Sugarwin: A Sugarcane Insect-Induced Gene with Antipathogenic Activity

Abstract

In sugarcane fields, colonization of the stalk by opportunistic fungi usually occurs after the caterpillar Diatraea saccharalis attacks the sugarcane plant. Plants respond to insect attack by inducing and accumulating a large set of defense proteins. Two homologues of a barley wound-inducible protein (BARWIN), sugarcane wound-inducible proteins SUGARWIN1 and SUGARWIN2, have been identified in sugarcane by an in silico analysis. Antifungal properties have been described for a number of BARWIN homologues. We report that a SUGARWIN::green fluorescent protein fusion protein is located in the endoplasmic reticulum and in the extracellular space of sugarcane plants. The induction of sugarwin transcripts occurs in response to mechanical wounding, D. saccharalis damage, and methyl jasmonate treatment. The accumulation of transcripts is late induced and is restricted to the site of the wound. Although the transcripts of sugarwin genes were strongly increased following insect attack, the protein itself did not show any effect on insect development; rather, it altered fungal morphology, leading to the apoptosis of the germlings. These results suggest that, in the course of evolution, sugarwin-encoding genes were recruited by sugarcane due to their antipathogenic activity. We rationalize that sugarcane is able to induce sugarwin gene expression in response to D. saccharalis feeding as a concerted plant response to the anticipated invasion by the fungi that typically penetrate the plant stalk after insect damage.

Differential gene expression in drought-tolerant sugarcane roots

“…According to Medeiros et al (2012), increased gene expression of the protease inhibitor protein in sugarcane observed in response to attacks by Diatraea saccharalis, was associated with injury caused by this caterpillar. Another study reported that accumulation of this protein in corn was related to mechanical damage (Tamayo et al, 2000).…”

Defense-related proteins involved in sugarcane responses to biotic stress

“…coeruleum (Que et al , 2014). Moreover, sugarcane chitinases showed action against C. falcatum and are also associated with Pseudomonas -mediated induced resistance (Viswanathan et al , 2003) and with sugarcane response to D. saccharalis attack (Medeiros et al ., 2012). …”

“…Sugarcane has two homologs (SUGARWIN1 and SUGARWIN2) of the antifungal barley wound-inducible protein BARWIN, a class II chitinase (PR-4 family) (Medeiros et al , 2012). BARWIN is a basic protein composed of 125 residues, with the tridimensional structure stabilized by three disulfide bonds (Ludvigsen and Poulsen, 1992; Svensson et al ., 1992).…”

“…Transcript levels of genes encoding SUGARWINs were up-regulated in response to mechanical wounding, sugarcane borer ( D. saccharalis ) attack and methyl jasmonate treatment (Medeiros et al ., 2012). Although induced by D. saccharalis damage, SUGARWIN2 proteins have no insecticidal activity; however, these proteins have an antimicrobial role against the opportunistic fungi Fusarium verticillioides (Medeiros et al , 2012) and C. falcatum (Franco et al ., 2014), which typically develop after sugarcane borer attacks.…”

Mechanisms of Resistance to Pests and Pathogens in Sugarcane and Related Crop Species

“…Two homologues of a Barwin were identified in sugarcane by in silico analysis and were designated Sugarwin-1 and Sugarwin-2 (Medeiros et al 2012). The induction of Sugarwin transcripts occurred in response to mechanical wounding and to feeding by the sugarcane stalk borer Diatraea saccharalis.…”