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Modification of tobacco plant development by sense and antisense expression of the tomato viroid-induced AGC VIIIa protein kinase PKV suggests involvement in gibberellin signaling.

Hammond RW, Zhao Y - BMC Plant Biol. (2009)

Bottom Line: The serine-threonine protein kinase gene, designated pkv (protein kinase- viroid induced) was previously found to be transcriptionally activated in tomato plants infected with the plant pathogen Potato spindle tuber viroid (PSTVd).Xanthi (tobacco) resulted in stunting, reduced root formation, and delay in flowering, phenotypes similar to symptoms of PSTVd infection of tomato.We have found that the over expression of the tomato protein kinase PKV resulted in stunting, modified vascular tissue development, reduced root formation, and male sterility in tobacco, and we propose that PKV regulates plant development by functioning in critical signaling pathways involved in gibberellic acid metabolism.

View Article: PubMed Central - HTML - PubMed

Affiliation: Molecular Plant Pathology Laboratory, United States Department of Agriculture, Agricultural Research Service, Beltsville, Maryland 20705, USA. rose.hammond@ars.usda.gov

ABSTRACT

Background: The serine-threonine protein kinase gene, designated pkv (protein kinase- viroid induced) was previously found to be transcriptionally activated in tomato plants infected with the plant pathogen Potato spindle tuber viroid (PSTVd). These plants exhibited symptoms of stunting, and abnormal development of leaf, root, and vascular tissues. The encoded protein, PKV, is a novel member of the AGC VIIIa group of signal-transducing protein kinases; however, the role of PKV in plant development is unknown. In this communication, we report the phenotypic results of over expression and silencing of pkv in transgenic tobacco.

Results: Over expression of pkv in Nicotiana tabacum cv. Xanthi (tobacco) resulted in stunting, reduced root formation, and delay in flowering, phenotypes similar to symptoms of PSTVd infection of tomato. In addition, homozygous T2 tobacco plants over expressing PKV were male sterile. Antisense expression of pkv, on the other hand, resulted in plants that were taller than non-transformed plants, produced an increased number of flowers, and were fertile. Exogenous application of GA3 stimulated stem elongation in the stunted, sense-expressing plants. PKV sense and antisense expression altered transcript levels of GA biosynthetic genes and genes involved in developmental and signaling pathways, but not genes involved in salicylic acid- or jasmonic acid-dependent pathways. Our data provide evidence suggesting that PKV plays an important role in a GA signaling pathway that controls plant height and fertility.

Conclusion: We have found that the over expression of the tomato protein kinase PKV resulted in stunting, modified vascular tissue development, reduced root formation, and male sterility in tobacco, and we propose that PKV regulates plant development by functioning in critical signaling pathways involved in gibberellic acid metabolism.

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Growth effects of in vitro application of hormone to control and transgenic seedlings. Ethanol (EtOH), GA3 (10-5M), pachlobutrazol (10-5M), or GA3(10-5M) plus pachlobutrazol (P) (10-5M) were added to solidified media. Plants were evaluated at 20 days after seeding.
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Figure 6: Growth effects of in vitro application of hormone to control and transgenic seedlings. Ethanol (EtOH), GA3 (10-5M), pachlobutrazol (10-5M), or GA3(10-5M) plus pachlobutrazol (P) (10-5M) were added to solidified media. Plants were evaluated at 20 days after seeding.

Mentions: To investigate whether the reduced stature of XS plants was due to a lower content of GA or to reduced response to GA, exogenous hormone applications were made to seedlings grown in vitro and seedling growth was monitored. The hypocotyl length of XS seedlings increased significantly in medium containing 10-5 M GA3, where it was not as greatly affected in control (X) or XAS seedlings (Figure 6, panel C). In medium containing 10-5 pachlobutrazol, an inhibitor of GA biosynthesis, the height of both control and transgenic seedlings was reduced, and this inhibition was fully reversed by addition of 10-5 M GA3 (Figure 6, panel D). Therefore the plants respond normally to GA. This suggests that the dwarf phenotype of XS plants is due to a lower content of active GAs. The phenotype of mature XAS plants suggests that these plants may be producing more GA than the control, non-transformed plants


Modification of tobacco plant development by sense and antisense expression of the tomato viroid-induced AGC VIIIa protein kinase PKV suggests involvement in gibberellin signaling.

