Sugarcane Demands Lower Nitrogen Supply to Sustain Mesophyll Chloroplast Integrity than Maximum Shoot Growth

Author(s)

Zambrosi, Fernando C. B. ; Mesquita, Geisa L. ; Tanaka, Francisco A. O.

• Document type: Journal article
• Source: SUGAR TECH; v. 25, n. 5, p. 5-pg., 2023-04-28.

Abstract

A deeper understanding of the mechanisms underlying impaired sugarcane performance (Saccharum spp.) under nitrogen (N) deficiency might help select targeted traits for developing N-efficient genotypes. In this regard, we focused on the study of the effects of low-N stress on mesophyll chloroplast integrity and its relationship with shoot growth traits. Plants were grown in sand culture under varying N supply (1.5, 3.0, 6.0 and 12.0 mM of N) for 60 days, when mature leaves were sampled for transmission electron microscopy analysis. Then, the number of tillers was counted and shoot was harvested to estimate leaf area, dry mass production and leaf N concentration. Images of transmission electron microscopy revealed pronounced damages exclusively to the ultrastructure of mesophyll chloroplast in the severely N-deficient plants (1.5 mM of N), including thylakoid membrane disarrangement and poorly stacked grana. Tillering, leaf area, shoot dry mass and leaf N concentration increased as function of nutrient supply. However, maximum values of these parameters were attained at higher N availability (9.1-9.9 mM of N) than that related to the maintenance of mesophyll chloroplast integrity. Our results suggest, hence, that impairments in the ultrastructure of this organelle plays a key role on poor sugarcane biomass production only under severe N deficiency condition. This finding adds insights into the reasons of impaired sugarcane performance under low-N stress and might assist the selection of suitable traits to be sought in N-efficient genotypes. (AU)

• FAPESP's process: 16/14058-9 - Does Manganese Nutritional Status Affect the Resistance of Sugarcane to Orange Rust?
• Grantee: Francisco André Ossamu Tanaka
• Support Opportunities: Regular Research Grants