Genetic architecture of limit dextrinase inhibitor (LDI) activity in Tibetan wild barley

Abstract

BackgroundLimit dextrinase inhibitor (LDI) inhibits starch degradation in barley grains during malting because it binds with limit dextrinase (LD). There is a wide genetic variation in LDI synthesis and inactivation during barley grain development and germination. However, the genetic control of LDI activity remains little understood.ResultsIn this study, association analysis was performed on 162 Tibetan wild accessions by using LDI activity, 835 Diversity Arrays Technology (DArT) markers and single nucleotide polymorphisms (SNPs) of the gene HvLDI encoding LDI. Two DArT markers, bpb-8347, bpb-0068, and 31 SNPs of HvLDI were significantly associated with LDI activity, explaining 10.0%, 6.6% and 13.4% of phenotypic variation, respectively. Bpb-8347 is located on chromosome 6H, near the locus of HvLDI, and bpb-0068 is located on 3H.ConclusionsThe current results confirmed the locus of the gene controlling LDI activity and identified a new DArT markers associated with LDI activity. The SNPs associated with LDI activity may provide a new insight into the genetic variation of LDI activity in barley grains.

Genome-Wide Association Study Reveals a New QTL for Salinity Tolerance in Barley (Hordeum vulgare L.)

“…P value < 0.01 have been used as a cut-off for barley GWAS in many studies ( Pasam et al, 2012 ; Shu et al, 2012 ; Huang et al, 2014 ). The marker bPb-9668 on 4H (145.0 cM) showed consistent significance ( P < 0.01) of marker-trait associations using the Q, K, and Q + K methods ( Figure 4 ; Table 1 ).…”

“…A mixed-linear model (MLM) approach has been developed which leads to a better performance ( Yu et al, 2006 ). In barley, GWAS has been used for detecting genetic variations underlying diverse complex traits such as agronomic and morphologic traits ( Cockram et al, 2010 ; Pasam et al, 2012 ; Wang et al, 2012 ; Munoz-Amatriain et al, 2014 ), malting quality related traits ( Huang et al, 2014 ; Matthies et al, 2014 ; Cai et al, 2015 ), cadmium accumulation ( Wu et al, 2015 ), frost tolerance ( Visioni et al, 2013 ), aluminum tolerance ( Cai et al, 2013 ; Zhou et al, 2016 ) and salinity tolerance ( Long et al, 2013 ).…”

New Starch Phenotypes Produced by TILLING in Barley

“…Barley limit dextrinase is coded by a single gene ( LDA1 ) and is apparently involved both in starch biosynthesis and degradation [48] . In vivo , the activity of LDA1 is regulated by a proteinaceous inhibitor LDI [49] , and antisense transgenic barley with lower expression of LDI showed higher LDA1 activity and a lower percentage of B-granules ( i.e. inhibition of granule initiation) and lower amylose/amylopectin ratio [50] .…”

Review: Amylopectin synthesis and hydrolysis – Understanding isoamylase and limit dextrinase and their impact on starch structure on barley ( Hordeum vulgare ) quality

“…Purity of the unbound enzyme form may influence activity; with a near total loss in LD activity in under 10 min at 65°C when pure. Low level of free LD activity is attributed to a combination of endogenous inhibitors and a limit dextrinase inhibitor (LDI) bound in key endosperm components (Huang et al 2014). The release of LD from its inhibiter promotes starch digestion and increases fermentable sugars formation.…”

“…The release of LD from its inhibiter promotes starch digestion and increases fermentable sugars formation. It is suggest that LD bound to the LDI is the a limiting factor for complete starch digestion during brewing (Bamforth 2003, Huang, Cai et al 2014).…”