The “Basic Research Team of Crop Molecular Genetics” is affiliated to the “State Key Laboratory of Crop Genetics and Germplasm Enhancement” of Nanjing Agricultural University, and mainly focuses on molecular breeding of crops with high nutrient use efficiency, physiological and molecular regulations of plant stress tolerance and genetic enhancement, etc. This team comprises of ten professors, two associate professors and three lectures. One of the team members has been awarded with “The National Science Fund for Distinguished Young Scholars”; another one member has won the titles of “National Distinguished Talent of Agricultural Scientific Research” and “Supervisors of Excellent National Doctorial Dissertations”; four have been supported by the “Program for New Century Excellent Talents in University” of Ministry of Education; and two have been elected as the “333 Senior Talents of Jiangsu Province”. In addition, this team has kept close cooperation with scientists from John Innes Center (UK), Kansas State University (USA), and Hong Kong Baptist University.

The team has been financially supported by several important programs [e.g. National High Technology Research and Development Program of China (863 program), Major State Basic Research Development Program of China (973 program), National Natural Science Foundation of China (NSFC), and National Major Project for Transgenic Research], and has specialized technical platforms in cell biology, functional genomics, proteomics, crop genetic breeding, which are facilitated by a suite of instruments and equipment, such as inductively coupled plasma-mass spectrometry (ICP-MS), liquid chromatography-mass spectrometry (LC-MS), patch clamp electrophysiology, real-time quantitative PCR, etc. In addition, the team is equipped with green house, phytotron, and field experiment base.

In recent years, the team has made outstanding achievements in elucidating the molecular mechanisms of plant plasma membrane nitrate and phosphate transporters (PTs), phospholipids-regulated salt tolerance and acquisition and utilization of nitrate and phosphate (Pi). Plasma membrane plays pivotal roles in sensing external signals, transport of various substances, stabilizing the internal environment of cells, and maintenance of cell metabolism. The plasma membrane-localized ion transporters not only serve as the facilitators of the transmembrane transport of mineral nutrients and salts, but also function as regulators of nutrient acquisition and utilization and plant salt tolerance, while plasma membrane phospholipids are rapid sensors of external signals, which is attributed to the easy transformation among their diverse chemical structures. Consequently, dissecting the functions and regulations of plasma membrane transporters and the mechanisms underlying phospholipid signaling are of theoretical and applicable importance for genetically modified crops in terms of acquisition of mineral nutrients and water, and salt tolerance.

The team has been working on the molecular mechanisms underlying the plasma membrane transporters-facilitated acquisition and utilization of nitrate and Pi as well as breeding of crops with high nutrient use efficiency. They identified rice nitrate transporter genes classified into the NAR2/NRT2 family, and studied their expression patterns, physiological functions, regulations and interactions, demonstrating the requirement of nitrate for rice growth and development. Specifically, the team showed many lines of evidence that OsNAR2.1 physically interacts with several NRT2 members to monitor the acquisition and mobilization of nitrate in rice. Among these genes, overexpression of OsNAR2.1 or OsNRT2.3b leads to an increase in rice yield and nitrogen (N) use efficiency. The current findings suggest that the maintenance of cytosolic pH is a fundamental requirements for high N use efficiency.

In addition, this team investigated the expression patterns and regulations of the plasma membrane PT genes of the PHT1 family in both rice (Oryza sativa) and soybean (Glycine max). Their results showed that OsPHT1;2 (OsPT2) and OsPT6 are two highly-induced PHT1 genes by Pi starvation, while the constitutively expressed OsPT1 and the Pi-starvation-induced OsPT8 encode, respectively, a dual-affinity and a high-affinity PT. OsPT2 is a low-affinity PT responsible for the mobilization of Pi from roots to shoots, while OsPT6 is involved in both acquisition and mobilization of Pi. Similar to OsPT6, OsPT1 and OsPT8 are responsible for not only the acquisition Pi, but also the re-distribution of Pi in shoots. OsPT1 and OsPT8 also have an effect in the tillering of rice plants and the filling of rice grains. Besides, soybean GmPT1 and GmPT2 have been demonstrated to be the functional orthologous genes of rice OsPT2 and OsPT6.

On the other hand, this team has dissected novel stress resistance pathways mediated by phospholipase D and its product phosphatidic acid. They identified several proteins regulated by phosphatidic acid [NADPH oxidase (RbohD), mitogen-activated protein kinase (MAPK6), microtubule-associated protein (MAP65-1)]. They also elucidated several cell biological processes regulated by phospholipids and these proteins targeted by phosphatidic acid (i.e. production of reactive oxygen species, protein phosphorylation, and microtubule polymerization and bundling), and determined the contribution of these cell biological processes in plant salt tolerance and ABA responses.

These studies identify several novel genes pivotal for the effective acquisition and utilization of N and Pi, and provide evidence that the utilization of N and Pi is closely correlated with plant yield. These studies also shed light on the importance of phospholipids in stress signalings.

Up to date, this team has published many research articles as well as review papers in a suite of high-impact journals, including Annual Review of Plant Biology, The Plant Cell, Current Opinion in Plant Biology, The Plant Journal, Plant Physiology, Plant Cell and Environment, Journal of Experimental Botany etc. In addition to the publications, they have applied patents for the new genes identified in their studies, and authorized the use of some genes to several domestic institutes for breeding of crops with high nutrient use efficiency. This team has also been granted with several awards, e.g. Excellent Scientific Research Award (Science and Technology) for Natural Science in Colleges and Universities (Ministry of Education), The 4^th Science and Technology Award of Chinese Soil Academy, National Excellent PhD Dissertation, and Excellent PhD Dissertation of Jiangsu Province.

Team Leader: Pro.Guohua Xu