A relationship between boron & auxin in C¹⁴ translocation in bean plants

Abstract

The essentiality of boron for higher plants is well established although no definitive role proposed for this element has remained undisputed. So many processes are affected indirectly by boron that the primary effect(s) have remained obscure (9). Gauch and Dugger (9) suggest that a relatively specific role in carbohydrate translocation is indicated. Sucrose translocation is considerably reduced in boron deficient plants before morphological symptoms are evident. Gauch and Dugger (8) maintain that subsequent symptoms are simply the expression of carbohydrate deficiency resulting from the impaired translocation system. They suggest that a negatively charged sugar-boron complex might more easily traverse cell membranes than non-borated sugar molecules or that boron might be a constituent of the membrane site across which the sugar moves. Skok (20,21,22) points out that it is also possible for the relationship of boron to translocation to be indirect. He proposes that the boron effect on translocation is the result of the elements' essentiality to the metabolic activity of meristematic regions which have large substrate requirements. The effect of this particular metabolic activity including that associated with cell enlargement can be called sink effect; its relationship to translocation is now well established (3,12,23). If Skok is correct, cessation of growth would be the cause rather than the result of impaired carbohydrate translocation in boron deficient plants. Dugger et al. (4) proposed that boron affects the rate of translocation through its effect on the sugarstarch balance of the leaves. Scott (18) presents a similar hypothesis: "It appears that boron performs a protective function in plants in that it prevents excessive polymerisation of sugars at sites of sugar synthesis". It would appear, however, that boron

Teor e acúmulo de nutrientes no feijoeiro em função da aplicação de bioestimulante

“…Muitos autores citam que pode haver interação entre esse regulador, teor de B e crescimento de primórdios radiculares, e ainda explicam que o B é responsável pelo controle da concentração da auxina na formação de raiz, da atividade da peroxidase ou ainda no controle dos compostos fenólicos como, por exemplo, ortodifenóis que, por complexação com o borato, atua na diminuição ou aumento da atividade da auxina (DYAR;WEBB, 1961;SHAHEED, 1983;JARVIS et al, 1984).…”

Boron deficiency alters root growth and development and interacts with auxin metabolism by influencing the expression of auxin synthesis and transport genes

“…[2,6,13,15,16,35] In this study, we compared the difference in root morphology and anatomy between ¡B and CB treatments by using eight-week hydroponic cultivation ( Figure 1 and Table 2). The results showed that the primary and lateral root length was markedly reduced under boron-deficient conditions (Figure 1(a) and (b)): the mean total root length per seedling was 50.03 cm § 9.43 cm in the ¡B treatment, significantly lower than that in the CB treatment, where the mean total root length was 101.12 cm § 8.99 cm.…”

“…Dyar and Webb [35] reported that the growth of bean roots was significantly inhibited by a seven-day boron-deficiency treatment and that the inhibitory effect could be alleviated by adding exogenous auxin. To date, although an interaction between boron and auxin or IAA metabolism has been reported in many plants, the relationship remains unresolved.…”

Boron, Lignification and the Origin of Vascular Plants‐a Unified Hypothesis

“…On these chemical and theoretical grounds, therefore, it is unlikely that sucrose-borate complexes have any major metabolic significance. The hypothesis that such complexes are involved in translocation has also been criticized and denied on experimental, physiological grounds (Mcllrath, Presley and Palser, 1955;Neales, 1959Neales, , 1960Dyar andWebb, 1961. Weiser, Blaney andLi, 1964;Yih and Clarke, 1965).…”