MECHANISM OF LOW-K TOLERANCE IN MODEL PLANTS AND CROPS

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: TERMINATED
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 1007818
• Project No.: CA-B-PLB-0156-H
• Project Start Date: Oct 1, 2015
• Project End Date: Sep 30, 2020

Project Director
Luan, S.

Recipient Organization
UNIVERSITY OF CALIFORNIA, BERKELEY
(N/A)
BERKELEY,CA 94720

Performing Department
Plant Biology, Berkeley

Non Technical Summary
Water and mineral nutrients are the major limiting factors for crop production, making irrigation and fertilizers a necessity for modern agriculture. With limited supplies of fresh water and energy resources, sustainability of agricultural practices directly depends on higher use efficiency of water and nutrients. Although extensive research effort has been directed toward understanding water use efficiency and drought tolerance, much less is known about the mechanisms of plant nutrient use efficiency and tolerance to low-nutrient status in the soil. Compared with N and P, the K+ nutrient is unique in that it functions in its ionic form and cannot be metabolized in plant cells. It is expected that mechanisms of K-use efficiency will be different from those controlling N and P nutrition. Our study will thus bridge a critical gap in our understanding of nutrient use efficiency. In this project, we will combine genomics, biochemistry and transformation, together with genetic analysis to identify genes controlling K-use efficiency in Arabidopsis and rice, a staple food crop and a cereal model. Further, these genes will be assembled into a functional network that illustrates how the gene products control the cellular processes related to low-K tolerance and K-use efficiency in rice. Results from this project will directly enhance our understanding of basic plant biology questions in membrane transport and mechanisms for environmental response and adaptation. This knowledge will also be applicable to other cereal crops in new practical approaches to modify plant growth under low-K conditions and improve crop yield with reduced use of fertilizers.

Animal Health Component

0%

Research Effort Categories

Basic

80%

Applied

20%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
206	2499	1030	100%

Knowledge Area
206 - Basic Plant Biology;

Subject Of Investigation
2499 - Plant research, general;

Field Of Science
1030 - Cellular biology;

Keywords

membrane transport

mineral nutrition

arabidopsis

rice

potassium

signal transduction

Goals / Objectives
In this project, we will combine genomics, biochemistry and transformation, together with the genetics in model plants to identify genes controlling K-use efficiency in Arabidopsis and rice, a staple food crop and a cereal model. Further, these genes will be assembled into a functional network that illustrates how the gene products control the cellular processes related to low-K tolerance and K-use efficiency in model and crop plants. Results from this project will directly enhance our understanding of basic plant biology questions in membrane transport and mechanisms for environmental response and adaptation. This knowledge will also be applicable to other cereal crops in new practical approaches to modify plant growth under low-K conditions and improve crop yield with reduced use of fertilizers.

Project Methods
1) Determination of gene expression pattern using Q-RT-PCR and GUS reporter in transgenic plants. 2) Analyzing protein localization in the cell using GFP fusion in transient assays and transgenic plants with microscopy. 3) Functional analysis of genes using genetic mutants and phenotypic analysis by examining various physiological processes in plants including arabidopsis and rice. 4) Determining gene loci responsible for phenotypes using QTL mapping and gene sequencing-based genome-wide association studies. 5) Determining protein-protein relationship by analysis of protein-protein interactions in yeast two hybrid and co-IP assays.

Progress 10/01/15 to 09/30/20

Outputs
Target Audience:Other scientists in the field Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?We trained one graduate student and several postdocs and undergraduate students when performing the project. How have the results been disseminated to communities of interest?Through publications. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? We discovered two pathways consisting of calcium sensors (CBLs) and their interacting kinases (CIPKs) that regulate trnasport proteins in the plasma membrane and vacuolar membrane to control ionic transport and homeostasis.

Publications

• Type: Journal Articles Status: Published Year Published: 2020 Citation: Tang RJ, Wang C, Li K, Luan S. The CBL-CIPK Calcium Signaling Network: Unified Paradigm from 20 Years of Discoveries. Trends Plant Sci. 2020 Jun;25(6):604-617. doi: 10.1016/j.tplants.2020.01.009. Epub 2020 Mar 19. PMID: 32407699.
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Tang RJ, Luan M, Wang C, Lhamo D, Yang Y, Zhao FG, Lan WZ, Fu AG, Luan S. Plant Membrane Transport Research in the Post-genomic Era. Plant Commun. 2019 Dec 10;1(1):100013. doi: 10.1016/j.xplc.2019.100013. PMID: 33404541; PMCID: PMC7747983.

