Root attributes affecting water uptake of rice (Oryza sativa) under drought

Abstract

Lowland rice roots have a unique physiological response to drought because of their adaptation to flooded soil. Rice root attributes that facilitate growth under flooded conditions may affect rice response to drought, but the relative roles of root structural and functional characteristics for water uptake under drought in rice are not known. Morphological, anatomical, biochemical, and molecular attributes of soil-grown rice roots were measured to investigate the genotypic variability and genotype×environment interactions of water uptake under variable soil water regimes. Drought-resistant genotypes had the lowest night-time bleeding rates of sap from the root system in the field. Diurnal fluctuation predominated as the strongest source of variation for bleeding rates in the field and root hydraulic conductivity ( Lp r ) in the greenhouse, and was related to expression trends of various PIP and TIP aquaporins. Root anatomy was generally more responsive to drought treatments in drought-resistant genotypes. Suberization and compaction of sclerenchyma layer cells decreased under drought, whereas suberization of the endodermis increased, suggesting differential roles of these two cell layers for the retention of oxygen under flooded conditions (sclerenchyma layer) and retention of water under drought (endodermis). The results of this study point to the genetic variability in responsiveness to drought of rice roots in terms of morphology, anatomy, and function.

Does Morphological and Anatomical Plasticity during the Vegetative Stage Make Wheat More Tolerant of Water Deficit Stress Than Rice?

“…6). A similar increase in SD:RD under water deficit stress was identified previously in rice (Henry et al, 2012). The above response demonstrates the attempt of rice to reduce radial distance under water deficit stress by decreasing cortex width (i.e.…”

“…To make a meaningful comparison between rice and wheat, the nodal root was investigated in our study. Across both rice and wheat cultivars, three replicate root sections (2-3 cm) were collected from three different positions along the nodal root for root anatomy study: (1) near the RSJ; (2) approximately 15 cm from the RA from water deficit-stressed samples and approximately 10 cm from the RA on control samples, following Henry et al (2012); and (3) at 6 cm from the RA in both treatments (Fig. 3A).…”

“…But the underlying mechanisms differing across diverse germplasm that influence water uptake under water deficit stress are not fully understood . A recent report has documented water deficit-tolerant genotypes recording a lower bleeding rate and narrow xylem diameter under stress (Henry et al, 2012). Contrastingly, a higher root hydraulic conductivity helped to maintain a higher photosynthetic rate (Adachi et al, 2010), with tolerant cultivars maintaining greater root hydraulic conductivity than susceptible cultivars (Matsuo et al, 2009).…”

Comparing Phenotypic Variation of Root Traits in Thai Rice (Oryza Sativa L.) Across Growing Systems

“…Similar trends were found in root systems of other monocots such as the Zea species (Burton et al, 2013). Anatomical variation related to differences in performance and stress response in many crop species, including maize (Saengwilai et al, 2014a), common bean (Peña-Valdivia et al, 2010) and rice (Henry et al, 2012). Variation in the number and diameter of xylem vessels is known to strongly affect axial water conductance and potentially enhance water use efficiency under terminal drought (Lynch et al, 2014).…”

Development of High-Yielding Rice Varieties Suitable for Swampy Lands in Indonesia

“…Physiological and agronomic traits related to tolerance to various abiotic stresses that may affect rice crops in swampy areas have been previously investigated (Sahrawat 2005;Castillo et al 2007;Singh et al 2009;Henry et al 2012;Kato et al 2014). Likewise, quantitative traits loci and genes for tolerance to various abiotic stresses, including drought, salinity, submergence during vegetative stage, submergence during germination, stagnant flooding and iron toxicity have been identified and used in molecular breeding programs Thomson et al 2010;Iftekharuddaula et al 2011;Septiningsih et al 2012;Septiningsih et al 2013b;Baltazar et al 2014;Dixit et al 2014;Kretzschmar et al 2015;Toledo et al 2015;Gonzaga et al 2016;Iftekharuddaula et al 2016a;Singh et al 2016).…”