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Identification of candidate genes associated with leaf senescence in cultivated sunflower (Helianthus annuus L.).

Moschen S, Bengoa Luoni S, Paniego NB, Hopp HE, Dosio GA, Fernandez P, Heinz RA - PLoS ONE (2014)

Bottom Line: The expression of Ha-NAC01, Ha-NAC03, Ha-NAC04, Ha-NAC05 and Ha-MYB01 TFs increased before the remobilization rate increased and therefore, before the appearance of the first physiological symptoms of senescence, whereas Ha-NAC02 expression decreased.Interestingly, Ha-NAC01 and Ha-EIN2 transcription profiles showed an earlier up-regulation in upper leaves of plants close to maturity, compared with basal leaves of plants at pre-anthesis stages.These results suggest that the H. annuus TFs characterized in this work could play important roles as potential triggers of leaf senescence and thus can be considered putative candidate genes for senescence in sunflower.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Biotecnología, Centro de Investigaciones en Ciencias Agronómicas y Veterinarias, Instituto Nacional de Tecnología Agropecuaria, Hurlingham, Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Argentina.

ABSTRACT
Cultivated sunflower (Helianthus annuus L.), an important source of edible vegetable oil, shows rapid onset of senescence, which limits production by reducing photosynthetic capacity under specific growing conditions. Carbon for grain filling depends strongly on light interception by green leaf area, which diminishes during grain filling due to leaf senescence. Transcription factors (TFs) regulate the progression of leaf senescence in plants and have been well explored in model systems, but information for many agronomic crops remains limited. Here, we characterize the expression profiles of a set of putative senescence associated genes (SAGs) identified by a candidate gene approach and sunflower microarray expression studies. We examined a time course of sunflower leaves undergoing natural senescence and used quantitative PCR (qPCR) to measure the expression of 11 candidate genes representing the NAC, WRKY, MYB and NF-Y TF families. In addition, we measured physiological parameters such as chlorophyll, total soluble sugars and nitrogen content. The expression of Ha-NAC01, Ha-NAC03, Ha-NAC04, Ha-NAC05 and Ha-MYB01 TFs increased before the remobilization rate increased and therefore, before the appearance of the first physiological symptoms of senescence, whereas Ha-NAC02 expression decreased. In addition, we also examined the trifurcate feed-forward pathway (involving ORE1, miR164, and ethylene insensitive 2) previously reported for Arabidopsis. We measured transcription of Ha-NAC01 (the sunflower homolog of ORE1) and Ha-EIN2, along with the levels of miR164, in two leaves from different stem positions, and identified differences in transcription between basal and upper leaves. Interestingly, Ha-NAC01 and Ha-EIN2 transcription profiles showed an earlier up-regulation in upper leaves of plants close to maturity, compared with basal leaves of plants at pre-anthesis stages. These results suggest that the H. annuus TFs characterized in this work could play important roles as potential triggers of leaf senescence and thus can be considered putative candidate genes for senescence in sunflower.

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Expression profiles of transcription factors.(A) NAC TFs relative transcript level at each sampled point in relation to the level at the first sampling point determined by qPCR in leaf 10 (Ha-EF1α as RG). (B) AP2/EREBP, MYB, WRKY, NF-Y and RAV TFs relative transcript level at each sampled point in relation to the level at the first sampling point determined by qPCR in leaf 10 (Ha-EF1α as RG). The red line indicates anthesis time. Error bars correspond to standard errors.
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pone-0104379-g003: Expression profiles of transcription factors.(A) NAC TFs relative transcript level at each sampled point in relation to the level at the first sampling point determined by qPCR in leaf 10 (Ha-EF1α as RG). (B) AP2/EREBP, MYB, WRKY, NF-Y and RAV TFs relative transcript level at each sampled point in relation to the level at the first sampling point determined by qPCR in leaf 10 (Ha-EF1α as RG). The red line indicates anthesis time. Error bars correspond to standard errors.

Mentions: NAC TF transcript levels increased significantly during leaf development (Figure 3A). All of the NAC TFs tested showed an up-regulation at early stages of leaf development, except Ha-NAC02, which showed down-regulated expression at an early stage. Ha-NAC01 and Ha-NAC04 transcript levels gradually increased from emergence, with high transcript levels in later developmental phases, close to anthesis. Moreover, Ha-NAC03 and Ha-NAC05 transcript levels increased at an early stage of leaf development, with continued increases in expression until anthesis, when they reached their highest levels. Transcript levels of Ha-EIN2 gradually increased at an early stage and then showed uniform expression through leaf development (Figure 3B). In contrast, Ha-MYB01 transcript levels gradually increased in early stages, then strongly increased from 700°Cd until the end of leaf development. Ha-RAV01 transcript levels also gradually increased up to 750°Cd and then declined until the last stage of development. Transcript levels of TFs Ha-MYB02, Ha-NF-YB3 and Ha-WRKY01 did not change during leaf development (Figure 3B).


