Probing allelochemical biosynthesis in sorghum root hairs

Abstract

Allelopathic interaction between plants is thought to involve the release of phytotoxic allelochemicals by one species, thus inhibiting the growth of neighboring species in competition for limited resources. Sorgoleone represents one of the more potent allelochemicals characterized to date, and its prolific production in root hair cells of Sorghum spp. has made the investigation of its biosynthetic pathway ideally-suited for functional genomics investigations. Through the use of a recently-released EST data set generated from isolated Sorghum bicolor root hair cells, significant inroads have been made toward the identification of genes and the corresponding enzymes involved in the biosynthesis of this compound in root hairs. Here we provide additional information concerning our recent report on the identification of a 5-n-alk(en) ylresorcinol utilizing O-methyltransferase, as well as other key enzymes likely to participate in the biosynthesis of this important allelochemical.

Temporal expression of the sor1 gene and inhibitory effects of Sorghum bicolor L. Moench on three weed species

“…These findings open a range of opportunities for genetic improvement of the germplasm containing this gene, in order to select crops with high allelopathic ability. Despite the great benefit of crops with allelopathic properties for the agroecological management of weeds, scientists emphasize the need to understand the genetic control of allelopathy (Baerson et al 2008b;Albuquerque et al 2010).…”

“…According to Marchi et al (2008), sorgoleone is rapidly degraded in soil and is mainly produced in younger plants, its production peaking by 10 days after emergence (DAE). However, other authors have reported that sorgoleone has a long half-life in the soil, with long-term effects on many cellular targets (Dayan et al 2007;Baerson et al 2008aBaerson et al , 2008bBarbosa et al 2010). …”

“…Although the cellular localization and the steps of the biosynthetic pathway of sorgoleone have been determined (Dayan et al 2003;Pan et al 2007;Baerson et al 2008aBaerson et al , 2008b, there is a lack of studies investigating its differential expression among genotypes and its bioactivity in vivo. Therefore, the evaluation of accessions that show variability for sorgoleone synthesis could contribute to the selection of the top lines in breeding programs for food production, as well as for weed control, in farming systems.…”

“…In the field, sorgoleone has an inhibitory effect on the growth of several species, including beans, wheat, and soy, although its greatest effect has been shown to be on the growth of weeds (Roth et al 2000;Souza Filho et al 2006). Sorgoleone is biosynthesized, during early seedling establishment, by root hairs, which possess the entire metabolic machinery (Dayan 2006;Baerson et al 2008aBaerson et al , 2008b. According to Marchi et al (2008), sorgoleone is rapidly degraded in soil and is mainly produced in younger plants, its production peaking by 10 days after emergence (DAE).…”

“…Molecular studies have described the metabolic pathway of sorgoleone, and a number of genes involved in the event cascade have been identified and characterized (Buchanan et al 2000;Dayan et al 2003;Pan et al 2007;Baerson et al 2008aBaerson et al , 2008b. According to Dayan et al (2003), the gene sor1, which encodes a membrane desaturase, is the main precursor of sorgoleone synthesis.…”