Proline, Betaine, and Choline Responses to Different Phosphorus Levels in Green Bean

Abstract

Proline, betaine, and choline are protector molecules, related with secondary metabolism, that protect cells against oxidative damage by reactive oxygen species. They are present in many organisms, including bacteria, fungi, and plants, in response to low water stress, salinity, availability of essential nutrients, diseases, and others abiotic stress. The objective of the present work was to determine the effect of phosphorus (P) (deficient, adequate, excessive, or toxic) levels on proline, betaine, and choline protectors in green bean plants (Phaseolus vulgaris L. cv. Strike) under intensive system crop conditions. Different P levels were applied to the nutrient solution: P₁, 0.5 mM; P₂, 1 mM; P₃, 2 mM; P₄, 4 mM; P₅, 6 mM; and P₆, 8 mM, with P₃ considered the optimal. Treatment P₃ caused the most important and significant increase on proline, betaine, and choline, with P₆ and P₁ (insufficient and toxic levels, respectively) registering the lowest concentrations. Plants do not react by increasing these compounds when P levels increase. On the other hand, the optimal P level (P₃) enhanced the tolerance of compounds, which could elevating the plant tolerance as regards the lowest and toxic P treatments. Subsequently, an adequate P level enhances the presence of proline, betaine, and choline in green bean plants and consequently tolerance to stress.

Keywords:

• Drought tolerance
• nutrient stress
• osmoprotectors