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Rapid Crown Root Development Confers Tolerance to Zinc Deficiency in Rice.

Nanda AK, Wissuwa M - Front Plant Sci (2016)

Bottom Line: Zinc (Zn) deficiency is one of the leading nutrient disorders in rice (Oryza sativa).We therefore conclude that the rate of crown root initiation was differentially affected by Zn deficiency between genotypes.Rapid crown root development, following transplanting, was identified as a main causative trait for tolerance to Zn deficiency and better Zn retranslocation from shoot to root was a key attribute of Zn-efficient genotypes.

View Article: PubMed Central - PubMed

Affiliation: Crop, Livestock and Environment Division, Japan International Research Center for Agricultural Sciences Tsukuba, Japan.

ABSTRACT
Zinc (Zn) deficiency is one of the leading nutrient disorders in rice (Oryza sativa). Many studies have identified Zn-efficient rice genotypes, but causal mechanisms for Zn deficiency tolerance remain poorly understood. Here, we report a detailed study of the impact of Zn deficiency on crown root development of rice genotypes, differing in their tolerance to this stress. Zn deficiency delayed crown root development and plant biomass accumulation in both Zn-efficient and inefficient genotypes, with the effects being much stronger in the latter. Zn-efficient genotypes had developed new crown roots as early as 3 days after transplanting (DAT) to a Zn deficient field and that was followed by a significant increase in total biomass by 7 DAT. Zn-inefficient genotypes developed few new crown roots and did not increase biomass during the first 7 days following transplanting. This correlated with Zn-efficient genotypes retranslocating a higher proportion of shoot-Zn to their roots, compared to Zn-inefficient genotypes. These latter genotypes were furthermore not efficient in utilizing the limited Zn for root development. Histological analyses indicated no anomalies in crown tissue of Zn-efficient or inefficient genotypes that would have suggested crown root emergence was impeded. We therefore conclude that the rate of crown root initiation was differentially affected by Zn deficiency between genotypes. Rapid crown root development, following transplanting, was identified as a main causative trait for tolerance to Zn deficiency and better Zn retranslocation from shoot to root was a key attribute of Zn-efficient genotypes.

No MeSH data available.


Related in: MedlinePlus

Root number and root and shoot dry weight at 0 and 2 weeks after transfer (WAT) to nutrient solutions. Nipponbare, Zn-efficient (IR55179 and RIL46) and Zn-inefficient (IR26, IR64, IR74) genotypes were transferred to nutrient solution with (+Zn) and without (-Zn) Zn. Root number (A) and root and shoot dry weights (B) in nutrient solution without Zn. Root number (C) and root and shoot dry weights (D) in nutrient solution with 1.5 μM Zn. Statistical significant differences (p < 0.05) are indicated by different letters within each time point or for each tissue. Error bars represent SEM (n = 3 per genotype).
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Figure 2: Root number and root and shoot dry weight at 0 and 2 weeks after transfer (WAT) to nutrient solutions. Nipponbare, Zn-efficient (IR55179 and RIL46) and Zn-inefficient (IR26, IR64, IR74) genotypes were transferred to nutrient solution with (+Zn) and without (-Zn) Zn. Root number (A) and root and shoot dry weights (B) in nutrient solution without Zn. Root number (C) and root and shoot dry weights (D) in nutrient solution with 1.5 μM Zn. Statistical significant differences (p < 0.05) are indicated by different letters within each time point or for each tissue. Error bars represent SEM (n = 3 per genotype).

Mentions: To ascertain whether IR15579 and other Zn-efficient genotypes are Zn-efficient because they grow faster and start out bigger, when exposed to Zn deficiency, we selected seedlings with the same number of roots and leaves (11–12 roots and four leaves) at the beginning of the treatment (0 WAT). This selection resulted in plants with similar shoot and root dry weights before treatment and, therefore, a more relevant comparison of plant development between Zn-efficient and inefficient genotypes, in response to Zn deficiency (Supplementary Table S1). Moreover, to our knowledge, Nipponbare has never been reported to be either Zn-efficient or inefficient. Considering the available resources around Nipponbare and its wide use as reference genome, this knowledge could be of great interest to help uncover new candidate genes controlling Zn efficiency. Nipponbare was, therefore, included in this experiment. RIL46 and IR55179 were used as Zn-efficient and IR26, IR64, and IR74 were used as Zn-inefficient genotypes. In order to highlight differences between Zn-efficient and inefficient genotypes, in response to Zn-deficiency, data from individual genotypes was pooled into three groups: Zn-efficient, Zn-inefficient, and Nipponbare. However, data for individual genotypes can be found in the supplementary data (Supplementary Table S2). At 2 WAT to nutrient solution without Zn (–Zn), root number of Zn-efficient genotypes had increased by 112% (from 11.6 to 24.6), while Zn-inefficient genotypes only increased by 67% (from 11.4 to 19; Figure 2A). The increase in root number of Nipponbare was similar to the Zn-efficient genotypes (106%, from 11.3 to 23.2). Significant differences between genotypes were detected in root dry weight, but not in shoot dry weight (Figure 2B). Root biomass of Zn-inefficient genotypes had increased by 218% (from 5.43 to 17.3 mg) since 0 WAT, compared to 324% (from 4.72 to 20.1 mg) for Zn-efficient genotypes and 459% (from 4.71 to 26.3 mg) in Nipponbare (Supplementary Table S1 and Figure 2B).


