Genotypic Variation in Root Growth Angle in Rice (Oryza sativa L.) and its Association with Deep Root Development in Upland Fields with Different Water Regimes

Background: Inoculation with Gluconacetobacter diazotrophicus has shown to influence root development in red rice plants, and more recently, the induced systemic tolerance (IST) response to drought was also demonstrated. The goal of this study was to evaluate the inoculation effect of G. diazotrophicus strain Pal5 on the amelioration of drought stress and root development in red rice (Oryza sativa L.). Methods: The experimental treatments consist of red rice plants inoculated with and without strain Pal5 in presence and absence of water restriction. Physiological, biochemical, and molecular analyses of plant roots were carried out, along with measurements of growth and biochemical components. Results: The plants showed a positive response to the bacterial inoculation, with root growth promotion and induction of tolerance to drought. An increase in the root area and higher levels of osmoprotectant solutes were observed in roots. Bacterial inoculation increased the drought tolerance and positively regulated certain root development genes against the water deficit in plants. Conclusion: G. diazotrophicus Pal5 strain inoculation favored red rice plants by promoting various root growth and developmental mechanisms against drought stress, enabling root development and improving biochemical composition.

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Genetic Relationship and Structural Variation of Root Growth Angle for Deep Rooting in Rice (Oryza sativa L.)

Current Journal of Applied Science and Technology ◽

10.9734/cjast/2020/v39i2930960 ◽

2020 ◽

pp. 79-90

Author(s):

R. Arulmozhi ◽

A. John Joel ◽

K. Sathiya Bama ◽

P. Boominathan ◽

R. Suresh

Keyword(s):

Drought Stress ◽

Drought Tolerance ◽

Root Growth ◽

Oryza Sativa L ◽

Association Studies ◽

Strong Association ◽

Root Traits ◽

Dry Weight ◽

Growth Angle ◽

Root Growth Angle

Breeding for drought tolerance revolves around selection of genotypes with desirable root characters. Root pattern studies in rice have shown significant relationship with drought tolerance. In order to understand the effects of deep rooting pattern and root growth angle in relation to water stress was assessed following basket method. The Backcross inbred lines (BILs) of ADT (R) 45*1/Apo and ADT (R) 45*1/Wayrarem with drought QTLs viz., qDTY1.1, qDTY3.1, qDTY4.1 and qDTY12.1 were evaluated for various root traits. Out of 20 BILs and three parental lines studied four BILs showed high values for root growth at deep angle 65-90 °and yield under drought stress. Based on association studies among the root traits positive and significant correlation was observed between yield and root traits viz., root dry weight, root growth at deep angle 65-90° (RA4), ratio of deep rooting and root length. Clustering of BILs and parents have grouped deep rooting BILs and drought tolerant donors into one cluster and drought susceptible ADT (R) 45 into a separate cluster II which clearly indicates, the importance of deep rooting and yield under drought stress. Strong association of root traits and drought tolerance clearly shows the importance in utilization of these traits as selection criteria for drought tolerance in rice.

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Water uptake dynamics under progressive drought stress in diverse accessions of the OryzaSNP panel of rice (Oryza sativa)

Functional Plant Biology ◽

10.1071/fp12015 ◽

2012 ◽

Vol 39 (5) ◽

pp. 402 ◽

Cited By ~ 28

Author(s):

Veeresh R. P. Gowda ◽

Amelia Henry ◽

Vincent Vadez ◽

H. E. Shashidhar ◽

Rachid Serraj

Keyword(s):

Oryza Sativa ◽

Drought Stress ◽

Root Growth ◽

Water Uptake ◽

Root Length Density ◽

Oryza Sativa L ◽

Root Water Uptake ◽

Snp Markers ◽

Drought Response ◽

Genotypic Differences

In addition to characterising root architecture, evaluating root water uptake ability is important for understanding drought response. A series of three lysimeter studies were conducted using the OryzaSNP panel, which consists of 20 diverse rice (Oryza sativa L.) genotypes. Large genotypic differences in drought response were observed in this genotype panel in terms of plant growth and water uptake. Total water uptake and daily water uptake rates in the drought-stress treatment were correlated with root length density, especially at depths below 30 cm. Patterns of water uptake among genotypes remained consistent throughout the stress treatments: genotypes that initially extracted more water were the same genotypes that extracted more water at the end of the study. These results suggest that response to drought by deep root growth, rather than a conservative soil water pattern, seems to be important for lowland rice. Genotypes in the O. sativa type aus group showed some of the greatest water uptake and root growth values. Since the OryzaSNP panel has been genotyped in detail with SNP markers, we expect that these results will be useful for understanding the genetics of rice root growth and function for water uptake in response to drought.

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