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Involvement of ethylene and polyamines biosynthesis and abdominal phloem tissues characters of wheat caryopsis during grain filling under stress conditions

View Article: PubMed Central - PubMed

ABSTRACT

Severe water deficit (SD) severely limited the photo-assimilate supply during the grain-filling stages. Although the ethylene and polyamines (PAs) have been identified as important signaling molecules involved in stress tolerance, it is yet unclear how 1-Aminocylopropane-1-carboxylic acid (ACC) and PA biosynthesis involving wheat abdominal phloem characters mitigate SD-induced filling inhibition. The results obtained indicated that the SD down-regulated the TaSUT1 expression and decreased the activities of sucrose synthase (SuSase, EC2.4.1.13), ADP glucose pyrophosphorylase (AGPase, EC2.7.7.27), soluble starch synthase (SSSase, EC2.4.1.21), then substantially limited grain filling. As a result, increased ACC and putrescine (Put) concentrations and their biosynthesis-related gene expression reduced spermidine (Spd) biosynthesis under SD condition. And, the ACC and PA biosynthesis in inferior grains was more sensitive to SD than that in superior grains. Intermediary cells (ICs) of caryopsis emerged prematurely under SD to compensate for the weakened photo-assimilate transport functions of sieve elements (SEs). Finally, plasmolysis and nuclear chromatin condensation of phloem parenchyma cells (PPC) and membrane degradation of SEs, as well as the decreased ATPase activity on plasma membranes of ICs and PPC at the later filling stage under SD were responsible for the considerably decreased weight of inferior grains.

No MeSH data available.


Post-anthesis severe water deficit effects on sucrose transporter (TaSUT1) expression and WSC concentration in superior and inferior grains.WW, well-watered; SD, severe water deficit; FW, Fresh weight.
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f4: Post-anthesis severe water deficit effects on sucrose transporter (TaSUT1) expression and WSC concentration in superior and inferior grains.WW, well-watered; SD, severe water deficit; FW, Fresh weight.

Mentions: Water soluble carbohydrates (WSC) content and TaSUT1 expression of both grain types generally increased with grain development, reaching a maximum at the middle-filling stage, and then decreased gradually until filling was completed (Fig. 4A–D). SD significantly decreased the WSC content of both grain types at 7DPA, while significantly increased the WSC content of both grain types at 14 and 21 DPA. The difference of WSC content in both grain types between SD and WW was not significant at 28 DPA(Fig. 4C and D). TaSUT1 had a major role in the post-phloem sugar transport pathway associated with grain filling. In the present study, SD apparently reduced the expression of TaSUT1 (Fig. 4A and B). The WSC content and TaSUT1 expression under SD varied with the grain types. The inferior grains had a higher WSC content and lower TaSUT1 expression than superior grains during middle grain filling period at all conditions (SD and WW).


Involvement of ethylene and polyamines biosynthesis and abdominal phloem tissues characters of wheat caryopsis during grain filling under stress conditions
Post-anthesis severe water deficit effects on sucrose transporter (TaSUT1) expression and WSC concentration in superior and inferior grains.WW, well-watered; SD, severe water deficit; FW, Fresh weight.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5382545&req=5

f4: Post-anthesis severe water deficit effects on sucrose transporter (TaSUT1) expression and WSC concentration in superior and inferior grains.WW, well-watered; SD, severe water deficit; FW, Fresh weight.
Mentions: Water soluble carbohydrates (WSC) content and TaSUT1 expression of both grain types generally increased with grain development, reaching a maximum at the middle-filling stage, and then decreased gradually until filling was completed (Fig. 4A–D). SD significantly decreased the WSC content of both grain types at 7DPA, while significantly increased the WSC content of both grain types at 14 and 21 DPA. The difference of WSC content in both grain types between SD and WW was not significant at 28 DPA(Fig. 4C and D). TaSUT1 had a major role in the post-phloem sugar transport pathway associated with grain filling. In the present study, SD apparently reduced the expression of TaSUT1 (Fig. 4A and B). The WSC content and TaSUT1 expression under SD varied with the grain types. The inferior grains had a higher WSC content and lower TaSUT1 expression than superior grains during middle grain filling period at all conditions (SD and WW).

View Article: PubMed Central - PubMed

ABSTRACT

Severe water deficit (SD) severely limited the photo-assimilate supply during the grain-filling stages. Although the ethylene and polyamines (PAs) have been identified as important signaling molecules involved in stress tolerance, it is yet unclear how 1-Aminocylopropane-1-carboxylic acid (ACC) and PA biosynthesis involving wheat abdominal phloem characters mitigate SD-induced filling inhibition. The results obtained indicated that the SD down-regulated the TaSUT1 expression and decreased the activities of sucrose synthase (SuSase, EC2.4.1.13), ADP glucose pyrophosphorylase (AGPase, EC2.7.7.27), soluble starch synthase (SSSase, EC2.4.1.21), then substantially limited grain filling. As a result, increased ACC and putrescine (Put) concentrations and their biosynthesis-related gene expression reduced spermidine (Spd) biosynthesis under SD condition. And, the ACC and PA biosynthesis in inferior grains was more sensitive to SD than that in superior grains. Intermediary cells (ICs) of caryopsis emerged prematurely under SD to compensate for the weakened photo-assimilate transport functions of sieve elements (SEs). Finally, plasmolysis and nuclear chromatin condensation of phloem parenchyma cells (PPC) and membrane degradation of SEs, as well as the decreased ATPase activity on plasma membranes of ICs and PPC at the later filling stage under SD were responsible for the considerably decreased weight of inferior grains.

No MeSH data available.