Limits...
Population-specific gene expression in the plant pathogenic nematode Heterodera glycines exists prior to infection and during the onset of a resistant or susceptible reaction in the roots of the Glycine max genotype Peking.

Klink VP, Hosseini P, MacDonald MH, Alkharouf NW, Matthews BF - BMC Genomics (2009)

Bottom Line: However, 1668 genes were found to be suppressed in NL1-RHg.These genes included steroid alpha reductase, serine proteinase and a collagen protein.The identification of genes like steroid alpha reductase and serine proteinase that are involved in feeding and nutritional uptake as being highly suppressed during the R response at 8d may indicate genes that the plant is targeting.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biological Sciences, Harned Hall, Mississippi State University, Mississippi State, MS 39762, USA. vklink@biology.msstate.edu

ABSTRACT

Background: A single Glycine max (soybean) genotype (Peking) reacts differently to two different populations of Heterodera glycines (soybean cyst nematode) within the first twelve hours of infection during resistant (R) and susceptible (S) reactions. This suggested that H. glycines has population-specific gene expression signatures. A microarray analysis of 7539 probe sets representing 7431 transcripts on the Affymetrix soybean GeneChip were used to identify population-specific gene expression signatures in pre-infective second stage larva (pi-L2) prior to their infection of Peking. Other analyses focused on the infective L2 at 12 hours post infection (i-L2(12h)), and the infective sedentary stages at 3 days post infection (i-L2(3d)) and 8 days post infection (i-L2/L3(8d)).

Results: Differential expression and false discovery rate (FDR) analyses comparing populations of pi-L2 (i.e., incompatible population, NL1-RHg to compatible population, TN8) identified 71 genes that were induced in NL1-RHg as compared to TN8. These genes included putative gland protein G23G12, putative esophageal gland protein Hgg-20 and arginine kinase. The comparative analysis of pi-L2 identified 44 genes that were suppressed in NL1-RHg as compared to TN8. These genes included a different Hgg-20 gene, an EXPB1 protein and a cuticular collagen. By 12 h, there were 7 induced genes and 0 suppressed genes in NL1-RHg. By 3d, there were 9 induced and 10 suppressed genes in NL1-RHg. Substantial changes in gene expression became evident subsequently. At 8d there were 13 induced genes in NL1-RHg. This included putative gland protein G20E03, ubiquitin extension protein, putative gland protein G30C02 and beta-1,4 endoglucanase. However, 1668 genes were found to be suppressed in NL1-RHg. These genes included steroid alpha reductase, serine proteinase and a collagen protein.

Conclusion: These analyses identify a genetic expression signature for these two populations both prior to and subsequently as they undergo an R or S reaction. The identification of genes like steroid alpha reductase and serine proteinase that are involved in feeding and nutritional uptake as being highly suppressed during the R response at 8d may indicate genes that the plant is targeting. The analyses also identified numerous putative parasitism genes that are differentially expressed. The 1668 genes that are suppressed in NL1-RHg, and hence induced in TN8 may represent genes that are important during the parasitic stages of H. glycines development. The potential for different arrays of putative parasitism genes to be expressed in different nematode populations may indicate how H. glycines evolve mechanisms to overcome resistance.

Show MeSH

Related in: MedlinePlus

Life cycle of H. glycines. A, cysts. B, pi-L2 (gray) hatch and migrate toward the root of G. max. CS, CR i-L2 nematodes burrow into the root and migrate toward the pericycle (green). DS, DR, i-L2 select a cell (yellow) for feeding site establishment. ES, i-L2 nematodes have molted into L3. ER, i-L2 nematodes do not increase in size. FS, The L3 undergo a subsequent molt into L4 nematodes. Meanwhile, the female continues to grow circumferentially as it feeds. The male discontinues feeding at the end of its L3 stage. Male and female L4 nematodes become adults. The vermiform male (blue) burrows outside the root and subsequently copulates with the female. FR, The syncytium collapses and the nematodes do not grow. G, After ~30 days, the female with eggs is clearly visible and emerging from the root. Figure adapted from Klink et al. (2008).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2662880&req=5

