Heavy metal stress is becoming a major detriment for plant growth,
development, and production worldwide. The walnut (Juglans regia) gene
JrVHAG1 was previously identified as a drought tolerance-related gene
involved in ABA (abscisic acid)-signal pathway. To better understand the
role of JrVHAG1, Zhenggang Xu of Central South University of Forestry and
Technology in China, studied further its function as well as its relation to
cadmium stress tolerance.

The expression of JrVHAG1 was found to be induced by ABA and increased
significantly in roots and leaves. Similarly, its expression was also
induced by cadmium chloride (CdCl2). When treated simultaneously with ABA
and CdCl2 (ABA+CdCl2), JrVHAG1 was upregulated to 110.13 times and 165.42
times in roots and leaves, respectively.

The team then overexpressed the gene in Arabidopsis. Compared to the wild
types, the transgenic Arabidopsis exhibited increased seed germination rate,
biomass accumulation, and proline content under treatments. Analysis of the
promoter of JrVHAG1 revealed that ABA, CdCl2, and ABA+CdCl2 significantly
enhanced the expression of the gene.

These results suggest that the JrVHAG1 gene functions as a cadmium stress
response regulator by participating in ABA-signal pathway. JrVHAG1 gene
could be a useful candidate gene for heavy metal stress tolerance in plant
molecular breeding.



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