Abstract
Different intra- or interspecific wheat show different interactions of Cd/Zn. Normally, Zn has been/being widely utilized to reduce the Cd toxicity. In the present study, the DPW seedlings exhibited strong Cd tolerance. Zn and Cd mutually inhibited their uptake in the roots, showed antagonistic Cd/Zn interactions. However, Zn promoted the Cd transport from the roots to shoots, showed synergistic. In order to discover the interactive molecular responses, a transcriptome, including 123,300 unigenes, was constructed using RNA-Sequencing (RNA-Seq). Compared with CK, the expression of 1,269, 820, and 1,254 unigenes was significantly affected by Cd, Zn, and Cd+Zn, respectively. Only 381 unigenes were co-induced by these three treatments. Several metal transporters, such as cadmium-transporting ATPase and plant cadmium resistance 4, were specifically regulated by Cd+Zn. Other metal-related unigenes, such as ABC transporters, metal chelator, nicotianamine synthase (NAS), vacuolar iron transporters (VIT), metal-nicotianamine transporter YSL (YSL), and nitrate transporter (NRT), were regulated by Cd, but were not regulated by Cd+Zn. These results indicated that these transporters participated in the mutual inhibition of the Cd/Zn uptake in the roots, and also participated in the Cd transport, accumulation and detoxification. Meanwhile, some unigenes involved in other processes, such as oxidation-reduction, auxin metabolism, glutathione (GSH) metabolism nitrate transport, played different and important roles in the detoxification of these heavy metals.
Highlights
In plants, non-essential heavy metals cause toxicity and eventually inhibit plant growth and development (Balen et al, 2011)
Cd and Zn mutually inhibited their uptake in the roots, Zn promoted the Cd transport from the roots to shoots (Figure 2), and these treatments affected growth (Figure 1)
DPW accumulated 992.29 ± 29.83 mg/Kg Cd in the roots and 40.82 ± 13.70 mg/Kg (DW) Cd in the shoots, the lengths of root and shoot were not affected (Figures 1A,B), which validated that DPW seedlings had stronger Cd tolerance than other types of durum and bread wheat (Hart et al, 2002, 2005)
Summary
Non-essential heavy metals cause toxicity and eventually inhibit plant growth and development (Balen et al, 2011). Cadmium (Cd), a heavy metal widespread in the environment, damages the photosynthetic apparatus, affects the respiratory and nitrogen metabolism, and alters the balance of water and nutrient uptake (Herbette et al, 2006; Balen et al, 2011). Cd absorbed by plants can be introduced into the food chain (McLaughlin et al, 1999). The Cd concentrations in several safe cereal grains were limited below 0.2 mg/Kg. In contrast, zinc (Zn) is an essential metal for plant growth. Zinc (Zn) is an essential metal for plant growth It has been/being widely utilized to reduce the Cd
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