Leaf structure and ultrastructure changes induced by heat stress and drought during seed filling in field-grown soybean and their relationship with grain yield

CARRERA, CONSTANZA S.; SOLÍS STELLA M.; FERRUCCI MARÍA SILVIA; VEGA CLAUDIA R.C.; GALATI BEATRIZ; ERGO VERÓNICA V.; ANDRADE FERNANDO H.; LASCANO RAMIRO H.

ANAIS DA ACADEMIA BRASILEIRA DE CIENCIAS.

ACAD BRASILEIRA DE CIENCIAS

Lugar: Rio de Janeiro; Año: 2021

0001-3765

Abstract: Current climate change scenarios potentially expose crop productivity to harmful effects of terminal drought combined with heat, therefore threats global food security. Despite its importance, studies focusing on their impact on plants of agronomic value remain scarce, and even less under field conditions. The objective of this study was to investigate leaf structural and ultrastructural changes induced by heat stress (HS) and drought stress (DS) during seed filling and their relationship with physiological variables and yield determination. Two soybean (Glycine max) cultivars were grown in field conditions. During seed filling four treatments were applied, including a control (without manipulation, at ambient temperature and field capacity), HS (episodes exceeding 32ºC for 6 h d-1) during 21-d, DS (20% of field capacity soil water content) during 35-d, and HS×DS. Drought principally reduced leaf area, whereas heat decreased leaf thickness, possible as acclimation strategies, but also irreversible reducing CO2 assimilation sites. Both stresses damaged outer and inner membranes of chloroplasts, causing swollen chloroplasts and accumulation of plastoglobules, loss of chlorophyll content and negatively affecting chlorophyll fluorescence. Thus, the performance and integrity of the photosynthetic machinery was reduced. Through a morpho-functional perspective and a holistic multiscale approach our results provide evidences of photosynthesis impairment and yield drops under stressful conditions which were associated to structural and ultrastructural (particularly at the level of chloroplasts) modifications of leaves.