Spike morphology alternations in androgenic progeny of hexaploid triticale (\xd7 Triticosecale Wittmack) caused by nullisomy of 2R and 5R chromosomes

Janetta Niemann,Roksana Skowrońska,Dorota Weigt,Agnieszka Tomkowiak,Zofia Banaszak,Jerzy Nawracała,Michał T Kwiatek,Danuta Kurasiak-Popowska,Sylwia Mikołajczyk

doi:10.1007/s11627-019-10021-7

Abstract

Induction of androgenesis, followed by chromosome doubling, is a crucial method to obtain complete homozygosity in one-generation route. However, in vitro androgenesis can result in various genetic and epigenetic changes in derived triticale plants. In this study, we evaluated chromosome alternations and we associated them with the changes of spike morphology in androgenic progeny of triticale. We karyotyped offspring plants that derived from double haploid plants using fluorescence in situ hybridization techniques. We distinguished four major groups of karyotypes: double ditelosomics, nullisomics N2R, nullisomics N5R, and triticale plants with a complete set of chromosomes. It is known that more than half of QTLs connected with androgenic response are located in R-genome of triticale but 2R, 5R, and 6R chromosomes are not included. We hypothesized that the reason why only aberrations of chromosomes 2R and 5R appear during androgenesis of triticale is that because these chromosomes are not involved in the stimulation of androgenic response and the following regeneration of plants is not disrupted. Concerning the established groups, we evaluated following quantitative traits: spike length, number of spikes per plant, number of spikelets per spike, and number of grains per spike. The nullisomy of chromosome 2R and 5R resulted in vast changes in spike architecture of triticale plants, which can be correlated with the location of major QTLs for spike morphology traits on these chromosomes. The spikes of nullisomic plants had significantly decreased spike length which correlated with the reduction of number of spikelets per spike and number of grains per spike.

Highlights

Triticale (× Triticosecale Wittmack) is an example of humanmade polyploid, which was produced through crossing between wheat (Triticum aestivum L.) and rye (Secale cereale L.)
Genomic in situ hybridization (GISH) was used to categorize the chromosomes according to their genomic belonging
Chromosome-specific fluorescence in situ hybridization (FISH) markers are considered as powerful tools for evaluation of genomic changes

Summary

Introduction

Triticale (× Triticosecale Wittmack) is an example of humanmade polyploid, which was produced through crossing between wheat (Triticum aestivum L.) and rye (Secale cereale L.). First triticale was produced by Wilson (1876), which launches the efforts to develop a new crop, that consolidate the quality properties of wheat with the resistance to environmental stresses of rye. Double haploid production is one of the most important improvements in modern breeding methods (Thomas et al 2003; Oettler et al 2005). It assures the one-generation route to homozygosity, which saves time, comparing to classical 5– 7-yr-long pedigree programs (Dwivedi et al 2015; Weigt et al 2016; Weigt et al 2017). Protocols used for DH production in triticale have been developing based on wheat protocols (Eudes and Chugh 2009). Androgenesis in triticale is performed both by the anther culture (Ślusarkiewicz-Jarzina et al 2017) and with the microspore culture methods (Pauk et al 2000)

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