Project Number: 6615-21000-009-00
Project Type: Appropriated

Start Date: Mar 22, 2006
End Date: Mar 21, 2011

Objective:
(1) To identify and analyze critical genes in sugar-hormone signaling and sugar metabolism during seed development, particularly in basal endosperm transfer cells, in maize. (2) To determine the bases for defective pollen biogenesis, including aberrations in sugar-starch metabolism, associated with heat stress and cytoplasmic male sterility in sorghum.

Approach:
Developmental profiles of various phytohormones in developing seeds of normal (wild type) and several carbohydrate mutants of known genetic bases in maize will be developed using high throughput chemical approaches, including gas chromatography / mass spectrometry (GC-MS). Contemporary genomic approaches will be used to identify genes that are critical to sugar - hormone cross-talk, especially those related to hormone metabolism, transcription factors and proteins that function as receptors and/or response factors. Such genes in developing seeds will be further analyzed in expression studies using both microarray and single gene approaches to dissect gene networks that may control normal seed development and sink strength, the two most critical components of crop yields. Gene discovery studies based on transcriptome and proteome approaches will be initiated to obtain a functional genomic profile of the Basal Endosperm Transfer Layer (BETL), a highly specialized cell layer known to be critical for transport and signaling functions in developing seeds. The emphasis in studying pollen biogenesis in sorghum is to understand the bases for defective biochemical, molecular and physiological processes (including aberrations in sugar-starch metabolism) associated with heat stress and cytoplasmic male sterility (CMS). Profiles of differentially expressed genes that characterize the expression of CMS, the restoration of male fertility and heat-induced pollen inviability will be obtained and analyzed through contemporary transcriptome and proteome technologies.