A betaine aldehyde dehydrogenase gene from <Emphasis Type="Italic">Ammopiptanthus nanus</Emphasis> enhances tolerance of <Emphasis Type="Italic">Arabidopsis</Emphasis> to high salt and drought stresses

YUCCA is an important enzyme which catalyzes a key rate-limiting step in the tryptophan-dependent pathway for auxin biosynthesis and implicated in several processes during plant growth and development. Genome wide analyses of YUCCA genes have been performed in Arabidopsis, rice, tomato, and Populus, but have never been characterized in soybean, one of the most important oil crops in the world. In this study, 22 GmYUCCA genes (GmYUCCA1-22) were identified and named based on soybean whole-genome sequence. Phylogenetic analysis of YUCCA proteins from Glycine max, Arabidopsis, Oryza sativa, tomato, and Populus euphratica revealed that GmYUCCA proteins could be divided into four subfamilies. Quantitative real-time RT-PCR (qRT-PCR) analysis showed that GmYUCCA genes have diverse expression patterns in different tissues and under various stress treatments. Compared to the wild type (WT), the transgenic GmYUCCA5 Arabidopsis plants displayed downward curling of the leaf blade margin, evident apical dominance, higher plant height, and shorter length of siliques. Our results provide a comprehensive analysis of the soybean YUCCA gene family and lay a solid foundation for further experiments in order to functionally characterize these gene members during soybean growth and development.