Understanding and development of environmentally friendly strategies to ameliorate plant stress

Open Access
- Author:
- Islam, Md Tariqul
- Graduate Program:
- Plant Pathology
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- February 24, 2023
- Committee Members:
- Cristina Rosa, Chair & Dissertation Advisor
Timothy Mcnellis, Major Field Member
Surinder Chopra, Outside Unit & Field Member
Maria Del Mar Jimenez Gasco, Program Head/Chair
Yinong Yang, Major Field Member - Keywords:
- Biostimulant
photosensitizer
phytohormones
abiotic-biotic stresses
RNA-Seq - Abstract:
- Plants are often exposed to a variety of abiotic and biotic stresses in the environment, which can cause significant yield losses in crops. Although the green revolution has marked a dramatic growth in food production, heavy use of synthetic pesticides and chemicals have been posing a threat to the environment. Moreover, many plant pathogens and pests have developed resistance against pesticides or have evolved to overcome resistance traits bred into a variety of plant species, thus, crop productivity has begun to plateau. In addition, social environmental consciousness has increased the consumption of healthier, sustainable food, leading to a twofold challenge: meet the food demand of the continuous growing world population; yet do so in a way that is environmentally friendly and socially acceptable. Given the circumstances, my overarching goal was to improve health in susceptible plants using environmentally friendly products such as plant biostimulants (PB), photosensitizers (PS), and phytohormones. My hypothesis is that, once we identified products that improve plant health and we understand what defenses they stimulate in susceptible plants to make them more resistant to different stressors, we can use this knowledge not only to develop better and sustainable agricultural products, but we can also engineer crops with moderate susceptibility or tolerance, and we can predict if they will be fortified against multiple biotic and abiotic factors. In my first chapter, I have discussed why we need alternative management practices of plant stress, what are the currently viable options, and how understanding the underlying molecular mechanisms of the interactions between novel products, plants and stress is crucial to improve crop health. In my second chapter, I have elucidated the protective mechanism of a PB, copper chlorophyllin (Cu-chl) in Arabidopsis thaliana under salinity stress. I demonstrated that Cu-chl protects plants from oxidative stresses by decreasing cellular reactive oxygen species (ROS) levels and promoting plant growth. I also identified by RNA-Seq analysis the genes upregulated by this PB and proposed a novel model of molecular interactions that connects ROS detoxification, and cellular growth. In the third chapter, I tested and optimized in planta application of a PS, sodium magnesium chlorophyllin (Mg-chl) to combat bacteria such as Pseudomonas syrinage pv. DC3000, Xanthomonas hortorum pv. gardneri, and Xanthomonas fragarie. My data showed that Mg-chl in combination with Na2EDTA (used as cell wall permeabilizing agent) was able to effectively inhibit Pseudomonas syringae pv. tomato DC3000 in vitro and in planta in tomato and N. benthamiana. More significantly, Mg-chl in combination with Na2EDTA and the common surfactant Morwet D-400 significantly reduced Xanthomonas hortorum pv. gardneri and Xanthomonas fragarie, respectively, in a commercial greenhouse trial against bacterial spot disease in tomato and in field experiments against angular leaf spot disease in strawberries. In my fourth chapter, I utilized and explored the potential of exogenous phytohormones application in management of drought stress and tomato spotted wilt orthotospovirus (TSWV). Here I proposed a model of how crosstalk among the phytohormones may play a pivotal role under the mentioned stress. In my fifth chapter, I explored the molecular interactions between spotted lanternfly, a newly invasive insect in the U.S and susceptible grapevines using RNASeq. I then compared my results to the ones obtained in other studies that looked at the gene regulation induced by different insects and pathogens in grapes, with the intend to build knowledge aimed at predicting responses to multiple stresses in susceptible grapes. I finally used this new framework and proposed a management strategy against spotted lanternfly In my sixth and last chapter, I summarized my findings and discussed their potentials and limitations.