Maximizing the identification of QTL for pre-harvest sprouting resistance using seed dormancy measures in a white-grained hexaploid wheat population

Abstract

Pre-harvest sprouting in spring wheat causes significant financial loss to growers throughout the world and sprouting damage can be reduced by growing resistant genotypes. Several genetic factors, especially those related to seed dormancy, are involved in the control of pre-harvest sprouting resistance. The objective of this study was to identify quantitative trait loci (QTL) influencing pre-harvest sprouting resistance from multiple measures of dormancy at multiple germination intervals on seed harvested across multiple environments. A doubled haploid mapping population of 91 individuals derived from a cross of two Canadian white-seeded spring wheat genotypes, SC8021-V2 (pre-harvest sprouting resistant) and AC Karma (moderately susceptible to pre-harvest sprouting) was used for QTL mapping. Daily germination counts were analysed using germination index, germination resistance and percent germination at intervals of 3, 5, 7, 10, 14 and 21 days from spike samples collected from six field and one greenhouse environments in Saskatchewan, Canada. Continuous frequency distributions at certain measure-durations indicated genetic complexity of dormancy segregation in the SC8021-V2/AC Karma cross. Composite interval mapping detected significant (p B 0.05) QTL associated with resistance to pre-harvest sprouting on all 21 wheat chromosomes. Of the 26 total QTL, six were novel and the rest were detected either at the same marker or overlapping a marker interval reported in other studies. QTL expressed consistently for germination index, germination resistance and percent germination at different germination durations on chromosomes 2B, 4A, 5D and 6D. QTL identified on homoeologous chromosomes 4A, 4B and 4D with chromosome specific molecular variants of SSR marker wmc617 suggest a conserved region for controlling dormancy on group four. The majority of QTL mapped in regions known to contain factors affecting different components of pre-harvest sprouting resistance like seed dormancy, seed coat colour, ABA responsiveness and alpha-amylase activity. This study demonstrated that using multiple measures of seed dormancy Electronic supplementary material The online version of this article (doi:10.1007/s10681-015-1460-x) contains supplementary material, which is available to authorized users. Euphytica (2015) 205:287-309 DOI 10.1007/s10681-015-1460 at multiple intervals of germination enhanced identification of QTL affecting dormancy in white-seeded hexaploid wheat.

Genome-wide association study of pre-harvest sprouting resistance in Chinese wheat founder parents

“…Germinated seeds were removed daily and counted. PHS resistance was assessed by PG based on seed dormancy ( Knox et al , 2005 ; 2012 ; Rasul et al , 2009 ; Singh et al , 2010 ; Kumar et al , 2015 ). PG (mean values of three repetitions in each environment) and the overall mean values of five environments were analyzed.…”

“…PHS in wheat ( Triticum aestivum L.) is the result of the early break in seed dormancy under humid and wet conditions prior to harvest ( Rikiishi and Maekawa, 2010 ; Kulwal et al , 2012 ), causing significant losses in grain weight and end-product quality. Percent germination (PG) is a variable commonly used to characterize the resistance to PHS based on seed dormancy ( Knox et al , 2005 , 2012 ; Rasul et al , 2009 ; Singh et al , 2010 ; Kumar et al , 2015 ). Previous studies reported that almost all 21 chromosomes of hexaploid wheat contain QTL for PHS resistance ( Roy et al.…”

Unraveling Molecular and Genetic Studies of Wheat (Triticum aestivum L.) Resistance against Factors Causing Pre-Harvest Sprouting

“…The interaction between QTL epistasis (Q × Q) and the environment (Q × E, Q × Q × E) for PHS resistance has been studied to understand the complex genetic structure of QTL [213][214][215]. In wheat, PHS resistance is controlled jointly by multiple QTLs located an almost 21 chromosomes (1A, 1B, 2A, 2B, 2D, 3A, 3B, 3D, 4A, 4B, 5B, 5D, 6A, 6B, 6D, 7A, 7B and 7D) [1,14,18,[21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][216][217][218][219][220] (Table 1).…”

“…PHS resistance is a typical quantitative trait controlled by numerous QTL/genes. Many quantitative trait loci (QTL) have been identified for PHS resistance in wheat [1,14,18,[21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]. Several candidate genes for PHS resistance have also identified, including TaSdr, TaPHS1, TaMFT, TaVp-1, Tamyb10, and TaMKK3-A [38][39][40][41][42][43][44][45][46].…”

Haplotype Analysis of the Pre-harvest Sprouting Resistance Locus Phs-A1 Reveals a Causal Role of TaMKK3-A in Global Germplasm

“…This enviromental dependency of PHS constitutes a constraint in selecting for PHS resistance in field conditions. In addition, resistance to PHS is highly quantitative and is controlled by numerous quantitative trait loci (QTL) located on all 21 chromosomes of bread wheat ( Flintham et al, 2002 ; Kulwal et al, 2005 ; Mori et al, 2005 ; Kottearachchi et al, 2006 ; Ogbonnaya et al, 2007 ; Liu et al, 2008 ; Torada et al, 2008 ; Xiao-bo et al, 2008 ; Mohan et al, 2009 ; Munkvold et al, 2009 ; Knox et al, 2012 ; Kulwal et al, 2012 ; Gao et al, 2013 ; Lohwasser et al, 2013 ; Mares and Mrva, 2014 ; Kumar et al, 2015 ). This makes resistance to PHS one of the most multi-genic traits in wheat and further highlights the complexity in breeding for this trait.…”