Short term salt treatment does not affect pistachio growth
Next, we examined the roots and shoots of salt treated plants for
developmental changes. It is known that UCB1 plants show more robust
growth, potentially as a result of hybrid vigor. Hence, in order to
avoid size effects on salinity tolerance and sequestration, we used 8
weeks old UCB1 plants and 10 weeks old P. integerrima plants for
all our assays. At these ages, the two genotypes have a virtually
identical fresh weight (Fig. 2a, NS, two-way ANOVA) After one week of
salt treatment, neither P. integerrima nor UCB1 showed
significant decreases in root or shoot growth (Fig. 2a, NS, two-way
ANOVA, Suppl. Fig 1a).
Since root system architecture remodeling is known to occur as a result
of salinity stress (Koevoets et al., 2016), we assessed the root
architecture and root weight of the treated plants. Although the root
weight of UCB1 and P. integerrima were comparable (Fig. 2a), the
UCB1 plants had more lateral roots compared to P. integerrima,and this difference was further enhanced after salt treatment (Fig. 2b,
P<0.05 between genotypes, P<0.01 between treatment,
two-way ANOVA, P=0.01 Tukey’s HSD). No significant difference in lateral
root lengths between the two genotypes was observed (Supp. Fig. 1b, NS,
two-way ANOVA). In Arabidopsis accession Columbia-0, low concentrations
of salt have been shown to induce more lateral root initiation, possibly
due to an enhanced cell cycle activity and cell elongation through
increased Na+ vacuolar sequestration (Julkowska et
al., 2014). Our results show that similar responses are occurring inPistacia spp. after short term salt treatment.