Influence of Exogenous Glycine Betaine and Abscisic Acid on Papaya in Responses to Water-deficit Stress |
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Authors: | Jalel Mahouachi Rosa Argamasilla Aurelio Gómez-Cadenas |
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Affiliation: | (1) Departamento de Suelos y Riegos, Instituto Canario de Investigaciones Agrarias, Apdo. 60, 38200 La Laguna, Santa Cruz de Tenerife, Spain;(2) Departament de Ci?ncies Agr?ries i del Medi Natural, Universitat Jaume I, Campus Riu Sec, 12071 Castell? de la Plana, Spain |
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Abstract: | The effects of exogenous foliar glycine betaine (GB) and abscisic acid (ABA) on papaya responses to water stress were investigated
under distinct water regimes. Papaya seedlings (Carica papaya L. cultivar “BH-65”) were pretreated with GB or ABA and subsequently subjected to consecutive periods of drought, rehydration,
and a second period of drought conditions. Results indicated that water stress induced ABA, jasmonic acid (JA), and proline
accumulation but did not modify malondialdehyde (MDA) concentration. In addition, water deprivation reduced photosynthetic
rate, stomatal conductance, relative water content (RWC), leaf fresh weight, and increased leaf abscission. GB applied prior
to drought imposition decreased the impact of water stress on ABA, JA, proline accumulation, leaf water status, growth, and
photosynthetic performance. However, ABA-pretreated plants did not show alteration of most of these parameters under water
stress conditions when compared with non-pretreated plants except a clear induction of JA accumulation. Taken together, the
data suggest that GB may modulate ABA, JA, and proline accumulation through the control of stomatal movement and the high
availability of compatible solutes, leading to improvement of leaf water status, growth, and photosynthetic machinery function.
In contrast, exogenous ABA did not stimulate papaya physiological responses under drought, but interestingly ABA in combination
with drought could induce progressive JA synthesis, unlike drought alone, which induces a transitory JA increase and may trigger
endogenous ABA accumulation. The data also suggest that irrespective of the pretreatments, papaya did not suffer oxidative
damage. |
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