Evaluation of Cell Wall Biosynthetic Genes in Barley Hordeum vulgare L

Lodging is a highly undesirable attribute for cereal crop plants because of increased disease infestations, decreased grain quality, uneven maturity, and increased harvesting costs.  Lodging in barley, Hordeum vulgare, can cause a 65% reduction in grain yield.  There are variations in straw (stem) strength among barley cultivars. Stiff-strawed cultivars tend to show higher resistance to lodging. We are investigating the genetic basis of straw stiffness in barley. We hypothesize that there are structural differences in the cell walls of stiff- and weak-stemmed genotypes of barley and, therefore, anticipate identifying polymorphism in the genes that are involved in their synthesis. In order to investigate this hypothesis, barley genotypes characterized as stiff- and weak-strawed were grown in the green house and the tissue harvested for DNA isolation. PCR primers were designed from cell wall biosynthetic genes either from the rice or wheat ESTs. Contrary to our hypothesis, data from PCR analysis showed largely monomorphic PCR products, suggesting that the cell wall genes evaluated are present in both the stiff- and weak-strawed genotypes of barley. This also suggests that the cell wall biosynthetic genes evaluated are likely orthologs and highly conserved among the three species; barley, rice and wheat. While these genes are present in both stiff- and weak-strawed barley genotypes, it is not known if they are differentially expressed. Efforts are underway to begin assessing the expression levels of these genes using qRT-PCR in an effort to see if they are differentially expressed in these genotypes. We are equally sequencing the PCR products in order to evaluate for single nucleotide polymorphisms (SNPs) among the genotypes. The ultimate goal for this project is to identify useful stiff straw genes that can be introgressed into elite barley germplasms showing the weak straw phenotypes. Funding: Funding support from the USDA-NIFA Triticeae Coordinated Agricultural Project (T-CAP) awarded CB.