Phytosiderophore release in bread and durum wheat genotypes differing in zinc efficiency

Abstract

The effect of the zinc (Zn) nutritional status on the rate of phytosiderophore release was studied in nutrient solution over 20 days in four bread wheat (Triticum aestivum cvs. Kirag-66, Gerek-79, Aroona and Kirkpinar) and four durum wheat (Triticum durum cvs. BDMM-19, Kunduru-1149, Kiziltan-91 and Durati) genotypes differing in Zn efficiency.Visual Zn deficiency symptoms, such as whitish-brown necrosis on leaves and reduction in plant height appeared first and more severe in Zn-inefficient durum wheat genotypes Kiziltan-91, Durati and Kunduru-1149. Compared to the bread wheat genotypes, all durum wheat genotypes were more sensitive to Zn deficiency. BDMM-19 was the least affected durum wheat genotype. Among the bread wheat genotypes, Kirkpinar was the most sensitive genotype. In all genotypes well supplied with Zn, the rate of phytosiderophore release was very low and did not exceed 1 #mol 32 plants-t 3h-1, or 0. 5/zmol g-1 root dry wt 3h-1, However, under Zn deficiency, with the onset of visual Zn deficiency symptoms, the release of phytosiderophores was enhanced in bread wheat genotypes up to 7.5 #mol 32 plants-1 3h-l, or 9/zmol g-1 root dry wt 3h-1, particularly in Zn-efficient Kirag-66, Gerek-79 and Aroona. In contrast to bread wheat genotypes, phytosiderophore release in Zn-deficient durum wheat genotypes remained at a very low rate. Among the durum wheat genotypes BDMM-19 had highest rate of phytosiderophore release. HPLC analysis of root exudates showed that U-deoxymugineic acid (DMA) is the dominating phytosiderophore released from roots of Zn-efficient genotypes. In root extracts concentration of DMA was also much higher in Zn-efficient than in inefficient genotypes. The results demonstrate that enhanced synthesis and release of phytosiderophores at deficient Zn supply is involved in Zn efficiency in wheat genotypes. It is suggested that the expression of Zn efficiency mechanism is causally related to phytosiderophore-mediated enhanced mobilization of Zn from sparingly soluble Zn pools and from adsorption sites, both in the rhizosphere and in plants.

Copper‐deficiency‐induced phytosiderophore release in in the calcicole grass Hordelymus europaeus

“…Enhanced PS release in Zn-deficient wheat has been reported by Zhang, Ro$ mheld & Marschner (1989, Cakmak et al (1994) and Walter et al D. Gries, S. Klatt and M. Runge (1994). However, results by Walter et al (1994) show that root-to-shoot transport of Fe is impaired in Zn-deficient plants.…”

Zinc deficiency as a practical problem in plant and human nutrition in Turkey: A NATO-science for stability project

“…Release of phytosiderophores is a well-known phenomenon occurring not only under Fe de®ciency, but also under Zn de®ciency (Zhang et al, 1989;Cakmak et al, 1994) and is involved in mobilization of Zn both in the rhizosphere (Treeby et al, 1989) and from the root cell walls (Zhang et al, 1991). Under Fe de®ciency, the release rate of phytosiderophores was closely associated with the differences in sensitivity to Fe de®ciency among and within cereal species (Takagi et al, 1984;Marschner et al, 1986;Jolley and Brown, 1989).…”

Effects of zinc activity in nutrient solution on uptake, translocation, and root export of cadmium and zinc in three wheat genotypes with different zinc efficiencies

“…Wheat genotypes differ widely in their ability to absorb, accumulate, and distribute Zn and Cd (Cakmak et al 1996(Cakmak et al , 1997Kalayci et al 1999). These differences among wheat genotypes in the tissue accumulation and partitioning of Zn and Cd may be associated with their Zn efficiency.…”