Evaluation of heterosis in Australian wheat

Melissa Garcia1, Pooja Vashist1, Mihiranga Ovitigala1, Chris Brien2, Martin Nguyen2, Delphine Fleury1, Peter Langridge1. 1 Australian Centre for Plant Functional Genomics, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Urrbrae, South Australia, 5064 2 Phenomics and Bioinformatics Research Centre, University of South Australia, Mawson Lakes Campus, Mawson Lakes, South Australia , 5095

Heterosis in wheat Results Yield improvements from conventional crop breeding in Better parent heterosis (BPH) was calculated for seeds per wheat have tapered off over the past decade. Consequently, spike and thousand grain weight (TGW). BPH for seeds per there is renewed interest in technologies that offer major spike ranged from -55% to 39%, with an average of -13%, yield advantages particularly for low yielding environments. while BPH for TGW ranged from -35% to 22% , with an One of the most promising options is to capture the yield average of 2%. Some hybrids showed higher BPH values benefits from heterosis in a hybrid wheat program. The under drought as compared to the well-watered condition. impact of heterosis in wheat has not received the level of A strong correlation was observed between the trait values attention seen in other crops, particularly maize. Although under the drought and the well-watered conditions in the - wheat is a self-pollinated species, reports of the yield field experiment, but no correlation was observed between benefit in hybrids range from 5% to over 20%, depending on field and TPA. the study and the nature of the crosses. The relative growth curves obtained from the analysis of the TPA image data showed little variation among genotypes, Cross Combinations with hybrids and inbreds showing similar patterns (Fig1). Seeds per spike has shown a negative correlation with the In order to evaluate the impact of heterosis in Australian area of the plant at later developmental stages, while single elite germplasm, crosses were made between three grain weight and flowering time showed a positive Australian varieties and ten diverse lines from different correlation with area at later stages. Seeds per plant was regions around the world. The diverse lines were chosen positively correlated with the plant area at earlier based on genetic diversity detected with the 9K SNP array as developmental stages (Fig2). well as the country of origin. Females Line Origin Kite Australia Carazinho Brazil Kazakhstan Line 9 Kazakhstan Males Kazakhstan Line 10 Kazakhstan •Gladius Pastor Mexico Volcani DD1 Israel •Mace AC Barrie Canada •Scout Xiaoyan 54 China

Alsen USA Fig1. Relative growth curves of F1 hybrids (green lines), male parents(blue lines) and female H45 Australia parent s(red lines).:

Phenotyping 1. The Plant Accelerator (TPA)- Adelaide • Automated imaged (20 to 60 DAS) • Well-watered • Relative growth rates

2. Semi-controlled field conditions Fig2. Heat map of the correlation of the different traits with the area of the plants at different days after • Urrbrae (South Australia) sowing. • Drought and Well-watered

Conclusions • Average better parent heterosis was low, but some crosses showed high BPH for all traits • Hybrids and inbreds seem to have similar relative growth rates • More data is necessary to understand the relationship between plant area and the other traits