Kali komarovii (Amaranthaceae) is a xero-halophyte with facultative NADP-ME subtype of С4 photosynthesis

- Intermediate NADP-ME/NAD-ME C4 photosynthesis in sea coastal species is supposed.
- Rebuilding in leaf anatomy promotes the adaptation to cold and wet conditions.
- Photosynthetic plasticity allows species of sect. Kali to expand their range.

Kali komarovii is a representative of C4 NADP-ME annual species of sect. Kali (subfam. Salsoloideae of fam. Amaranthaceae). This species is genetically close (Ney's distance is 0.16-0.17) to K. paulsenii and K. tragus, which are similar species of this section of the Central Asian desert flora. The difference is that K. komarovii inhabits Japanese Sea coasts and occurs at 9000-10,000 km away from Central Asia. Comparative analysis of K. komarovii and arid NADP-ME xero-halophytes (K. paulsenii, K. tragus) and NAD-ME halophytes (Caroxylon incanescens, Climacoptera lanata) was carried out using anatomical, physiological and population genetic methods aimed to reveal structural and functional rearrangements, which provide the adaptation of NADP-ME species to saline, wet and cool conditions of sea coasts. The analysis of changes in Na+ and K+ accumulations, the Na+/K+ ratio, water content and quantitative parameters of photosynthetic apparatus in K. komarovii showed less expressed NADP-ME, but more expressed NAD-ME features. A unique characteristic of K. komarovii is the formation of specific structural-functional subtype C4 photosynthesis related to adaptation to low temperatures, which differs from desert ancient NAD-ME subtype. Thus K. komarovii is identified as a species with a facultative NADP-ME or intermediate NADP-ME − NAD-ME subtype C4 photosynthesis based on anatomical, biochemical and genetic characteristics.