Contributions of TaSUTs to grain weight in wheat under drought
The homologous genes to OsSUT1-5 in wheat were identified and detailed analysed. TaSUT1 was the predominant sucrose transporter group and it illustrated the genotypic variations towards drought during grain filling.
Sucrose transporters (SUT) play crucial roles in wheat stem water soluble carbohydrate (WSC) remobilization to grain. To determine the major functional SUT gene groups in shoot parts of wheat during grain development, drought tolerant varieties, Westonia and Kauz, were investigated in field drought experiments. Fourteen homologous genes to OsSUT1-5 were identified on five homeologous groups, namely TaSUT1_4A, TaSUT1_4B, TaSUT1_4D; TaSUT2_5A, TaSUT2_5B, TaSUT2_5D; TaSUT3_1A, TaSUT3_1D; TaSUT4_6A, TaSUT4_6B, TaSUT4_6D; TaSUT5_2A, TaSUT5_2B, and TaSUT5_2D, and their gene structures were analysed. Wheat plants above the ground were harvested from pre-anthesis to grain maturity and the stem, leaf sheath, rachis, lemma and developing grain were used for analysing TaSUT gene expression. Grain weight, thousand grain weight, kernel number per spike, biomass and stem WSC were characterized. The study showed that among the five TaSUT groups, TaSUT1 was the predominant sucrose transporting group in all organs sampled, and the expression was particularly high in the developing grain. In contrast to TaSUT1, the gene expression levels of TaSUT2, TaSUT3 and TaSUT4 were lower, except for TaSUT3 which showed preferential expression in the lemma before anthesis. The TaSUT5 gene group was very weakly expressed in all tissues. The upregulated gene expression of TaSUT1 Westonia type in stem and grain reveal a crucial role in stem WSC remobilization to grain under drought. The high TaSUT1 gene expression and the significant correlations with thousand grain weight (TGW) and kernel number per spike demonstrated the contribution in Kauz’s high grain yield in an irrigated environment and high TGW in Westonia under drought stress. Further molecular level identification is required for gene marker development.
KeywordsDrought Gene expression Grain filling Sucrose transporter Water soluble carbohydrate remobilization Wheat
Days after anthesis
Kernel number per spike
Thousand grain weight
Water soluble carbohydrate
This work was supported by a Scholarship of Iraqi Ministry of Higher Education and Scientific Research to the first author, Grain Research & Development Corporation ‘Grant Number UMU00039 and Murdoch University. The Western Australian Agriculture and Biotechnology Centre provided facilities for molecular analyses. The work involved collaboration with staff from the Department of Agricultural and Food Western Australia, Merredin station.
SA, JZ, WM, BD conceived the research. SA and JZ performed the experiments and analysed the data. SA, JZ, WM and BD wrote and reviewed the manuscript.
Compliance with ethical standards
Conflict of interest
The authors claim that there is no conflict of interest.
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