Potential involvement of drought-induced Ran GTPase CLRan1 in root growth enhancement in a xerophyte wild watermelon

Abstract

Enhanced root growth is known as the survival strategy of plants under drought. Previous proteome analysis in drought-resistant wild watermelon has shown that Ran GTPase, an essential regulator of cell division and proliferation, was induced in the roots under drought. In this study, two cDNAs were isolated from wild watermelon, CLRan1 and CLRan2, which showed a high degree of structural similarity with those of other plant Ran GTPases. Quantitative RT-PCR and promoter-GUS assays suggested that CLRan1 was expressed mainly in the root apex and lateral root primordia, whereas CLRan2 was more broadly expressed in other part of the roots. Immunoblotting analysis confirmed that the abundance of CLRan proteins was elevated in the root apex region under drought stress. Transgenic Arabidopsis overexpressing CLRan1 showed enhanced primary root growth, and the growth was maintained under osmotic stress, indicating that CLRan1 functions as a positive factor for maintaining root growth under stress conditions.

Citron Watermelon Potential to Improve Crop Diversification and Reduce Negative Impacts of Climate Change

“…Plant phenology has a decisive effect on yield under water stress conditions. Early maturity in wild watermelon [32] was found to be correlated with root length density to leaf area ratio, which translates to the plant's ability to maintain high leaf water potential under soil moisture stress. Plants that escape drought, such as the desert ephemeral (Alyssum alyssoides), exhibit early flowering, short plant life cycle, and developmental plasticity [72].…”

“…included change in gene expression [13][14][15][16][17][18][19][20][21][22][23] and accumulation of osmolytes (citrulline, glutamate, arginine) in leaves and roots [24][25][26][27][28][29][30][31]. Drought avoidance studies include reduced leaf water loss [32][33][34][35], enhanced water uptake [36][37][38][39] and accelerated transition from vegetative growth to reproductive growth to avoid complete abortion at the severe drought stress stage [35,40]…”

Quantitative proteome and PTMome analysis ofArabidopsis thalianaroot responses to persistent osmotic and salinity stress

“…Moreover, Ran facilitates mitotic spindle assembly by promoting the release of spindle assembly factors from importin complexes in the nucleus (Carazo-Salas et al, 1999). The role of Ran in mitotic spindle assembly has been proposed as an important role in root growth during drought stress (Akashi et al, 2016), and to intersect with ABA response and drought tolerance (Luo et al, 2013). In particular, both AtRAN1 and AtRAN3 are known to be induced by salt treatment, with ran1/ran3 double mutants showing higher sensitivity to salt treatment, displaying significantly reduced root growth after being treated for 5 days with 100 mM NaCl (Xu et al, 2016).…”

Identification of promoter for adventitious root-specific gene expression from sweet potato

“…5B). Akashi et al (2016) isolated a Ran GTPase1 (CLRan1) gene from wild watermelon (Citrullus lanatus). The expression of CLRan1 was in the apex region of roots.…”

“…The expression of CLRan1 was in the apex region of roots. Interestingly, transgenic Arabidopsis plants that overexpressed CLRan1 showed enhanced root growth (Akashi et al 2016), suggesting that CLRan1 could have a potential to increase sink potential. Transcriptional regulation of endogenous genes and the precise control of transgene expression are major challenges in plant biotechnology (Liu et al 2013).…”