Contrasting hypoxia tolerance and adaptation in Malus species is linked to differences in stomatal behavior and photosynthesis

Abstract

We examined the potential differences in tolerance to hypoxia by two species of apple rootstocks. Stomatal behavior and photosynthesis were compared between Malus sieversii and Malus hupehensis. Plants were hydroponically grown for 15 days in normoxic or hypoxic nutrient solutions. Those of M. sieversii showed much greater sensitivity, with exposure to hypoxia resulting in higher leaf concentrations of abscisic acid (ABA) that prompted stomatal closure. Compared with the control plants of that species, stomatal density was greater in both new and mature leaves under stress conditions. In contrast, stomatal density was significantly decreased in leaves from M. hupehensis, while stomatal length was unaffected. Under stress, the net photosynthetic rate, stomatal conductance and chlorophyll contents were markedly reduced in M. sieversii. The relatively hypoxia-tolerant genotype M. hupehensis, however, showed only minor changes in net photosynthesis or chlorophyll content, and only a slight decrease in stomatal conductance due to such treatment. Therefore, we conclude that the more tolerant M. hupehensis utilizes a better protective mechanism for retaining higher photosynthetic capacity than does the hypoxia-sensitive M. sieversii. Moreover, this contrast in tolerance and adaptation to stress is linked to differences in their stomatal behavior, photosynthetic capacity and possibly their patterns of native distribution.

Impact of post-infiltration soil aeration at different growth stages of sub-surface trickle-irrigated tomato plants

“…The ABA which leads to stomatal closure is intensely studied, there was a positive correlation between ABA and stomatal resistance (Bai et al, 2013;Comstock, 2002;Loverys et al, 1987). Plant root zone aeration led to the reduction of ABA in their leaves, and the reduction of ABA can directly promote the photosynthetic rate, so the leaf area index increased.…”

Plant water stress: Associations between ethylene and abscisic acid response

“…In leaf gas exchange, the most common effect of flooding stress is a reduction in leaf transpiration and stomatal closure (Blanke and Cooke, 2004;Yetisir et al, 2006;Atkinson et al, 2008;Bai et al, 2013). In avocado trees (Persea americana Mill.…”

Effects of transient soil waterlogging and its importance for rootstock selection

“…Since an oxygen decrease is one of the first effects of soil waterlogging, most published studies have evaluated the effect of hypoxia and anoxia on plants, either via hydroponic trials or using inert substrates (Morard and Silvestre, 1996;Striker, 2008;Arbona et al, 2009;Bai et al, 2013), but few studies have included the soil as a factor in their analyses. The absence of molecular oxygen triggers a sequence of changes in the physical-chemical properties of the soil.…”