Improving Finger Millet for Blast Resistance
Finger
millet is a subsistence crop grown by farmers in India and East and Central
Africa. The grain has high nutritional value and excellent storage qualities,
which make it an important famine food. It is often grown on marginal soils
in rainfed conditions and intermittent drought spells have a negative effect
on yield. The major biotic constraints to yield are neck and finger blast. The
project aims to improve finger millet for resistance to blast and drought using
a combination of conventional and marker-assisted breeding. Genotypes with improved
resistance to these stresses will be selected on the basis of field performance
and molecular data and backcrossed with farmers’ choice varieties. To
ensure adaptation and preferences of the plant materials by farmers, many of
the field trials will take place in participation with farmers. Blast and, to a lesser extent, drought resistance have been studied extensively in rice and other cereals. Finger millet can benefit from the information and knowledge already available in other cereals through comparative genomics. Cross-genome studies may lead to the identification of genes putatively involved in stress response in finger millet. We also aim to develop resources for the exploitation in fine-tuned genetic studies and genomics.
The project is funded by the McKnight foundation and the partnership includes my lab, the Leong lab at the University of Wisconsin, Madison and the lab of Dr. Hittalmani at the University of Agricultural Sciences, Bangalore, India.
The
aim of this small-scale pilot project funded by USAID is to generate the first
significant marker analysis of genetic diversity in finger millet. It will also
generate some of the tools such as finger millet microsatellites for this analysis,
tools that will be tested and will then be available for all future characterizations.
Fifty accessions of cultivated finger millet, E. coracana subsp. coracana and
ten accessions of the wild progenitor, E. coracana subsp. africana will be assessed
for morphological characters by Dr. Dida at Maseno University, Kenya and Dr.
Nelson Wanyera at SAARI, Uganda. These, plus a further 40 finger millet accessions
will be genotyped in my lab using a set of 50 SSRs. This is the first time that
genetic diversity in finger millet will be compared to morphological and agronomic
trait variability. This preliminary project will provide the foundation for
comprehensive identification and use of finger millet genetic diversity, thus
contributing both to finger millet improvement and the integration of finger
millet into the cereal comparative genetics community.
The d2 dwarfing gene in pearl millet reduces plant height by about 50% and is widely used in pearl millet hybrids for fodder as well as grain. The reduced plant height leads to a higher proportion of leaves with better digestibility compared to tall varieties. The d4 mutant is an extreme dwarf with no economic value. However, my lab has demonstrated that the d4 plant height can be modified through the interaction of a second gene, designated Br1 . Work is underway to isolate the d2 , d4 and Br1 genes using comparative information from rice. The rice sequence is used as a source of new markers for chromosome landing experiments ( d2 ) or to provide candidate genes for the traits of interest ( d4, Br1 ). The ultimate aim is to conduct comparative functional analyses of the d4 , d2 and Br1 genes across the major cereals. 
The current view of the composition of the wheat genome is that genes are compartmentalized in ‘gene-rich' and ‘gene-poor' regions. This organizational pattern has been deduced from molecular-cytological observations and from sequence data of a limited number of BAC clones. My lab is involved in collaborative research with Dr. Bennetzen at UGA and Dr. San Miguel at Purdue University , and funded by the NSF Plant Genome Program, to rigorously test this model. Some 220 randomly chosen BAC clones from the hexaploid wheat variety Chinese Spring will be sequenced and annotated. The BACs will subsequently be mapped to the wheat deletion map, which divides each chromosome into bins. Anchoring of BAC clones with known gene density to bins will provide insight into the interspersion pattern of genes and repeats and to what extent this pattern varies along the length of a chromosome. 
Comparative analyses among Triticeae species (wheat and its relatives) have revealed a number of gross chromosomal translocations that differentiate the different species. One of these translocations involves the long arms of chromosomes 4 and 5, and appears to have occurred independently in different lineages. Another rearrangement that may have taken place multiple times involves the long arm of chromosome 7. We aim to determine the molecular base of these chromosomal rearrangements. Breakpoint analysis at the molecular level represents the first research of its kind in plants.