Genomic factors responsible for abnormal morphology of pollen tubes in theinterspecific cross Nicotiana tabacum x N-rustica

Nicotiana tabacum shows unilateral pollen-pistil incongruity with N. rustic a. If N. tabacum is pollinated with N. rustica, growth of the pollen tube i s arrested in the middle of the style, and abundant callose deposition, tub e swelling and tube winding are observed. An attempt was made to clarify th e genomic factors responsible for this pollen-pistil incongruity. N. tabacu m was pollinated with hi paniculata or N. undulata, progenitors of amphidip loid N. rustica. When pollinated with N. undulata, growth of the pollen tub e was arrested in the middle of the style and showed abnormal morphology si milar to that with N. rustica, but when pollinated with N. paniculata the p ollen tube reached near the base of the style and was almost normal in appe arance. These observations suggest that the factors responsible for the pol len tube abnormality of N. rustica are derived from the N. undulata genome. We also used N. sylvestris, N. glutinosa and N. otophora as pistilar paren ts and N. rustica or its progenitors as pollen parents to examine the genom ic factors of the pistilate parents. The pollen tube features of these thre e species in the Distils of N. sylvestris were similar to those in the pist il of N. tabacum.