Overexpression of Zoysia ZjCIGR1 gene confers cold stress resistance to zoysiagrass

Zoysia japonica Steud. is a warm-season lawn grass popular in Korea and elsewhere. They are cultivated in many places such as river banks, roadside, and play grounds. However, there still is a disadvantage of frequent mowing, and the grass grows poorly under the chilly conditions. To develop a grass variety that circumvents these drawbacks, we cloned the chitin-inducible gibberellins-responsive1 gene (CIGR1) from zoysiagrass. The full length of the ZjCIGR1 (Zj; Zoysia japonica Steud.) gene was obtained by 5′/3′ RACE PCR and the phylogenetic tree showed that it belonged to the CIGR1-subgroup in the PAT1-group of GRAS protein family. Expression of the ZjCIGR1 in wild-type plants was confirmed in roots, meristems, leaves, and flowers, especially high in the flowers. The transgenic zoysiagrass was confirmed by PCR using gene-specific primers, phosphinothricin-acetyl-transferase (PAT) strip test, and Southern blot analysis. ZjCIGR1-overexpressing plants acquired tolerance to cold stress displaying morphological phenotypes characteristic of stress resistance. In addition, in the transformants, expression of the ZjCIGR1 as well as cold-regulated (COR) gene was increased compared to the wild-type plants under cold stress condition. These results suggest that ZjCIGR1 gene is an important candidate for regulating cold stress resistance.