LYS3 encodes a prolamin-box-binding transcription factor that controls embryo growth in barley and wheat

Abstract

Tel +44 (0)1223 34249. 23 24 Keywords: high lysine, PBF, large embryo, shrunken endosperm.  Wheat and barley LYS3/PBF mutants have enlarged embryos suggesting that this gene 40 suppresses embryo growth. 41  The down-stream target genes of PBF in wheat are predicted to be involved in a wide 42 range of biological processes including organ development and starch metabolism. 43 3 ABSTRACT 44 Mutations at the LYS3 locus in barley have multiple effects on grain development, including 45 an increase in embryo size and a decrease in endosperm starch content. The gene underlying 46 LYS3 was identified by genetic mapping and mutations in this gene were identified in all four 47 6 2. Materials and methods 102 2.1. Barley germplasm 103 Grains of Bomi, Morex and Risø1508 were obtained from the Germplasm Resources Unit, 104 John Innes Centre, Norwich, UK and Risø18, Risø19, M1460 and Minerva were kindly 105 supplied by Birthe Møller Jespersen, University of Copenhagen, Denmark. 106 107 2.2. Plant growth 108For mapping experiments, individual grains were germinated in Petri dishes on moist filter 109 paper. After over-night incubation at 4 C, plates were transferred to room temperature. 110When roots and shoots were established, each seedling was transplanted into a 1 L pot 111containing Levington M2 compost (Scotts Professional, Ipswich, UK) and grown in a 112 glasshouse. In winter, additional lighting was provided by sodium lamps for 16 h per day and 113 temperatures were maintained between 15 C (night) and 20 °C (day). In summer, plants 114were grown in a glasshouse under ambient conditions. 115Wheat TILLING mutants were sown directly into M2 compost, incubated at 4 C for 3 116 days and then transferred to a glasshouse with a 22-hour photoperiod and temperatures of 21 117 C (night) and 18 C (day). Supplementary lighting was provided by a mixture of high-118pressure sodium lamps and both far red and white LED lights (Conviron, Winnipeg, US). 119 120 Analysis of grain and embryo development 121Anthesis occurred whilst the ear was enveloped in the flag leaf so the exact day of anthesis 122 was difficult to determine without damaging the developing spike. Accordingly, flowering 123 time was defined as the day on which the awns of the developing ear protruded more than 1 124 cm above the leaf sheath and grain/embryo age was measured in days after flowering (DAF). 125

TRA1: A Locus Responsible for Controlling Agrobacterium-Mediated Transformability in Barley

“…When we embarked on this study, our hypothesis was that transformability in M1460 might be due to the lys3 gene since this mutation is known to affect embryo development (Cook et al, 2018;Orman-Ligeza et al, 2019). Consequently, we selected the M1460 x Optic backcrossed lines at each generation for the presence of lys3 (using shrunken endosperm as a phenotypic marker for lys3).…”

“…Whilst working on mutants of barley affected at the LYS3 locus, we noticed that their developing embryos had an unusual cellular organization reminiscent of callus tissue (Cook et al, 2018). The LYS3 gene encodes a transcription factor called Prolamin Box-Binding Factor, and is expressed in developing and germinating grain (Moehs et al, 2019;Orman-Ligeza et al, 2019). The scutellar epidermis in lys3 mutants consists of multiple layers of cells instead of the usual single layer (Deggerdal et al, 1986;Cook et al, 2018).…”