Abstract
Two citrus rootstocks, Rangpur lime (RL) and Sunki Maravilha mandarin (SM), were analyzed either ungrafted or grafted with their reciprocal graft combinations or with shoot scions of two commercial citrus varieties: Valencia orange (VO) and Tahiti acid lime (TAL). All graft combinations were subjected to distinct watering regimes: well-watered, severe drought and rehydration. Growth and water relation parameters, gas exchange as well as sugar and hormone profiles were determined. Data indicated that RL adopted a dehydration avoidance strategy and maintained growth, whereas SM adopted a dehydration tolerance strategy focused on plant survival. Compared with RL, the leaves and roots of SM exhibited higher concentrations of abscisic acid and salicylic acid, which induced drought tolerance, and accumulation of carbohydrates such as trehalose and raffinose, which are important reactive oxygen species scavengers. SM rootstocks were able to transfer their survival strategy to the grafted shoot scions (RL, VO, TAL). Because of their contrasting survival strategies, RL reached the permanent wilting point more quickly than SM whereas SM recovered from prolonged droughts more efficiently than RL. This is one of the most complete studies of drought tolerance mechanisms in citrus crops and is the first to use reciprocal grafting to clarify scion/rootstock interactions.
Highlights
Two citrus rootstocks, Rangpur lime (RL) and Sunki Maravilha mandarin (SM), were analyzed either ungrafted or grafted with their reciprocal graft combinations or with shoot scions of two commercial citrus varieties: Valencia orange (VO) and Tahiti acid lime (TAL)
In the present work, marked changes in leaf water potential, leaf osmotic potential, gas exchange, hormone and carbohydrate profiles were triggered by drought in distinct scion/rootstock combinations in citrus plants
The reciprocal graft combinations (SM/RL and RL/SM), as well as two commercial scions were used–Valencia orange (VO) and Tahiti acid lime (TAL)–which were grafted onto SM and RL rootstocks, were used to further investigate scion/rootstock interactions
Summary
Rangpur lime (RL) and Sunki Maravilha mandarin (SM), were analyzed either ungrafted or grafted with their reciprocal graft combinations or with shoot scions of two commercial citrus varieties: Valencia orange (VO) and Tahiti acid lime (TAL). SAA results from plant physiological responses that may include changes at the transcriptional, proteomic and post-transcriptional modification levels, as well as metabolic changes and/or metabolite accumulation[16] These responses to abiotic stresses comprise, for instance, hormonal changes[17,18,19,20] or the accumulation of solutes such as aminoacids and carbohydrates[16,21,22]. Depending on their intrinsic characteristics, plants may adopt different strategies to cope with drought periods.
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