Journal of Genetics and Genomics

New insights into plant nutrient signaling and adaptation to fluctuating environments

Xiangdong Fu

2016, 43(11): 621-622. doi: 10.1016/j.jgg.2016.11.004

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Sulfur metabolism and its manipulation in crops

Anna Koprivova, Stanislav Kopriva

2016, 43(11): 623-629. doi: 10.1016/j.jgg.2016.07.001

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Organic acid anions: An effective defensive weapon for plants against aluminum toxicity and phosphorus deficiency in acidic soils

Zhi Chang Chen, Hong Liao

2016, 43(11): 631-638. doi: 10.1016/j.jgg.2016.11.003

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Aluminum (Al) toxicity and phosphorous (P) deficiency are two major limiting factors for plant growth on acidic soils. Thus, the physiological mechanisms for Al tolerance and P acquisition have been intensively studied. A commonly observed trait is that plants have developed the ability to utilize organic acid anions (OAs; mainly malate, citrate and oxalate) to combat Al toxicity and P deficiency. OAs secreted by roots into the rhizosphere can externally chelate Al³⁺ and mobilize phosphate (Pi), while OAs synthesized in the cell can internally sequester Al³⁺ into the vacuole and release free Pi for metabolism. Molecular mechanisms involved in OA synthesis and transport have been described in detail. Ensuing genetic improvement for Al tolerance and P efficiency through increased OA exudation and/or synthesis in crops has been achieved by transgenic and marker-assisted breeding. This review mainly elucidates the crucial roles of OAs in plant Al tolerance and P efficiency through summarizing associated physiological mechanisms, molecular traits and genetic manipulation of crops.

The OsAMT1.1 gene functions in ammonium uptake and ammonium–potassium homeostasis over low and high ammonium concentration ranges

Chang Li, Zhong Tang, Jia Wei, Hongye Qu, Yanjie Xie, Guohua Xu

2016, 43(11): 639-649. doi: 10.1016/j.jgg.2016.11.001

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Rice (Oryza sativa) grown in paddy fields is an ammonium (NH₄⁺)-preferring crop; however, its AMT-type NH₄⁺ transporters that mediate root N acquisition have not been well characterized yet. In this study, we analyzed the expression pattern and physiological function of the OsAMT1.1 gene of the AMT1 subfamily in rice. OsAMT1.1 is located in the plasma membrane and is mainly expressed in the root epidermis, stele and mesophyll cells. Disruption of the OsAMT1.1 gene decreased the uptake of NH₄⁺, and the growth of roots and shoots under both low NH₄⁺ and high NH₄⁺ conditions. OsAMT1.1 contributed to the short-term (5 min) ¹⁵NH₄⁺ influx rate by approximately one-quarter, irrespective of the NH₄⁺ concentration. Knockout of OsAMT1.1 significantly decreased the total N transport from roots to shoots under low NH₄⁺ conditions. Moreover, compared with the wild type, the osamt1.1 mutant showed an increase in the potassium (K) absorption rate under high NH₄⁺ conditions and a decrease under low NH₄⁺ conditions. The mutants contained a significantly high concentration of K in both the roots and shoots at a limited K (0.1 mmol/L) supply when NH₄⁺ was replete. Taken together, the results indicated that OsAMT1.1 significantly contributes to the NH₄⁺ uptake under both low and high NH₄⁺ conditions and plays an important role in N–K homeostasis in rice.

Identification of microRNAs in rice root in response to nitrate and ammonium

Hua Li, Bin Hu, Wei Wang, Zhihua Zhang, Yan Liang, Xiaokai Gao, Peng Li, Yongqiang Liu, Lianhe Zhang, Chengcai Chu

2016, 43(11): 651-661. doi: 10.1016/j.jgg.2015.12.002

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Nitrate and ammonium are two major nitrogen (N) sources for higher plants, but they differ in utilization and signaling. MicroRNAs (miRNAs) play an essential role in N signal transduction; however, knowledge remains limited about the regulatory role of miRNAs responsive to different N sources, especially in crop plants. To get global overview on miRNAs involved in N response in rice, we performed high-throughput small RNA-sequencing under different nitrate and ammonium treatments. The results demonstrated that only 16 and 11 miRNAs were significantly induced by nitrate and ammonium under short-term treatment, respectively. However, 60 differentially expressed miRNAs were found between nitrate and ammonium under long-term cultivation. These results suggested that miRNA response greatly differentiates between nitrate and ammonium treatments. Furthermore, 44 miRNAs were found to be differentially expressed between high- and low-N conditions. Our study reveals comprehensive expression profiling of miRNAs responsive to different N sources and different N treatments, which advances our understanding on the regulation of different N signaling and homeostasis mediated by miRNAs.

Enhancing phosphorus uptake efficiency through QTL-based selection for root system architecture in maize

Riliang Gu, Fanjun Chen, Lizhi Long, Hongguang Cai, Zhigang Liu, Jiabo Yang, Lifeng Wang, Huiyong Li, Junhui Li, Wenxin Liu, Guohua Mi, Fusuo Zhang, Lixing Yuan

2016, 43(11): 663-672. doi: 10.1016/j.jgg.2016.11.002

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Root system architecture (RSA) plays an important role in phosphorus (P) acquisition, but enhancing P use efficiency (PUE) in maize via genetic manipulation of RSA has not yet been reported. Here, using a maize recombinant inbred line (RIL) population, we investigated the genetic relationships between PUE and RSA, and developed P-efficient lines by selection of quantitative trait loci (QTLs) that coincide for both traits. In low-P (LP) fields, P uptake efficiency (PupE) was more closely correlated with PUE (r = 0.48–0.54), and RSA in hydroponics was significantly related to PupE (r = 0.25–0.30) but not to P utilization efficiency (PutE). QTL analysis detected a chromosome region where two QTLs for PUE, three for PupE and three for RSA were assigned into two QTL clusters, Cl-bin3.04a and Cl-bin3.04b. These QTLs had favorable effects from alleles derived from the large-rooted and high-PupE parent. Marker-assisted selection (MAS) identified nine advanced backcross-derived lines carrying Cl-bin3.04a or Cl-bin3.04b that displayed mean increases of 22%–26% in PUE in LP fields. Furthermore, a line L224 pyramiding Cl-bin3.04a and Cl-bin3.04b showed enhanced PupE, relying mainly on changes in root morphology, rather than root physiology, under both hydroponic and field conditions. These results highlight the physiological and genetic contributions of RSA to maize PupE, and provide a successful study case of developing P-efficient crops through QTL-based selection.

Overexpression of OsSPL9 enhances accumulation of Cu in rice grain and improves its digestibility and metabolism

Mingfeng Tang, Chuanshe Zhou, Lu Meng, Donghai Mao, Can Peng, Yuxing Zhu, Daoyou Huang, Zhiliang Tan, Caiyan Chen, Chengbing Liu, Dechun Zhang

2016, 43(11): 673-676. doi: 10.1016/j.jgg.2016.09.004

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2016 Vol. 43, No. 11