Morphological and anatomical modifications in leaf, stem and roots of four plant species under boron deficiency conditions

Abstract

Boron (B) is a structural component of plant cell wall and B deficiency causes disruption in development of plants. In this work, influence of low B supply on plants morphology and anatomy was studied in turnip (Brassica rapa L.), red cabbage (B. oleracea L. var. capitata f. rubra), tobacco (Nicotiana rustica L.) and celery (Apium graveolens L.). Visual B deficiency symptoms were observed in all studied species including curling of leaf margins in turnip, reduction of red coloration in red cabbage, shoot stunting in tobacco and turning dark purple colors in celery. Microscopic examination of cross-sections revealed that diameter of tracheary elements decreased and the phloem tissue became disorganized. Hypertrophy of leaf parenchyma cells in tobacco and increased thickening of collenchyma cell walls in the stem of celery were also observed. Anatomical alterations due to B deficiency were more pronouncedly observed in the leaf blades followed by the petiole, stem and roots. Our results indicated that remarkable disruptions occur in development of leaf primordia and vascular bundles upon B starvation.

El boro es un componente estructural de las paredes celulares y su deficiencia causa interrupción del desarrollo. En este trabajo, se estudia la influencia del bajo suplemento de B sobre la morfología y anatomía del nabo (Brassica rapa L.), lombarda (Brassica oleracea L. var. capitata f. rubra), tabaco de pota (Nicotiana rustica L.) y apio (Apium graveolens L.). Se observaron síntomas visuales en todas las especies. El examen microscópico de secciones transversales de hojas, tallos y raíces mostró disminución del diámetro de elementos traqueales y desorganización del tejido del floema. Así mismo, se produjo hipertrofia del parénquima foliar en tabaco y adelgazamiento de paredes celulares en células del colénquima del tallo, en apio. Las alteraciones anatómicas fueron más pronunciadas en limbo, seguidas de peciolo, tallo y raíces. Estos resultados señalan importantes interrupciones en el desarrollo de los primordios foliares y los haces vasculares con carestía de B.