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A Systematic View of the MLO Family in Rice Suggests Their Novel Roles in Morphological Development, Diurnal Responses, the Light-Signaling Pathway, and Various Stress Responses

View Article: PubMed Central - PubMed

ABSTRACT

The Mildew resistance Locus O (MLO) family is unique to plants, containing genes that were initially identified as a susceptibility factor to powdery mildew pathogens. However, little is known about the roles and functional diversity of this family in rice, a model crop plant. The rice genome has 12 potential MLO family members. To achieve systematic functional assignments, we performed a phylogenomic analysis by integrating meta-expression data obtained from public sources of microarray data and real-time expression data into a phylogenic tree. Subsequently, we identified 12 MLO genes with various tissue-preferred patterns, including leaf, root, pollen, and ubiquitous expression. This suggested their functional diversity for morphological agronomic traits. We also used these integrated transcriptome data within a phylogenetic context to estimate the functional redundancy or specificity among OsMLO family members. Here, OsMLO12 showed preferential expression in mature pollen; OsMLO4, in the root tips; OsMLO10, throughout the roots except at the tips; and OsMLO8, expression preferential to the leaves and trinucleate pollen. Of particular interest to us was the diurnal expression of OsMLO1, OsMLO3, and OsMLO8, which indicated that they are potentially significant in responses to environmental changes. In osdxr mutants that show defects in the light response, OsMLO1, OsMLO3, OsMLO8, and four calmodulin genes were down-regulated. This finding provides insight into the novel functions of MLO proteins associated with the light-responsive methylerythritol 4-phosphate pathway. In addition, abiotic stress meta-expression data and real-time expression analysis implied that four and five MLO genes in rice are associated with responses to heat and cold stress, respectively. Upregulation of OsMLO3 by Magnaporthe oryzae infection further suggested that this gene participates in the response to pathogens. Our analysis has produced fundamental information that will enhance future studies of the diverse developmental or physiological phenomena mediated by the MLO family in this model plant system.

No MeSH data available.


Related in: MedlinePlus

Expression profiles of OsMLO genes under cold stress evaluated by real-time PCR. OsNAC6 served as a positive marker for cold-stress response. OsUbi5 was used as internal control. C, cold treatment; R, recovery. Numbers after C and R indicate time points (hours) after stress treatment. **p < 0.01; *0.01 < p < 0.05.
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Figure 8: Expression profiles of OsMLO genes under cold stress evaluated by real-time PCR. OsNAC6 served as a positive marker for cold-stress response. OsUbi5 was used as internal control. C, cold treatment; R, recovery. Numbers after C and R indicate time points (hours) after stress treatment. **p < 0.01; *0.01 < p < 0.05.

Mentions: In response to cold stress, OsMLO1 and OsMLO3 were up-regulated at 48 h after treatment was applied. However, their level of expression declined to that measured from the control when the chilled plants were allowed to recover at 28°C (Figure 8). Both OsMLO4 and OsMLO11 were quickly induced by low temperatures, with expression increasing after just 24 h of treatment and transcripts being retained at higher levels until Hour 48. By contrast, OsMLO9 was down-regulated by 24 h of chilling. This response was the opposite of its upregulation by heat stress, implying that the gene has separate functions in determining the plant response to temperature extremes. All of these findings provided evidence that the expression of these rice MLO genes is influenced by cold and/or heat stress.


A Systematic View of the MLO Family in Rice Suggests Their Novel Roles in Morphological Development, Diurnal Responses, the Light-Signaling Pathway, and Various Stress Responses
Expression profiles of OsMLO genes under cold stress evaluated by real-time PCR. OsNAC6 served as a positive marker for cold-stress response. OsUbi5 was used as internal control. C, cold treatment; R, recovery. Numbers after C and R indicate time points (hours) after stress treatment. **p < 0.01; *0.01 < p < 0.05.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037229&req=5

Figure 8: Expression profiles of OsMLO genes under cold stress evaluated by real-time PCR. OsNAC6 served as a positive marker for cold-stress response. OsUbi5 was used as internal control. C, cold treatment; R, recovery. Numbers after C and R indicate time points (hours) after stress treatment. **p < 0.01; *0.01 < p < 0.05.
Mentions: In response to cold stress, OsMLO1 and OsMLO3 were up-regulated at 48 h after treatment was applied. However, their level of expression declined to that measured from the control when the chilled plants were allowed to recover at 28°C (Figure 8). Both OsMLO4 and OsMLO11 were quickly induced by low temperatures, with expression increasing after just 24 h of treatment and transcripts being retained at higher levels until Hour 48. By contrast, OsMLO9 was down-regulated by 24 h of chilling. This response was the opposite of its upregulation by heat stress, implying that the gene has separate functions in determining the plant response to temperature extremes. All of these findings provided evidence that the expression of these rice MLO genes is influenced by cold and/or heat stress.

View Article: PubMed Central - PubMed

ABSTRACT

The Mildew resistance Locus O (MLO) family is unique to plants, containing genes that were initially identified as a susceptibility factor to powdery mildew pathogens. However, little is known about the roles and functional diversity of this family in rice, a model crop plant. The rice genome has 12 potential MLO family members. To achieve systematic functional assignments, we performed a phylogenomic analysis by integrating meta-expression data obtained from public sources of microarray data and real-time expression data into a phylogenic tree. Subsequently, we identified 12 MLO genes with various tissue-preferred patterns, including leaf, root, pollen, and ubiquitous expression. This suggested their functional diversity for morphological agronomic traits. We also used these integrated transcriptome data within a phylogenetic context to estimate the functional redundancy or specificity among OsMLO family members. Here, OsMLO12 showed preferential expression in mature pollen; OsMLO4, in the root tips; OsMLO10, throughout the roots except at the tips; and OsMLO8, expression preferential to the leaves and trinucleate pollen. Of particular interest to us was the diurnal expression of OsMLO1, OsMLO3, and OsMLO8, which indicated that they are potentially significant in responses to environmental changes. In osdxr mutants that show defects in the light response, OsMLO1, OsMLO3, OsMLO8, and four calmodulin genes were down-regulated. This finding provides insight into the novel functions of MLO proteins associated with the light-responsive methylerythritol 4-phosphate pathway. In addition, abiotic stress meta-expression data and real-time expression analysis implied that four and five MLO genes in rice are associated with responses to heat and cold stress, respectively. Upregulation of OsMLO3 by Magnaporthe oryzae infection further suggested that this gene participates in the response to pathogens. Our analysis has produced fundamental information that will enhance future studies of the diverse developmental or physiological phenomena mediated by the MLO family in this model plant system.

No MeSH data available.


Related in: MedlinePlus