Rapid Crown Root Development Confers Tolerance to Zinc Deficiency in Rice.

Nanda AK, Wissuwa M - Front Plant Sci (2016)

Root number and root and shoot dry weight at 0 and 2 weeks after transfer (WAT) to nutrient solutions. Nipponbare, Zn-efficient (IR55179 and RIL46) and Zn-inefficient (IR26, IR64, IR74) genotypes were transferred to nutrient solution with (+Zn) and without (-Zn) Zn. Root number (A) and root and shoot dry weights (B) in nutrient solution without Zn. Root number (C) and root and shoot dry weights (D) in nutrient solution with 1.5 μM Zn. Statistical significant differences (p < 0.05) are indicated by different letters within each time point or for each tissue. Error bars represent SEM (n = 3 per genotype).
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4815024&req=5

Figure 2: Root number and root and shoot dry weight at 0 and 2 weeks after transfer (WAT) to nutrient solutions. Nipponbare, Zn-efficient (IR55179 and RIL46) and Zn-inefficient (IR26, IR64, IR74) genotypes were transferred to nutrient solution with (+Zn) and without (-Zn) Zn. Root number (A) and root and shoot dry weights (B) in nutrient solution without Zn. Root number (C) and root and shoot dry weights (D) in nutrient solution with 1.5 μM Zn. Statistical significant differences (p < 0.05) are indicated by different letters within each time point or for each tissue. Error bars represent SEM (n = 3 per genotype).
Mentions: To ascertain whether IR15579 and other Zn-efficient genotypes are Zn-efficient because they grow faster and start out bigger, when exposed to Zn deficiency, we selected seedlings with the same number of roots and leaves (11–12 roots and four leaves) at the beginning of the treatment (0 WAT). This selection resulted in plants with similar shoot and root dry weights before treatment and, therefore, a more relevant comparison of plant development between Zn-efficient and inefficient genotypes, in response to Zn deficiency (Supplementary Table S1). Moreover, to our knowledge, Nipponbare has never been reported to be either Zn-efficient or inefficient. Considering the available resources around Nipponbare and its wide use as reference genome, this knowledge could be of great interest to help uncover new candidate genes controlling Zn efficiency. Nipponbare was, therefore, included in this experiment. RIL46 and IR55179 were used as Zn-efficient and IR26, IR64, and IR74 were used as Zn-inefficient genotypes. In order to highlight differences between Zn-efficient and inefficient genotypes, in response to Zn-deficiency, data from individual genotypes was pooled into three groups: Zn-efficient, Zn-inefficient, and Nipponbare. However, data for individual genotypes can be found in the supplementary data (Supplementary Table S2). At 2 WAT to nutrient solution without Zn (–Zn), root number of Zn-efficient genotypes had increased by 112% (from 11.6 to 24.6), while Zn-inefficient genotypes only increased by 67% (from 11.4 to 19; Figure 2A). The increase in root number of Nipponbare was similar to the Zn-efficient genotypes (106%, from 11.3 to 23.2). Significant differences between genotypes were detected in root dry weight, but not in shoot dry weight (Figure 2B). Root biomass of Zn-inefficient genotypes had increased by 218% (from 5.43 to 17.3 mg) since 0 WAT, compared to 324% (from 4.72 to 20.1 mg) for Zn-efficient genotypes and 459% (from 4.71 to 26.3 mg) in Nipponbare (Supplementary Table S1 and Figure 2B).

Bottom Line: Zinc (Zn) deficiency is one of the leading nutrient disorders in rice (Oryza sativa).We therefore conclude that the rate of crown root initiation was differentially affected by Zn deficiency between genotypes.Rapid crown root development, following transplanting, was identified as a main causative trait for tolerance to Zn deficiency and better Zn retranslocation from shoot to root was a key attribute of Zn-efficient genotypes.

View Article: PubMed Central - PubMed

Affiliation: Crop, Livestock and Environment Division, Japan International Research Center for Agricultural Sciences Tsukuba, Japan.

ABSTRACT
Zinc (Zn) deficiency is one of the leading nutrient disorders in rice (Oryza sativa). Many studies have identified Zn-efficient rice genotypes, but causal mechanisms for Zn deficiency tolerance remain poorly understood. Here, we report a detailed study of the impact of Zn deficiency on crown root development of rice genotypes, differing in their tolerance to this stress. Zn deficiency delayed crown root development and plant biomass accumulation in both Zn-efficient and inefficient genotypes, with the effects being much stronger in the latter. Zn-efficient genotypes had developed new crown roots as early as 3 days after transplanting (DAT) to a Zn deficient field and that was followed by a significant increase in total biomass by 7 DAT. Zn-inefficient genotypes developed few new crown roots and did not increase biomass during the first 7 days following transplanting. This correlated with Zn-efficient genotypes retranslocating a higher proportion of shoot-Zn to their roots, compared to Zn-inefficient genotypes. These latter genotypes were furthermore not efficient in utilizing the limited Zn for root development. Histological analyses indicated no anomalies in crown tissue of Zn-efficient or inefficient genotypes that would have suggested crown root emergence was impeded. We therefore conclude that the rate of crown root initiation was differentially affected by Zn deficiency between genotypes. Rapid crown root development, following transplanting, was identified as a main causative trait for tolerance to Zn deficiency and better Zn retranslocation from shoot to root was a key attribute of Zn-efficient genotypes.

No MeSH data available.


Related in: MedlinePlus