Sequence and expression divergence of the AOC gene family in soybean: insights into functional diversity for stress responses

Abstract

As a signaling molecule, jasmonate plays a crucial role in orchestrating plant defense responses to a variety of biotic and abiotic stresses. Allene oxide cyclase (AOC: EC5.3.99.6) catalyzes the most important step in the jasmonate biosynthesis pathway. Six AOC genes were isolated from soybean, randomly distributed on chromosomes 1, 2, 8, 13, 18 and 19. The six AOC proteins were clustered into three groups with similarity values ranging from 55 to 95%. Real-time PCR revealed that the AOC genes have specific and complex expression patterns in multiple organs and under several stresses. Overexpression of GmAOC1 and GmAOC5 gene in transgenic tobacco, respectively enhanced tolerance to salinity and oxidative stresses. Such a large diversity within the AOC gene family might be an adaptive mechanism that developed during soybean genome evolution.

Cloning and characterization of peanut allene oxide cyclase gene involved in salt-stressed responses

“…Analysis of tissue-specific expression revealed AhAOC expression in 5 different tissues, with the highest relative expression in the roots (Figure 2A). A previous study in soybean also found that GmAOC2 was predominantly expressed in the roots (Wu et al, 2011). This is reasonable because roots are buried in soil and can sense the presence of salt.…”

“…For example, overexpression of JcAOC in Escherichia coli improved its resistance to salt and low temperature stresses (Liu et al, 2010). Wu et al (2011) examined the expression and functional diversity of the AOC gene family in soybean. They found that 6 AOC genes had specific and different expression patterns in multiple organs and under several stresses.…”

“…In soybean, GmAOC2 shows relatively higher expression only in roots, GmAOC5 is only strongly expressed in stems, and GmAOC3 is expressed highly in flowers (Wu et al, 2011). In tomato, the AOC gene is specifically expressed in vascular bundles and surrounding parenchymatic cells .…”

Soybean GmAOC3 promotes plant resistance to the common cutworm by increasing the expression of genes involved in resistance and volatile substance emission in transgenic tobaccos

“…In addition, the expression of AOC genes is closely related to the accumulation of JA, and AOC suppression can reduce JA in certain plant species (Fortes et al 2005;Stenzel et al 2003a). To date, AOC genes have been cloned from several species, including a single copy from tomato, two copies from Medicago truncatula, as well as small gene families from Arabidopsis thaliana and soybean that expanded during polyploidization (Ziegler et al 2000;Isayenkov et al 2005;Stenzel et al 2003b;Wu et al 2011). The expansion of the AOC gene family during evolution likely led to the divergence of expression and function.…”

“…In Physcomitrella patens, two AOC proteins (PpAOC1 and PpAOC2) with different substrate specificities catalyze the formation of different products from defined substrates in the biosynthesis of oxylipins (Neumann et al 2012). In our previous study, the six genes cloned from the GmAOC gene family exhibited differential performance under abiotic stresses; GmAOC1 and GmAOC5 responded to salinity and oxidative stresses, respectively, and the corresponding functions of these genes were identified via transgenic experiments (Wu et al 2011).…”