Identification of candidate genes associated with leaf senescence in cultivated sunflower (Helianthus annuus L.).

Moschen S, Bengoa Luoni S, Paniego NB, Hopp HE, Dosio GA, Fernandez P, Heinz RA - PLoS ONE (2014)

Expression profiles of transcription factors.(A) NAC TFs relative transcript level at each sampled point in relation to the level at the first sampling point determined by qPCR in leaf 10 (Ha-EF1α as RG). (B) AP2/EREBP, MYB, WRKY, NF-Y and RAV TFs relative transcript level at each sampled point in relation to the level at the first sampling point determined by qPCR in leaf 10 (Ha-EF1α as RG). The red line indicates anthesis time. Error bars correspond to standard errors.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4128711&req=5

pone-0104379-g003: Expression profiles of transcription factors.(A) NAC TFs relative transcript level at each sampled point in relation to the level at the first sampling point determined by qPCR in leaf 10 (Ha-EF1α as RG). (B) AP2/EREBP, MYB, WRKY, NF-Y and RAV TFs relative transcript level at each sampled point in relation to the level at the first sampling point determined by qPCR in leaf 10 (Ha-EF1α as RG). The red line indicates anthesis time. Error bars correspond to standard errors.
Mentions: NAC TF transcript levels increased significantly during leaf development (Figure 3A). All of the NAC TFs tested showed an up-regulation at early stages of leaf development, except Ha-NAC02, which showed down-regulated expression at an early stage. Ha-NAC01 and Ha-NAC04 transcript levels gradually increased from emergence, with high transcript levels in later developmental phases, close to anthesis. Moreover, Ha-NAC03 and Ha-NAC05 transcript levels increased at an early stage of leaf development, with continued increases in expression until anthesis, when they reached their highest levels. Transcript levels of Ha-EIN2 gradually increased at an early stage and then showed uniform expression through leaf development (Figure 3B). In contrast, Ha-MYB01 transcript levels gradually increased in early stages, then strongly increased from 700°Cd until the end of leaf development. Ha-RAV01 transcript levels also gradually increased up to 750°Cd and then declined until the last stage of development. Transcript levels of TFs Ha-MYB02, Ha-NF-YB3 and Ha-WRKY01 did not change during leaf development (Figure 3B).

Bottom Line: The expression of Ha-NAC01, Ha-NAC03, Ha-NAC04, Ha-NAC05 and Ha-MYB01 TFs increased before the remobilization rate increased and therefore, before the appearance of the first physiological symptoms of senescence, whereas Ha-NAC02 expression decreased.Interestingly, Ha-NAC01 and Ha-EIN2 transcription profiles showed an earlier up-regulation in upper leaves of plants close to maturity, compared with basal leaves of plants at pre-anthesis stages.These results suggest that the H. annuus TFs characterized in this work could play important roles as potential triggers of leaf senescence and thus can be considered putative candidate genes for senescence in sunflower.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Biotecnología, Centro de Investigaciones en Ciencias Agronómicas y Veterinarias, Instituto Nacional de Tecnología Agropecuaria, Hurlingham, Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Argentina.

ABSTRACT
Cultivated sunflower (Helianthus annuus L.), an important source of edible vegetable oil, shows rapid onset of senescence, which limits production by reducing photosynthetic capacity under specific growing conditions. Carbon for grain filling depends strongly on light interception by green leaf area, which diminishes during grain filling due to leaf senescence. Transcription factors (TFs) regulate the progression of leaf senescence in plants and have been well explored in model systems, but information for many agronomic crops remains limited. Here, we characterize the expression profiles of a set of putative senescence associated genes (SAGs) identified by a candidate gene approach and sunflower microarray expression studies. We examined a time course of sunflower leaves undergoing natural senescence and used quantitative PCR (qPCR) to measure the expression of 11 candidate genes representing the NAC, WRKY, MYB and NF-Y TF families. In addition, we measured physiological parameters such as chlorophyll, total soluble sugars and nitrogen content. The expression of Ha-NAC01, Ha-NAC03, Ha-NAC04, Ha-NAC05 and Ha-MYB01 TFs increased before the remobilization rate increased and therefore, before the appearance of the first physiological symptoms of senescence, whereas Ha-NAC02 expression decreased. In addition, we also examined the trifurcate feed-forward pathway (involving ORE1, miR164, and ethylene insensitive 2) previously reported for Arabidopsis. We measured transcription of Ha-NAC01 (the sunflower homolog of ORE1) and Ha-EIN2, along with the levels of miR164, in two leaves from different stem positions, and identified differences in transcription between basal and upper leaves. Interestingly, Ha-NAC01 and Ha-EIN2 transcription profiles showed an earlier up-regulation in upper leaves of plants close to maturity, compared with basal leaves of plants at pre-anthesis stages. These results suggest that the H. annuus TFs characterized in this work could play important roles as potential triggers of leaf senescence and thus can be considered putative candidate genes for senescence in sunflower.

Show MeSH
Related in: MedlinePlus