Changes Of Microtubule In Leaf Abscission Signaling, Revealed By Analysis With An In Vitro Abscission System In Cotton(Gossypium Hirsutum L.)

Study of the mechanism of abseission has great value in agronomy and industry of natural of plant remnant bodies.Microtubule organization and biogenesis is important to cell growth, division, and the stress response.Some indirect evidence supported a possible link between microtubules and abscission.Nevertheless, the possibility has not been proved directly.To demonstrated that microtubules is involved in the abscission process. We carry out positive APM treatment and reverse Paclitaxe treatment.The results showed that:In vitro, in the leaf functional period, microtubules in sclerenchyma of petioles non-AZ were generally oriented to the oblique hypocotyl growth axis. But, the arrangement of microtubules in sclerenchyma of petioles AZ is complicated and variable. In some cells, microtubule microtubules were generally oriented to the oblique hypocotyl growth axis. In other cells, the arrangement of microtubules is random. Preliminary experimental results indicate that the arrangement of microtubules in sclerenchyma of petioles non-AZ changed during the early stage of abscission, which is Obliquearrays to longitudinalcortieal, then to Obliquearrays. But in this process, microtubules in sclerenchyma of petioles AZ was depolymerized, initially, and then repolymerized.In vitro, treatment of the whole petiole segments with amiprophos-methyl promoted abscission;Only treatment of non-AZ of the petiole segments with amiprophos-methyl, didn’t promote abscission. The results suggest that a possible positive link between microtubule depolymerization in sclerenchyma of petioles AZ rather than non-AZ and abscission. In vitro, treatment of the whole petiole segments with Paclitaxe delayed off abscission; only treatment of non-AZ of the petiole segments with Paclitaxe, didn’t delayed off abscission. The results suggest that a possible negative link between Microtubule stability in sclerenchyma of petioles AZ rather than non-AZ and abscission.Defoliant treatment experiments were performed in planta. Experimental results indicate that the arrangement of microtubules in sclerenchyma of petioles non-AZ changed during the early stage of abscission, which is obliquearrays to longitudinalcortieal, then to obliquearrays. But in this process, microtubules in sclerenchyma of petioles AZ was depolymerized, initially, and then repolymerized. In brief, microtubules in sclerenchyma of petioles non-AZ and AZ both changed during the early stage of abscission. Variation trends of microtubules in sclerenchyma of petioles non-AZ and AZ during the early stage of abscission in planta are similar to that of in vitro.These results demonstrate that microtubule in sclerenchyma of petioles AZ rather than non-AZ has roles in leaf abscission both in vitro and in planta.