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Gibberellin acts through jasmonate to control the expression of MYB21, MYB24, and MYB57 to promote stamen filament growth in Arabidopsis.

Cheng H, Song S, Xiao L, Soo HM, Cheng Z, Xie D, Peng J - PLoS Genet. (2009)

Bottom Line: Further genetic and molecular studies demonstrate that GA suppresses DELLAs to mobilize the expression of the key JA biosynthesis gene DAD1, and this is consistent with the observation that the JA content in the young flower buds of the GA-deficient quadruple mutant ga1-3 gai-t6 rga-t2 rgl1-1 is much lower than that in the WT.We conclude that GA promotes JA biosynthesis to control the expression of MYB21, MYB24, and MYB57.Therefore, we have established a hierarchical relationship between GA and JA in that modulation of JA pathway by GA is one of the prerequisites for GA to regulate the normal stamen development in Arabidopsis.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Proteos, Singapore.

ABSTRACT
Precise coordination between stamen and pistil development is essential to make a fertile flower. Mutations impairing stamen filament elongation, pollen maturation, or anther dehiscence will cause male sterility. Deficiency in plant hormone gibberellin (GA) causes male sterility due to accumulation of DELLA proteins, and GA triggers DELLA degradation to promote stamen development. Deficiency in plant hormone jasmonate (JA) also causes male sterility. However, little is known about the relationship between GA and JA in controlling stamen development. Here, we show that MYB21, MYB24, and MYB57 are GA-dependent stamen-enriched genes. Loss-of-function of two DELLAs RGA and RGL2 restores the expression of these three MYB genes together with restoration of stamen filament growth in GA-deficient plants. Genetic analysis showed that the myb21-t1 myb24-t1 myb57-t1 triple mutant confers a short stamen phenotype leading to male sterility. Further genetic and molecular studies demonstrate that GA suppresses DELLAs to mobilize the expression of the key JA biosynthesis gene DAD1, and this is consistent with the observation that the JA content in the young flower buds of the GA-deficient quadruple mutant ga1-3 gai-t6 rga-t2 rgl1-1 is much lower than that in the WT. We conclude that GA promotes JA biosynthesis to control the expression of MYB21, MYB24, and MYB57. Therefore, we have established a hierarchical relationship between GA and JA in that modulation of JA pathway by GA is one of the prerequisites for GA to regulate the normal stamen development in Arabidopsis.

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MYB21, MYB24, and MYB57 Are Necessary but Insufficient to Complete the Normal Stamen Filament Development.Pictures are shown to compare the stamen phenotype in JA or GA repeatedly treated ga1-3 gai-t6 rga-t2 rgl1-1 (Q3) and opr3 plants with respective untreated controls.
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pgen-1000440-g008: MYB21, MYB24, and MYB57 Are Necessary but Insufficient to Complete the Normal Stamen Filament Development.Pictures are shown to compare the stamen phenotype in JA or GA repeatedly treated ga1-3 gai-t6 rga-t2 rgl1-1 (Q3) and opr3 plants with respective untreated controls.

Mentions: As shown in the above, MYB21, MYB24 and MYB57 act downstream of DELLAs in controlling stamen filament elongation. Expression of MYB21, MYB24 and MYB57 was repressed and floral development was arrested in the ga1-3 gai-t6 rga-t2 rgl1-1 Q3 quadruple mutant (Figure 2B and 2C). Regarding the fact that JA content is reduced in the young flower buds of Q3 we questioned whether restoration of expression of these MYBs by exogenous application of JA could rescue the stamen development to the ga1-3 gai-t6 rga-t2 rgl1-1 Q3 plants. We analyzed the flowers of JA-treated ga1-3 gai-t6 rga-t2 rgl1-1 plants and found that repeated JA application was unable to rescue the stamen development (Figure 8) though JA could restore the expression of the three MYB genes (Figure 5D), indicating that expression of MYB21, MYB24 and MYB57 alone was insufficient for normal stamen development in the ga1-3 gai-t6 rga-t2 rgl1-1 mutant. Furthermore, we found that exogenous application of GA to the ga1-3 gai-t6 rga-t2 rgl1-1 plants was able to induce the expression of MYB21, MYB24 and MYB57 (Figure 7B) and recover normal floral development (Figure 8). Taken together, our results demonstrate that besides these JA-inducible MYBs, other important GA-regulated JA-independent factors are needed for normal stamen filament development in ga1-3 gai-t6 rga-t2 rgl1-1.


