Mutant/mutation
The mutant lacks expression of thioredoxin peroxidase 1 (TPx-1, typical 2-Cys peroxiredoxin).

Protein (function)
Peroxiredoxins (Prxs) constitute a family of proteins structurally homologous to the thiol-specific antioxidant of yeast. There are three subtypes of Prxs, 1-Cys Prx, typical 2-Cys Prx, and atypical 2-Cys Prx. 2-Cys Prxs have been found to act as a terminal peroxidase that reduces hydrogen peroxide and organic hydroperoxides with the use of electrons donated by the thioredoxin (Trx) system. Plasmodium contains 1-Cys Prx and two typical 2-Cys Prxs; TPx-1 (cytosolic) and TPx-2 (mitochondrial); see also 'Additional information').

Phenotype
The phenotype analyses are described in three/four (!!) papers (see references, PMID numbers above and reference given below). These analyses indicate that TPx-1 is not essential for parasite development during blood stage development, mosquito development and development in the liver. The analyses indicate that the lack of expression of TPx-1 has an (slight) effect on gametocyte production, oocyst development, sporozoite infectivity and development of liver stages. Evidence is presented for a slightly reduced liver stage development.

See also the paper: Turturice BA et al., 2013 PloS Pathogen 9(1): e1003136. In this paper they analysed 1-Cys Prx (PBANKA_122800) expression in the TPx-1 knock-out parasites.

Additional information
The effect on gametocyte production, as described in the first paper, has been determined in vivo in asynchronous infections in mice. No detailed information is further provided on the effect on gametocytes or on fertilisation and ookinete development/production. In the second paper, mice are used to infect mosquitoes that have 'high' numbers of gametocytes. Electron microscope analysis of mature oocysts showed damaged oocysts with 'irregular sporogonic development'. No quantitative data is provided on the damaged oocysts.
 
In most eukaryotic organisms, redox-active enzymes, such as catalase, superoxide dismutase, and peroxidases as well as an enzymatic cascade that generates reduced electron donors, i.e. glutathione (GSH) and thioredoxin (Trx), sustain the cellular redox homeostasis. This redox network is split into two major arms, the GSH and the Trx system, that serve complementary functions in antioxidant defence and DNA synthesis. The malarial parasite Plasmodium lacks two central antioxidant enzymes: (i) catalase that typically detoxifies hydrogen peroxide and (ii) a classical glutathione peroxidase, a selenoenyzme that reduces lipid hydroperoxides to their alcohols. This apparent deficiency  underscores the possible central importance of the thioredoxin system in the parasite. 

See also mutant RMgm-791 which lacks expression of the 2-Cys peroxiredoxin, thioredoxin peroxidase 2 (TPx-2)

Other mutants
RMgm-791: A mutant lacking expression of thioredoxin peroxidase 2 (TPx-2)
RMgm-586: A mutant lacking expression of thioredoxin reductase (TrxR)