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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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Northern blot analysis of the expression pattern of salicylic acid- and jasmonic acid- regulated genes. (A) Northern blot analysis of the accumulation Pr1a, Pr1b, and LAP transcripts in 20 μg of total RNA extracted from healthy tomato (lane 1), PSTVd-infected tomato (Viroid-infected tomato, lane 2), non-transformed control (X, lane 3), transgenic plants XS (lane 4) and XAS (lane 5), and tomatoes infected with Potato virus X (PVX-infected tomato, lane 7). Ethidium bromide staining of ribosomal RNA (rRNA) is shown to illustrate equal loading of RNAs. SA, salicylic acid-inducible genes; JA-jasmonic acid-inducible gene. (B) Northern blot analysis of total RNA samples as in (A) using only the Pr1b probe. Lane 1, Healthy tomato; Lane 2, PSTVd-infected tomato; Lane 3, X; Lane 4, XS; Lane 5, XAS; Lane 6, PSTVd-infected Xanthi tobacco.
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Figure 5: Northern blot analysis of the expression pattern of salicylic acid- and jasmonic acid- regulated genes. (A) Northern blot analysis of the accumulation Pr1a, Pr1b, and LAP transcripts in 20 μg of total RNA extracted from healthy tomato (lane 1), PSTVd-infected tomato (Viroid-infected tomato, lane 2), non-transformed control (X, lane 3), transgenic plants XS (lane 4) and XAS (lane 5), and tomatoes infected with Potato virus X (PVX-infected tomato, lane 7). Ethidium bromide staining of ribosomal RNA (rRNA) is shown to illustrate equal loading of RNAs. SA, salicylic acid-inducible genes; JA-jasmonic acid-inducible gene. (B) Northern blot analysis of total RNA samples as in (A) using only the Pr1b probe. Lane 1, Healthy tomato; Lane 2, PSTVd-infected tomato; Lane 3, X; Lane 4, XS; Lane 5, XAS; Lane 6, PSTVd-infected Xanthi tobacco.

Mentions: Induced defense and/or pathogenesis-related (PR) gene expression occurs in PSTVd-infected, dwarfed tomato plants [15]. To determine if PR expression is associated with stunting caused by over expression of PKV in tobacco, we probed Northern blots containing total RNA isolated from leaf tissue for transcripts of Pr1a1 and Pr1b, whose expression is salicylic acid-mediated. These genes were transcriptionally activated in viroid-infected tomato plants, as previously reported, but not in XS or XAS transformants, nor in PSTVd-infected tobacco plants, indicating that neither PSTVd infection nor PKV over expression induce a general pathogenesis response in tobacco (compare lane 2 with lanes 4 and 5 in Figure 5A and lane 2 and lanes 4-6 in Figure 5B). In addition, transcripts of the leucine aminopeptidase gene (LAP) (jasmonic acid-mediated; [36]) did not increase in transgenic tobacco plants, nor in viroid-infected tomato (whereas such transcripts did accumulate in Potato virus X-infected tomato), indicating that neither the dwarfing caused by PKV over expression in tobacco nor PSTVd pathogenesis in tomato involve jasmonic acid signaling (Figure 5A).


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)

Northern blot analysis of the expression pattern of salicylic acid- and jasmonic acid- regulated genes. (A) Northern blot analysis of the accumulation Pr1a, Pr1b, and LAP transcripts in 20 μg of total RNA extracted from healthy tomato (lane 1), PSTVd-infected tomato (Viroid-infected tomato, lane 2), non-transformed control (X, lane 3), transgenic plants XS (lane 4) and XAS (lane 5), and tomatoes infected with Potato virus X (PVX-infected tomato, lane 7). Ethidium bromide staining of ribosomal RNA (rRNA) is shown to illustrate equal loading of RNAs. SA, salicylic acid-inducible genes; JA-jasmonic acid-inducible gene. (B) Northern blot analysis of total RNA samples as in (A) using only the Pr1b probe. Lane 1, Healthy tomato; Lane 2, PSTVd-infected tomato; Lane 3, X; Lane 4, XS; Lane 5, XAS; Lane 6, PSTVd-infected Xanthi tobacco.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2735738&req=5

Figure 5: Northern blot analysis of the expression pattern of salicylic acid- and jasmonic acid- regulated genes. (A) Northern blot analysis of the accumulation Pr1a, Pr1b, and LAP transcripts in 20 μg of total RNA extracted from healthy tomato (lane 1), PSTVd-infected tomato (Viroid-infected tomato, lane 2), non-transformed control (X, lane 3), transgenic plants XS (lane 4) and XAS (lane 5), and tomatoes infected with Potato virus X (PVX-infected tomato, lane 7). Ethidium bromide staining of ribosomal RNA (rRNA) is shown to illustrate equal loading of RNAs. SA, salicylic acid-inducible genes; JA-jasmonic acid-inducible gene. (B) Northern blot analysis of total RNA samples as in (A) using only the Pr1b probe. Lane 1, Healthy tomato; Lane 2, PSTVd-infected tomato; Lane 3, X; Lane 4, XS; Lane 5, XAS; Lane 6, PSTVd-infected Xanthi tobacco.
Mentions: Induced defense and/or pathogenesis-related (PR) gene expression occurs in PSTVd-infected, dwarfed tomato plants [15]. To determine if PR expression is associated with stunting caused by over expression of PKV in tobacco, we probed Northern blots containing total RNA isolated from leaf tissue for transcripts of Pr1a1 and Pr1b, whose expression is salicylic acid-mediated. These genes were transcriptionally activated in viroid-infected tomato plants, as previously reported, but not in XS or XAS transformants, nor in PSTVd-infected tobacco plants, indicating that neither PSTVd infection nor PKV over expression induce a general pathogenesis response in tobacco (compare lane 2 with lanes 4 and 5 in Figure 5A and lane 2 and lanes 4-6 in Figure 5B). In addition, transcripts of the leucine aminopeptidase gene (LAP) (jasmonic acid-mediated; [36]) did not increase in transgenic tobacco plants, nor in viroid-infected tomato (whereas such transcripts did accumulate in Potato virus X-infected tomato), indicating that neither the dwarfing caused by PKV over expression in tobacco nor PSTVd pathogenesis in tomato involve jasmonic acid signaling (Figure 5A).

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