Kaempferia galangal, belonging to the ginger family, is an important plant widely used as a traditional spice and medicine in Asia. Recent cytological studies show that Kaempferia has various ploidy levels. K. galanga var. latifolia, a variety of K. galanga, is morphologically different from K. galanga var. galanga by the suborbicular leaves with short petiole and leaves laying on the ground. However, some species ploidy level remains unexplored.

In a study published in Scientia Horticulturae, researchers from the Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences have systematically analyzed the differences between K. galanga var. galanga and K. galanga var. latifolia using cytology, morphological comparisons of leaves, stomata, flowers, and active compounds. 

The researchers used flow cytometry to measure cell types (cytotypes) and found that K. galanga var. latifolia is tetraploid while K. galanga var. galanga is pentaploid. Leaves of tetraploid Kaempferia galanga var. latifolia are wider compared with pentaploid Kaempferia galanga var. galanga. 

Comparative analyses of morphological characters showed that polyploidization significantly affected some traits; tetraploid individuals had wider leaves, and pentaploid individuals displayed a higher stomatal density, wider lateral staminodes, longer bracteoles, and bracts. 

The results confirmed that the morphological differences are explained by the different cytotypes. Pentaploids had bigger flowers, higher stomatal density, and higher (E)-Ethyl-p-methoxycinnamate content in rhizomes than the tetraploids. Kaempferia has multiple ploidy levels from 2x, 3x, 4x, to 5x. 

"We believe that this study will help explain more unknown biological phenomena including more species and varieties and provide a reference for spice crops breeding," said XU Youkai of XTBG. 

Kaempferia galanga var. galanga. (Image by LU Jianmei)

Kaempferia galanga var. galanga. (Image by LU Jianmei)

Kaempferia galanga var. latifolia. (Image by LU Jianmei)

Kaempferia galanga var. latifolia. (Image by LU Jianmei)