Pea (Pisum sativum L.) Growth Mutants

This review is devoted to the Pisum sativum L. growth mutants. These mutants are presented by several groups of plants. The first group is characterized by short internodes (dwarf mutants le, na, lk, la, lh, ls) or by elongated internodes (slender mutant sln). The stem growth of mutants of both types (dwarf and slender) is controlled by hormones (GA and IAA) in the stem or in seeds. Mutants characterized by decreased apical bud growth and predominated axillary bud growth belong to another group. They exhibit a multi-branching phenotype. Based on grafting studies with these mutants, several genes have been identified that operate in the shoot and roots in order to moderate the level or transport of graft-transmissible signal involved in branching control (genes rms1, rms2, rms3, rms4, rms5, rms6, rms7). The level and transport of auxins, cytokinins and shoot-multiplicational signal (SMS) take part in the regulation of stem branching. SMS can be surmised to be proteins, among them carotenoid cleavage dioxygenases. The third mutant group is defined as the foliage mutants (genes af, tl, tac, st) characterized by different total leaf weights and areas per plant: high positive correlations of root weight with leaf and stem weight and also of root weight with leaf area are observed. The “chameleon” phenotype is controlled by two recessive genes af and tac, which characterize heterophyllia. The determinate habit mutation is controlled by a recessive allele of the deh gene and result in the reduction of reproductive node number. The recessive det mutant forms an apical raceme, stops growth of the main stem and also exhibits a determinant habit. The lupinoid phenotype is controlled by recessive det and fas genes and determines the apical multi-flower inflorescence which is analogous to a lupine inflorescence. These mutants are important for studying the regulation of plant growth and for progress in improving high productive pea varieties. _____________________________________________________________________________________________________________