Progress 10/01/18 to 09/30/19

Outputs
Target Audience:Other scientists and general public. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project provided training of a postdoc, a graduate student, and several undergraduate students. How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals?We will further define the mechanism underlying K-channel regulation by the calcium signaling pathway.

Impacts
What was accomplished under these goals? We have studied the function of a vacuolar calcium signaling pathway for the regulation of potassium (K) remobilization in plant adaptation to low-K environment and made a breakthrough discovery: we found that plant cells utilize K stored in the vacuole to cope with soil K deficiency through activation of a calcium-dependent signaling pathway that in turn activates a K-permeable channel allowing K to be mobilized from vacuolar pool. This explains at the molecular level how plant cells respond and adapt to the low-nutrient (K) conditions in the soil and will benefit our breeding effort to produce high K-use efficiency in crops. We have just submitted the story to a high-impact journal and hopefully will be published soon.

Publications

Progress 10/01/17 to 09/30/18

Outputs
Target Audience:Our research has been published in scientific journals and thereby targeting the plant biology community. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project provide training to 2 postdocs, one graduate student, and two unbdergraduate students. How have the results been disseminated to communities of interest?Results have been published in journals and disseminated to international plant biology communities. What do you plan to do during the next reporting period to accomplish the goals?We continue to work on low-K tolerance in arabidopsis and rice and at the same time we have expanded the work to other mineral nutrients such as phosphate and magnesium.

Impacts
What was accomplished under these goals? We have found that 1) vacuolar phosphate transporters are important for plant reproduction and seed yield in Arabidopsis; 2) vacuolar phosphate transporters are involved inarsenate toxicity; and 3) The K-transporter may be helpful in tolerance to high magnesium conditions.

Publications

• Type: Journal Articles Status: Published Year Published: 2018 Citation: Vacuolar phosphate transporters contribute to systemic phosphate homeostasis vital for reproductive development in Arabidopsis. Luan M, Zhao F, Han X, Sun G, Yang Y, Liu J, Shi J, Fu A, Lan W, Luan S. Plant Physiol. 2018 Dec 14. pii: pp.01424.2018. doi: 10.1104/pp.18.01424. [Epub ahead of print]
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Vacuolar Phosphate Transporter 1 (VPT1) Affects Arsenate Tolerance by Regulating Phosphate Homeostasis in Arabidopsis. Luan M, Liu J, Liu Y, Han X, Sun G, Lan W, Luan S. Plant Cell Physiol. 2018 Jul 1;59(7):1345-1352. doi: 10.1093/pcp/pcy025.
• Type: Journal Articles Status: Published Year Published: 2017 Citation: The Rice High-Affinity K+ Transporter OsHKT2;4 Mediates Mg2+ Homeostasis under High-Mg2+ Conditions in Transgenic Arabidopsis. Zhang C, Li H, Wang J, Zhang B, Wang W, Lin H, Luan S, Gao J, Lan W. Front Plant Sci. 2017 Oct 24;8:1823. doi: 10.3389/fpls.2017.01823. eCollection 2017.

Progress 10/01/16 to 09/30/17

Outputs
Target Audience:Plant Biology research community. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project trained 2 postdocs and one graduate student and 2 undergraduates. How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals?We will further characterize the mutants in rice and link the mehcanism of low-K toelrance with the genes encoding K-transporters and their regulators.

Impacts
What was accomplished under these goals? In the past year, we have established transgenic rice lines containing mutations in genes encoding K-transporters, as generated by CRISPR technology, and have analyzed some of the lines for their defects in plant physiology and development. One of the mutant appeared to be male sterile suggesting that K is cristial for anther development. We also identified a transcriptional factor involved in low-K tolerance in rice. These findings will provide leads to further understanding the mechanisms underlying low-K tolerance in cereals.

Publications

Progress 10/01/15 to 09/30/16

Outputs
Target Audience:Other scientists, postdocs and graduate students, public outreach audience, high school students, community college students. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?Published a book What do you plan to do during the next reporting period to accomplish the goals?As planned in hte original proposal, we will continue to study rice low-K tolerance.

Impacts
What was accomplished under these goals? We have established rice as crop model to study low-K tolerance in cereals. Trangenic rice plants were made to examine the expression pattern and function of K-transporters and their regulators.

Publications

• Type: Books Status: Published Year Published: 2016 Citation: The Enzymes Vol. 40: Developmental Signaling in Plants