are shown in blue letters and less conserved ones in green letters. An LRR domain is underlined. The position of an extra E in P5 is indicated by a red triangle. Genomic DNA and protein sequences were deposited in DDBJ with accession numbers of AB570371 (Pb1) and AB570370 (from reference  <ref name="ref2" />).'']]
 ''Pb1'' encodes a coiled-coil–nucleotidebinding-site–leucine-rich repeat (CC–NBS–LRR) protein. The Pb1 protein sequence differed from previously reported R-proteins, particularly in the NBS domain, in which the P-loop was apparently absent and some other motifs were degenerated. Pb1 has two putative CC domains, CC1 and CC2, located in its N-terminus, with an nT motif-like sequence intervening them.CC

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 === Expression ===
 ''Pb1'' encodes a coiled-coil–nucleotidebinding-site–leucine-rich repeat (CC–NBS–LRR) protein. The Pb1 protein sequence differed from previously reported R-proteins, particularly in the NBS domain, in which the P-loop was apparently absent and some other motifs were degenerated. Pb1 has two putative CC domains, CC1 and CC2, located in its N-terminus, with an nT motif-like sequence intervening them.CC
 domains have periodical occurrence of leucine, or other hydrophobic amino acids, showing extensive amino acid sequence similarity to the CC domains of other CC-NBS-LRR proteins.An NBS-like domain is present in the central region of Pb1 protein; however, its sequence is quite diverged from those in reported NBS-LRR proteins.A long stretch of polypeptide with no significant sequence similarity to other sequences is inserted after the CC region of Pb1 and A Walker B-like sequence is present at amino acid position 641 of Pb1

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 === Mutation ===
+Pb1-Quad is a coiled-coil domain mutant that had weak interaction with WRKY45.
 === Expression ===

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 === Function ===
-   Panicle blast 1(''Pb1'') is a panicle blast resistance gene derived from the indica rice cultivar “Modan”<ref name="ref3" />. ''Pb1'' encodes a coiled-coil–nucleotide-binding site–leucine-rich repeat (CC-NB-LRR) protein and confers durable, broad-spectrum resistance to Magnaporthe oryzae races<ref name="ref1" />. Its molecular mechanism is  that CC-NB-LRR protein Pb1 interacts with WRKY45, a key transcription factor of the SA pathway, and that the blast resistance by Pb1 depends on WRKY45 <ref name="ref2" />.
+   Panicle blast 1(''Pb1'') is a panicle blast resistance gene derived from the indica rice cultivar “Modan”<ref name="ref1" />. ''Pb1'' encodes a coiled-coil–nucleotide-binding site–leucine-rich repeat (CC-NB-LRR) protein and confers durable, broad-spectrum resistance to Magnaporthe oryzae races<ref name="ref2" />. Its molecular mechanism is  that CC-NB-LRR protein Pb1 interacts with WRKY45, a key transcription factor of the SA pathway, and that the blast resistance by Pb1 depends on WRKY45 <ref name="ref3" />.
 ====''Pb1'' is a broad-spectrum panicle blast-resistance gene and Expression pattern of ''Pb1'' accounts for adult resistance in ''Pb1'' lines<ref name="ref2" />====
    Even if rice plants survive leaf blast, they can be damaged by panicle blast in the field (Figure 1a,''Pb1-''). Rice cultivars with ''Pb1''(''Pb1+''  cultivars) are rather weakly resistant to leaf blast, however, they show remarkable resistance to panicle blast (Figure 1a, ''Pb1+''). Evaluation of diseased grains indicated that the resistance was of quantitative nature (Figure 1a).
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 == Labs working on this gene ==
 == References ==

