Dr. Mona Mapar initiated her research collaboration with ABRII in September, 2019 on Genetic and Molecular Analysis of Trichome and Root Hair Development in Arabis Alpina.

Dr. Mapar presented her research outcome for scientific members and students of ABRII as follows: evolutionary developmental (Evo-Devo) approaches are commonly used to compare homologous processes in closely related species. In this study, we use Arabis alpina, as a second model system of Brassicaceae to study trichome and root hair development and compare it to Arabidopsis thaliana. It has been shown previously that trichome and root hair pattern in A. alpina is different from A. thaliana. In Arabidopsis, trichomes are regularly spaced on the surface of the leaf and root hairs are found in single cell files (H-files) adjacent to the non-hair files (N-files). Arabis leaves are densely covered with small and big trichomes, and roots produce ectopic hairs in N file (Chopra et al. 2014). To understand the genetic basis of trihchome and root hair development in A. alpina, two EMS populations were screened. Mutants with defects in trichome (Chopra 2015, PhD thesis) and root hair patterning and morphology were selected. Screen results in A. alpina show a similar range of mutant phenotypes as known in A. thaliana. Mutants were then sequenced for candidate genes to find the specific mutant alleles in A. alpina. Mutations in Arabis TTG1 (Chopra et al. 2014) and TRY (Chopra 2015, PhD thesis) lead to the same phenotypes as expected from A. thaliana. However, Aagl3 mutants showed glabrous leaf and hairy root phenotype similar as the gl3 egl3 double mutant in A. thaliana. Moreover, overexpression of AaGL3 in A.alpina resulted in reduced number of trichomes; indicating an evolutionary change of the GL3 function. Similarly, Arabis GL2 function appears to be changed as it functions only in a subset of trichomes. I also present the identification of morphogenesis mutants affecting root hair development. Aakjk, Aacow1, Aascn1, Aaark1 and Aaspi are identified root hair mutants affecting root hair formation in A. alpina. Several morphology mutant alleles showing amino acid exchanges have been also identified.