Comparative Study on Genome Size and Phytochemical Profile of Three Potential Species of Acacia: Threatened and Endemic to Saudi Arabia

Abstract

Acacias are widely distributed in tropical and subtropical regions of the world and have both economic as well as medicinal value. The estimation of genome size is very important as it changes due to the change in noncoding DNA sequence as well as genome duplication among organisms for their evolutionary aspects. Three potential species of the genus Acacia including Acacia etbaica, Acacia johnwoodii and Acacia origena, which are threatened and nearly endemic to Saudi Arabia, were collected. The present study was carried out to determine the genome size (2C DNA contents), total phenolic content (TPC), total flavonoid (TFC) and some bioactive compounds in these species for their comparison. The genome size ranged from 1.91 pg (A. etbaica) to 2.45 pg/2C (A. origena) among the Acacia species, which correspond to genome sizes 1843.15–2364.25 Mbp, respectively. The variation was observed in genome size within Acacia species as nuclei were extracted using different extraction buffers except for GB and MB01 buffers. The FTIR analysis revealed the presence of various functional groups in compounds that might be responsible for different types of phytochemicals in these Acacia species. Total flavonoid content (TFC) ranged from 0.647 (A. origena) to 1.084 mg QE/g DW (A. etbaica), whereas the total phenolic f content (TPC) ranged between 15.322 (A. origena) to 28.849 (A. johnwoodii) mg/g DW of GAE. HPLC analysis revealed the presence of quercetin 3-β-D-glucoside and luteolin 7-rutinoside in the leaves of all three Acacia species in considerable amounts, and these might have good health-promoting effects. This is our first study on genome size (2C DNA content) using flow cytometry and phytochemical profiling on these Acacias. Thus, estimated genome size and phytochemical study of these species could help to understand the biosynthesis of secondary metabolites under various genes and the evolutionary relationships among them.