Screening, Identification And Primary Analysis On Physiological Characteristics Of Two Novel SDD1 Alleles In Arabidopsis Thaliana

Stomata are specialized cellular structures in the epidermis of aerial plant which control gas exchange (H₂O release and CO₂ uptake) between leaves and the atmosphere by modulating the aperture of a pore flanked by two guard cells. They are nonrandomly distributed, and their density is controlled by endogenous and environmental factors.SDD1 is a crucial gene regulating Stomatal development, which encodes a subtilisin-like serine protease. Here, we isolated two mutants (e281 and g204) with altered Stomatal characteristic by treating the seeds with EMS. They both exhibit about 1.5 times increase of Stomatal density and formation of clustered stomata, whereas the internal leaf architecture is not altered. Genetic analysis and sequencing results confirm that e281 and g204 are two novel SDD1 alleles, the mutation of which result in the amino acid changes of catalytic triade and the substrate binding site, respectively. Moreover, morphological and physiological data (such as water loss of leaves being detached, the response of stomata to exogenous ABA) indicate that mutation of different sites within the SDD1 gene lead to different biological effects. The antagonism among SDD1 alleles can be a negative effect of the gene transvection.We also identified a Stomatal and epidermal cell mutant: G39, which is dwarf and lacks the apical dominance. The number and length of lobe decreases apparently in the epidermal cells, while its Stomatal density and index are lower than Col. In addition, the microspore development of G39 is inhibited, leading to its shape becoming irregular. The number of normal pollen grain is significantly less than Col. There are some abnormal phenomenon during the anther chamber development, such as its degradation and deformation. In the G39 mutant, cell vertical height in stem is about 2/3 times as much as that of Col, but there is no change in cell division.