Abstract

ZONETTI, P. da Costa et al. High temperatures on root growth and lignification of transgenic glyphosate-resistant soybean. Agrociencia [online]. 2012, vol.46, n.6, pp.557-565. ISSN 2521-9766.

Glyphosate resistant transgenic soybean [Glycine max (L.) Mettill] expresses a glyphosate insensitive EPSPS (5-enolpyruvylshikimate-3-phosphate synthase). This enzyme is involved in important secondary metabolism pathways, including lignin biosynthesis. Thus, differences in lignin content and growth between susceptible (OC14) and glyphosate-resistant soybean may be observed. The objective of this study was to evaluate differences between growth and lignin content of roots in transgenic and OC14 soybean cultivated at high temperatures. Seeds from the OC14 soybean and its transgenic cultivar, CD213RR, were germinated at 25, 27.5, 30 and 32.5 °C. After 3 d, seedlings were cultivated in Hoagland half-strength nutrient solution during 12 h photoperiods and at the same germination temperature. After 4 d, roots' relative length, fresh and dry biomass, and lignin content were determined. Increasing temperatures promoted root growth. There was decreased growth and higher lignin content in roots in CD213RR soybean as compared to OC14. The transgenic soybean may present a different lignin metabolism since it showed higher lignification independently of temperatures, which is important because can be associated to a higher tolerance to drought and heat, but also with impaired growth and higher susceptibility to breakage of the stem.

Keywords : glyphosate; abiotic stress; Glycine max; plants; climatic changes.