KNOX2 Genes Regulate the Haploid-to-Diploid Morphological Transition in Land Plants
2013
Sakakibara, Keiko | Ando, Sayuri | Yip, Hoichong Karen | Tamada, Yosuke | Hiwatashi, Yuji | Murata, Takashi | Deguchi, Hironori | Hasebe, Mitsuyasu | Bowman, John L.
A Mossy Veil Land plants have two distinct generations: a haploid gametophyte responsible for producing the gametes, and a diploid sporophyte, that in most land plants is the dominant form observed. However, in mosses, a basal land plant, the primary biomass is composed of the haploid gametophyte. Sakakibara et al. (p. 1067; see the Perspective by Friedman) analyzed loss-of-function mutants of KNOX2 (class 2 KNOTTED1-LIKE HOMEOBOX) genes in the moss Physcomitrella patens. Mutant plants exhibit apospory, where fertilization apparently occurs, but the normal sporophyte phase is bypassed and instead a diploid structure resembling a haploid gametophyte is produced. The results suggest that KNOX2 regulates the alternation of generations by suppressing the haploid body plan in the diploid phase.
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