Genome-wide characterization and expression profiling of the MAPKKK genes in Gossypium arboreum L

Molecular characterization, expression and interaction of MAPK, MAPKK and MAPKKK genes in upland cotton

Mitogen-activated protein kinase (MAPK) signaling cascades, consisting of three types of sequentially phosphorylated kinases (MAPKKK, MAPKK, and MAPK), play vital roles in various processes including plant development and stress response. In this study, 52 GhMAPKs, 23 GhMAPKKs, and 166 GhMAPKKKs were identified in upland cotton. Chromosomal locations, gene duplication and structure, motifs, cis-regulatory elements, and protein subcellular localization were further analyzed. With the identified MAPK cascade genes in G. arboretum and G. raimondii, a syntenic diagram of three cotton species was constructed. The interactions of seven GhMAPK cascade genes were investigated. Two complete signaling modules were defined: The GhMEKK24/GhMEKK31-GhMAPKK9-GhMAPK10 and GhMEKK3/GhMEKK24/GhMEKK31-GhMAPKK16-GhMAPK10/GhMAPK11 cascades. Moreover, interaction networks and the interaction pairs were combined with their expression patterns and demonstrated that the network mediated by the MAPK signaling cascade participates in abiotic stress signaling. Our research provides a foundation for studying the molecular mechanism of the MAPK signaling pathway under abiotic stress.

Extent of Bollworm and Sucking Pest Damage on Modern and Traditional Cotton Species and Potential for Breeding in Organic Cotton

Resistance against cotton bollworm is one of the main arguments for the use of genetically modified (GM) Bt cotton around the globe. The use of GM is prohibited in organic systems and thus the remunerative value of organic cotton cultivation depends on effective bollworm control. In this study, we investigated the extent of bollworm and sucking pest damage in 68 different hybrid and varietal lines of Gossypium hirsutum and varietal lines of G. arboreum at two different locations with contrasting soil fertility and water dynamics. The damage potential of bollworms was assessed from open capsules at two time points. Sucking pests were assessed at three time points using a scoring method. G. arboreum varietal lines and G. hirsutum hybrids were on average significantly more tolerant than G. hirsutum varietal lines to bollworm under fertile and irrigated situations. For sucking pests, the G. arboreum varietal lines were clearly more tolerant than G. hirsutum hybrids and varietal lines. Since, recently, pink bollworm (Pectinophora gossypiella) became resistant against Bt cotton and pressure of sucking pests severely increased, screening of genetic resources and systems-based cotton breeding for bollworm and sucking pest tolerance will improve sustainability of organic and conventional cotton production.