The constitutive expression and induction of three β-1,3-glucanases by bird cherry-oat aphid in relation to aphid resistance in 15 barley breeding lines

Abstract

In this study, 15 closely related barley genotypes were analyzed for the abundance of three b-1,3-glucanase transcripts immediately before and during infestation by the bird cherry-oat aphid (Rhopalosiphum padi L.). The barley lines are doubled haploid lines in backcross (BC) generations BC1 and BC2 from a cross between cultivar Lina and a wild barley accession. Previously, they have been characterized as susceptible (S) or resistant (R) to R. padi based on their ability to support nymphal growth. Here we also tested whether resistance was manifested as reduced aphid settling on the plants. Indeed, aphid numbers were lower on R than on S lines in all cases where there were significant differences between R and S lines. The choice of b-1,3-glucanase sequences is based on earlier results comparing two S and two R genotypes, suggesting that at least two of the three studied sequences are susceptibility factors. The comparisons of transcript abundance in plants with aphids showed for two of the b-1,3-glucanase sequences that there were several cases where an S genotype had significantly higher abundance than an R genotype, and in no case did an R line have significantly higher abundance than an S line. Thus, there was some support for the idea that b-1,3-glucanase sequences are susceptibility factors in the interaction between barley and R. padi.

Introgression of resistance to Rhopalosiphum padi L. from wild barley into cultivated barley facilitated by doubled haploid and molecular marker techniques

“…However, plant traits may influence not only aphid physiology but also aphid behavior. Mehrabi et al ( 2016 ) found that aphid settling rate of apterous aphids confined for 2 days with selected lines from this breeding material was lower on resistant than susceptible genotypes in those cases where there were significant differences between such lines. This indicates that plant resistance traits influence host acceptance, which in turn may influence food intake, aphid growth and reproduction of successive aphid generations in the field.…”

Functional Evaluation of Proteins in Watery and Gel Saliva of Aphids

“…It is much more logical; therefore, that callose breakdown is facilitated by upregulation of plant glucanases (Van der Westhuizen et al, 1998) probably making use of salivary effectors. In keeping with this idea, infestation with R. padi induced a transcript abundance of three β-1,3-glucanases in 15 barley breeding lines (Mehrabi et al, 2016). In Mp55-expressing Arabidopsis plants, callose deposition in response to aphid infestation is reduced (Elzinga et al, 2014), but the molecular action of Mp55 is yet to be identified.…”

Overexpression of the aphid-induced serine protease inhibitor CI2c gene in barley affects the generalist green peach aphid, not the specialist bird cherry-oat aphid

“…To investigate aphid-induced responses, five genes were studied: CI2c , thionin proprotein-processing enzyme ( TPPE ) [ 48 ], a subtilisin-like serine endoprotease, hordolisin [ 49 ], allene oxide synthase ( AOS ) and a β -1,3-glucanase [ 50 ]. The genes are induced similarly by BCA and GPA ( S4 Fig ).…”

“…Their expression was stable or suppressed by aphids in the transgenic lines, when compared to control or resistant plants ( Fig 4 ). As a putative positive factor, we considered a β -1,3-glucanase, suggested as a susceptibility factor towards BCA [ 50 ]. In our study, it was induced by aphids at the highest transcript levels in the CI2c 6–4 transgenic line ( Fig 4 ).…”