Single Nucleotide Polymorphisms in Starch Biosynthetic Genes Associated With Increased Resistant Starch Concentration in Rice Mutant.

Selvakumar Gurunathan,Elsayed Fathi Abd_Allah,Chandranayaka Siddaiah,Abdulaziz A Alqarawi,Jutti Rajendran Kannan Bapu,Venkataramana Mudili,Abeer Hashem,Bharathi Raja Ramadoss,Chakrabhavi Dhananjaya Mohan,Naveen Kumar Kalagatur

doi:10.3389/fgene.2019.00946

Abstract

Resistant Starch (RS), plays a crucial role in human health and nutrition by controlling glucose metabolism. RS or dietary fibre content in rice is low because it goes through a variety of process before it is ready for cooking and consumption. Hence, this study was carried out to develop a rice mutant with increased RS. The rice mutant (γ278) with increased RS was developed by utilizing gamma (γ) rays as a mutagen. Mutant γ278 was characterized for mutations in the starch biosynthetic genes viz., GBSSI, SSI, SSIIa, SSIIIa, SBEIa, and SBEIIb to reveal the functional mutations/variations led to high RS content in rice. A total of 31 sequence variants/mutations in six genes were identified. We report the discovery of three deleterious mutation/variants each in GBSSI, SSIIa, and SSIIIa with the potential to increase RS content in rice. Further, wild × mutant crosses were made to develop an F2 population to study the effect of combination of deleterious mutations. The SNP (GBSSI:ssIIa:ssIIIa) combination responsible for high RS content in F2 population was identified and recorded highest amylose content (AC) (26.18%) and RS (8.68%) content. In conclusion, this marker combination will be highly useful to develop a rice variety with increased RS.

Highlights

Diabetes mellitus (DM) is a major global threat and its prevalence is increasing at an alarming rate worldwide, especially in Asian countries (Cummings and Englyst, 1991; Chan et al, 2009)
LD50 value of γ-radiation was determined as 250 Gray for ADT 43 rice variety
Results of Resistant Starch (RS) estimation further revealed that there is a significant change in the RS concentration ranged from 3.61 ± 0.4% to 6.62 ± 0.4%

Summary

Introduction

Diabetes mellitus (DM) is a major global threat and its prevalence is increasing at an alarming rate worldwide, especially in Asian countries (Cummings and Englyst, 1991; Chan et al, 2009). About 415 million adults suffered with type 2 diabetes mellitus (T2DM) globally during 2015, which is predicted to increase to 642 million by 2040 (Herman, 2017). Apart from obesity and physical inactivity, another major cause of high T2DM prevalence is the consumption of rapidly digestible carbohydrate-rich foods capable of increasing the blood sugar concentration. Rice grain lacks several micronutrients including vitamins and rapidly releases energy after consumption, has a relatively higher glycemic response compared to other starchy foods (Chassy et al, 2008)

Objectives

Methods

Results

Conclusion