Dados do Trabalho

Título

SPECIES-DEPENDENT RESPONSES IN GIRDLED EUCALYPTUS PLANTS UNDER LOW PHOSPHORUS CONDITIONS

Resumo

Girdling is a technique used to interrupt the transport of photoassimilates ad a variety of molecules, which can have a signaling function. In roots, the lack of carbohydrates associated with the low availability of phosphorus (P) in the soil leads to coordinated genetic reprogramming to increase P absorption. Our aim was to verify the genetic and nutritional shoot-root signaling of girdling eucalyptus species (E. grandis, E. tereticornis and E. acmenoides). Plants were fertilized with –P and +P solutions for three months before the girdling procedure (G: girdled; NG: non-girdled). After 44 days, plants were harvested, and biomass, nutrient concentration and the expression of P starvation response genes were assessed. E. tereticornis and E. grandis obtained the highest root biomass in +P/NG and +P/G, while in -P E. grandis was more sensitive to the lack of P, presenting lower root biomass in this condition. Regarding leaf biomass, the highest biomass gains occurred in +P/NG and +P/G1 (G1: above girdling) treatments. In the roots, girdling did not influence the P concentration in E. tereticornis and E. acmenoides, being the opposite in E. grandis, with higher concentration of this nutrient in NG plants. Leaf P concentration was not altered by girdling in any of the analyzed species, and either in the root or in the leaf, the highest concentration occurred in the +P treatment. In leaves and roots, girdling influenced the activity of PHT1 transporters, SQD and SCR, with this activity being different for each species. Girdling had the greatest influence on gene activity related to lack of P, and both gene activity and P concentration were different for each species.

Palavras-chave

plant nutrition; girdling; nutrient transport; phosphorus starvation.

Instituição financiadora

Fundação de Amparo à Pesquisa do Estado de São Paulo – Fapesp.

Agradecimentos

The authors thank Fapesp (grant 2016/25498-0 and 2020/02867-5).