Hammond RW, Zhao Y - BMC Plant Biol. (2009)

Growth effects of in vitro application of hormone to control and transgenic seedlings. Ethanol (EtOH), GA3 (10-5M), pachlobutrazol (10-5M), or GA3(10-5M) plus pachlobutrazol (P) (10-5M) were added to solidified media. Plants were evaluated at 20 days after seeding.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2735738&req=5

Figure 6: Growth effects of in vitro application of hormone to control and transgenic seedlings. Ethanol (EtOH), GA3 (10-5M), pachlobutrazol (10-5M), or GA3(10-5M) plus pachlobutrazol (P) (10-5M) were added to solidified media. Plants were evaluated at 20 days after seeding.
Mentions: To investigate whether the reduced stature of XS plants was due to a lower content of GA or to reduced response to GA, exogenous hormone applications were made to seedlings grown in vitro and seedling growth was monitored. The hypocotyl length of XS seedlings increased significantly in medium containing 10-5 M GA3, where it was not as greatly affected in control (X) or XAS seedlings (Figure 6, panel C). In medium containing 10-5 pachlobutrazol, an inhibitor of GA biosynthesis, the height of both control and transgenic seedlings was reduced, and this inhibition was fully reversed by addition of 10-5 M GA3 (Figure 6, panel D). Therefore the plants respond normally to GA. This suggests that the dwarf phenotype of XS plants is due to a lower content of active GAs. The phenotype of mature XAS plants suggests that these plants may be producing more GA than the control, non-transformed plants

Bottom Line: The serine-threonine protein kinase gene, designated pkv (protein kinase- viroid induced) was previously found to be transcriptionally activated in tomato plants infected with the plant pathogen Potato spindle tuber viroid (PSTVd).Xanthi (tobacco) resulted in stunting, reduced root formation, and delay in flowering, phenotypes similar to symptoms of PSTVd infection of tomato.We have found that the over expression of the tomato protein kinase PKV resulted in stunting, modified vascular tissue development, reduced root formation, and male sterility in tobacco, and we propose that PKV regulates plant development by functioning in critical signaling pathways involved in gibberellic acid metabolism.

View Article: PubMed Central - HTML - PubMed

Affiliation: Molecular Plant Pathology Laboratory, United States Department of Agriculture, Agricultural Research Service, Beltsville, Maryland 20705, USA. rose.hammond@ars.usda.gov

ABSTRACT

Background: The serine-threonine protein kinase gene, designated pkv (protein kinase- viroid induced) was previously found to be transcriptionally activated in tomato plants infected with the plant pathogen Potato spindle tuber viroid (PSTVd). These plants exhibited symptoms of stunting, and abnormal development of leaf, root, and vascular tissues. The encoded protein, PKV, is a novel member of the AGC VIIIa group of signal-transducing protein kinases; however, the role of PKV in plant development is unknown. In this communication, we report the phenotypic results of over expression and silencing of pkv in transgenic tobacco.

Results: Over expression of pkv in Nicotiana tabacum cv. Xanthi (tobacco) resulted in stunting, reduced root formation, and delay in flowering, phenotypes similar to symptoms of PSTVd infection of tomato. In addition, homozygous T2 tobacco plants over expressing PKV were male sterile. Antisense expression of pkv, on the other hand, resulted in plants that were taller than non-transformed plants, produced an increased number of flowers, and were fertile. Exogenous application of GA3 stimulated stem elongation in the stunted, sense-expressing plants. PKV sense and antisense expression altered transcript levels of GA biosynthetic genes and genes involved in developmental and signaling pathways, but not genes involved in salicylic acid- or jasmonic acid-dependent pathways. Our data provide evidence suggesting that PKV plays an important role in a GA signaling pathway that controls plant height and fertility.

Conclusion: We have found that the over expression of the tomato protein kinase PKV resulted in stunting, modified vascular tissue development, reduced root formation, and male sterility in tobacco, and we propose that PKV regulates plant development by functioning in critical signaling pathways involved in gibberellic acid metabolism.

Show MeSH
Related in: MedlinePlus