In the event of getting a hybrid lacking a stigma I could still use the hybrid as the male parent for generation F[SUB]2[/SUB], by using its pollen, as it is the female part that is sterile in this scenario. I think you might be right that they stumbled upon this non-self-fertile cross unanticipated. Then again, talk of this sterile cross is
before the section where they state that "to this point, only events occurring in self-pollinated species have been considered here". That leads me to think it was a
N. tabacum x
N. tabacum cross. I can not be sure.
But let's take a leap here and assume that perhaps this is exactly what occurs with hybrids of
N. rustica x
N. tabacum. We know that there there are reported cases of people growing a hybrid that is not self-fertile. If that is indeed caused by the stigma not being present, you could indeed use the cross as the male parent for next the next generation, as I was suggesting above. It seems as if the limited possibilities may steer you in that direction.
If that is what happens to the
N. rustica x
N. tabacum cross, it would be interesting to consider the reciprocal. Although it's close to impossible to make one in a natural way, let's consider that one might, by finding a
N. tabacum variety with a relatively short stylus. Would the same thing happen? Would it also be self-sterile? Would there not be a stigma?
Interestingly this article was written at the University of Nijmegen, 35 km from where I grew up. Maybe I should have been looking for this stuff closer to home. Anyway...
So a few more things taken from this article. Happy to see you post it China. It says that "tobacco pollen tubes, for instance, [FONT="]take ∼26 to 30 h to reach the ovary, at a distance of 4 cm from the stigma. This makes the speed of pollen tube growth ∼1.7 mm/h." [/FONT]I thought it'd be interesting to compare with the research in the article I posted previously, the ne called
The diversity of interspecific pollen-pistil incongruity in Nicotiana. There we see in Fig. 4 that the pollen of self-fertilising
N. tabacum grows 36 mm in 24 hours. This is a speed of [FONT="]∼1.5 mm/h, which is not to dissimilar from what ChinaVoodoo's article says.
[/FONT]I was pleasantly surprised to find that the current article actually refers to the one I posted earlier, which I mentioned just now. Actually, it completely summarizes it. When we go to the heading of Interspecies Pollen Rejection, we read the following:
[FONT="]An interesting study of incongruity was performed by Kuboyama et al. (1994)[/FONT][FONT="]. They used the SC tobacco as the female parent in distinct crosses with three other SC species, [/FONT]N. repanda[FONT="], [/FONT]N. rustica[FONT="], and [/FONT]N. trygonofilla[FONT="]. Pollen tubes of these latter species arrested in three different places in the mature pistils of tobacco. Figure 3 [/FONT][FONT="]shows pollen tubes of [/FONT]N. rustica[FONT="] arrested halfway in the style of tobacco at ∼20 h after pollination. Pollen tubes also curl and wind and in some cases bend back toward the stigma (A.M. Sanchez and C. Mariani, unpublished results). In the reciprocal cross, using [/FONT]N. rustica[FONT="] as the female parent, tobacco pollen tubes easily reach the ovary. Interestingly, when the three types of incongruous pollinations were performed on immature tobacco pistils, all pollen tubes reached the ovary (Kuboyama et al., 1994[/FONT][FONT="]). This finding suggests that, if the arresting factor is determined by the pistil, it is most likely produced during pistil maturation. It could be argued that the arrest of pollen tubes is caused by the longer distance they have to grow in the tobacco pistil compared with their own pistil (i.e., 3.6-cm tobacco style versus 1-cm [/FONT]N. rustica[FONT="] style). We used [/FONT]N. rustica[FONT="] pollen on the pistil of [/FONT]N. sylvestris[FONT="] and the tubes grew 3.2 cm, which is approximately the length of the tobacco style (A.M. Sanchez and C. Mariani, unpublished results). This finding indicates that [/FONT]N. rustica[FONT="] pollen tubes are capable of growing longer than the length of their own styles.[/FONT]
They interpret the results of the Japanese and Korean researches pretty much the same way as I did a couple of posts before. I should be using very young female pistils. But so far no-one has mentioned looking for
N. tabacum varieties with short pistils. I have to thank Bob for that one.