Approximately 185,000 Gossypium EST sequences comprising >94,800,000 nucleotides were amassed from 30 cDNA libraries constructed from a variety of tissues and organs under a range of conditions, including drought stress and pathogen challenges. These libraries were derived from allopolyploid cotton (Gossypium hirsutum; AT and DT genomes) as well as its two diploid progenitors, Gossypium arboreum (A genome) and Gossypium raimondii (D genome). ESTs were assembled using the Program for Assembling and Viewing ESTs (PAVE), resulting in 22,030 contigs and 29,077 singletons (51,107 unigenes). Further comparisons among the singletons and contigs led to recognition of 33,665 exemplar sequences that represent a nonredundant set of putative Gossypium genes containing partial or full-length coding regions and usually one or two UTRs. The assembly, along with their UniProt BLASTX hits, GO annotation, and Pfam analysis results, are freely accessible as a public resource for cotton genomics. Because ESTs from diploid and allotetraploid Gossypium were combined in a single assembly, we were in many cases able to bioinformatically distinguish duplicated genes in allotetraploid cotton and assign them to either the A or D genome. The assembly and associated information provide a framework for future investigation of cotton functional and evolutionary genomics.

Collective evldence demonstrates that the MInlaturel (Mnl) seed locus in maize encodes an endosperm-specific lsozyme of cell wall Invertase, CWI-2. l h e evidence includes (1) isolatlon and characterizatlon of ethyl methanesulfonate-lnduced mnl mutants wlth altered enzyme actlvlty and (2) a near-linear relatlonshlp between geneldose and Invertase actlvlty and the CWI-2 proteln. In addltlon, molecular analyses showed that the cDNA clone Incw2 maps to the Mnl locus and dlfferentlates the slx ethyl methanesulfonate-lnduced mnl mutants of lndependent orlgin lnto two classes when RNA gel blot analyses were used. We also report two unexpected observatlons that provide slgnlflcant new lnslght lnto the physlologlcal role of Invertase and Its mgulatlon ln a developlng seed. First, a l a g e proportlon of total enzyme actlvlty (&90%) was dlspensable &e., nonllmltlng). However, below the threshold leve1 of -6% of wlld-type activlty, the endosperm enzyme controlled both the slnk strength of the developing endosperm as well as the developmental stablllty of maternal cells ln the pedicel ln a rate-limltlng manner. Our data also suggest an unusually tlght coordinate control between the cell wall-bound and the soluble forms of invertase, which are most likely encoded by two separate genes, presumably through metabolic controls mediated by the sugam

Background: Cotton (Gossypium hirsutum L.) fibers are trichomes that initiate from the ovule epidermis. Little is known about the developmental pathway causing fiber to differentiate from ovular epidermal cells even though limits on the number of cells that differentiate into fiber will limit yield.

In maize, two paralogous genes, Sh1 and Sus1, encode two biochemically similar isozymes of sucrose synthase, SS1 and SS2, respectively. Previous studies have attributed the mild starch deficiency of the shrunken1 (sh1) endosperm to the loss of the SS1 isozyme in the mutant. Here we describe the first mutation in the sucrose synthase1 (Sus1) gene, sus1-1, and the isolation of a double recessive genotype, sh1 sus1-1. Combined data from diverse studies, including Northern and Western analyses, RT-PCR and genomic PCR, cloning and sequencing data for the 3' region, show that the mutant sus1-1 gene has a complex pattern of expression, albeit at much reduced levels as compared to the Sus1 gene. Endosperm sucrose synthase activity in sh1 sus1-1 was barely 0.5% of the total activity in the Sh1 Sus1 genotype. Significantly, comparative analyses of Sh1 Sus1, sh1 Sus1 and sh1 sus1-1 genotypes have, for the first time, allowed us to dissect the relative contributions of each isozyme to endosperm development. Starch contents in endosperm of the three related genotypes were 100, 78 and 53%, respectively. Anatomical analyses, which confirmed the previously described early cell degeneration phenotype unique to the sh1 Sus1 endosperm, revealed no detectable difference between the two sh1 genotypes. We conclude that the SS1 isozyme plays the dominant role in providing the substrate for cellulose biosynthesis, whereas the SS2 protein is needed mainly for generating precursors for starch biosynthesis.