Figure 1: Life cycle of H. glycines. A, cysts. B, pi-L2 (gray) hatch and migrate toward the root of G. max. CS, CR i-L2 nematodes burrow into the root and migrate toward the pericycle (green). DS, DR, i-L2 select a cell (yellow) for feeding site establishment. ES, i-L2 nematodes have molted into L3. ER, i-L2 nematodes do not increase in size. FS, The L3 undergo a subsequent molt into L4 nematodes. Meanwhile, the female continues to grow circumferentially as it feeds. The male discontinues feeding at the end of its L3 stage. Male and female L4 nematodes become adults. The vermiform male (blue) burrows outside the root and subsequently copulates with the female. FR, The syncytium collapses and the nematodes do not grow. G, After ~30 days, the female with eggs is clearly visible and emerging from the root. Figure adapted from Klink et al. (2008).

Mentions: The H. glycines life cycle (Fig. 1) is approximately one month in duration [9,10]. Well-defined H. glycines populations that accomplish resistant (R) and susceptible (S) reactions are available for examining G. max-H. glycines interactions [7,8]. Those histological studies of the R and S interactions between G. max roots and H. glycines have been performed [11-18] and demonstrated the anatomical changes that occur in G. max roots during H. glycines invasion. Interestingly, nematodes burrow into the roots of G. max genotypes that are either resistant or susceptible. They subsequently migrate at similar rates [19,20] toward the vascular tissue, select a cell adjacent to the vascular tissue and pierce it with its stylet to initiate the development of a feeding site. This occurs at approximately 2days post inoculation (2d). Subsequently, syncytia are established during both R and S reactions. During this process, the cells adjacent to the feeding site become metabolically hyperactive [13,15]. Then, the walls of the cells adjacent to the selected cell begin to dissolve. The infected plant cell incorporates additional cells by fusion events with neighboring cells by 3d. Eventually these recruited cells merge to form a syncytium. The diverse mechanisms that accompany the R or S reaction become evident subsequently.


Population-specific gene expression in the plant pathogenic nematode Heterodera glycines exists prior to infection and during the onset of a resistant or susceptible reaction in the roots of the Glycine max genotype Peking.

Klink VP, Hosseini P, MacDonald MH, Alkharouf NW, Matthews BF - BMC Genomics (2009)

Life cycle of H. glycines. A, cysts. B, pi-L2 (gray) hatch and migrate toward the root of G. max. CS, CR i-L2 nematodes burrow into the root and migrate toward the pericycle (green). DS, DR, i-L2 select a cell (yellow) for feeding site establishment. ES, i-L2 nematodes have molted into L3. ER, i-L2 nematodes do not increase in size. FS, The L3 undergo a subsequent molt into L4 nematodes. Meanwhile, the female continues to grow circumferentially as it feeds. The male discontinues feeding at the end of its L3 stage. Male and female L4 nematodes become adults. The vermiform male (blue) burrows outside the root and subsequently copulates with the female. FR, The syncytium collapses and the nematodes do not grow. G, After ~30 days, the female with eggs is clearly visible and emerging from the root. Figure adapted from Klink et al. (2008).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2662880&req=5

