Study toward the development of relationship between Ref gene expression and yield potential of Hevea clones Gunasekara S. D. T. S.1, Palihakkara I. R.2, Withanage S. P.3* 1Department of Crop Science, Faculty of Agriculture, Ruhuna University of Sri Lanka, Mapalana, Kamburuupitiya, Sri Lanka 2Department of Crop Science, Faculty of Agriculture, Ruhuna University of Sri Lanka, Mapalana, Kamburuupitiya, Sri Lanka 3Department of Genetics and Plant Breeding, Rubber Research Institute of Sri Lanka, Nivithigalakele, Mathugama, Sri Lanka * Corresponding Author: pamuditharama@yahoo.co.uk
Online published on 4 January, 2021. Abstract Rubber is the third largest plantation crop in Sri Lanka. In 2018, Rubber production was declined from 83.1 million kilograms to 82.6 million kilograms. Development of high yielding clones to the rubber industry is a prime objective of Hevea breeding and selection. Rubber Elongation Factor (Ref) protein mainly helps for the biosynthesis of natural rubber in Hevea brasiliensis. Rubber particles are tightly bound to this Ref protein. Genomic sequence of Ref gene is 1367 bp long. Previous studies found that the positive correlation between Ref gene expression pattern and latex yield. The clones in the group III clone recommendation are needed to upgrade in to group II gradually with their performance. Selected three clones in the group III as RRISL 2006, RRISL Centennial 3 and RRISL Centennial 4 were undertaken to study their Ref gene expression and promoter analysis with latex yield to verify their performance. Quantitative gene expression of Ref gene was done to identify the expression pattern of Ref gene and promoter. Livak method (2−δδCT) used to analyze the quantitative gene expression and paired t test was used to identify significant difference between control and treatments. Compared to the control clone RRISL 203, the yields of all other three clones were significantly higher as well as their Ref gene expression was up-regulated differently with 2 to 7 fold difference. Up-regulation of Ref gene in the clone RRISL 2006 is significantly higher with seven fold compared to the control clone RRISL 203. The average yield of RRISL 2006 in the year 2019 was 27.3 g/t/t and average yield of RRISL Centennial 3 was 28.3 g/t/t. But the difference was not significant. In January 2020, where samples were collected, the RRISL 2006 recorded highest 55.77 g/t/t. RRISL Centennial 4 was showed around four fold up-regulation compared to the clone RRISL 203 as well as yield also higher to RRISL 203. The clone RRISL Centennial 3 also followed the same pattern but the fold difference was around 2.5 over the control clone RRISL 203. The results we reproved the positive correlation between Ref gene expression and the high yield. However this relationship was not observed between RRISL Centennial 3 and RRISL Centennial 4, as the clone RRISL Centennial 4 showed higher fold difference over to RRISL Centennial 3 but yield was low. Therefore this relationship is needed to be further analyzed. The copy number of Ref promoter also important to understand the clear relationship between Ref gene expression and yield potential of Hevea clones. Top Keywords Hevea brasiliensis, Ref gene, Ref promoter, Real Time PCR. Top |