A Cold‐Regulated Protein from Bermudagrass Crowns Is a Chitinase

Abstract

Sodium dodecylsulfate (SDS) polyacrylamide gel electrophoresis (PAGE) and fluorography of in vivo radiolabeled proteins has revealed that protein synthesis in crowns of ‘Midiron’ and ‘Tifgreen’ bermudagrasses (Cynodon dactylon L. Pers. × C. transvaalensis Burtt‐Davy) is altered in association with cold acclimation (CA). Increased synthesis of some proteins in association with CA in Midiron crowns correlates with the greater freezing tolerance of Midiron compared with Tifgreen. This study was undertaken to (i) characterize further alterations in protein synthesis in Midiron and Tifgreen crowns utilizing analytical isoelectric focusing (IEF)/SDS‐PAGE [two‐dimensional (2D‐) PAGE], and (ii) identify cold‐regulated (COR) proteins, proteins encoded by genes persistently upregulated during CA, through sequence analysis of peptides recovered after micropreparative 2D‐PAGE and protease digestion. Plants were grown for 26 d in controlled‐environment chambers under acclimating [8/2°C (day/night) cycles with 10 h photoperiods] or nonacclimating [28/24°C] conditions. Proteins synthesized by isolated crowns were radiolabeled in vivo for 16 h with 35S‐methionine and 35S‐cysteine. Among several groups of COR proteins synthesized in Midiron and Tifgreen crowns, low molecular weight (about 20–28 kilodalton) basic (LB) COR proteins were synthesized in greater amounts and numbers in Midiron than Tifgreen crowns. Among the LB COR proteins, a 27‐kD basic COR protein was synthesized prominently in crowns of both Midiron and Tifgreen plants. This protein from Midiron crowns was designated COR27 and identified as a chitinase (E.C. 3.2.1.14) through protein sequencing.

Antifreeze Proteins in Winter Rye Are Similar to Pathogenesis-Related Proteins

“…In fact, there have been severa1 previous reports of PR proteins induced by low temperature: acidic PR proteins and a basic endochitinase are induced during cold acclimation in barley ; the gene for osmotin, a TL protein, is expressed during cold acclimation in the potato Solanum commersonii (Zhu et al, 1993); and a 27-kD chitinase accumulates during cold acclimation in bermudagrass crowns (Gatschet et al, 1995). However, these earlier reports have not defined a specific role for developmentally induced or environmentally induced PR proteins.…”

Snow-Mold-Induced Apoplastic Proteins in Winter Rye Leaves Lack Antifreeze Activity

“…Winter rye (Secale cereale L.), wheat, and barley leaves accumulate proteins similar to PR proteins (Hon et al, 1995;Antikainen and Griffith, 1997). Bermudagrass expresses a gene encoding chitinase (Gatschet et al, 1996) and carrot expresses a gene encoding a polygalacturonase inhibitor protein (Worrall et al, 1998;Meyer et al, 1999). Tamás et al (1997) also detected the accumulation of three unidentified proteins in the apoplast of barley leaves in response to powdery mildew attack as well as during low-temperature stress.…”

Immunolocalization of Antifreeze Proteins in Winter Rye Leaves, Crowns, and Roots by Tissue Printing

“…Proteins similar to PR proteins are also induced by other conditions unrelated to pathogen induction, such as ethylene (Boller et al, 1983), UV light (Yalpani et al, 1994), ozone (Ernst et al, 1992;Karenlampi et al, 1994;Yalpani et al, 1994), high salt (Esaka et al, 1994), heat (Margis-Pinheiro et al, 1994), phytotoxic metals (Jacobsen et al, 1992), and wounding (Zhang and Punja, 1994). Cold-induced accumulation of chitinase has been observed in barley (Tronsmo et al, 1993) and bermudagrass (Gatschet et al, 1996). Moreover, low temperature has been shown to increase accumulation of three mRNAs in potato that correspond to transcripts of cDNAs encoding osmotin-like proteins (Zhu et al, 1995).…”