Polyamines and flavonoids: key compounds in mycorrhizal colonization of improved and unimproved soybean genotypes

SALLOUM MS; MENDUNI MF; BENAVIDES MP; LARRAURI M; LUNA CM; SILVENTE S

SYMBIOSIS

SPRINGER

Lugar: Berlin; Año: 2018

0334-5114

Modern breeding programs might have caused a reduction in plant responsiveness to arbuscular mycorrhizal fungi (AMF).Flavonoids and polyamines (PAs) are hypothesized to play a role in this symbiosis.We tested the effects of them inAMF roots ofimproved (I-1) and unimproved (UI-4) soybean genotypes, under the hypothesis that domestication decreased their concentrationin roots, affecting AMF colonization, particularly arbuscule formation. After 20 days of treatment, AMF roots of UI-4 genotypehad greater amount of total flavonoids/phenols and PAs while in I-1 genotype no differences were observed between roots ofmycorrhizal (M) and non mycorrhizal (NM) plants. Exogenous application of flavonoids led to an increase in arbuscules in bothgenotypes. Improved-1 genotype needed higher levels of flavonoids to reach the percentage of mycorrhization achieved by UI-4control. In regard to PAs, mycorrhizal plants of both genotypes had higher endogenous concentration than NM plants, however,the highest concentration, especially of putrescine (put) was in UI-4 M genotype. To check the participation of put in symbiosiswe used RNAi silencing methodology. Down regulation of the GmADC transcript, involved in put formation, had a profoundnegative effect on mycorrhizal colonization and also affected the normal development of the plant. By contrast, down regulationof GmDAO, in which ADC transcript was expressed, arbuscule formation was similar to control plant. Our results suggest thatmycorrhizal colonization is affected by soybean domestication particularly arbuscule formation and this effect seems to bemediated by the endogenous roots levels of flavonoids and PAs, especially put.