PI: Ramesh Kantety (Alabama Agricultural and Mechanical University)
CoPIs: Elica S. Moss (Alabama Agricultural and Mechanical University) and Katheryn S. Lawrence (Auburn University, subawardee)
Collaborators: Yong-Li Xiao (J. Craig Venter Institute, Inc., subawardee) and Bruce Roe (University of Oklahoma - Norman, subawardee)
Cotton is the most extensively cultivated natural fiber in the world. However cotton requires intensive management in order to control pests and pathogens. Damage to cotton caused by nematodes alone is poised to reach $1 billion in the near future; thus far there are no cotton cultivars resistant to reniform nematodes. Interaction of reniform nematodes with cotton roots elicit complex plant responses at biochemical, morphological and physiological levels which in turn are regulated by transcriptional, translational, and environmental signals. To help address such phenomena, various cotton species will be characterized for their responses to the reniform nematode infection while building much needed functional genomic resources. The project will develop and sequence cDNA and small RNA libraries from cotton roots infected with reniform or root-knot nematodes as well as from cotton roots treated with various elicitors of plant defense responses. Four cotton species which react differently to the reniform nematode infection will be included in these studies. Sequences generated will be used in the development of microarrays that can then be used in the functional genomic studies of cotton-reniform nematode interactions. The genomic data generated in this project will be shared with cotton research community to facilitate the development of unigenes sets for cotton roots, global gene expression tools, and comparative genomic analyses in silico. EST sequences will be deposited at the National Center for Biotechnology Information at http://ncbi.nlm.nih.gov. All research outcomes will be made available publicly on the project website at http://reniform.aamu.edu. Educational outcomes and resources will be available at the project website and through www.plantgdb.org/PGROP/pgrop.php.
Broader Impacts: Reniform nematode is the most important emerging pest of cotton in the US and its damage has been significantly rising every year for the last decade. This project aims to develop resources to understand the global gene expression changes during susceptible and resistant responses of cotton roots when infected with reniform nematodes. The resulting information can aid geneticists, plant breeders and biotechnologists in devising effective strategies for the control of reniform nematodes. This project undertakes outreach and training of 7-12 graders up to post-doctoral level with a major emphasis on underrepresented minorities and science teachers from at-risk schools located in the Black Belt regions of Alabama.
Cotton is a major agricultural crop grown extensively in the southern states of US. In the past three decades, a soil-dwelling microscopic reniform nematode (Rotylenchulus reniformis) has become a major pest that damages the cotton roots and draws the food produced by photosynthesis away from the plant and from cotton bolls thus drastically reducing the cotton yield. This pest makes it difficult to produce cotton competitively with other cotton producing regions of the world and its control strategy requires additional expenditures in chemicals which add to the cost of production substantially and also affects environmental quality. Intellectual Merit: The real practical solution therefore is to identify and fully utilize inherent resistance found in wild relatives of cotton. But first we need to better understand the biology of cotton and of reniform nematode to come up with effective management strategy to manage this pest and reduce the economic damage associated with it. Under this study, we have identified several species of cotton (cultivated and wild) and we are studying their genetic make-up at the gene level. Parallel to these we are also sequencing the genes of nematode and determining if more than one race of nematode may be emerging. If another race of nematode emerges then our nematode control strategy will need to be based on nematode race or biotype. This effort over the past five years has therefore focused on issues such as the types of proteins that are present in cotton root where nematode anchor and feed, on the types or molecular markers or sequencing methods we can best employ to know the sequence of cotton or nematode genes, and on the types of proteins that are being produced both in cotton and in nematode individually or when nematode attacks the host plant and acts as a parasite. We are also finding that once the resistance genes are inherited in a cotton plant or a cotton variety and become part of plant, the changes in gene function can still occur by mechanisms such as micro-RNA activating or inactivating the function of an inherited gene. An extensive focus is given to understanding such mechanisms both in the plant as well as the changes that may occur in the nematode thus increasing its virulence. One of the interesting aspects we have studied is to see if a key gene in nematode has one or more variable form. We have observed that this gene, the 18S rRNA gene which is generally considered as highly stable in many higher organisms has two forms in this nematode. Does this mean that having this character gives this nematode some exceptional survivability or allows it to expand the host range? Such intriguing questions have emerged and will need to be studied as a result of finding these two variable forms of this 18S gene. In another study undertaken by associating plant and nematode together, we have identified some genes that are expressed by the nematode. Many of these genes help this nematode digest or destroy cell wall a natural barrier unique to higher plants and thus gain faster and more damaging entry in root cells. The broadening impact of this work is the ability to utilize the research resources made available by the grant support which were used to train teachers and young high school aged students to become more interested in science and in learning about the approaches utilized in pursuing biological research. Therefore we have undertaken special training programs to bring high school science teachers and students to learn molecular biology techniques and principles. In addition we have also trained several undergraduate and graduate students especially focusing on students that are under-represented in the sciences.
