Internal Zinc Accumulation Is Correlated with Increased Growth in Rice Suspension Culture

Abstract

A high zinc concentration of 520 M, approximately 100 times that used most often in standard plant tissue culture media, was found to be superior in liquid callus cultures of japonica rice, increasing growth to 146% compared with standard N6 medium. At the same time, the internal zinc concentration increased 40 times in fast growing cells; soluble protein doubled, and free amino acids decreased. Under zinc-free conditions the cultures slowed in growth, and several free amino acids such as aspartic acid, glutamic acid, asparagine, and glutamine accumulated. We suggest that zinc acts as a direct regulatory factor in inducing auxin activity, but not auxin levels, making high internal zinc accumulation mandatory if high auxin concentrations are required as in rice callus cultures.

Fortification of micronutrients for efficient agronomic production: a review

“…This cofactor role of micronutrients is crucial for enzyme and nonenzyme activities in plant metabolism under different environmental conditions (Table 2). For instance, Zn specifically plays a role in the enzymatic processes involved in the biosynthesis of the plant growth regulator, auxin (Hossain et al 1997;Fageria 2002). This is an important function given the role of auxins in enhancing root growth, with agronomic consequences in terms of allowing the plant greater ability to access nutrients and water.…”

Tansley Review No. 111

“…4 (Reicheld et al, 1999). Very high concentrations of Zn in meristematic plant cells (Kitagishi & Obata, 1986 ;Hossain et al, 1997) …”

Zinc sulphate improved microspore embryogenesis in barley

“…This study shows Zn 2+ seems to play an important role in the biosynthesis and metabolism of auxin (Skoog 1940;Tsui 1948;Cakmak et al 1989). Processes regulated by auxins were stimulated with a high concentration of this micronutrient (Hossain et al 1997;Saeki et al 2000;Oguchi et al 2004a, b). Zn 2+ modulated auxin action by regulation of different proteins including an ascorbato peroxidase and a late embryogenesis abundant (LEA) protein (Oguchi et al 2004a, b).…”

“…Although studies about the influence of this micronutrient are limited, requirements of Zn 2+ seem to be species-and system-dependent (He et al 1991;Hossain et al 1997;Teasdale 1986). This is the first study about the influence of ZnSO 4 on microspore embryogenesis.…”

“…Concentration from 52 to 520 μM in rice and 1,000 μM in tobacco resulted in increased growth (Hirt et al 1989;Hossain et al 1997), whereas 10 mM became toxic in tobacco (Bueno and Piqueras 2002). The elimination of Zn 2+ stimulated somatic embryogenesis in wheat (He et al 1991).…”