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 === Function ===
    Panicle blast 1(''Pb1'') is a panicle blast resistance gene derived from the indica rice cultivar “Modan”<ref name="ref3" />. ''Pb1'' encodes a coiled-coil–nucleotide-binding site–leucine-rich repeat (CC-NB-LRR) protein and confers durable, broad-spectrum resistance to Magnaporthe oryzae races<ref name="ref1" />. Its molecular mechanism is  that CC-NB-LRR protein Pb1 interacts with WRKY45, a key transcription factor of the SA pathway, and that the blast resistance by Pb1 depends on WRKY45 <ref name="ref2" />.
-====''Pb1'' is a broad-spectrum panicle blast-resistance gene and Expression pattern of ''Pb1'' accounts for adult resistance in ''Pb1'' lines<ref name="ref1" />====
+====''Pb1'' is a broad-spectrum panicle blast-resistance gene and Expression pattern of ''Pb1'' accounts for adult resistance in ''Pb1'' lines<ref name="ref2" />====
    Even if rice plants survive leaf blast, they can be damaged by panicle blast in the field (Figure 1a,''Pb1-''). Rice cultivars with ''Pb1''(''Pb1+''  cultivars) are rather weakly resistant to leaf blast, however, they show remarkable resistance to panicle blast (Figure 1a, ''Pb1+''). Evaluation of diseased grains indicated that the resistance was of quantitative nature (Figure 1a).
    To examine the race specificity of ''Pb1''-based panicle blast resistance, a ''Pb1+''cultivar, Aichinokaori-SBL (''Pb1+''), and its near-isogenic cultivar, Aichinokaori (''Pb1-''), were inoculated with various isolates of blast fungus at the full heading stage. Evaluation of diseased grains 2 weeks after inoculation showed that Aichinokaori-SBL (''Pb1+'') was more resistant to panicle blast than Aichinokaori ''(Pb1-'') with all the blast isolates tested (Figure 1b). This demonstrates the broad-spectrum nature of ''Pb1''-based panicle blast resistance
    In a ''Pb1+'' cultivar Koshihikari-Aichi-SBL, the level of blast resistance increased with plant growth. The resistance was weak during young stages, but became stronger in adult stages (adult resistance and panicle resistance, Figure 2). the expression pattern of Pb1 is a determinant for the developmental pattern of blast resistance in ''Pb1+'' cultivars
-====Pb1 Interacts with WRKY45 Through Its CC Domain, Prevents Ubiquitin-Proteasome Degradation of WRKY45 and its Blast Resistance Depends on WRKY45<ref name="ref2" />====
+====Pb1 Interacts with WRKY45 Through Its CC Domain, Prevents Ubiquitin-Proteasome Degradation of WRKY45 and its Blast Resistance Depends on WRKY45<ref name="ref3" />====
    Pb1-CC interacted with only WRKY45, but not with other WRKY proteins including WRKY47, another group III WRKY protein, in yeast cells (Figure. 3A). The interaction was also observed between wild-type Pb1-CC (Pb1-CC1–44and Pb1-CC1–51) and full ength WRKY45 in a GST-pull down assay (Figure. 3B). Mutants of Pb1-CC that had mutations in the two hydrophobic amino acids (Pb1-CC1–5116A23A and Pb1-CC1–5130A37A) interacted with WRKY45 similarly to wild-type Pb1-CC1–51,Pb1-16A23A30A37A (Quad), in which the four hydrophobic amino acids were mutated, showed markedly decreased interaction with WRKY45 in comparison with its corresponding wild-type (Pb1-CC1–51) (Figure. 3B). A coimmunoprecipitation assay showed that full-length Pb1 interacted with full-length WRKY45, but Pb1-Quad (full-length) interacted very weakly (Figure. 3C). This Pb1–WRKY45 interaction and the reduction of the interaction by CC mutation were also observed in a split LUC system by using N-terminal and C-terminal luciferases fused with Pb1 and WRKY45, respectively, in rice leaf sheath cells (Figure. 3D)
    To examine whether the panicle blast resistance by Pb1 depends on WRKY45, WRKY45 knockdown (WRKY45-kd) lines (Pb1+/WRKY45-kd and Pb1–/WRKY45-kd) were constructed. WRKY45 knockdown did not affect Pb1expression in these transformants. But the levels of panicle resistance in Pb1–/WRKY45-kd plants were similar to those in the Pb1–(Koshihikari) line, indicating that WRKY45 knockdown did not affect the basal levels of blast resistance in the panicle (Pb1 figure 4A)