Mutant/mutation
The mutant lacks expression of AP2-SP2 and expresses GFP-luciferase under control of the constitutive eef1a promoter

Protein (function)
Most sequence-specific transcription factor families found in other eukaryotes seem to be absent from Plasmodium. Instead, an expansion of a protein family containing one or more apetala2 (AP2) DNA-binding domains was observed across the phylum apicomplexa. In total, 27 members of this family have been found in the human malaria parasite Plasmodium falciparum (although a possible 28th member of the family may be present. In total, 26 of these have syntenic orthologs in rodent malaria species, each with its unique stage-specific expression profile.
The paper presents a systematic knockout (KO) screen targeting the ApiAP2 family in the rodent malaria parasite P. berghei. Phenotyping of eleven viable ApiAP2 KO mutants reveals ten critical gene functions at different points in the life cycle.

From the paper: To target P. berghei ApiAP2 genes systematically, we succeeded in producing deletion vectors for all but one member of the family (PBANKA_1313200) and transfected each of them into a reporter line constitutively expressing GFP to facilitate phenotyping. Fourteen ApiAP2 genes resisted at least four disruption attempts with up to two different vector designs, providing tentative evidence that more than half of the genes in this family are potentially essential for asexual blood stage growth in vivo. For the remaining eleven, a KO line could be generated. These included six genes that had not previously been studied in Plasmodium.

Phenotype
Normal numbers of oocysts with a size comparable to wild type oocysts. Oocyst development was blocked at the sporoblast stage. The oocysts ceased to mature at a point when sporozoites were beginning to form around the edges of cytoplasmic islands and remained arrested at this point until at least day 22 post-infection. No salivary gland sporozoites.

Additional information

From the paper:

Other mutants
See ApiAP2