TIP1 is required for both tip growth and non-tip growth in Arabidopsis

TIP1 is a gene defined by an X-ray induced allele tip1-2 and a previously described EMS-induced allele tip1-1. TIP1 is involved in plant cell growth. tip1-2 plants display growth defects throughout the plant and exhibit defects in both root-hair and pollen-tube growth. tip1-2 plants are partly male sterile resulting from a combination of pollen germination and pollen-tube defects; their root-hairs are short, exhibit a tendency to branch and 24 hairs can initiate from each hair cell. They are also slightly dwarf in stature as a result of a general decrease in celt growth indicating that TIP1 activity is required for general cell growth. We propose a role for TIP in both the initiation and maintenance of growth in tip-growing cells. In addition TIP1 activity is required for normal cell expansion (non-tip cell growth) indicating that TIP1 is not exclusively involved in tip-growth.