Mapping of a Cellulose-Deficient Mutant Named dwarf1-1 in Sorghum bicolor to the Green Revolution Gene gibberellin20-oxidase Reveals a Positive Regulatory Association between Gibberellin and Cellulose Biosynthesis

Abstract

ORCID IDs: 0000-0001-7521-3615 (C.P.); 0000-0002-5473-526X (J.S.).Here, we show a mechanism for expansion regulation through mutations in the green revolution gene gibberellin20 (GA20)-oxidase and show that GAs control biosynthesis of the plants main structural polymer cellulose. Within a 12,000 mutagenized Sorghum bicolor plant population, we identified a single cellulose-deficient and male gametophyte-dysfunctional mutant named dwarf1-1 (dwf1-1). Through the Sorghum propinquum male/dwf1-1 female F2 population, we mapped dwf1-1 to a frameshift in GA20-oxidase. Assessment of GAs in dwf1-1 revealed ablation of GA. GA ablation was antagonistic to the expression of three specific cellulose synthase genes resulting in cellulose deficiency and growth dwarfism, which were complemented by exogenous bioactive gibberellic acid application. Using quantitative polymerase chain reaction, we found that GA was positively regulating the expression of a subset of specific cellulose synthase genes. To cross reference data from our mapped Sorghum sp. allele with another monocotyledonous plant, a series of rice (Oryza sativa) mutants involved in GA biosynthesis and signaling were isolated, and these too displayed cellulose deficit. Taken together, data support a model whereby suppressed expansion in green revolution GA genes involves regulation of cellulose biosynthesis.In all higher plants, development of upright plant growth is advanced by a highly regulated process of cell division, cell fate determination, and cell expansion (Xie et al., 2011). Cell shape and morphogenesis are largely acquired through anisotropic expansion, during which the plant cell wall provides the structural integrity needed to resist internal turgor pressure and simultaneously extend in a controlled and organized manner (Cosgrove and Jarvis, 2012). Cellulose is the main loadbearing component on the plant cell wall, and cellulose is synthesized in a highly organized manner according to the expansion state and growth pattern (Tsekos, 1999). A number of phytohormones are involved in regulating expansion, including auxin (Paque et al., 2014), brassinosteroid (Xie et al., 2011, the rapid alkalinization factor peptide hormone (Haruta et al., 2014), cytokinin (Downes andCrowell, 1998), and GAs (Keyes et al., 1989). A complex and still poorly understood interplay exists among phytohormones to precisely regulate cellular expansion machinery.Sorghum bicolor is one of the most agriculturally important grains produced worldwide (Paterson, 2008). It is largely cultivated in Africa, India, China, and the United States for both grain and biomass. An advantage that Sorghum sp. holds over many other grain crops is drought tolerance, an important trait in low-rainfall conditions and anticipated climate change shifts (Schmidhuber and Tubiello, 2007 (Paterson et al., 2009;Liu and Godwin, 2012). Here, we aimed to isolate a cellulosedeficient mutant from within a chemical mutagenesis population, which we named dwarf1-1 (dwf1-1). From here, we aimed to characterize the geneti...

Transcriptional Regulation of Brassinosteroid Accumulation during Carrot Development and the Potential Role of Brassinosteroids in Petiole Elongation

“…The petioles of GmBRI1b over-expression lines were longer than that of wild plants ( Peng et al, 2016 ). Many BR-deficient mutants, such as dwarf4 ( dwf4 ), and dwf7-1 in Arabidopsis, dwarf1-1 in sorghum, exhibited dwarf phenotypes due to deficiency in BR biosynthesis ( Choe and Feldmann, 1998 ; Cheon et al, 2010 ; Fridman and Savaldi-Goldstein, 2013 ; Petti et al, 2015 ). Here, the biosynthesis genes and catabolism genes showed higher expression levels at the first two stages which suggested that BRs may be involved in actively growing of petioles.…”

Rhizobacterial species richness improves sorghum growth and soil nutrient synergism in a nutrient-poor greenhouse soil

“…Briefly, prior to inoculation, the seeds were washed in the sterile deionized water (diH 2 O). Then, these seeds were surface-sterilized with a 20% household bleach solution for 10 min followed by three washes in the diH 2 O 51 .…”

Transcriptional Regulation of Sorghum Stem Composition: Key Players Identified Through Co-expression Gene Network and Comparative Genomics Analyses

“…A custom gene list of CW related genes was obtained from the aggregation of genes listed in previous publications (Petti et al, 2015;McKinley et al, 2016;Rai et al, 2016) Table S3). In addition to the GO enrichment analysis, Fisher's exact test was also performed for every module to detect enrichment in these candidate CW related genes.…”

“…In addition to the bmr phenotype, additional phenotypic mutants related to the composition of the SCW have been identified. Petti et al (2013Petti et al ( , 2015 identified that REDforGREEN and dwarf1.1 mutants affected lignin and cellulose abundance in leaves and stems, in addition to their respective red coloration and shortened internodes.…”