当前位置： SCI文献检索 > PLANT PHYSIOLOGY期刊下所有文献 > Photosynthesis, Rubisco Activity and Amount, and Their Regulation by Transcription in Senescing Soybean Leaves.

Photosynthesis, Rubisco Activity and Amount, and Their Regulation by Transcription in Senescing Soybean Leaves.

Abstract：

:Senescence is a phase of leaf ontogeny marked by declining photosynthetic activity that, in soybean (Glycine max [L.] Merr.), is paralleled by a decline in chloroplast function. Soybean leaves have different patterns of decline in photosynthetic capacity and chloroplast function associated with nodal position and sink activity. The objective of this work was to determine whether leaves from nodes 3 and 6 of soybean, which show these different patterns, are similarly regulated with respect to ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity and content and also to ascertain the degree of regulation of Rubisco content by transcription. Leaves from nodes 3 and 6 of field-grown soybean plants were sampled periodically from the time of their unfolding until near death. In situ CO2-exchange rate (CER) increased to a maximal level in both leaves and then declined slowly. For node 3 leaves the decline was progressive, but for node 6 leaves the decline was arrested at about 75% of maximum CER for a period of about 20 d, coincident with the onset of rapid seed growth, before a short period of very rapid decline immediately preceding leaf death. Rubisco activities and Rubisco content were directly correlated with CER in the leaves exhibiting the two different patterns. Rubisco activation ratio was similar for the two leaves and did not change throughout development. The primary regulator of photosynthesis at the physiological level, thus, was the amount of Rubisco protein. Decreases in Rubisco holoenzyme during senescence of both leaves were accompanied by coordinate decreases in the levels of mRNAs for the small and large subunits of Rubisco, suggesting that the decrease in Rubisco enzyme amounts during soybean leaf senescence is due to slower transcription rates and that levels of these mRNAs are coordinately controlled during senescence as they are during chloroplast development. However, plastid DNA template availability and posttranscriptional controls may also influence Rubisco content during senescence of these leaves. We conclude that soybean leaf photosynthesis likely unfolds according to a single developmental program but that modifications can be superimposed upon this program to maximize photosynthetic rates.

journal_name

Plant Physiol

journal_title

Plant physiology

authors

Jiang CZ,Rodermel SR,Shibles RM

doi

10.1104/pp.101.1.105

subject

Has Abstract

pub_date

1993-01-01 00:00:00

pages

105-112

issue

eissn

0032-0889

issn

1532-2548

pii

101/1/105

journal_volume

101

pub_type

杂志文章

在线工具

Photosynthesis, Rubisco Activity and Amount, and Their Regulation by Transcription in Senescing Soybean Leaves.