Research > System Plant Physiology


The Systems Plant Physiology program is developing crops with enhanced nutritional qualities and identifying new methods to improve environmental attributes. This program focuses on plant biology and its integrations with micro and macro environments, utilizing physiological, molecular, or metabolic traits to understand associated biological processes. Our broad goal is developing crop varieties with enhanced crop productivity, nutritional qualities and tolerance to abiotic stresses for greater adaptability. The critical areas of research we focus on are:

  • Nitrogen use efficiency, nitrogen sensing, transport and assimilation
  • Molecular and genetic aspects of plant metabolism

Advancing the Sustainability Practices of Organic Vegetable Production

Poor productivity of organic crops is in part attributed to the lack of nutrient management strategy, a lack of genetics designed for optimal utilization of resources, and ineffective methods to enhance nutrient uptake.  To improve yield stability, we are investigating biochemical aspects of nutrient uptake, their interactions with soil microbiomes and evaluation of nutraceutical potential of organic vegetables for human consumption and processing.

Enhancing the Nutraceutical Potential of Plants

Non-protein amino acid “citrulline” is universal in animals, plants, bacteria, and fungi. It has extensive clinical and therapeutic implications for human and animal health. We focus on many intriguing aspects of its metabolism; such as synthesis, regulation, long-distance transport, its role as an N-carrier, and as an osmolyte using molecular and metabolic cues. We are using Arabidopsis and watermelon systems to characterize citrulline metabolism.


Photo of Spinach

Enhancing the nutrient use efficiency of plants

The leaching of excessive nitrogenous fertilizers applied to commercial crops leads to environmental problems. To understand the dynamics of nutrient use efficiency we are using cutting-edge tools in genomics to identify spinach genotypes efficient in nutrient uptake, assimilation, utilization. We are using natural variation as a tool to identify the genetic variation for the anti-microbial compounds in spinach and variation in the indigenous microbiota for it’s effectiveness against food-borne pathogens.

Dr. Vijay Joshi

Assistant Professor of Systems Plant Physiology

830-278-9151 ext. 236

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Team Members

  • Blake M. Greene, Research Associate
  • Ashley Rubio, Non-Affiliated Student Assistant
  • Kayla Flores, Non-Affiliated Student Assistant
  • Qiushuo Song, MS Student
  • Haramrit Kaur Gill, PhD Student
  • Amit Kumar Mishra, Post Doc Student


  • Shi T, Joshi V, Joshi M, Vitha S, Gibbs H, Wang K, Okumoto S (2019) Broad-spectrum amino acid transporters ClAAP3 and ClAAP6 expressed in watermelon fruits. Accepted paper Int. J. Molecular Sciences.
  • Awika HO, Cochran K, Joshi V, Bedre R, Mandadi KK, Avila CA (2019) Single‐marker and haplotype‐based association analysis of anthracnose (Colletotrichum dematium) resistance in spinach (Spinacia oleracea). Plant Breed.; 1– 17.
  • Joshi, V, Shinde S., Nimmakayala P, Abburi VL, Alaparthi SB, Lopez-Ortiz C, Levi A, Panicker G, Reddy UK (2019) Haplotype Networking of GWAS Hits for Citrulline Variation Associated with the Domestication of Watermelon. Int. J. Molecular Sciences. 20, 5392.
  • Joshi V, Joshi M, Silwal D, Noonan K*, Rodriguez S*, Penalosa A* (2019) Systematized biosynthesis, and catabolism regulates citrulline accumulation in watermelon. Phytochemistry 162: 129-140.
  • Joshi V, Fernie A (2017) Citrulline Metabolism in Plants. Amino Acids 49(9): 1543-1559.
  • Huang T, Joshi V, Jander G (2014) The catabolic enzyme MGL methionine gamma-lyase limits methionine accumulation in potato tubers. Plant Biotechnology 12(7): 883-893
  • Adio AM, Casteel CL, De Vos Martin, Kim J, Joshi, V et al., (2011) Biosynthesis and defensive function of Nd-acetylornithine, a jasmonate induced Arabidopsis metabolite. Plant Cell 23(9): 3303-18
  • Jander and Joshi (2010) Deciphering the biosynthesis of aspartate-derived amino acids in plants: Metabolic networks and molecular mechanisms. Molecular Plant 3:54-65.
  • Joshi V, Joung J, Fei Z., Jander G (2009) Transcriptional regulation and synthesis of branched chain amino acids as osmolytes in plants under drough tand cold stress. Amino Acids 39(4):933-47.