|Kinzler, Amy - Slippery Rock University|
|Prokopiak, Zoey - Slippery Rock University|
|Dafoe, Nicole - Slippery Rock University|
Submitted to: Biologia Plantarum
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/22/2016
Publication Date: 8/11/2016
Citation: Kinzler, A.L., Prokopiak, Z.A., Vaughan, M.M., Erhardt, P.W., Sarver, J.G., Trendel, J.A., Zhang, Z., Dafoe, N.J. 2016. Cytochrome P450, CYP93A1, as a defense marker in soybean. Biologia Plantarum. doi: 10.1007/s10535-016-0629-z.
Interpretive Summary: Despite the numerous insects and pathogens that feed on soybean stem tissues, relatively little is known about the stem tissue specific defense response. Scientists at Slippery Rock University in collaboration with scientists at the USDA-ARS National Center for Agricultural Utilization Research wounded soybean stems to mimic insect feeding and examined the response. The gene expression levels of several genes known to be upregulated in response to leaf damage were analyzed. The expression of cytochrome P450 (CYP93A1) was upregulated as early as 4 hours and remained elevated 48 hours after stem wounding. Expression of the genes coding for vegetative storage proteins (vspA and vspB) were also significantly upregulated but only at the later time point examined. This increase in gene expression was localized to the sight of damage and was not observed in other tissues. In contrast to their expression in leaves, the genes cysteine protease inhibitor (R1) and chitinase (Chib1-b) were constitutively expressed in the stems of both control and wounded plants. These expression patterns were observed in the three soybean strains examined. Our results suggest that the soybean stem defense response is different from leaf defense response and therefore warrants additional tissue specific investigations.
Technical Abstract: CYP93A1 is a cytochrome P450 that is involved in the synthesis of the phytoalexin glyceollin in soybean (Glycine max L. Merr). The gene encoding CYP93A1 has been used as a defense marker in soybean cell cultures, however, little is known regarding how this gene is expressed in the intact plant. To further understand the tissue-specific role of CYP93A1 in soybean defense, we analyzed the expression of this gene in mechanically damaged leaves and stems. In leaves, CYP93A1 was constitutively expressed; its expression did not change in response to mechanical damage. In stems, however, expression of CYP93A1 was induced as quickly as 4 h after mechanical damage and remained upregulated for at least 48 h. The induction of CYP93A1 was associated with the synthesis of glyceollin. In comparison to several other defense-related genes encoding cysteine protease inhibitors L1 and R1 and storage proteins vspA and vspB, CYP93A1 was the most strongly induced by stem wounding. The induction of CYP93A1 was only observed locally, not systemically. Similar stem expression patterns were consistently observed among three different soybean genotypes. The strong induction of CYP93A1 in mechanically damaged stems suggests an important role in the soybean stem defense response; therefore, this study expands the use of CYP93A1 as a defense response marker to stems, not just soybean cell cultures.