Structural And Hblmyc1 Gene Correlated With Natural Rubber Yield In Hevea Brasilensis Muell. Arg.

Lack of early selection for hibrids is the bottleneck constrant of rubber tree breeding. On the basis of our findings that laticifer differentiation and natural rubber biosynthesis are mainly regulated by jasmonate signaling, we postulate that the expression and structure of Hb1MYC1 gene encoding for a key linker of jasmonate signaling is correlated with rubber yield. In this paper, difference in the expression and structure of Hb1MYC1 gene among seven high-yield rubber tree clones and nineteen 1981'IRRDB germplasm, and its correlation with rubber yield were investigated by realtime PCR and Northern-blot techniques. The results as follows:1. Bark structure properties associated with rubber yield were tested in three groups of rubber tree clones, seven high-yield rubber clones, nineteen 1981'IRRDB germplasm and five rubber clones were analyzed by cell biological techniques. Ratio of secondary laticifer lines in secondary functional phloem to the width of secondary functional phloem was significantly positive correlated with rubber yield among rubber clones with or without same genetic background. The ratio of secondary laticifer lines in the area between the innest stone cell layer and cambium to the width of this area was significantly positive correlated with rubber yield among rubber clones with different genetic background, but not among rubber clones with same (or very similar) genetic background. These two parameters which are easy for observation are expected to be applied for early selection for high-yield potential of adult rubber tree; 2. Hb1MYC1 gene was correlated with rubber yield and its expression was determined by both exploitation and genetic background; 3. A sigle nucleotide polymorphism (SNP) site was found in the 3'untranscription region of Hb1MYC1 gene. These results are theoretical bases for developing quick and accurate techniques for early selection of rubber clone with high yield potential.