Hevein has been found to be an essential element in coagulation of rubber particles in latex of rubber trees. In a previous study, we cloned a 1 241-bp fragment of a 5＇ upstream region of the hevein gene by genome walking. This fragment was analyzed by a 5＇ end nested deletion method in the present study, fused with a uidA （gus） gene to produce a series of tested constructs, which were transferred into C-serum of latex and the Gus activities were detected. Results showed that the fragment from -749 to -292 was sufficient for expression of gus gene in latex, and the fragment from -292 to -168 was crucial in response to abscisic acid inducement. In a transient transgenic test of rubber leaf with particle bombardment, construct Hev749 conferred gus-specific expression in veins, in which the latex tubes mainly distributed. This implies that the fragment from -749 to -292 was laticiferous-specific.
Hevein, a lectin_like protein, is a major factor of lutoids in the latex of rubber trees ( Hevea brasiliensis Muell._Arg.). This factor is involved in coagulation of the latex and has the ability to bind chitin. The hevein gene with a length of 680 bp was cloned by the method of RT_PCR. Its promoter region with 1 306 bp of this gene was also isolated by genome walking, and its sequence included the typical TATA and CAAT boxes as well as the homologous sequence of abscisic acid (ABA) response elements. Expression of the hevein gene in the latex and leaves was detected by Northern blot. After treatment of the trees with ethylene and ABA, the results showed that the hevein gene was expressed principally in latex, and the expression could be induced by ethylene and ABA.