Figure 1: Life cycle of H. glycines. A, cysts. B, pi-L2 (gray) hatch and migrate toward the root of G. max. CS, CR i-L2 nematodes burrow into the root and migrate toward the pericycle (green). DS, DR, i-L2 select a cell (yellow) for feeding site establishment. ES, i-L2 nematodes have molted into L3. ER, i-L2 nematodes do not increase in size. FS, The L3 undergo a subsequent molt into L4 nematodes. Meanwhile, the female continues to grow circumferentially as it feeds. The male discontinues feeding at the end of its L3 stage. Male and female L4 nematodes become adults. The vermiform male (blue) burrows outside the root and subsequently copulates with the female. FR, The syncytium collapses and the nematodes do not grow. G, After ~30 days, the female with eggs is clearly visible and emerging from the root. Figure adapted from Klink et al. (2008).
Mentions: The H. glycines life cycle (Fig. 1) is approximately one month in duration [9,10]. Well-defined H. glycines populations that accomplish resistant (R) and susceptible (S) reactions are available for examining G. max-H. glycines interactions [7,8]. Those histological studies of the R and S interactions between G. max roots and H. glycines have been performed [11-18] and demonstrated the anatomical changes that occur in G. max roots during H. glycines invasion. Interestingly, nematodes burrow into the roots of G. max genotypes that are either resistant or susceptible. They subsequently migrate at similar rates [19,20] toward the vascular tissue, select a cell adjacent to the vascular tissue and pierce it with its stylet to initiate the development of a feeding site. This occurs at approximately 2days post inoculation (2d). Subsequently, syncytia are established during both R and S reactions. During this process, the cells adjacent to the feeding site become metabolically hyperactive [13,15]. Then, the walls of the cells adjacent to the selected cell begin to dissolve. The infected plant cell incorporates additional cells by fusion events with neighboring cells by 3d. Eventually these recruited cells merge to form a syncytium. The diverse mechanisms that accompany the R or S reaction become evident subsequently.

Bottom Line: However, 1668 genes were found to be suppressed in NL1-RHg.These genes included steroid alpha reductase, serine proteinase and a collagen protein.The identification of genes like steroid alpha reductase and serine proteinase that are involved in feeding and nutritional uptake as being highly suppressed during the R response at 8d may indicate genes that the plant is targeting.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biological Sciences, Harned Hall, Mississippi State University, Mississippi State, MS 39762, USA. vklink@biology.msstate.edu

ABSTRACT

Background: A single Glycine max (soybean) genotype (Peking) reacts differently to two different populations of Heterodera glycines (soybean cyst nematode) within the first twelve hours of infection during resistant (R) and susceptible (S) reactions. This suggested that H. glycines has population-specific gene expression signatures. A microarray analysis of 7539 probe sets representing 7431 transcripts on the Affymetrix soybean GeneChip were used to identify population-specific gene expression signatures in pre-infective second stage larva (pi-L2) prior to their infection of Peking. Other analyses focused on the infective L2 at 12 hours post infection (i-L2(12h)), and the infective sedentary stages at 3 days post infection (i-L2(3d)) and 8 days post infection (i-L2/L3(8d)).

Results: Differential expression and false discovery rate (FDR) analyses comparing populations of pi-L2 (i.e., incompatible population, NL1-RHg to compatible population, TN8) identified 71 genes that were induced in NL1-RHg as compared to TN8. These genes included putative gland protein G23G12, putative esophageal gland protein Hgg-20 and arginine kinase. The comparative analysis of pi-L2 identified 44 genes that were suppressed in NL1-RHg as compared to TN8. These genes included a different Hgg-20 gene, an EXPB1 protein and a cuticular collagen. By 12 h, there were 7 induced genes and 0 suppressed genes in NL1-RHg. By 3d, there were 9 induced and 10 suppressed genes in NL1-RHg. Substantial changes in gene expression became evident subsequently. At 8d there were 13 induced genes in NL1-RHg. This included putative gland protein G20E03, ubiquitin extension protein, putative gland protein G30C02 and beta-1,4 endoglucanase. However, 1668 genes were found to be suppressed in NL1-RHg. These genes included steroid alpha reductase, serine proteinase and a collagen protein.

Conclusion: These analyses identify a genetic expression signature for these two populations both prior to and subsequently as they undergo an R or S reaction. The identification of genes like steroid alpha reductase and serine proteinase that are involved in feeding and nutritional uptake as being highly suppressed during the R response at 8d may indicate genes that the plant is targeting. The analyses also identified numerous putative parasitism genes that are differentially expressed. The 1668 genes that are suppressed in NL1-RHg, and hence induced in TN8 may represent genes that are important during the parasitic stages of H. glycines development. The potential for different arrays of putative parasitism genes to be expressed in different nematode populations may indicate how H. glycines evolve mechanisms to overcome resistance.

Show MeSH
Related in: MedlinePlus