From Wikimedia; image lightened and sharpened to bring out detail.
Maria Antonia's dress and coiffure are passé if this is 1846 suggesting this is a retrospective portrait. She may be wearing the dress she wears in her 1836 portrait.
Keywords: Bezzuoli, Maria Antonia of the Two Sicilies, Princess, Grand Duchess, Borbone family, Italian, straight coiffure, knotted coiffure, off shoulder scoop neckline, modesty piece, pleated bodice, vee neckline, upper puffed sleeves, vee waistline, necklace, robes