Asymmetrical leaves induced by water deficit show asymmetric photosynthesis in common bean

Abstract

In this study we tested the hypothesis that leaf asymmetric growth induced by water deficit in common bean (Phaseolus vulgaris L.) might be correlated with different net photosynthesis rates between the two opposed leaflets (right and left) considering a bilateral symmetric plane. In order to induce developmental instability, the drought-sensitive common bean genotype "Jalo Precoce" was subjected to periods of suspended irrigation during its vegetative growth. Developmental instability was evaluated by measurements of leaflets asymmetry, and the effects of drought on gas exchanges were taken in both symmetrical leaflets (right and left) in relation to the central leaflet. Water deficit induced an increase of 80 % in leaf asymmetry. Net photosynthesis of P. vulgaris was affected by water deficit in two ways, reducing its physiological yield and increasing its variability between leaflets. Thus, as we hypothesized, the increase in developmental instability, measured by leaf symmetry deviations, was supported by a variable net photosynthesis distribution in the leaves induced by drought.

Fluorescência da clorofila-a e variação da simetria como ferramentas de investigação de plantas sob estresse

“…Flutuações na simetria também foram relatadas por Freeman et al (1993) estudando a alga marrom Fucus furcatus latifrons sob diferentes níveis de poluição, Souza et. al.…”

“…al. (2005) em folhas de Phaseolus vulgaris sob déficit hídrico, e Daloso et al (2009) em folhas de Rapanea ferruginea sob UV-C. Souza et. al.…”

Pulse productivity : physiological constraints /

“…Net photosynthetic rate, transpiration rate, stomatal conductance and water-use efficiency are reported to be 15.72 ^umol m 2 sec1, 5.08 mmol m2 sec1 and 3.09 /xmol C02 mol'1 H20, respectively. Under water deficit condition photosynthetic rate and transpiration decreases significantly, while water-use efficiency increases (Souza et al, 2005).…”

The ecological context of bilateral symmetry of organ and organisms

“…Studies involving FA in response to stress has been investigated in a wide range of organisms with bilateral structure. The stress has been reported as a disturbing source capable to induce qualitative and quantitative changes in the symmetry of organs or bodies with bilateral structure, such as reported in birds [13], mammals [14,15], fish [16], insects [17,18], human [19][20][21], and plants [22][23][24][25][26][27]. Thus, FA has been used as a marker of the biologic quality of individuals [19] as well as an ecological indicator to identify environmental stress [12].…”