In higher plants, the shoot apical meristem produces lateral organs in a regular spacing (phyllotaxy) and timing (plastochron).  The molecular analysis of mutants associated with phyllotaxy and plastochron would increase our understanding of the mechanism of shoot architecture formation.  In this study, we identified mutant mnd8^ynp5 that shows an increased rate of leaf emergence and a larger number of nodes in combination with a dwarfed growth habit from an EMS-treated population of the elite barley cultivar Yangnongpi 5.  Using a map-based cloning strategy, the mnd8 gene was narrowed down to a 6.7-kb genomic interval on the long arm of chromosome 5H.  Sequence analysis revealed that a C to T single-nucleotide mutation occurred at the first exon (position 953) of HORVU5Hr1G118820, leading to an alanine (Ala) to valine (Val) substitution at the 318th amino acid site.  Next, HORVU5Hr1G118820 was defined as the candidate gene of MND8 encoding 514 amino acids and containing two multidrug and toxic compound extrusion (MATE) domains.  It is highly homologous to maize Bige1 and has a conserved function in the regulation of plant development by controlling the leaf initiation rate.  Examination of modern barely varieties showed that Hap-1 was the dominant haplotype and was selected in barley breeding around the world.  Collectively, our results indicated that mnd8^ynp5 is a novel allele of the HORVU5Hr1G118820 gene that is possibly responsible for the shortened plastochron and many noded dwarf phenotype in barley.

Small auxin up RNA (SAUR) is a large gene family that is widely distributed among land plants.  In this study, a comprehensive analysis of the SAUR family was performed in sweet cherry, and the potential biological functions of PavSAUR55 were identified using the method of genetic transformation.  The sweet cherry genome encodes 86 SAUR members, the majority of which are intron-less.  These genes appear to be divided into seven subfamilies through evolution.  Gene duplication events indicate that fragment duplication and tandem duplication events occurred in the sweet cherry.  Most of the members mainly underwent purification selection pressure during evolution.  During fruit development, the expression levels of PavSAUR16/45/56/63 were up-regulated, and conversely, those of PavSAUR12/61 were down-regulated.  Due to the significantly differential expressions of PavSAUR13/16/55/61 during the fruitlet abscission process, they might be the candidate genes involved in the regulation of physiological fruit abscission in sweet cherry.  Overexpression of PavSAUR55 in Arabidopsis produced earlier reproductive growth, root elongation, and delayed petal abscission.  In addition, this gene did not cause any change in the germination time of seeds and was able to increase the number of lateral roots under abscisic acid (ABA) treatment.  The identified SAURs of sweet cherry play a crucial role in fruitlet abscission and will facilitate future insights into the mechanism underlying the heavy fruitlet abscission that can occur in this fruit crop.