FACULTY

Chinese
Ph.D., Professor
Tel:13661399818(M)
E-mail:tianxl@cau.edu.cn
Areas of Expertise: Potassium nutrition of cotton

EDUCTION
1986.9-1990.7,B.S.in Agronomy, Beijing Agricultural University
1990.9-1993.7,M.S.in Agronomy, Beijing Agricultural University
1995.9-1999.7,Ph.D.in Agronomy, China Agricultural University

EMPLOYMENT
1993.7-1995.8,Assistants, Beijing Agricultural University
1995.9-2000.12,Lecturer, China Agricultural University
2001.1-2008.1,Associate professor, China Agricultural University
2008.2-Present,Professor, China Agricultural University
2010.9-2011.3,Visiting Scholar, Penn State University
Research of Special Interest

Research Interests
Potassium nutrition of cotton

Premature senescence of cotton induced by potassium deficiency has become one of the major constraints to cotton production in China. Our team has studied the screening of K+-efficient genotypes in cotton, the physiological mechanism underlying the difference in potassium efficiency among different cotton genotypes, and heterosis for cotton potassium nutrition since 2003. Currently, we focus on the cloning and functional identification of potassium channel and transporter gene in cotton, the long-distance feedback regulation of leaf senescence induced by potassium deficiency in cotton, and novel potassium nutrition diagnosis in cotton.



1. Cloning, expressional and functional studies of GhAKT1 in cotton (Gossypium hirsutum L.)
A K+ channel GhAKT1 cDNA was isolated from the cotton cultivar of Liaomian 17. A phylogenetic analysis showed that GhAKT1 belongs to the AKT1-subfamily in the Shaker K+ channel family. Subsequently, the pGhAKT1::GUS transgenic Arabidopsis plants were generated. Histochemical staining indicated that GhAKT1 is mainly expressed in the vascular tissues of leaves and roots. Using Arabidopsis akt1 mutant and its GhAKT1 overexpression lines, we observed that GhAKT1 affected Arabidopsis seed germination and plant biomass. By using the noninvasive micro-test technique, we found that the GhAKT1 overexpression lines had higher K+ influx rate in the root tip under low-K+ stress relative to akt1 mutant and wild type of Arabidopsis. Recently, we are doing GhAKT1 overexpression and silence in cotton plant.

2. The long-distance feedback regulation of leaf senescence induced by potassium deficiency in cotton
In this study, two contrasting cultivars (CCRI41, more sensitive to K deficiency; and SCRC22, a less sensitive cultivar) were hypocotyl-to-hypocotyl grafted (one scion/one rootstock, two scions/one rootstock, and one scion/two rootstocks) at the seedling stage. We found that cotton shoot plays a major role in mediating leaf senescence induced by potassium deficiency via influencing cytokinins and abscisic acid levels in xylem sap and leaves. The main action site of basipetal feedback signal(s) involved in xylem phytohormones is the hypocotyl, the target of this feedback signal(s) is more likely to be the changes in xylem phytohormones within tissues of the hypocotyl rather than the export of phytohormones from the roots. Currently, we are uncovering the mechanisms involved in feedback regulation of xylem cytokinins and abscisic acid by shoot in terms of anatomy, physiological and biochemical and molecular levels.

3. Novel potassium nutrition diagnosis in cotton
In traditional view, the symptoms of potassium deficiency first occur on older leaves, because K+ can readily move in plants. However, we found that potassium deficiency symptoms first appeared on the functional leaf (the fourth or fifth leaf from the main stem terminal) in certain conditions, whether it adhere in plants in field or seedlings in growth chamber. Our recent work showed that the patterns which potassium deficiency symptoms occur in cotton leaves are associated with external potassium levels. Under severe potassium deficiency, the symptom starts from old leaf. Nevertheless, the symptom starts from functional leaf under moderate potassium deficiency. Recently, we are investigating the transport and redistribution of K+ in plants in order to reveal the mechanism. The result would be an important and useful supplement to potassium nutrition diagnosis in cotton.


 

Publications      *Correspondence Author