Identification of a Gene in the Process of Being Lost from the Genus Agrostis

Abstract

Lineage-specific gene loss is considered one of the processes contributing to speciation and genome diversity. Such gene loss has been inferred from interspecies comparisons of orthologous DNA segments. Examples of intraspecific gene loss are rare. Here we report identification of a gene, designated Crs-1 (creeping specific-1), that appears to be in the process of being lost from heterozygous populations of the species creeping bentgrass (Agrostis stolonifera). The Crs-1 gene encodes a protein with an N-terminal dirigent protein domain and a C-terminal lectin domain and is similar to the maize (Zea mays) β-glucosidase aggregating factor. Most individual creeping bentgrass plants examined are lacking Crs-1. Some individuals are hemizygous for the Crs-1 locus, indicating major haplotype noncolinearity at that locus. Crs-1 was not detected in several other Agrostis species, indicating it is being lost from the genus. The Crs-1 locus in creeping bentgrass provides a rare example of the evolutionary process of gene loss occurring within a plant species.

A jacalin-related lectin-like gene in wheat is a component of the plant defence system

“…Both Hfr - 1 and WCI - 1 are up-regulated by SA treatment and the latter is also responsive to MeJA treatment (Subramanyam et al , 2006). In addition to defence hormone inducibility, mJRL-like genes including AtNSP1 , Hfr - 1 , creeping bentgrass Crs1 , WCI - 1 , and Orysata have been associated with defence due to their induction by pathogen infection or pest attack (Williams et al , 2002; Qin et al , 2003; Li et al , 2005; Subramanyam et al , 2006; Burow et al , 2009). …”

Monocot chimeric jacalins: a novel subfamily of plant lectins

“…Further, Crs-1 homologs were not found in other members of the genus, such as Agrostis capillaries, Agrostis castellana, Agrostis gigantean, Agrostis canina, Agrostis mongolica, Agrostis nebulosa, Agrostis pallida, Agrostis transcaspica and Agrostis vinealis. This suggests that Crs-1 genes are lost from the Agrostis genus (Li et al, 2005). Figure 2.…”

“…Furthermore, tobacco plants overexpressing TaJA1 exhibited a strong resistance to bacterial, fungal and viral pathogens (Ma et al, 2010). The creeping bentgrass Crs-1 gene is induced by the fungal pathogen Sclerotinia homoeocarpa (the causal agent of dollar spot disease; Li et al, 2005), while the wheat TaWCI-1 gene is induced by benzothiadiazole (a SAR inducer; Gorlach et al, 1996). All of these actions are directly related to their lectin properties.…”

“…DOI: 10.3109/07388551.2013.793650 Examined more closely, maize and rice monocot chimeric jacalin homologs diverged from a common ancestor 50 million years ago. The tribe Aveneae diverged from rice 46 million years ago, while the tribe Triticeae (barley and wheat) diverged from Aveneae 25 million years ago (Li et al, 2005). It is concluded that the monocot chimeric jacalins are only present in a small group of taxa (Triticeae, Oryzeae and Andropogoneae) and came into existence during a specific period of time (from 50 to 25 million years ago).…”

“…Creeping bentgrass (A. stolonifera L.) is the only non-crop plant to have a monocot chimeric jacalin homolog (creeping specific-1, or Crs-1; Li et al, 2005). It is interesting that most A. stolonifera plants examined lack Crs-1, and some individuals are hemizygous for the Crs-1 locus.…”