Amino acid transporter gene TaATLa1 from Triticum aestivum L. improves growth under nitrogen sufficiency and is down regulated under nitrogen deficiency.

MAIN CONCLUSION: TaATLa1 was identified to respond to nitrogen deprivation through transcriptome analysis of wheat seedlings. TaATLa1 specifically transports Gln, Glu, and Asp, and affects the biomass of Arabidopsis and wheat. Nitrogen is an essential macronutrient and plays a crucial role in wheat production. Amino acids, the major form of organic nitrogen, are remobilized by amino acid transporters (AATs) in plants. AATs are commonly described as central components of essential developmental processes and yield formation via taking up and transporting amino acids in plants. However, few studies have reported the detailed biochemical properties and biological functions of these AATs in wheat. In this study, key genes encoding AATs were screened from transcriptome analysis of wheat seedlings treated with normal nitrogen (NN) and nitrogen deprivation (ND). Among them, 21 AATs were down-regulated and eight AATs were up-regulated under ND treatment. Among the homoeologs, TaATLa1.1-3A, TaATLa1.1-3B, and TaATLa1.1-3D (TaATLa1.1-3A, -3B, and -3D), belonging to amino acid transporter-like a (ATLa) subfamily, were significantly down-regulated in response to ND in wheat, and accordingly were selected for functional analyses. The results demonstrated that TaATLa1.1-3A, -3B, and -3D effectively transported glutamine (Gln), glutamate (Glu), and aspartate (Asp) in yeast. Overexpression of TaAILa1.1-3A, -3B, and -3D in Arabidopsis thaliana L. significantly increased amino acid content in leaves, storage protein content in seeds and the plant biomass under NN. Knockdown of TaATLa1.1-3A, -3B, and -3D in wheat seedlings resulted in a significant block of amino acid remobilization and growth inhibition. Taken together, TaATLa1.1-3A, -3B, and -3D contribute substantially to Arabidopsis and wheat growth. We propose that TaATLa1.1-3A, -3B, and -3D may participate in the source-sink translocation of amino acid, and they may have profound implications for wheat yield improvement.

Moderate addition of B-type starch granules improves the rheological properties of wheat dough.

The quality traits of wheat grain ultimately determine the performance of wheat flour and dough, which is crucial to end-products. However, to combine high yield and good grain quality has been a great challenge in wheat breeding. In this study, the different sized A- and B-type starch granules were fractioned to investigate their effects on the physicochemical properties of wheat flour and rheological properties of wheat dough using three substitution levels (5, 10, and 15%). Results showed that 5% B-type starch granules addition increased the percentage of SDS-unextractable polymeric protein, optimized the dough network, and increased the bond water content, and thus improved the dough rheological properties. The addition of A-type starch granules or excessive B-type starch granules diluted and destroyed the structure of gluten, and reduced the dough strength. Therefore, a possible strategy for combining wheat quality and yield was proposed, that is, replacing protein content with B-type starch granules at a proper level, which has profound implications for wheat breeders to look at and address trade-offs between the quality and yield of wheat in future.