Clonal variation in apical growth and content in vegetative storage proteins in Populus

Abstract

Summary.Apical shoot growth and storage protein content in various poplar species and clones were followed in trees growing in the field and in micropropagated plants cultivated in the growth chamber under a controlled environment. In autumn a 32 kD and a 36 kD vegetative storage protein accumulate in wood, bark and roots of poplar and comprise together about 25% of the soluble proteins. In spring, at the time of dormancy break, the storage proteins are degraded and 3 weeks after budburst these proteins are no longer immunologically detectable. As in autumn, short day exposure of black cottonwood plants (Populus trichocarpa Torr. and Gray) induces cessation of apical growth and accumulation of the 32 kD and 36 kD vegetative storage proteins in all clones studied. In order to simulate spring conditions, short day induced plants were transferred back to long days. Like the situation in spring, budburst and storage protein degradation occurred considerably earlier in clone 9/60 than in clone Muhle Larsen. The latter clone accumulates both in winter and after short day exposure more storage proteins than the former. Furthermore two P. trichocarpa clones differ qualitatively in storage protein content: they possess an additional 34 kD polypeptide which cross-reacts with the anti-32 kD antibody. In conclusion, apical shoot growth and the capacity to synthesize storage proteins can be easily followed in micropropagated poplar cultivated in the growth chamber under inducing photoperiods. This offers the major advantage of independence from the annual growth cycle. Within one species considerable clonal variance in storage protein content and in the induction times needed for dormancy and dormancy break were observed. The suitability of storage protein content and apical growth as early selection traits in breeding programs focusing on nitrogen efficient poplar and clones adapted to specific latitudes will be discussed.

Seasonal dynamics and effects of nitrogen supply rate on nitrogen and carbohydrate reserves in cutting-derived Salix viminalis plants

“…Sauter et al (1989) measured 10-25 mg protein·g -1 DM in autumnal roots and slightly higher levels in branches of Populus ×canadensis Moench. Langheinrich (1993) referred to unpublished data showing that storage proteins accumulated in the bark of older poplar roots. In fruit trees, roots differ from aerial parts by storing N primarily as amino acids (Tromp 1983), which is in agreement with our results for Salix.…”

Source and sink mechanisms of nitrogen transport and use

“…Vegetative storage proteins (VSPs) are specifically dedicated to N storage in vegetative tissues. VSPs have been mainly described in legumes, but they exist in all plant species (Langheinrich, ; Berger et al ., ; Liu et al ., ), where they accumulate under stress conditions when plant growth slows down (Avice et al ., ; Lee et al ., ). VSPs possess high sequence homology with pathogenesis‐related proteins such as abscisic acid and jasmonic acid‐responsive proteins (Staswick, ; Berger et al ., ; Avice et al ., ) suggesting an additional role of VSPs in plant adaption to abiotic or biotic stresses (Liu et al ., ; Lee et al ., ).…”

Nitrogen storage and seasonal nitrogen cycling in Populus: bridging molecular physiology and ecophysiology

“…The timing of spring BSP mobilization has been correlated with budburst phenology in Populus (Langheinrich, 1993). Black et al .…”