Gibberellin acts through jasmonate to control the expression of MYB21, MYB24, and MYB57 to promote stamen filament growth in Arabidopsis.

Cheng H, Song S, Xiao L, Soo HM, Cheng Z, Xie D, Peng J - PLoS Genet. (2009)

MYB21, MYB24, and MYB57 Are Necessary but Insufficient to Complete the Normal Stamen Filament Development.Pictures are shown to compare the stamen phenotype in JA or GA repeatedly treated ga1-3 gai-t6 rga-t2 rgl1-1 (Q3) and opr3 plants with respective untreated controls.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2654962&req=5

pgen-1000440-g008: MYB21, MYB24, and MYB57 Are Necessary but Insufficient to Complete the Normal Stamen Filament Development.Pictures are shown to compare the stamen phenotype in JA or GA repeatedly treated ga1-3 gai-t6 rga-t2 rgl1-1 (Q3) and opr3 plants with respective untreated controls.
Mentions: As shown in the above, MYB21, MYB24 and MYB57 act downstream of DELLAs in controlling stamen filament elongation. Expression of MYB21, MYB24 and MYB57 was repressed and floral development was arrested in the ga1-3 gai-t6 rga-t2 rgl1-1 Q3 quadruple mutant (Figure 2B and 2C). Regarding the fact that JA content is reduced in the young flower buds of Q3 we questioned whether restoration of expression of these MYBs by exogenous application of JA could rescue the stamen development to the ga1-3 gai-t6 rga-t2 rgl1-1 Q3 plants. We analyzed the flowers of JA-treated ga1-3 gai-t6 rga-t2 rgl1-1 plants and found that repeated JA application was unable to rescue the stamen development (Figure 8) though JA could restore the expression of the three MYB genes (Figure 5D), indicating that expression of MYB21, MYB24 and MYB57 alone was insufficient for normal stamen development in the ga1-3 gai-t6 rga-t2 rgl1-1 mutant. Furthermore, we found that exogenous application of GA to the ga1-3 gai-t6 rga-t2 rgl1-1 plants was able to induce the expression of MYB21, MYB24 and MYB57 (Figure 7B) and recover normal floral development (Figure 8). Taken together, our results demonstrate that besides these JA-inducible MYBs, other important GA-regulated JA-independent factors are needed for normal stamen filament development in ga1-3 gai-t6 rga-t2 rgl1-1.

Bottom Line: Further genetic and molecular studies demonstrate that GA suppresses DELLAs to mobilize the expression of the key JA biosynthesis gene DAD1, and this is consistent with the observation that the JA content in the young flower buds of the GA-deficient quadruple mutant ga1-3 gai-t6 rga-t2 rgl1-1 is much lower than that in the WT.We conclude that GA promotes JA biosynthesis to control the expression of MYB21, MYB24, and MYB57.Therefore, we have established a hierarchical relationship between GA and JA in that modulation of JA pathway by GA is one of the prerequisites for GA to regulate the normal stamen development in Arabidopsis.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Proteos, Singapore.

ABSTRACT
Precise coordination between stamen and pistil development is essential to make a fertile flower. Mutations impairing stamen filament elongation, pollen maturation, or anther dehiscence will cause male sterility. Deficiency in plant hormone gibberellin (GA) causes male sterility due to accumulation of DELLA proteins, and GA triggers DELLA degradation to promote stamen development. Deficiency in plant hormone jasmonate (JA) also causes male sterility. However, little is known about the relationship between GA and JA in controlling stamen development. Here, we show that MYB21, MYB24, and MYB57 are GA-dependent stamen-enriched genes. Loss-of-function of two DELLAs RGA and RGL2 restores the expression of these three MYB genes together with restoration of stamen filament growth in GA-deficient plants. Genetic analysis showed that the myb21-t1 myb24-t1 myb57-t1 triple mutant confers a short stamen phenotype leading to male sterility. Further genetic and molecular studies demonstrate that GA suppresses DELLAs to mobilize the expression of the key JA biosynthesis gene DAD1, and this is consistent with the observation that the JA content in the young flower buds of the GA-deficient quadruple mutant ga1-3 gai-t6 rga-t2 rgl1-1 is much lower than that in the WT. We conclude that GA promotes JA biosynthesis to control the expression of MYB21, MYB24, and MYB57. Therefore, we have established a hierarchical relationship between GA and JA in that modulation of JA pathway by GA is one of the prerequisites for GA to regulate the normal stamen development in Arabidopsis.

Show MeSH
Related in: MedlinePlus