Rapid Development and Characterization of Chromosome Specific Translocation Line of Thinopyrum elongatum with Improved Dough Strength.

Aman Kumar,Saloni Sharma,Quan-Wen Dou,Navneet Kaur,Hisashi Tsujimoto,Monika Garg,Swati Misser,Raj K Gupta,Venkatesh Chunduri,Ashish Kumar

doi:10.3389/fpls.2017.01593

Abstract

The protein content and its type are principal factors affecting wheat (Triticum aestivum) end product quality. Among the wheat proteins, glutenin proteins, especially, high molecular weight glutenin subunits (HMW-GS) are major determinants of processing quality. Wheat and its primary gene pool have limited variation in terms of HMW-GS alleles. Wild relatives of wheat are an important source of genetic variation. For improvement of wheat processing quality its wild relative Thinopyrum elongatum with significant potential was utilized. An attempt was made to replace Th. elongatum chromosome long arm (1EL) carrying HMW-GS genes related to high dough strength with chromosome 1AL of wheat with least or negative effect on dough strength while retaining the chromosomes 1DL and 1BL with a positive effect on bread making quality. To create chromosome specific translocation line [1EL(1AS)], double monosomic of chromosomes 1E and 1A were created and further crossed with different cultivars and homoeologous pairing suppressor mutant line PhI. The primary selection was based upon glutenin and gliadin protein profiles, followed by sequential genomic in situ hybridization (GISH) and fluorescent in situ hybridization (FISH). These steps significantly reduced time, efforts, and economic cost in the generation of translocation line. In order to assess the effect of translocation on wheat quality, background recovery was carried out by backcrossing with recurrent parent for several generations and then selfing while selecting in each generation. Good recovery of parent background indicated the development of almost near isogenic line (NIL). Morphologically also translocation line was similar to recipient cultivar N61 that was further confirmed by seed storage protein profiles, RP-HPLC and scanning electron microscopy. The processing quality characteristics of translocation line (BC4F6) indicated significant improvement in the gluten performance index (GPI), dough mixing properties, dough strength, and extensibility. Our work aims to address the challenge of limited genetic diversity especially at chromosome 1A HMW-GS locus. We report successful development of chromosome 1A specific translocation line of Th. elongatum in wheat with improved dough strength.

Highlights

Wheat is one of the major cereal food crops with worldwide consumption
The plant materials utilized in this study included (1) disomic addition line of Th. elongatum chromosome 1E and disomic substitution line of Th. elongatum chromosome 1E with chromosome 1D of wheat, both in the background of Chinese Spring (CS) {DSL-1E(1D)}, (2) genetic stocks nulli for chromosome 1A and tetra for chromosome 1D (N1AT1D), N1AT1B, N1BT1A, N1BT1D, and N1DT1B in the background of CS, and (3) four cultivars: AcDomain-hard Canadian, Norin 61 (N61)-soft Japanese, PBW343-hard Indian, Cham 6-hard Syrian
For generation of chromosome specific translocation line Th. elongatum substitution line DSL-1E(1D) and N1AT1D were utilized. As both are in the genetic background of CS, their glutenin, and gliadin seed storage protein electrophoretic profiles were studied for identification of protein markers (Supplementary Figure 1)

Summary

Introduction

Wheat is one of the major cereal food crops with worldwide consumption. More than 700 million metric tons of wheat have been produced globally each year since 2013 which means it accounts for more than 30% of total cereal production and provides almost 20% of total calorific input to the world (USDA/ARS, 2017). Wheat flour protein combination distinguishes it from other cereals as it confers properties of viscoelasticity and extensibility to the dough (Wang et al, 2013). To accomplish sufficient yield and resistance to diseases, many economically important genes have been transferred to wheat through chromosome translocations from many different relative genera (Feldman and Levy, 2015; Ma et al, 2015) such as, resistance genes Pm53, Yr40, and Yr42 from Aegilops spp. It has substantially contributed to yield enhancement, productivity increase, and has affected agricultural economy (Rabinovich, 1998) Despite their wide use in conferring resistance traits to wheat cultivars not too many translocation lines have been developed for quality traits such as, dough strength and extensibility.

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Conclusion