Biochemical indicators of drought tolerance in the common bean (Phaseolus vulgaris L.)

Abstract

The common bean (Phaseolus vulgaris L.) is an important crop that is often planted in areas that suffer from low water availability, leading to significant reductions in productivity. The breeding of genotypes better able to tolerate such conditions requires the efficient incorporation of resources present in germplasm banks. To this end, we investigated the responses of thirty bean genotypes to intermittent drought stress, with the aim of identifying biochemical markers for drought tolerance. The genotypes analyzed presented significant variability in both productivity and levels of soluble sugars, starch and amino acids under both irrigated and drought conditions. Moreover, we observed changes in the levels of these components under drought stress, providing information on the responses of the bean plants to this condition. Correlation analysis indicated a lack of relationship between components of the stem and productivity. On the other hand, levels of several components of the grain, including starch, total soluble sugars and amino acids were strongly positively correlated with productivity under drought and irrigated conditions, making these components potentially useful biochemical markers for the selection of genotypes for breeding programs. Principal components analysis also indicated the presence of a relationship between biochemical composition and productivity, but reinforced the fact that multiple mechanisms are responsible for explaining the differences in productivity between tolerant and susceptible genotypes.

Effects of Drought and Elevated Atmospheric Carbon Dioxide on Seed Nutrition and 15N and 13C Natural Abundance Isotopes in Soybean Under Controlled Environments

“…The effects of climate changes on yield were previously reported [1], and it was shown that severe drought stress can lead to crop losses of up to 90% [10][11][12]. While there has been considerable progress in understanding the sensitivities of crop yield to climate change, evaluation of climate change factors such as CO 2 , elevated temperature, or drought on seed nutrition remains rather limited [13].…”

“…The mechanisms of involvement of these sugars in drought tolerance are still not fully understood [19][20][21]. The accumulation of proline, amino acids, and organic acid such as malic acid, fumaric acid, and citric acid is also a common biochemical indicator occurring at high level under drought stress [12]. The accumulation of these compounds is a part of the mechanism of osmotic adjustment to maintain water potential gradient under drought conditions and to protect subcellular structure from the damaging effects of drought stress [22].…”

“…The accumulation of these compounds is a part of the mechanism of osmotic adjustment to maintain water potential gradient under drought conditions and to protect subcellular structure from the damaging effects of drought stress [22]. The high level of proline accumulation under drought stress was previously identified as a mechanism for the protection of cytosolic proteins and organelles [12]. Therefore, these biochemical compounds are important to understand the relationship between drought stress and drought tolerance and for decision-making when breeding for drought tolerance [23].…”

“…Therefore, these biochemical compounds are important to understand the relationship between drought stress and drought tolerance and for decision-making when breeding for drought tolerance [23]. Since drought stress results in limiting the growth and development of the plant and consequently the supply of the photosynthate to grain during grain filling [24], the chemical composition of the grain and its quality can be affected by drought stress [12,25]. The effect of drought on seed quality could be due to the decrease of total soluble sugars especially in the grain under drought stress due to decreases in the levels of sucrose, stachyose, and verbascose.…”

“…Sucrose plays an important role in the development of the grain and is sensitive to drought stress and involved in the synthesis of raffinose oligosaccharides including stachyose and verbascose, and these sugars play an important role in seed tolerance to desiccation and against oxidative effects of drought stress [18,26]. Some sugars, for example, maltose, accumulate in the grain under drought stress, maybe due to starch degradation [12]. For example, during the remobilization phase, starch remobilized was significantly lower under drought stress, but the total amounts of soluble sugars and amino acids remobilized were greater [12], contrasting previous studies that showed higher carbohydrate accumulation under drought stress [27].…”